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Pavelis, George A., Ed.Farm Drainage in the United States. History, Status,and Prospects. Miscellaneous Publication Number1455.Economic Research Service (DOA), Washington, D.C.Dec 87186p.; Photographs may not reproduce clearly.Superintendent of Documents, U.S. Government PrintingOffice, Washington, DC 20402.Collected Works - General (020) -- Books (010)

MF01/PC08 Plus Postage.Agricultural Engineering; Agricultural Production;*Agriculture; Agronomy; Depleted Resources! Ecology;Estuaries; *Farm Management; *Land Use; NaturalResources; *Soil Conservation; *Soil Science;*Water*Drainage

ABSTRACTThis publication covers the historical,

technological, economic, and environmental aspects of agriculturaldrainage. It draws from the combined knowledge of academic and U.S.Department of Agriculture professionals in public policy, drainagetheory, planning, engineering, environmental science, and economics.The main purpose is to review the evolution of modern farm drainageand to identify farm drainage objectives for agricultural extensionspecialists and agents, environmental specialists, drainageconsultants, installation contractors, and educators. Chaptersinclude "A Framework for Future Farm Drainage Policy" (Smith,Massey); "A History of Drainage and Drainage Methods" (Beauchamp);"Advances in Drainage Technology: 1955-85" (Fouss, Reeve); "Purposesand Benefits of Drainage" (Fausey et al.); "Preserving Environmental.Values" (Thomas); "Principles of Drainage" (Skaggs); "Drainage SystemElements" (Ochs et al.); "Planning Farm and Project Drainage"(Hodges, Christensen); "Drainage for Irrigation" (Hoffman, vanSchilfgaarde); "Drainage Institutions" (Sandretto); "Economic Surveyof Farm Drainage" (Pavelis); "Drainage Potential and InformationNeeds" (Daugherty, Lewis); and "Drainage Challenges andOpportunities" (Swader, Pavelis). (KC)

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Farm Drainage in the United States: History, Status, and Prospects.Edited by George A. Pave lis. Economic Research Service, U.S. Depart.ment of Agriculture. Miscellaneous Publication No. 1455.

Abstract

This publication covers the historical, technological, economic, and environ-mental aspects of cgricultural drainage. It draws from the combinedknowledge of academic and U.S. Department of Agriculture professionals inpublic policy, drainage theory, planning, engineering, environmental science,and economics. The main purpose is to review the evolution of modern farmdrainage and to identify farm drainage objectives for agricultural extensionspecialists and agents, environmental specialists, drainage consultants, in-stallation contractors, and educators. Farm production, water management,and other benefits and costs associated with the drainage of wet soils onfarms are described within the context of existing USDA programs andother Federal policies for protecting wetlands.

Keywords: Soil and water management, irrigation, drainage development,drainage benefits, environmental improvement, drainagedistricts, drainage models, drainage planning.

Cooperators

Agricultural Research ServiceCooperative State Research ServiceEconomic Research ServiceExtension ServiceSoil Conservation ServiceCornell UniversityNorth Carolina State UniversityOhio State UniversityUtah State UniversityUniversity of Wisconsin-Madison

This bulletin was processed in the Information Division, Economics ManagementStaff, USDA, by Jim Carlin, editorial assistance, and Susan Yanero, graphics.

Washington, DC 20005-4788 December 1987

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Foreword

The U.S. Department of Agriculture (USDA) is pleased to release thiscooperative publication on farm drainage, primarily as a general i formationdocument. Several factors prompted its preparation: (1) wide recognition ofthe public policy connections between the economic and environmentalaspects of drainage, accentuated-most recently by stringent wetland protec-tion provisions in the Food Security Act of 1985; (2) a drainage technologystill undergoing important changes; and (3) the uncertain status of informa-tion collection activities on drainage, particularly at the Federal level.

The most recent rapid developmental era for :?linage reclamation drew toa close about 1965. Drainage is the most extensive soil and water manage-ment activity in agriculture. Approximately 110 million acres of the landwithin farms are artificially drained in the United States. About 9 millionacres, or 25 percent, of the irrigated cropland in the Western States areartificially drained.

Drainage can also have adverse effects in some situations by reducing ordegrading wetlands vital to wildlife and serving hydrologic functions such asflood flow regulation. Drainage activities can also affect the quality of waterbodies receiving drainage water.

Drainage investigations in USDA began with the Reclamation Act of 1902.This act is best known as creating the Bureau of Reclamation in the Depart-ment of the Interior. A drainage unit to service irrigation project planningwas simultaneously authorized for USDA. In 1962, Public Law 87-732, theDrainage Referral Act, was enacted which prohibited USDA from assistinglandowners in draining potholes and marshes in Minnesota and the Dakotasif wildlife would be materially harmed.

Currently, USDA technical and financial assistance is no longer provided asa matter of policy except in unique circumstances as part of a conservationsystem related to irrigation water control, or as an essential element of anenvironmental system of practices. Thus, for USDA, this publicationrepresents an end to the era of strong USDA support and assistance fordrainage development activities.

Under USDA's Water Bank Program, begun in 1970 under the authority ofPublic Law 91-559, wetlands along major migratory waterfowl flyways canbe protected from agricultural use or drainage development by 10-yearrental agreements with eligible owners or operators. As of 1987, about8,000 agreements covering 870,000 acres of wetlands or adjacent land hadbeen negotiated with farmers. Two-thirds of these agreements are still inforce. In USDA's Agricultural Conservation Program (ACP), financialassistance for farm drainage is prohibited by appropriation language unlessit is an essential element of an erosion control, water quality, or environ-mental system of practices. By the late 1970's, less than 4 percent of allcosts of installing or maintaining farm drainage systems came from ACPcost sharing or Farmers Home Administration loans. Cost sharing for limiteddrainage assistance as described above is now less than 1/20th of 1 percentof all ACP cost shares.

Since 1973, USDA's Soil Conservation Service has not provided technicalassistance for the drainage of specified wetlands. as defined by the Fish andWildlife Service of the Department of the Interior. Since 1975. the policy hasbeen broadened to include nearly all freshwater and saline-water areas.

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Drainage activities of USDA are subject also to the provisions of ExecutiveOrder 11990, issued in May 1977. Executive Order 11990 is intended to"avoid to the extent possible the long and short term adverse impactsassociated with the destruction or modification of wetlands and to avoiddirect or indirect support of new construction in wetlands whenever there isa practicable alternative." The Food Security Act, signed by PresidentReagan in December 1985, denies farm program benefits to producers whogrow annual crops on wetlands drained after December 1985.

It is within such laws and policies that USDA will assist in improvingdrainage on existing cropland through better design, construction, andmaintenance. For example, adequate drainage is sometimes necessary forsuccessful no-till conservation farming. Also, intensive irrigation, as practicedon a large scale in the Western States, requires continued attention todrainage to prevent rising water tables and damaging accumulations ofsoluble salts in soils, and in controlling chemicals or other harmful agentsin drainage waters.

This publication is the product of efforts by several USDA agencies andcooperating universities to consolidate up-to-date knowledge on farmdrainage. It draws from ".:e combined knowledge of specialists in publicpolicy, drainage science, planning, engineering, and economics (see appendixC). It is not highly technical or policy oriented, but reviews the history, pur-poses, social and economic implications, and modern methods of farmdrainage.

USDA greatly appreciates the assistance of the following academiccooperators:

Cornell University, College of Agriculture and Life Sciences, Depart-ment of Agricultural Economics.

North Carolina State University, College of Agriculture, Department ofAgricultural and Biological Engineering.

Ohio State University, Department of Agricultural Engineering.

Utah State University, College of Agriculture and Agricultural Experi-ment Station, Department of Agricultural and Irrigation Engineering.

University of Wisconsin-Madison, College of Agricultural and LifeSciences, School of Natural Resources.

Orville G. BentleyAssistant SecretaryScience and Education

George S. DunlopAssistant SecretaryNatural Resources

and Environment

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Ewen M. WilsonAssistant Secretary

for Economics

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Summary

Drainage, the practice of removing excess water from agricultural land, hasits origin at least 2,500 years ago when Herodotus wrote about drainageworks near the city of Memphis in Egypt. Today, drainage is practiced widely,being criticized severely by some and praised by others.

Without drainage, it is hard to imagine the U.S. Midwest as we know it inthe 20th century, the epitome of agricultural production. Much of Ohio,Indiana, Illinois, and Iowa originally was swamp, or at least too wet to farm.Aquatic plants, swarms of mosquitoes, and outbreaks of malaria and otherdiseases were common. Without drainage, irrigation development in theWestern United States would have failed through waterlogging and saline-tion, as is happening in some areas. Drainage was part of the "developmen-tal ethos," the drive to develop the land and make it productive.

Because of drainage, better than half the original wetlands in this countryare no more. In addition to impairing various hydrologic functions ofwetlands, drainage has drastically reduced the habitat for water-basedwildlife, and flyways for migrating birds have been severely affected. Insome States, as much as 95 percent of the wetlands have been converted.These conversions have affected the opportunities for hunters and recrea-tionists to enjoy their sport. Possibly more important, they have affected thenatural balance of nature and may well have endangered, or at least severelyrestricted, a number of species of birds and other wildlife.

Recently, evidence shows that not only the loss of wetland habitat is involved,but that drainage effluent can have severe adverse effects on water andland quality. High concentrations of toxic elements in California's KestersonReservoir have been attributed to agricultural drainage upslope. Thus the"environmental ethic" is at odds with the "developmental ethic." While thebenefits of drainage can be counted in terms of enhanced development andincreased economic activity, the cost to the environment may also be high.

This bulletin provides an overview of.agricultural drainage. Included are ahistorical perspective of drainage, a review of its practical purposes, anassessment of technological progress, some economic evaluations, a discus-sion of institutional mechanisms, and a consideration of environmentalvalues. Finally, an attempt is made to place these various components into achallenging perspective in relation to present and future needs.

Highlights

Controversy has frequently been associated with drainage. In the MiddleAges, the fens in England were drained to stabilize and increaseagricultural production. These actions were not appreciated by thefishermen and fowlers, who saw their livelihood threatened. Interest indrainage ebbed from the early years until the 19th century, when there wasrenewed activity in Europe and the United States. Early interest in theUnited States was not confined to development and enhanced agriculturalproduction, but also stressed human health aspects, as illustrated by thedraining of Central Park in New York City in 1858. In recent years, thesehealth benefits were taken for granted, or overlooked, in part because wenow operate at the margin: the great swamps and extensive breedinggrounds for mosquitoes have been eliminated.

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An important initial Federal milestone was the passage of the SwamplandActs of 1849 and 1850. These acts transferred federally held swamplands tothe States on condition that proceeds from their sale be invested in worksneeded to reclaim them. The Reclamation Act of 1902 illustrates anothermilestone in Government policy in that it signaled the intention of theFederal Government to become directly involved in land reclamation andassociated drainage enterprises.

The Flood Control Act of 1944 and the Federal Watershed Protection andFlood Prevention Act of 1954 broadened Government involvement indrainage activities. They were preceded by the work of the CivilianConservation Corps during the Depression and the technical or financialassistance programs of USDA's Soil Conservation Service (SCS) andAgricultural Stabilization and Conservation Service (ASCS). While ASCSfinancial assistance is no longer provided and technical assistance from SCSis restricted, these programs have played an important role in improved soiland water management on farms.

The pendulum has swung away from development in the last 20 years as abalance was sought between development, reclamation, and drainage on theone hand, and preservation of environmental values Jn the other. Thisbalance is illustrated by the National Environmental Policy Act of 1969, theClean Water Act as amended in 1977, and Executive Order 11990 issued byPresident Carter in 1977. The order instructs Federal agencies to avoidwhere possible the long- and short-term adverse effects of destroying ormodifying wetlands.

Further, new farm legislation, the Food Security Act of 1985 signed by Presi-dent Reagan in December 1985, denies price support and other farm pro-gram benefits to producers who grow crops on converted wetlands. Also,the elimination of investment tax credits and restrictions on expending farmconservation investments under the Tax Reform Act of 1986 are furtherdisincentives to bringing new lands into production through drainage.

Thus, current USDA programs are intended, within the limitations notedabove, to help landowners improve drainage on existing agricultural fieldswhere excessive wetness, waterlogging, or salinity hamper efficient produc-tion. It is USDA policy to preserve remaining wetlands and protect wildlifevalues wherever possible. Corrective measures are also required whereagricultural practices, including drainage, threaten offsite environmentalvalues.

Technology has evolved along with drainage policy. After centuries of hand-installed drainage systems, the introduction of the trenching machine andthe steam engine revolutionized the practice in the late 19th century.Another leap forward occurred in the 1960's with the introduction of cor-rugated plastic tubing installed with laser-beam controlled high-speedtrenchers or drain plows. In the late 1970's, there came into practice theapplication of drainage theory in the form of computerized design methodsand models. Thus, we have witnessed in the past 20 years a dramaticmodernization of drainage practices, with tie potential for cost reduction,better design, and advanced installation practices. The most recenttechnological change is the application of water management systems thatincorporate drainage, drainage restrictions, and subirrigation in onesophisticated operation to optimize soil water conditions for crop growth. Atthe same time, sufficient experimental data are available to make at leastapproximate assessments of the effect of drainage on crop yield, so that

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economic optimization procedures can be applied to develop "best"drainage system designs.

In making the decision whether and how to drain land, one must be awareof the benefits end drawbacks associated with the practice. The purpose ofdrainage varies v `!.1 the climate and the type of farming. In humid areas, itsdominant purpose is to remove excess soil water. This allows equipmentmovement into fields for timely farm operations, warms soils early in theseason, provides adequate aeration for root activity and crop growth,reduces diseases in livestock and crops, and reduces surface runoff. Thesebenefits in turn reduce erosion and surface waste pollution, especially byphosphates. The benefits include reduced risk in farming and highcr yieldsof better quality crops, thus tending to increase income as well as reduce itsvariability.

In arid regions where land is irrigated, the dominant purpose of drainage i3to remove salts from the root zone. Salts always accumulate in irrigatedfields unless drainage is present, ultimately causing severe salination andenvironmental degradation. "Ultimately" may be in a matter of a few years,or many decades.

Juxtaposed to the benefits are potential disbenefits. Nitrogen, from fertilizeror natural sources, may be leached out of the soil and contribute toeutrophication (a reduction in oxygen) in downstream water bodies. Somemobile pesticides may also be leached out. The leaching of salts fromirrigated lands to keep the lands productive may cause increased salt loadsdownstream. Primarily, the removal of wetlands by drainage changes thelandscape, alters hydrologic processes, and reduces habitat for waterfowland other wildlife.

Not recognized as a significant potential problem until recently was theleaching by drainage waters of trace elements in toxic concentrations fromnatural geologic formations. Unexpected high levels of selenium (andpossibly other elements, such as boron and molybdenum) were found in theearly 1980's in soils, waters, plants, and wildlife in the Kesterson Reservoir,an area used for dispodal of agricultural drainage water. Similar naturalresource problems related to irrigation drainage may be occurringelsewhere. The Department of the Interior is currently investigating 19 suchsituations in the Western States.

The planning and design of drainage systems require a thorough under-standing of the various components of such systems and their interaction.The primary components are the outlet, the collection system (including bothsurface and subsurface drains), and certain land treatment systems such asbedding or smoothing. The planning may involve one landowner or many andoften concerns agricultural interests as well as environmental groups. Goodplanning takes into account various environmental values as well as those ofagriculture, provides for flood protection if large projects are involved, andconsiders the economic impacts as well as the financial and politicalrealities of implementing the plan.

Because of the need for cooperation among landowners to provideappropriate outlets to dispose of drainage waters, a variety of drainageorganizations has been created under State laws. The most common of theseis the corporate drainage district. This is an organization with taxingpowers that constructs and maintains drainage outlets for the area itserves. In recent years, a number of States have enacted legislation permit-

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ting multiple-purpose districts, often called conservancy districts. Theirobjectives may include drainage but can go well beyond that to considernumerous other water and resource management objectives. Whereas in thepast, the activity of drainage districts often has been dominant in thedrainage field, of late more drainage is completed privately than throughdistrict organizations.

At what rate have drainage organizations and individual farmers improvedland by drainage and invested in drainage improvement? How does thisinvestment compare to the total capital investment in agriculture and whathave been the returns? Reliable information on these questions is hard toobtain. Combining whatever data could be gleaned from the Census ofDrainage and the Census of Agriculture from 1920 forward, with statisticsfrom USDA and other specialists, reveals the following picture.

As of 1985, an estimated 110 million acres of agricultural land in the UnitedStates benefited from artificial drainage. At least 70 percent of the drainedland is in crops, 12 percent in pasture, 16 percent in woodland, and 2 per-cent in miscellaneous uses. Although recent trends have been toward morefarm drainage systems, 60 percent of the area drained still depends onpublic outlets installed by counties or drainage and conservancy districts.

The average U.S. real cost of providing group drainage outlets was $225/acrein 1985, and has been essentially constant since 1915. The cost of providingsurface drainage has risen since 1965 (to $140/acre), while the cost of subsur-face drainage has dropped substantially (to $415/acre). These trends reflectthe impact of the new plastic materials for subsurface drains and more effi-cient trenching methods.

The capital value of all U.S. farm drainage work now in place is estimatedto be over $40 billion, based on replacement costs as of 1985. This includes$15 billion (36 percent) for public drains and $25 billion (64 percent) foronfarm systems. £owing for depreciation, the net capital value of all U.S.farm drainage work as of 1985 was estimate: to be near $25 billion$15billion (60 percent) for public drains and $10 billion (40 percent) for onfarmsystems.

Compared with the market value of all farm real estate in the United States($690 billion in 1985), drainage improvements represent between 4 and 6percent of the total (up to 7 percent if buildings are excluded). Percentagesfor highly drained States range considerably moreup to 30 percent inMichigan; 25 percent in Indiana and Ohio; 20 percent in Louisiana; 15 per-cent in Arkansas, Delaware, and Mississippi; and 10 percent in Florida,Iowa, Minnesota, and the two Carolinas. Details are in table 11-7.

The aggts.gate nature of available data makes it impossible to estimate theactual increase in value for all land that has been drained. However, byseparating economic statistics for counties with a relatively high incidencefrom those with a low incidence of drainage, one can show a substantial dif-ference in value of crops and livestock sold, and of land values, in favor of ahigh incidence of drainage. An analysis of 1982 Census of Agriculture dataindicates that real estate values per acre for 256 predominantly agriculturalcounties throughout the Eastern States with a high incidence of drainageaveraged 27 percent more than values in 1,422 other agricultural counties.This translates to an expected average capital benefit of about $270 perdrained acre in 1982. By 1985 the average benefit was down to $200 peracre, the result of generally declining agricultural land values. In 1986, theaverage expected benefit figure fell further, to about $175 per acre.

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It would be useful to-have continuing overall estimates of the increasedvalue of production associated with drainage, or of the returns on theinvestment, because the feasibility of drainage changes with costs, commodityprices, and other factors. While a general farm-level benefit/cost (B/C) ratiofor drainage in the East fell from 1.30 to 0.75 between 1982-86, the B/Cratios appeared to still exceed 1.0 in seven Eastern States: Arkansas,Missouri, Kentucky, Virginia, Missisippi, South Carolina, and Florida.

The technologies exist to make fairly precise B/C evaluations for specificfield situations, as illustrated in figure 6-10. Such "anecdotal" calculationsverify that the return on investment can be very high. It also is clear thatthe response is highly site specific. For example, the irrigated ImperialValley in California would be out of production for all practical purposeswere it not for intensive drainage. In other irrigated areas, natural drainagerates are high enough to require no artificial drainage at all.

To the extent statistics are available, it is clear that investment in drainagehas been substantial. It is equally clear that investment will continue. Firstof all, there will be an increasing need for repair, maintenance, andreplacement of existing systems. Second, there will be pressures for addi-tional drainage, either to control salinity in irrigated soils or to enhance pro-duction on presently cultivated land.

Perceptions about the status and trends of agricultural drainage are a func-tion of the extent and quality of available data. Existing information tends togive an incomplete picture. It is based on "unstable" data in the sense thatthe data collected at different times are based on different definitions andtechniques and thus tend to be unreliable, especially for comparisons overtime. Interest in drainage as such may be decreasing, but interest inwetlands, or their remnants, is increasing. A good data base is crucial to in-formed decisionmaking or policy development.

Future Trends and Prospects

What of the future? USDA's National Resources Inventory (NRI) of 1982 in-dicates that nearly 28 million acres of existing nonirrigated crops andpastures have drainage problems, of which 15-20 percent are also con-sidered wetlands. An added 12 million acres of rural land have at least amedium potential for drainage and conversion to crop production. Nearly 30percent of the potentially drained and converted acres are now wetlands.About 25 percent of the wetlands vulnerable to conversion are prime water-fowl habitat. Thus, the pressure for drainage to expand agriculture tends tobe for lands generally not considered of prime value to waterfowl, althoughother environmental benefits may also be sacrificed. There are definiterestrictions, and no national need to expand the cultivated land basethrough drainage.

Unless economic conditions change drastically, it is expected that drainageactivity will be concentrated at the "intensive margin" rather than the "ex-tensive margin." Landowners will strive to improve production efficiency byraising production per acre and product quality. This will place greaterdemands on intensive drainage on currently cultivated lands. In the samevein, there is likely to be more emphasis on repair and maintenance ofexisting systems, and on replacement of deteriorating systems, activities notusually in conflict with the environment, wildlife, or other interests.

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There is a growing realization that drainage is simply a component of a totalwater management system. Total water management may be seen as a com-bination drainage and subirrigation system with semiautomatic feedback.controls. On a broader scale, it may be seen as also including managementof ground-water quality and offsite effects. One may expect technologicaladvances to make far more effective control of soil water status possibleand profitable. One also may anticipate greater conceptusl recognition in in-tegrating various interests in the development and execui.on of watermanagement plans.

A specific example of the need for a total water management approach isprovided by the drainage of irrigated land. The 1982 NRI indicated thatimproved drainage or other water conservation and management measureswould be..', it at least a third of our irrigated cropland. More and fnore, itwill be imperative to integrate the planning and operation of irrigation anddrainage systems so as to provide maximum benefit to the land andminimum disbenefit downstream. To achieve this, the salt load in thedrainage water must be managed explicitly. The occurrence of toxicsubstances other then the traditionally recognized salts may introduceimportant new management challenges.

Drainage technology plays an important role in these situations, but it doesnot operate in isolation. Returning to the Kesterson Reservoir case, a solu-tion to the kinds of complex environmental issues encountered there mayinvolve, besides drainage, irrigation technology, desalting, waterfowl, andother wildlife toxicology investigations, wildlife management, institutionalchanges, and legal or contractual arrangements.

On a broader base, the need is clear for better and more explicit standardsfor decisionmaking. Using an assumed value of waterfowl hunting, aneconomic comparison can be made of the relative value of wetlands foragricultural production or for recreation. In the abstract, the same can bedone for other, intrinsic or explicit, values of wetlands. In practice, neitherthe methodology nor the drte base exist for such an analysis. Whether atotally rational economic analysis ever can or should be the basis fordeciding the advisability of further drainage may be debated. However,there can be no argument that better decisions can be expected if the infor-mation base is improved.

The improved data base requires information ou the value of drainage foragricultural production; the value of wildlife habitat for recreation andother ecologic purposes; the value of wetlands for hydrologic management ofground and surface water; and the value of wetlands for maintainingflyways. Specific decisions on individual parcels of land require specific in-formation. Assessing the effectiveness of existing policies and institutions, ordetermining the need for changes in them, one needs aggregate data.Historic data bases have suffered from lack of continuity, from changes indefinitions over time, and from inconsistencies of data from differentsources.

Better information is needed. The decennial census of drainage was elim-inated by Congress late in 1986. This will require new approaches and (..-ir-nirlated data collection programs. The slack may be taken up by periodic

.entories conducted in USDA. The importance of drainage in terms ofMal investment as well as its effect on production warrant good data,,ecially because interactions with wildlife and environmental interests

ze becoming more important wMi time. There is more interest in environ-

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mental issues than in past decades. Moreover, the stress on the environmentfrom expanding development and growing populations makes the interactionmore acute technically.

Drainage will continue to play an important part in water and land manage-ment, Drainage technology will continue to change as it has in the last 30years. Emphasis will shift to management of total systems, with increasingimportance of offsite effects and of interaction between agricultural produc-tion interests and nonagricultural concerns. The need for national assess-ment of alternative strati 9gies, using sound economic methodology, willbecome greater as the pressure on natural resources continues to increase.

Drainage in the past could be characterized as driven by the developmentalethos, It then encountered, and clashed with, the environmental ethic, In thefuture, one can expect a coming to terms of the two viewpoints, Solutionswill be sought that enhance both agricultural production and a variety ofenvironmental values, including wildlife protection.

Jan van SchilfgaardeDirector, Mountain States AreaAgricultural Research Service, USDA

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Contents

Page

Chapter 1. A Framework for Future Farm Drainage Policy: TheEnvironmental and Economic Settingby Stephen C. Smith and Dean T. Massey 1

The Policy Context for Future Drainage 2The Extensive Margin 5The Intensive Margin 8References 11

Chapter 2. A History of Drainage and Drainage Methodsby Keith H. Beauchamp 13

The Early Background 13Drainage in the United States 15Materials and Methods for Sub Surface Drainage 19Surface Drainage Measures and Techniques 24Excavating Ditches and Channels 25Pumping for Drainage 27References 28

Chapter 3. Advances in Drainage Technology: 1955.85by James L. Fouss and Ronald C. Reeve 30

Technological Challenges 30Advances in Materials and Materials Handling 31Corrugated Plastic Tubing 33Synthetic Drain Envelope Materials 36Drainage Equipment 38Laser Automatic Grade Control 43Drainage and Water Management Systems 45References 45

Chapter 4. Purposes and Benefits of Drainageby N. R. Fausey, E. J. Doering, and M. L. Palmer 48

Purposes of Drainage 48Primary Benefits of Drainage 49Associated Benefits of Drainage 51

Chapter 5. Preserving Environmental Valuesby Carl H. Thomas 52

Identification and Measurement 52Ecological Concerns 59Comprehensive Evaluations 61References 61

Chapter 6. Principles of Drainageby R. Wayne Skaggs 62

Drainage Requirements 63Drainage Theory and Practice 65Surface Drainage 70

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Contents

Page

Simulation of Drainage Systems 71

Subirrigation 72

Offsite Effects 74

References 76

Chapter 7. Drainage System Elementsby Walter J. Ochs, Richard D. Wenberg, andGordon W. Stroup 79

Outlets 79

Collection Systems 80

Land Treatment Practices 83Land Protection Practices 89Drainage System Combinations 89References 90

Chapter 8. Planning Farm and Project Drainageby Thomas C. G. Hodges and Douglas A. C h r i s t e n s e n 91

General Design and Economic Considerations 91

Planning Farm Drainage 92

Planning Project Drainage 93

Drainage in Irrigation Project Planning 95

References 95

Chapter 9. Drainage for Irrigation: Managing Soil Salinityand Drain-Water Qualityby Glenn J. Hoffman and Jan van Schilfgaarde 96

Elements in Salinity Control 96

Leaching 96

Additional Drainage 97

Drain Depth 98

Drain Water Disposal 98Minimizing Adverse Effects 99

References 100

Chapter 10. Drainage Institutionsby Carmen Sandretto 101

Elements of Drainage Law 101

Public Drainage Organizations 103

Multipurpose Districts 107

References 108

Chapter 11. Economic Survey of Farm Drainageby George A. Pavelis 110

Areas and Uses of Drained Land 110

Investment and Drainage Cost 117

Growth of Drainage Capital 119

Status of Drainage in 1985 120

Drainage in the Humid East 126

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Contents

Page

Drainage and Irrigation 131References 135

Chapter 12. Drainage Potential and 'Irmation Needsby Arthur B. Daugherty anti Douglas G. Lewis 137

Remaining Drainage Potential 137Drainage Information 139References 142

Chapter 13. Drainage Challenges and Opportunitiesby Fred Swader and George A. Pave lis 144

Preservation of Wetlands 144The Function of Wetlands 14CRates of Wetland Conversion 146Supply of Wetland Products 147Do Wetlands Need More Protection? 147National and Regional Wetland Conversions 148Balancing Competing Natural Resource Values 152Improving Drainage Information 154Maintenance and Repair Challenges 155Salinity and Water Quality Control 156Drainage is Water Management 156Challenges for Research and Education 157References 158

Appendix A: Executive Order No. 11990:Protection of Wetlands 160

Appendix B: Selected State Drainage Authorities 162

Appendix C: Acknowledgments and Contributors 167

Appendix D: English and Metric Conversion Equivalents 170

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Chapter 1

A Framework for Future FarmDrainage Policy:The Environmental andEconomic SettingStephen C. SmithSchool of Natural ResourcesCollege of Agriculture and Life SciencesUniversity of Wisconsin-Madison

Dean T. MasseyEconomic Research Service, USDAUniversity of Wisconsin-Madison'

Farm drainage had been a part of U.S. land policydebates since colonial times and will remain an ac-tive policy issue into the foreseeable future. Thesocioeconomic context for making these policy deci-sions has not been static over the centuries, despitea similarity in the issues underlying arguments overmajor land use changes. Conflicts have arisen overa broad array of policy questions, such as clearingand draining the Mississippi Delta, draining prairiepotholes, managing return flows irrigated land, con-trolling water levels on coastal lands, and drainingwet soils.

Figure 1-1 shows the distribution of remaining wet-lands in the United States. Conflicts have also focusedon definitional differences between wetlands andwet soils for use in State or local legislation. Thesestatements can help achieve broader agreement:Wetlands are lands where saturation with water isthe dominant factor determining the nature of soildevelopment and the types of plant and animal com-munities living in the soil and on its surface.Technically, wetlands are lands transitional be-tween terrestrial and aquatic systems, where thetable is usually at or near the surface or the land iscovered by shallow water. Wetlands must have oneor more of the following three attributes: (1) at least

'The authors appreciate the assistance and contributions ofMarc D. Robertson. Jane Kohlwey. Carla Eakins, and SusanCollins. University of Wisconsin-Madison.

periodically, the land supports predominantly hydro-phytes; (2) the substrate is predominantly undrainedhydric soil; and (3) the substrate is nonsoil and issaturated with water or covered by shallow waterat some time during the growing season of eachyear (Cownrdin and others, 1979).

"Wet soils" are those in which excess water is thedominant limitation on their use for crops in anarea. They are not synonymous with hydric soils orwetlands (Diedrick, 1980). USDA's National ResourceInventory for 1982 indicated that there were 78million acres of remaining non-Federal "wetlands,"but 96 million acres of undrained "wet soils" not incrops. Heimlich (1986) reports that about 40 percentof the wet soils cropped in 1982 were also classedas wetlands under the Cowardin system now usedby the Fish and Wildlife Service.

In this chapter we will first outline some importantgeneral considerations influencing current andfuture drainage policy. We will then examine con-flicts at the "extensive margin," or where majorland use change is occurring, such as convertingwetlands to agricultural or urban uses. Institutionalinnovations are taking place because of the shift inthe forces impinging upon the decisions to extendagriculture and urban land uses onto wetlands. Thedemands for land use products and the politicalcontext in which these demands are expressed arein transition. The last section deals with the "inten-sive margin," the situation of obtaining more pro-

1

Figure 1-1U.S. wetlands he mostly east of the Rocky Mountains.

duction from existing agricultural land. An exampleis achieving higher yields from wet soils. Technolog-ical research, farm economics, and agriculturalenvironmental considerations will continue to playdominant roles in programs at this margin.

The Policy Context for Future Drainage

Drainage policy has been a part of the Nation'sdevelopmental ethos, of the historic westward move-ment, and of U.S. land policy for two centuries. Thefrontier was to be co,,quered. Governmental policyenhanced land development by converting the publicdomain into privately owned land and developedinstitutional mechanisms for individuals to deal withproblems that extended beyond the farm fence. TheJeffersonian concept cf landownership was a driv-ing ideal even though it provided cover for landspeculation, aggrandizement, and, at times, fraud.Yet land did become widely owned, and the conceptof the individual's landed stake in the future hascontinued to be a force driving individuals and

policy.

18

LEGEND

Less than 5%

5-15%

11115-25%

III Greater than 25%

Standing water often lay in the way of such landdevelopment. Large portions of the forested frontier,the land east of the "famous 100th meridian," had tobe both cleared and drained to sustain agriculture.For example, horses walked belly-deep in water overlarge sections of northeastern Indiana (Wooten,1955).* Drainage and clearing were part of an early,unsuccessful attempt to convert northern Wisconsininto a dairy land (Christensen, 1958). The "AlluvialEmpire" of the lower Mississippi Valley requireddiking and draining to manage water so the landcould be cleared and tilled (Harrison, 1961). Sur-veyors' notes from Iowa and Minnesota report thatthey had to hold instruments high over their headsas they waded in water (Murray, 1953).

The Swamp Land Acts of 1849, 1850, and 1860 con-verted 64.9 million acres of public domain land inboth Eastern and Western States from Federal toState ownership so it could be sold in order to drainselected portions (U.S. Dept. of Interior, Fish and

*References are listed at the end of this chapter.

Wildlife Service, 1972). In the arid West, drainagepresented different problems because of the variablecharacter of the soil, and irrigation. Yet drainagewas often still necessary for a sustained agriculture.

Drainage continues to inspire public debate almost100 years after Frederick Jackson Turner, the Uni-versity of Wisconsin historian, observed that theCensus of 1890 no longer marked a line distinguish-ing a frontier (Turner, 1938). Turner outlined theways in which the frontier shaped the character ofits inhabitants and their culture. These traits of in-dependence and the value of land can still be seenin the drive to drain and "conquer" the swamp. Ofcourse, the underlying potential for substantialcapital gains and a better life for the developershould not be neglected. The strength of this drivecan be seen today in the continued loss of wetlands.Yet, "... thoughtful students will remember thatacross the Delta lie the skeletons of many abandonedattempts toward its reclamation" (Harrison, 1961).The same is true of all regions of the Nation.

The push to drain is very old. Early settlers broughtwith them experience in drainage and an awarenessof the differing and conflicting values involved. Thedraining of England's fens is an example. In theMiddle Ages, fishers and fowlers did not appreciatethe reduction of the natural channels and habitat,although farmers were pleased that the productivityof marketable crops increased per acre (Summers,1976). Drained land produced different products.People valued these products and activities dif-ferently, resulting in conflicts. Such conflicts overwetland use persist in England today and are thesubject of intense political struggles and headlinesin the daily press (Observer, June 24; July 1;October 5, 1984).

Many of these same values ere at stake today, butwith a difference. The developmental ethos todayfaces a strong challenge from proponents of the"environmental ethic" (Leopold, 1949). This counter-balancing is the essence of the current public policydebate over draining wetlands. The 1960's and1970's were decades of expanded and deepenedenvironmental understanding. The issues raised bythe environmentalists were not new, because peoplehad been expressing concerns about drainingwetlands for decades.

The 1960's and 1970's were, nevertheless, thresholdyears of change. For the first time, a broad base ofpublic support was mobilized for significant polit-ical, legislative, and judicial action favoring anenvironmental perspective. Federal and State lawswere enacted, new administrative rules were pro-mulgated, and court decisions were rendered deal-ing with vanishing wetlands.

r! 19

The environmental ethic encompassed more thanthe older conservation ethic by considering wholeecological systems.2 Greater attention will be givento the ecological-environmental effects of drainingboth wetlands and wet soils. The steps in decidingto drain will need clear delineation, and the marketand nonmarket effects from draining or not drainingwill have to be analyzed. At times these considera-tions may limit drainage; at other times, drainagemay be essential for achieving the desired publicand private products.

The 1960's and 1970's were also years of expandingworld agricultural markets and of productionadjustments to meet market demands of timliness.Agriculture's response to these market developmentsput pressure on both the extensive and intensivemargins. The extensive margin was changed bydraining wetlands and converting them to agricul-tural uses, as in the Mississippi Delta. Intensivemargins were likewise pushed by tiling wet soils,which increased production per acre. The area ofintensive land use increased while the area ofextensive land use decreased. The boundary oftransference between these margins is at the heartof the debate between using land for food and fiberor for "environmental" products and services.Market forces will continue to affect the demand foragricultural products and, consequently, the demandfor optimally drained land. The dynamics of thesemarkets put a premium on avoiding risks fromexcessive moisture and thus tend to encouragedrainage.

Technological change in agriculture will be anotherstrong force affecting drainage. The history oftechnical change is well known, and the productivityof U.S. agriculture is a wonder in today's world.American consumers have benefited by resultantlow-cost food and fiber. Farm numbers, especiallymidsized farms, and farm production have declined.The number of smaller and larger farms continuesto increase. These changes have produced greaterincome equity between commercial farm and non-farm employment.

All of the ramifications of past technological triumphsin agriculture are not the primary concern here, butthe forces that shaped these trends must be con-sidered because they bear on drainage policy. Thefuture will be shaped by a blend of these shiftingforces and will include new technologies. Within

2The conservation ethic received broad-based support at theturn of the century with the establishment of the Forest Serviceand the National Park Service. Notable conservation leaders ofthe time were Theodore Roosevelt. John Muir. and GiffordPinchot.

3

this context, there lies a potential for revolutionarychange in agricultural production.

Estimating future production, however, is increas-ingly difficult because of the changing structure ofagriculture and its supporting industries. Not onlywill new production techniques have to be mas-tered, but their articulation into the system willfollow new and significantly different institutionaland organizational channels (Ruttan and others,1979). In fact, agriculture could avoid the problemsthat have plagued sectors of U.S. manufacturing,like the automobile and steel industries, if the issuesof articulation are appropriately addressed.

Why will the future be different? Smaller anddecreasing numbers of farms and farmers will havehad and continue to have important political impli-cations in terms of legislative representation at alllevels of government. Coalitions between agricul-tural interests and other groups will be increasinglyimportant in accomplishing related legislative objec-tives. Marshalling legislative support for consider-ing agricultural as well as other views of wetlandlaws will require skilled political talent to attracturban votes and to gain the understanding of thosewho promote environmental interests. Thesechanges become significant since the demands forthe environmental products of wetlands are largelyexpressed through governmental organizations.

The market for technical innovations will change,altering the path of technology adoption. The num-ber of buying firms will continue to decline but theywill be bimodally distributed in size, lumped at thelower and higher ends of the scale. The characteris-tics of the remaining firms will determine whetherthis distribution and organization will affect the useof pesticides, seed corn, semen, and induced animal"twinning." Projections for increased productivityhave been based on the traditionally correct assump-tion of a large number of competitive farms. Thatmarket is changing, and this may affect both theproduction and application of new technology. Willthe same forces for rapid adoption work with asmaller number of highly commercial farms as inthe past? Will the incentive structure for innovationremain the same? How will contract sales as a formof production and marketing affect innovation andper-unit production?

The structure of the everchanging farm supplyindustry will significantly determine when andunder what conditions new technology is released.The "biotech" industry has gone through the firstflutter of adjustment. As maturity comes, as foreigncompetition becomes more intense, and as large cor-

porate structures and their decision processes exertinfluence, estimating future onfarm productivitybecomes very difficult because of the multipleforces affecting new technology.

The thrust for future productivity increases willcome from research (English and others, 1984).There is a ferment and excitement in laboratoriesacross the Nation about potentials for major tech-nical change. In some areas, commercialization ismoving rapidly and broadly covering sectors of foodand fiber production. The technical capability of in-creasing food and fiber productivity appears to beat the threshold of a dramatic upward surge.

Observers suggest that photosynthesis enhance-ment, crop bioregulators, and twinning techniquesare ready for early adoption by farm operators (Luand others, 1979). A survey of plant scientists byMerz and Neumeyer indicates that new technologiescan increase the yield of corn up to 40 percent(Rosenblum, 1983).

Gains in livestock production can come from suchinnovations as shortening the time between genera-tions, determining sex, increasing efficiency in theuse of feed, improving health, and transplantingembryos. For example, "Milk production may beincreased by between 10 to 33 percent without pro-portionately increasing feed intake" (Rosenblum,1983).

The Economic Research Service (ERS) labels thefuture as fueled by "science power" in contrast tothe mechanical power, horse power, or hand powerof past decades (Lu and Quance, 1979). Conferencesand studies during the past few years point in thisdirection. ERS economists have recently summarizedproductivity growth estimates for purposes of mak-ing long-range projections to the year 2000 andbeyond (Maetzold and others, 1983). These authorssuggest using an annual growth rate of 1.5 to 2 per-cent for estimating future agricultural productivity.Rates of productivity increase have not tapered offor flattened, as was projected in the late 1970's.

ProLtictivity increases are highly correlated withpublic and private investment in research (Johnsonand Wittner, 1984). By continuing to invest in pro-ductivity increases, the Nation will be offered abroader array of policy options for resource man-agement, including drainage, than would happenwithout a priority on research to incr ase produc-tivity. Thus, the argument for both private andpublic investment in research is justified by morethan greater farm income and low-cost food andfiber. The ability to consider alternative resource

° 04,

management options is generated by the ability tosupply food and fiber from a smaller land base.Thus, innovative policy options are increasinglyviable. Within the intensive margin, policy optionspreserve prime agricultural land and, at the exten-sive margin, they restrict using land for agriculturewith severe limitations, such as wetlands, highlyerosive land, and land with a depleted ground-watersupply.

If the increased per-unit productivity potential isrealized, the Nation may be able to produce enoughfood and fiber to satisfy the U.S. market and helpsupply the world on a smaller land base. Pressureon the extensive margin, such as draining wetlands,could be reduced. Drainage policymakers wouldhave to consider this change in pressure anddevelop program options which encourage agricul-tural production only on areas of highest productiv-ity. In such a situation, wetlands most valuable aswetlands would not have to be drained. Productionincreases would come at the intensive margin byimproving the use of the existing land base, includ-ing the use of drainage. In the competition for landfor agricultural use, a policy premium assisted bylegislation might be placed on prime agriculturalland.

The Extensive Margin

Nationally, the extensive margin of agriculturallane use is dynamic, with land continuouslj goinginto and out of agricultural uses. If the total agri-cultural land base is conceptualized, the extensivemargin is at the edge of transference between farm-ing and extensive land uses such as forest land,rangeland, and wetlands. As a part of the processof change, wetlands continue to be converted toagricultural and other uses. "New" land also con-tinues to be brought into cultivation by irrigation,with drainage often being an integral component.

Because drainage has been an essential part of theNation's agricultural development for the past twocenturies, the area of wetlands has continued todiminish. Clear quantitative estimates of the loss of"original" wetlands are not available due to "lackof sound baseline data . ..." (Weller, 1981). How-ever, estimates by the U.S. Congress' Office ofTechnology Assessment (OTA) indicate that " ... asmucn as 50 percent of the original wetlands mayhave been converted" (OTA, 1984). In some regions,only "remnant" wetlands remain with between 90and 95 percent of the original area lost in Illinois,Iowa, and lowland forests in Missouri (Weller,1981).

In other regions, according to the OTA, the percent-age of remaining wetlands is substantial, still with anational estimate of " ... 50 percent of the originalwetland ... being ... converted." This percentageis based on an original area of 185 million acres.Between the mid-1950's and 1970's, the "actual lossof freshwater vegetated wetlands totaled 14.6million acres. Agricultural land use was responsiblefor 80 percent of these losses" (OTA, 1984). Esti-mates from the National Wetlands Inventory aresimilar. They indicate that 54 percent of the originalwetlands have been drained, of which 87 percenthave been converted to agriculture (Tiner, 1984).The extensive agricultural margin has continued toexpand into wetlands in all regions of the Nation.

Estimates from a National Research Council (NRC)report on "Impacts of Emerging Agricultural Trendson Fish and Wildlife Habitat" indicate that "86 per-cent of the original Mississippi bottom land will bedestroyed by 1995 ... and ... all of the remaining(prairie potholes) area will be lost by 2055 ..."(NRC, 1982). Weller contends "... most wetlandswould disappear between 2000 and 2200 if the pres-ent rate of drainage continues" (Weller, 1981). Suchdeclines are sufficient to render the small size of re-maining wetlands increasingly visible. A broadlybased public with a heightened environmental ethicis capable of focusing attention on the environmen-tal and ecological consequences of these losses.Such a concentrated focus plays a significant rolein the process of social and public valuation as wellas in benefit-cost calculation of whether or not todrain. Many of the contending interests and valuesare not new and were evidenced 500 years ago inthe British fens. The fowlers of that day valued thewater fowl breeding grounds, much as the duckhunters of today value the prairie potholes and thebackwaters of the Mississippi Delta.

Agriculture's expansion across the Nation with theassistance of drainage was accomplished throughthe use of a set of institutions built both upon con-cepts of private property and the valuation of theserights through markets for land, corn, wheat, soy-beans, cotton, timber, and the like. Governmentalagricultural policy generally supported thesemarkets and the resulting distribution of income.Land and water policies (even levee construction)were used to subsidize this system of propertyrights and markets.

The products of wetlands, such as water fowl,water quality, water flow regulation, or fisheriesare not owned as private property. Evaluating themin their natural state involves a nonmarket decisionmade without market criteria. During periods of

5

"abundance" in the 1880's, wildlife product., weresold after capture on local markets, but extinctionand dramatic population reductions raised issues ofpublic concern. Federal and State governments havemaintained their proprietary interests and devel-oped systems cr reRulations for managing theseresources, but they have not generally relied uponthe market as a mechanism for evaluating or dis-tributing rights.

The public policy actions supporting drainage havebeen numerous at all levels of government, withFederal policy dating back to the Swamp Land Actsof 1849, 1850, and 1860. The Agricultural Conserva-tion Program (ACP), the Soil Conservation Service(SCS), and federally supported educational andresearch programs also furthered the extension ofdrainage. In addition, general agricultural pricesupport programs and other policies have encour-aged the expansion of agriculture onto newlydrained land (Goldstein, 1971).

State laws enabled drainage districts at the locallevel to deal with legal and financial problems ofdrainage extending beyond the farm fence. Federaland local efforts in levee construction, dating backto the early 1700's, contributed to uoth urban andagricultural development, including irrigation andrelated drainage. Governmental structures havebeen ased by local interests to support the historicdevelopment policy which included drainage andthe loss of wetlands. For the most part, thesepolicies have been fashioned around and supportiveof private property and markets.

Products from drained land are largely valuedthrough markets while products from undrainedland are valued outside of the market. They are"nonmarket" goods and services. Nonmarket valua-tions depend on other institutional forms, such asreferenda, legislative bodies, and governmentaladministrative agencies. For these institutions to beeffective, a base of public consensus must becreated and reflected through the organizationalprocesses.

The environmental movement of the 1960's and1970's spawned increasing interest in the impor-tance of wetlands and support for restrictingdrainage. Environmental and supply-managementconsiderations prompted the elimination of ACPcost-share payments to farmers who drained land tobring new farmland into production. SCS Regulation108 recognized the value of wetlands and elim-inated technical assistance for bringing newwetlands into production. Environmentalists alsoused the National Environmental Policy Act (NEPA)

6ka02

to oppose drainage projects, and they supported theFederal Water Bank Program in 1970, which pro-vided Federal funds to rent wetlands from land-owners for a 10-year period to prevent theirdrainage.3.4

The lack of clear, understandable, and additivenational wetland data was recognized with theestablishment of a national inventory and with in-ventories in many States. Such inventories grewfrom an understanding that wetlands were dis-appearing increment by increment without a clearappreciation of the effect of losing one more incre-ment. It was not possible to focus public decision-making without knowing the size and importance ofthe remaining aggregate of all wetlands and how anincremental loss would affect that whole. Publicdecisions at the local, State, and national levelsneeded to be based upon a definition of theresource and upon reasonably accurate estimates ofits quality and quantity. Such a perspective is nodifferent than that of the agricultural or urban landdevelopers. They also look at the resources undertheir control, and generally evaluate their actionson the basis of a market outcome for the proposedproduct. Because markets do not exist for the publicgoods and services of wetlands, a public interestover private property had to be established. Thisprocesss is going on in the courts, Congress, Statelegislatures, and administrative agencies. Michigan.Minnesota, and Wisconsin have adopted legislationrequiring statewide programs for mapping and in-ventorying wetland resources.5. 6.7

Much of the political argument over these programsfocused upon disagreements over the definition ofwetlands. Circular 39 (U.S. Dept. Interior, 1972)and other Fish and Wildlife Service classificationschemes (Cowardii , 1979) have significantly amelio-rated many disputes. State legislators and politicalinterests, however, have had their own economicconcerns tc protect, thus necessitating negotiationas well as self-education. Farm drainage interestshave often questioned and, at times, on principle.opposed inventories as well as wetland managementlegislation. The redefinition of property rights hasbeen at issue.

The States have related their mapping programs toState decisionmaking. For example, Minnesota has aprovision for its own water bank and wetland taxcredits 8.9 Michigan has a program giving the Statean option to purchase wetlands.", Wisconsin estab-lishes links with shoreland protection legislation."

*These and subsequent footnotes refer to legal citations listedafter the chanter's text.

Wetland inventories are increasingly viewed asessential for proper wetland management and formaking decisions on whether to allow the drainageof additional wetlands.

State laws relating to wetlands have increaseddramatically in the past 50 years. States adopted 79laws relating to wetlands from 1795 to 1934. In the20 years from 1935 to 1954 the number was 110.Then 70 were adopted during 1955-64. But duringthe 14-year period from 1965 to 1978, State legisla-tures adopted 355 wetland-related laws (USDA,RCA, 1980).

Navigable waterways have historically been aFederal responsibility. This was recognized furtherin the Rivers and Harbors Act of 1899, which gavethe Army Corps of Engineers authority over the dis-charge of refuse, dredge, and fill material.12 Theauthority evolved in part into section 404 of theClean Water Act of 1977, which extends theauthority beyond navigation to one of preventingpollutant discharges and of promoting the purposesof the Act.13 Environmental groups have used thissection to restrict drainage and to insure cleanwater. Permits issued under section 404 are for in-dividual actions, and backlogs can exist if a highpercentage of permits are contested. The Corpswanted to speed up decisionmaking by changing thepermit procedure. Interim rules were issued in1982, and the procedure became part of thereauthorization debate for the Clean Water Act.

Environmental groups feared that wetlands wouldbe more rapidly depleted under the interim rulesand that a basis for litigation would be denied." Anagreement was reached February 10, 1984, andapproved by the U.S. District Court for the Districtof Columbia, on an order that overturned some ofthe interim rules. The court's order gives protectionto wetlands, such as an estimated 700,000 acres ofprairie potholes, and directs the Corps to apply.nationwide, the decision in Avoyelles SportsmenLeague v. Alexander. It held that discharges causedby land clearing are subject to section 404 permits.15Before then, the Corps had applied the Alexanderdecision only within Louisiana.

The coastal zone also has received national andState attention because of the effect of drainage.Recognizing the National Marine Fisheries Serviceas a consultant for section 404 determinations aswell as other Federal and State interests, highlightsthe importance of fishery interests in the wetlandsof the thin perimeter around the contiguous 48States.

Wildlife and other supporting groups see section404 authority as important legislation and wouldlike to have it continue to be a part of the wetlanddecision process. In essence, a complex of legisla-tive authorities come into play with the control ofnavigable waters, such as the authority in the CleanWater Act to prevent pollutant discharges, theauthority of the Fish and Wildlife Service overmigratory waterfowl, the authority of USDA to pro-vide cost-sharing and technical assistance for con-servation practices, and USDA's general farm sup-port programs with incentives for moving onto lessproductive agricultural land (Goldstein, 1971).

The above complex is pluralistic, and built uponolder authorities. But the pieces are beginning totake shape for a reformulation of propertied rela-tionships. New public interests are emerging.Perhaps it is time to stand back from the fray ofeconomic and jurisdictional controversy and beginto evaluate the adequacy of Federal, State, andlocal wetland policies.

Several areas of concern related to drainage mightbe noted, such as fishery values or flood waterretention, but migratory waterfowl and its habitatillustrate the need for policy re-evaluation and areformulation of propertied relationships. Habitatfor migratory waterfowl, of course, is internationalin character, but we shall only note the prairiepothole situation, the river backwaters and flood-plains, and bayous and waterways along the Missis-sippi and the coast. Farm drainage has interactedwith the ecology of these flyways for many years.The potholes are often grouped within the intensivemargin in our terminology. Draining potholes,however, means changing land use and pushingcultivated agriculture onto noncultivated land, eventhough the geographic area is within the farm firm.

We have had a Federal policy (and many Stateshave had their own policies) of purchasing selectedwetlands to preserve migratory waterfowl habitat,but can enough land be purchased in the rightplaces to do an adequate job? To make these deci-sions, not only are wetland inventories needed, butalso better ecological ini'brmation on the variousspecies to be protected. The direction or muchpublic action is to attach clear public value to theecological system and to consider this whole as theeconomic product. Migratory birds are covered byFederal legislation: can the value attached to thesebirds be extended to their habitat? The full defini-tion of this product needs exploration in economic,legal, scientific, and aesthetic terms (Stone, 1976).An array of public processes such as purchase, tax-ation, cost-sharing, and police power could be

7

brought to a focus, including attaching public prop-erty rights to the ecological system. (Note theWyoming Federal Court ruling to eliminate fencingon private land to protect antelope habitat underthe Unlawful Enclosures of Public Lands Act. U.S.A.vs. Wyoming Wildlife Federation. Case No. C84-0136-B, U.S. Dist. Court, Wyoming.)

The movement for wetland protection at the Statelevel has gone boyend the inventory, taxation, andpublic purchase stages to the use of police power.As of 1986, 13 States had adopted comprehensivelegislation addressing the issue of freshwater andcoastal wetland preservation. For example, see 19.17.18. II 2°. These statutes depend on good wetland map-ping programs and other :Information, and establishpolice power authority by findings that describewetland values and consequences of unregulateddevelopment. These findings provide the policyunderlying the statute, alert property owners andthe general public to the need for regulation, andaid the appropriate agency in interpreting the actand administering permits. At least five other Statesare at various stages of discussing and passing com-prehensive legislation: California, Idaho, Illinois,Indiana, and Nebraska.

Regulated activities vary from State to State andare the subject of heated debate. They includespecific conduct, such as drainage and filling, aswell as any activity that impairs the natural valueof wetlands. Exemptions to drainage are bargained,as in Massachusetts, where the statute specifiesthat the regulation shall not apply to any mosquitocontrol work, to maintenance of drainage and flood-ing systems of cranberry bogs, or to work performedfor normal maintenance or improvement of land inagricultural use.21 Some issues under this statutehave been litigated, with its constitutionality sup-ported. For our purposes, it is enough to note themovement toward comprehensive wetland legislationto deal with the specific land at the extensivemargin through the use of policing.

The developmental ethos with its strong private prop-erty value is still an active national force. It hasfueled the drainage movement and given it a base oflegitimacy. The economic gain from converting vastareas of wetlands was reflected in increased in-come, capital gains, and settlement of the continent.But the markets that produce such benefits do notreflect all the societal values in drainage or wet-lands. The environmental movement gave new policyweight to the conservation and the environmentalethic as largely nonmarkci values. The synthesis ofthis confrontation, arising from a maturing Nation,is really just beginning.

8

0 /C

The earlier expansion of the extensive margin wasseldom easy or cost-free, but there was a supportingconsensus that it was right. That consensus nolonger exists, and future drainage will have to bejustified in an increasingly detailed fashion, Im-agination and innovation will be needed in policy,and new legal doctrines will be developed. Thejustification will assume an added dimension as newtechnology contributes to per-unit production in-creases. Are the acres drained to extend the marginfor agricultural pi _Auction necessary to meetagricultural production goals, and are they in thepublic interest?

The pushing back of the extensive margin bydrainage is only partly market-driven. The marketfor farm and forest products and the market forland remain major forces, but nonmarket valuationwill be increasingly important. The valuations willbe made by Federal, State, and local agencies, andalso by courts, legislatures, and a variety of othermeans. The pluralistic character of this process isfrequently of great value since incremental ad-justments at times forestall all-out commitmentswith possible major pitfalls. Pluralism also requiresinsight and imagination to insure the decisions willnot be choked by the burden of "too many wheels toturn." The challenge is to define more clearly theproduct to be created with this interaction betweendrainage and wetlands.

The intensive Margin

The intensive margin refers to additional drainageon existing farms. Generally, the issue is not theconversion of nonagricultural land to agriculturebut increasing the intensity of agriculture throughdrainage and achieving greater production and netreturn.

Increasing the intensity of use is not a new objec-tive of drainage. The tile drain introduced in NewYork State in 1835 by John Johnston was an effortin this direction. Johnston claimed that "he nevermade any money farming until he drained his land"(USDA, Yearbook of Agriculture, 1938). Land grantcollege experiment stations and USDA have formany years directed research toward a betterunaerstanding of soil-plant-moisture relationships.The science of dealing with wet soils and drainagehas moved forward on a worldwide basis, supportedby a long history of work in the Netherlands and inless developed countries. With an excellent networkof scientific communication, these efforts are partand parcel of current and future high-technologyagriculture. Hanson and Larson observed that

e.rough drainage, irrigation, and improved tillage.significant physical improvements in soil have beenmade. "But relative to the changes that will bemade, we have literally scratched the surface.Substantial acres...produce low yields because oftoo much or too little water" (Hanson and Larson.1983). Drainage research and practice will be amajor issue in an age of "high-tech." An increasinglyimportant element of crop production will be provid-ing the plant with optimum water for an economicreturn as well as a high-quality environment.

The intensive margin has been and continues to beinfluenced by the major forces noted in the policyintroduction to our discussion. The developmentalethos contained a drive for exdansion onto newland. But increased productivity per unit was alsoan ingrained social value master workmanship(Brewster, 1953). These values were expressed insuch common phrases as "making two blades ofgrass grow where only one did before," and "mak-ing the desert bloom through irrigation rather thandryland farming."

Accepted modes of behavior are beginning to shiftwith the environmental movement playing no smallpart. Some new programs are in place, so whenfarmers calculate a net return from an investmentin drainage, they must relate to the water bank,property tax credits, income tax considerations, andinterest rates, besides yield changes on various soilsunder alternative conditions of wetness and dryness.The work habits of yesterday are quite differentthan those of today. The "rubble" of conservationtillage is beginning to "look good," and wetlands forhabitat have a broader base of acceptance amongagricultural landowners.

Drainage has an environmental effect that is onlynow being recognized in some regions of the Nation.though not new to the irrigated West. This is nolonger just a Western issue. In fact, the AmericanSociety of Civil Engineers held a 1982 Conferenceon "Environmentally Sound Water and Soil Manage-ment" in Florida (Kruse, 1982). Soil salinity control,flows, ground-water protection from contamination,managed recharge percolation, and reduced floodflows are environmental benefits of drainage. Thus,drainage at the intensive margin also has values notclearly reflected in the market.

Drainage is an important water management toolfor achieving acceptable levels of quality as well asquantity in both the East and West. The quality ofthe return flow, with or without irrigatior,. will beincreasingly important and will become a part ofenvironmental chemical management. Questions

be asked about the chemical composition of thewater that comes out of farm drains and flows intodistrict systems. For example, water purity prob-lems plagued the Kesterson Wildlife Refuge, Calif.,when excess selenium appeared in return flows.The necessity of an environmentally sound manage-ment of agricultural chemicals is clear: some aspectsare understood, but the research agenda is tang anddifficult. Drainage in water-quality management willbe a significant issue for the next two decades.

Today's science will be pushing tomorrow's technol-ogy. Commercial plant breeders are moving with themarket and developing varieties designed for con-servation tir-icte and greater salinity tolerance aswell as highs. yields on prime land. Many questions,however, await better answers. To what extent canplants be adapted to conditions which will reducethe need for drainage? And, can pest resistance beintegrated to reduce the need for chemicals andthus the need to drain for improved water quality?

Managing water will be an important component ofmore intensive plant management, and in manysituations drainage will help achieve technicalprecision. Because of the variability of conditionsthroughout the Nation, the role of drainage will dif-fer by locality, necessitating area-by-area evalua-tions. Questions concerning both new investmentand reinvestment will be raised. Millions of acresare already drained, and many farm operations willhave to evaluate their existing drainage systems.They must determine if the existing system performsoptimally, or if reinvestment would yield a suffi-ciently high economic return to warrant change andredesign.

These determinations can be complex. Curren.technologies of drainage must be assessed as wellas those of related disciplines associated with in-tegrated crop management. Also, new materials, ad-vanced equipment, and computer assistance haveadded a precision unknown in earlier days. Theseadvances, coupled with progress in soil science andin determining soil-water-plant relationships, aswell ea improved operating techniques, result in adecision process that is a process of sophisticatedintegration.

The decisionmaking sciences have continued toadvance along with the biological and physicalsciences. Studies have revealed the diversity ofneeds on a State-by-State basis. These studies inte-grate the appropriate information into an economicframe of reference with indicators of profitability,or lack of it, under specified conditions. Suchresearch is useful for local situations, but because

9

of limited assumptions and purposes, it does notprovide details for making 17roader generalizations.For example, interest rates, discount rates, rentalalternatives, tax assumptions, and the effects ofexcess moisture on crops are dealt with in a varietyof ways. An outline of the decision path and anexplanation of alternatives would be useful for indi-vidual farmers and public entities. Such an outlinewould not only aid farm opere' -s and public of-ficials, but also soil scientists, a 'nage engineers,and plant specialists as they approach their respec-tive tasks.

Computer software is beginning to address thisproblem through programs which relate drainagesystem design, crop yield, water management, andeconomic return. The number of economic andengineering modeling packages such as DRAINMOPwill increase. As these programs are improved, ac-cepted, and used, the ability to compare analysesfrom various regions will increase. Thus, the areaswhere drainage at the intensive margin is profitablecan be more clearly defined. A review of selectedresearch suggests that drainage can be a profitableinvestment at the district and individual farm levelon some of the most poorly drained land. In othersituations, the net benefit is zero or a loss. At somelocations, drainage is going forward with the objec-tive of achieving a break-even level of intensifica-tion, with the long-term goal being a capital gainassociated with a change in land use. (The studiesexamined included Barrows and others, 1982;Dudek and Horner, 1981; Fritz and others, 1980;Homer and Dudek, 1980; Horner and other3, 1983;Kanwar and others, 1983; Leitch and Scott, 1977;Leitch and Keresters, 1981; Nolte and Dudek, 1984;Schwab and others, 1975; Schwab and others, 1981;and Skaggs and NassehzadehTabrizi, 1983.)

The focus on the intensive margin, however, doesnot mean that individual farm operators can alwaysaccomplish successful water management by them-selves. Collective action for water management hasa long history and will remain important for carry-ing water management beyond the farm. For example,drainage districts were organized to conveydrainage water from many farms to a "natural"waterway. Some form of collective action wasnecessary to finance projects, to deal with questionsof trespass, and ter' overcome blocking action by un-cooperative individuals. For example, in 1639, theMichigan legislature provided that, upon petition,the lands of persons "who would not voluntarilypermit the construction of a ditch" could be openedto drain swamps, bogs, : ieadows, or other lowlands(Lauer, 1959). Many States developed comparablelegislation for formalizing collective action into

10 26

district-enabling acts. History and the associatedlaw cannot be delineated in detail here other thanto note a complex legal and political backgound.Districts represent local economic interests attempt-ing to extend and enhance individual propertyvelum Today the role of the older, single-purposedrainne district is often incorporated into countygove:nments or commissions.

If exploiting the intensive margin continues to beeconomical, the increased sophistication and size offarm businesses may require a rethinking of manyfarm drainage systems because of the increasedload such systems will have to handle and the needto control soil moisture and chemicals more precisely.Old small districts may have to reorganize to dealwith today's larger problems. Such reorganizationstend to create organizations oapable of providingmore comprehensive water mo,.;agement. This trendwill be important for providing adequate service tothe farmer as well as for meeting an increasinglybroad spectrum of Federal and State water re-quirements. Farm drainage at the intensive marginwill be included within the web of comprehensivewater planning and management, requiring the in-tegration of water quality, quantity, and rights.

The full potential of drainage at the intensivemargin has not been realized. Productivity gainsfrom better water control and longer term resourceenhancement are often possible. Also, environmen-tal enhancement at the intensive margin throughwater quality control will be significant. Achieve-ment of these values will depend upon scientifit,advances and market value of agricultural products.

Footnotes342 U.S. Code, Sec. 4321 et seq. (1982).16 U.S. Code, Secs. 1301 to 1311 (1982).

5Michigan Compiled Laws Annotated, Secs. 321.10(1)(j), (g)(Supp. 1983.1984).MInnesota Statutes Annotated, Se:. 195.391 (Subd. 1) (West

Cum. Supp. 1984).?Wisconsin Statutes, Sec. 23.32(2)(a) (1981.1992).eMinnesota Statutes Annotated, Sec. 105.392 (1/i 1st 1977 &Cum. Supp. 1984).9Minnesota Statues Annotated, Secs. 272.1.i2 (Subd. 1) (15),273.115 (West Cum. Supp. 1984).loMichigan Complied Laws An stated, sec. 321.206(2) (Cum.Supp. 1983.1984)."Wisconsin Statutes. Sec. 59.971 (1981.82).1233 U.S. Code, Sec. 401.412 (1982).'333 U.S. Code, Sec. 1344 (1982)."Nebraska v. Rural Electrification Admin., 12 EnvironmentalReporterCases 1156 (D. Neb. 1978).'5511 Fed. Supp. 278 (Western District Louisiana 1981).'Itonnecticut General Statutes, Sec. 22a36 to 45 (1983).oMassachusetts Annotate( Law, Chap. 131, Secs. 40, 40A(MichielLawyers C op, 1981)."New Hampshire Revised Statutes Annotated, Secs. 483.A:1to :6 (1983 and Cum. Supp. 1983).'New York Environmental Conservation Law, Sec. 24.0101 to1543601 (McKinney Cum. Supp. 1983.1984).20Rhode Island General Laws, Sec. 2.1-18 to .25 (1976 & CumSupp. 1983).21Massachusetts Annotated Laws, Chap. 131, Sec. 40(MlchielLawyers Coop, 19;1).

References

Barrows, R., David Henneberry, and SarahSchwartz. 1982. "Individual Economic Incentives,The Tax System and Wetland Protection Policy: AStudy of Returns to Wetland Drainage inSoutheastern Wisconsin." ASAE Paper No. 82-2034.Am. Soc. Agr. Engr., St. Joseph, Mich.

Bishop, R. A. 1981. Iowa's Wetlands. Proceedings,Iowa Academy of Science, Vol. 88, pp. 11-16.

Brewster, John M. 1958. "Technological Advanceand the Future of the Family Farm," Journal ofFarm Economics, Vol. 40, pp. 1,596-1,612.

Carstensca, Vernon. 1958. Farms or Forests. Collegeof Agriculture, Univ. of Wisconsin, Madison, July,p. 6.

Cowardin, Lewis M., Virginia Carter, Francis Go let,and Edward La Roe. 1979. Classification of Wetlandsand Deepwater Habitats of the United States. U.S.Dept. Int., Fish and Wildlife Serv., p. 103.

Diedrick, R. T. 1980. The Agriculture Value of WetSoils in the Upper Midwest. Staff paper, U.S. Dept.Agr., Soil Cons. Serv., St. Paul, Minn.

Dudek, Daniel, and Gerald L. Homer. 1981. "ReturnFlow Control Policy and Income Distribution AmongIrrigators," American Journal of AgriculturalEconomics, Vol. 63, No. 3, pp. 4°1-446.

English, Burton C., James A. Maetzold, Brian R.Holding, and Earl 0. Heady. 1984. Future Agricul-turd Technology and Resource Conservation. Pro-ceedings of the RCA Symposium: Future Agricul-tural Technology and Resource Conservation. Ames,Iowa: Iowa State Univ. Press.

Frayer, W. E., T. J. Monahan, D. C. Bowden, and F.A. Gaybill. 1983. Status and Trends of Wetlandsand Deepwater Habitats in the Conterminous UnitedStates, 1950's to 1970's. U.S. Dept. Int., Fish andWildlife Serv., p. 32.

Fredrickson, L. H. 1981. Paper prepared for theHouse Subcommittee on Fisheries and Wildlife.

Fritz, J. C., Gerald Homer, and J. H. Snyder. 1980.The Economic Feasibility of Installing SubsurfaceTile Drainage in the Panoche Water District, SanJoaquin Valley, California. Information Series 80-3,Giannini Foundation of Agricultural Economics,Univ. of California.

Goldstein, Jon. 1971. Competition for Wetland in theMidwest: An Economic Analysis. Resources for theFuture, Inc. Baltimore: The Johns Hopkins Press.

Hanson, L., and W. E. Larson. 1983. "Frontiers inSoil Science: The Next Twenty Years," MinnesotaScience, Vol. 38, No. 3, pp. 2, 3, 14.

Harrison, Robert W. 1981. Alluvial Empire: A Studyof State and Local Efforts Toward Land Develop-ment in the Alluvial Valley of the Lower MississippiRiver. Little Rock, Arkansas: Pioneer Press.

Heathcote, J. M. 1876. Reminiscences of Fen andMere. London: Longmans, Green & Co.

Heimlich, Ralph E. 1986. Personal compilation ofland use capability subclass "w" land by types ofwetla id; data from the 1982 National ResourcesInventory.

Horner, G., and D. J. Dudek. 1980. "An AnalyticalSystem for the Evaluation of Land Use and WaterQuality Policy Impacts upon Irrigated Agriculture,"Operations Research in Agriculture and WaterResources. Amsterdam: North Holland PublishingCo., pp. 537-568.

Homer, G. L., C. V. Moore, and R. E. Howitt. 1983."Increasing Farm Water Supply by Conservation,"California Agriculture, Vol. 37, Nos. 11 and 12, pp.6-7.

Johnson, G. L., and S. H. Wittner. 1984. AgriculturalTechnology Until 2030. Special Report No. 12, Mich.Agr. Expt. Sta., East Lalising.

Kanwar, R. S., H. P. Johnson, D. Schult, T. E. Fenton,and R. D. Hickman. 1983. "Drainage Needs andReturns in North Central Iowa," Transactions of theASAE, Vol. 26, No. 2, pp. 457-464.

Korte, P., and L. H. Fredrickson. 1977. "Loss ofMissouri's Lowland Hardwood Ecosystem," Trans-actions of North American Wildlife and NaturalResources Conference, Vol. 42, pp. 31-41.

Kruse, E. Gordon, Chuck R. Burdick, and Yousef A.Yousel (co-editors). 1982. Environmentally SoundWater and Soil Management. New York: Am. Soc.Civ. Engr.

Lauer, T. E. 1959. "District Control of WaterResoumes," University of Detroit Law Journal, Vol.37, No. 1, pp. 28-35.

Leitch, Jay A., and Daniel Kerestes. 1981.Agricultural Land Drainage: Costs and Returns inMinnesota. Staff Paper P 81-15, Dept. Agr. andAppl. Econ., Univ. of Minnesota, St. Paul.

Leitch, Jay A., and D. P. Scott. 1977. "EconomicImpact of Flooding on Agricultural Production inNortheast Central North Dakota." Agr. Econ. Rpt.No. 120, Dept. Agr. Econ., No. Dak. Agr. Exp. Sta.,Fargo.

Leopold, Aldo. 1949. A Sand County Almanac.Oxford Univ. Press.

Lu, Yeo-Chi, and Leroy Quance. 1979. AgriculturalProductivity: Expanding the Limits. AI3-431. U.S.Dept. Agr., Econ. Res. Serv.

Lu, Yeo-Chi, Philip Cline, and Leroy Quance. 1979.Prospects for Productivity Growth in U.S. Agricul-ture. AER-435. U.S. Dept. Agr., Econ. Res. Serv.

Maetzold, Jim, Thyreie Robertson, Klaus Alt, NeillSchaller, and Tom Dempster. 1983. "Issue Paper forBasic Assumptions Work Group: Agricultural Pro-duction Technology Estimates for the RCA and RPAProcess." U.S. Dept. Agr., Econ. Res. Serv.

McLean, J. J. P., and G. 0. Schwab. 1983. "FloodPeak Flows and Subsurface Drainage." ASAE PaperNo. 82-2053, Am. Soc. Agr. Engr., St. Joseph, Mich.

Murray, William G. 1953. Appraisal of PotawatomiTracts in Iowa and Kansas, 1846. Prepared for theU.S. Dept. Justice. Ames, Iowa.

National Research Council. 1982. Impacts of Emerg-ing Agricultural Trends on Fish and WildlifeHabitat. Wash., DC: National Academy Press.

Nolte, B. H., and R. D. Devick. 1984. "Economic Fac-tors of Drainage Related to Corn Production," Na-tional Corn Handbook. Coop. Ext. Serv., Ohio StateUniv., Columbus.

Pavelis, George A. 1978. Natural Resource CapitalStocks: Measurement and Significance for U.S. Agri-culture Since 1900. Abstract No. 199, Proceedings ofthe American Association for the Advancement ofScience. AAAS Pub. 78-2.

Redelfs, Ann Ellen. 1983. "Wetland Values andLosses in the United States." M.S. thesis, OklahomaState Univ., Stillwater.

Rosenblum, John W. (editor). 1983. Agriculture inthe Twenty-first Century. New York: John Wiley andSons.

Ruttan, Vernon W., Robert E. Evenson, and Paul E.Waggoner. 1979. "Economic Benefits fromResearch: An Example from Agriculture," Science,Vol. 205. pp. 1,101-1,107.

Schrader, T. A. 1955. "Waterfowl and the Potholesof the North Central States," Water: Yearbook ofAgriculture, 1955. U.S. Dept. Agr., pp. 596-604.

s12

Schwab, G. 0., N. R. Fausey, and C. R.Weaver.1975. Tile and Surface Drainage of Clay Soils. OhioAgr. Res. and Dev. Ctr., Wooster.

Schwab, G. 0., B. H. Nolte, and M. L. Palmer. 1981and 1982. Drainage-What is it Worth on CornLand, and Drainage-What is it Worth for SoybeansLand? Soil and Water Series Nos. 23 and 24, Agr.Engr., Ohio State Univ., Columbus.

Skaggs, R. W., and A. Nassehzadeh-Tabrizi. 1983.Optimum Drainage for Corn Production. Tech. Bul.No. 273, North Carolina Agr. Res. Serv., State Univ..Raleigh.

Stone, Christopher. 1976. Toward Legal Rights forNatural Systems. Proceedings from the 41st NorthAmerican Wildlife Conference, Wash., DC, pp. 31-38.

Summers, Dorothy. 1976. The Great Level, A Historyof Drainage and Land Reclamation in the Fens.North Pomfret, Vermont: David and Charles.

Tiner, Ralph W. 1938. Wetlands of the United States:Current Status and Recent Trends. U.S. Dept. Int.,Fish and Wildlife Serv.

Turner, Henry Jackson. 1938. "The Significance ofthe Frontier in. American History." Presented atAm. Hist. Assoc., July 12, 1938. In The EarlyWritings of Frederick Jackson Turner. Freeport,N.Y.: Books for Libraries Press.

U.S. Congress, Office of Technology Assessment.1984. Wetlands: Their Use and Regulation.

U.S. Congress, U.S. Department of Agriculture.1980. "Soil, Water and Related Resources of theUnited States: Analysis of Resource Trends." PartII, 1980 RCA Appraisal.

U.S. Department of Agriculture. 1938. Soils andMen: Yearbook of Agriculture, 1938.

U.S. Department of the Interior, Fish and WildlifeService. 1972. Wetlands of the United States. Circ.No. 39.

van Schilfgaarde, Jan. (editor). 1974. Drainage forAgriculture. Monograph No. 17, Am. Soc. Agronomy,Madison, Wisc.

Weller, Milton W. 1981. "Estimating Wildlife andWetland Losses Due to Drainage and Other Pertur-bations," Jour. Paper No. 1794. Minn. Agr. Exp.Sta., St. Paul.Wooten, Hugh H., and Lewis A. Jones. 1955. "TheHistory of Our Drainage Enterprises," Water: Year-book of Agriculture, 1955. U.S. Dept. Agr., pp.478-491.

2.8

Chapter 2

A History ofDrainage andDrainage Methods

Keith H. BeauchampConsulting Drainage EngineerSoil Conservation Service Engineer (ret.)Jacksonville, Illinois

From earliest days, mankind has devised ways ofmanaging water by various means involving its sup-ply, removal, or regulation. Archeological studies in-dicate that land drainage began thousands of yearsbefore the Christian era. In one account vanSchilfgaarde (1971) reported that water manage-ment for agricultural purposes could be traced toMesopotamia some 9,000 years ago. Hercdotus, aGreek historian of the fifth century B.C., wrote thaton a voyage to Egypt, the priests there told him ofdrainage work around the ancient city of Memphis,accomplished by Min, the first king of Egypt.

This chapter documents how farm drainage hasevolved from the contributions of various civiliza-tions and individuals, first in the Old World andthen in the United States. These original develop-ments are the conteNt of the subsequent discussionof present-day technologies by Fouss and Reeve.

The Early Background

About 400 B.C., the Egyptians and Greeks drainedland using a system of surface ditches to drain in-dividual areas. The oldest known engineering draw-ing, illustrated on Egyptian papyrus around 250B.C., is a Greek plan of a rectangular ditchingsystem. It is preserved at the University of Lille inFrance (Sutton, 1958).

Historic evidence indicates that serious drainageproblems developed in irrigated areas. A majorreason for the decline and disappearance of someancient civilizations based on irrigation was theirfailure to heed the drainage hazard (Dorman, 1976).

Marcus Porcius Cato, 234 to 149 B.C., apparentlywrote the first specific directions for draining land.A Roman statesman and orator and also the firstimportant Latin prose writer, Cato, late in lifeturned to agriculture and farmed on a large scale.His only complete surviving work is a treatise onagriculture written about 160 B.C. Manley Miles(1892) quotes Cato:

In the winter it is necessary that the water beled off from the fields. On a declivity it isnecessary to have many drains. When the firstof the autumn is rainy there is a great dangerfrom water; when it begins to rain the whole ofthe servants ought to go out with sarcles, andother iron tools, open the drains, turn thewater into its channels, and take care of thecorn fields, that flow from them. Wherever thewater stands amongst the growing corn, or inother parts of the corn fields, or in the ditchesor where there is anything that obstructs itspassage, that should be removed, the ditchesopened, and the wafer let away ... If theplace is wet, it is necessary that the drains bemade shelving, three feet broad at the top, fourfeet deep, and one foot and a quarter wide atthe bottom. Lay them in the bottom with stones.If there are no stones to be got, lay them withgreen willow rods, placed contraryways; ifrods cannot be got, tie twigs together.

The Romans first used open drains toremove pondedsurface water; closed drains soon followed forremoving surplus water from the soil itself. Placinga layer of gutter or house tile face up in the bottomof the drain to prevent washing was recommendedfor covered drains. The trenches were then half filled

13

with stones or gravel or bundles of brush fittedtogether. The rest of the trench was filled in withthe excavated material. These Romans were appar-ently the sole authorities on land drainage, andtheir methods were used with little improvement formore than 1,000 years. Donnan (1976) reported thatthe Roman Empire's easternmost province ofPanonia had drainage ditches constructed in thethird century A.D. which are still functional. TheRomans drained the Po, Arno, and Tiber Valleysand exported their knowledge of drainage to col-onies in North Africa and Asia Minor. Later writersgenerally followed Cato's recommendation withsome improvements and variations (Weaver, 1964).

The European Heritage

Weaver (1964) reported on a 1770 discovery inEngland of an underground drain in Sussex Countyfilled with alder branches, probably built about1400 A.D. The reclamation of the English fens is dis-cussed by Pickels (1925), Doman (1976), and in anunpublished paper by Elmer Gain, a former drain-age engineer in SCS. Gain lists Wheeler (1868) andDarby (1940) in his references. The English fenscover an area of about 680,00J acres on the eastcoast of England. This area originally consisted offresh and tidewater peat marshes, frequentlyflooded by storm tides from the North Sea and theoverflow from several converging rivers. The land isnow protected from the sea by dikes and levees. In-terior drainage is through numerous ditches leadingto the dikes, where water is raised and discharged bypumps.

The Romans were the first to install drainage inBritain with considerable success. However, theirworks generally deteriorated after their occupationended.

About 1250 A.D., work began in England to preventflooding. About 1500, the first large design fordrainage was started. An Act of Parliament in 1600provided for the reclamation of hundreds of thou-sands of acres of marshes. However, the drainedpeat land subsided over time and natural flow wasno longer possible by 1700.

Windmills were used to pump the water from smalldikes to a main drain and from the drain to therivers, probably starting about 1640. Eventuallyflows from the rivers were pumped against the tideinto the sea. About 1820, the steam engine beganreplacing the windmill. Drainage improvements con-tinued during the 19th and 20th centuries. The fensare now a prosperous agricultural region.

14

0

The practice of building dikes to protect and reclaimlands along the lower reaches of the rivers and seacoasts abounds in most of northern Europe. Prob-ably the most important and successful drainageworks of this nature are in The Netherlands(Donnan, 1976).

Approximately two-fifths of The Netherlands liesbelow sea level. Without protection bl dikes anddunes, these areas would be inundated by tidestwice daily. In the first century A.D., the inhabi-tants of these marsh areas built extensive moundsto live on. Attempts to secure greater protection bybuilding dikes were made in the eighth and ninthcenturies. By 1300, various regions of the nation'scoastal belt were enclosed by dikes as protectionagainst either the sea or rivers. Up until 1450,bursting dikes devastated many villages or causedwhole areas to disappear. Better dike placementand construction have since provided more suc-cessful reclamation projects.

A problem from protective embankments that arosealmost immediately in Holland was the need for alsoremoving excess precipitation. Since the 13th cen-tury, a complicated organization of landholdersgradually developed to deal with this problem.Small tracts of land reclaimed by dikes, known aspolders, wore directly or indirectly used as storagebasins for collecting this water, which was thenpumped to the sea or rivers by windmill power.

In 1839, the Government of Holland began drainingHaarlem Lake (Pickels, 1925). The original plans forthis project, calling for windmills, had been devel-oped by Leeghwater some 200 years before. Thelake was about 15 miles long, 8 miles wide, 13 feetdeep, and covered about 44,000 acres, with the lakebottom below sea level. It was emptied by largepumps after being enclosed by a dike. The workwas completed in 1848. The bottom of the formerlake is now cultivated and provides homes forseveral thousand people. Large pumps are used toremove the interior drainage water from openditches.

Pickels also notes that several similar large projectswere carried out in France, including the La Girondeproject, with about 1.5 million acres, and the Forezproject, with about 140,000 acres.

Early Methods and Materials

Subsurface drainage conduits made of sticks, brush,and stones were generally used in Europe until atleast the 17th century. However, Weaver (1964) sug-

gested that clay tiles similar to those used todaymay have been used at the time of Christ. Frenchfarmers are generally credited with being the firstto use clay tile for farm drainage purposes. Theyused a modified form of medieval clay roofing tile.This type of tile drainage was used at least into the14th or 15th centuries.

Weaver indicated that in the garden of the Monasteryof Maubeuge, in France, a system of pipe drainswas discovered laid at a depth of 4 feet throughoutthe whole garden. This work had probably beencompleted before 1620. About 10 inches long and 4inches in diameter, these pipes are the first knowncylindrical tile drains. These types of early claydrain tile became forgotten for generations.

In Britain, the use of tile drainage has been tracedat least to the 15th century, but it seems that in-terest in drainage waned after the decline of theRomans; its potential was "rediscovered" in the18th century (van Schilfgaarde, 1971).

A horseshoe-shaped tile was the first form of claytile drainage used in England. The tiles formed asimple arch or tunnel when placed open side down,end to end, along the bottom of a trench andcovered with soil. Later, these horseshoe tiles wereplaced on a flat piece of burned clay or pallet thelength and width of the tile. The pallet protected thebottom of the trench and made a closed conduit forthe water to flow through. These tiles were hand-made and consequently very costly. Weaver (1964)reported on the use of horseshoe tile laid in 1760 onthe Grandbury estate in Suffolk, England.

Cylindrical drainage pipes were first manufacturedin England in 1810 by John Reade, a gardener atHorsemenden. His handmade tiles were a greatimprovement over the old brush and stone drainsand proved more popular than horseshoe drains. Amachine for making clay tile was invented in 1840;it became the forerunner of a clay pipe extruderpatented in 1843. This new machine greatly reducedthe cost of drain tile and led to its increased use.Portland cement was first used to make drain tile in1830 (Dorman, 1976).

Mole drainage was also used centuries ago inEurope. This was accomplished by a machine knownas a mole ditcher. It consisted of a bullet-nosedsteel cylinder attached to some type of wheel frameor plow. The ditcher was pulled by oxen throughthe soil to form a tunnel to carry away drainagewater (King and Lynes, 1946).

Drainage in the United States

American farmers have drained their lands sincethe early days of settlement. Land drainage hasbeen an important factor in developing our Nationand increasing farm wealth. Even urban develop-ment has depended upon drainage. In New York City,for example, Central Park was drained in 1858,primarily for public health purposes.

Colonial Period

Events and developments in Europe from the closeof the 15th through the 17th centuries set thegroundwork for American drainage practices. Earlysettlers in America brought European drainagemethods with them, such as small open ditches todrain wet spots in fields and cleaning out smallstreams. At first only small, scattered areas weredrained by the individual owners. Extensive drain-age outlets beyond individual property boundarieswere at first seldom necessary along the easternseaboard. There was one notable exception: in1754, the Colony of South Carolina passed an actfor draining the Cacaw Swamp.

In 1763, the Dismal Swamp area of Virginia andNorth Carolina was surveyed by George Washingtonand others with a view to land reclamation and in-land water transportation. In 1778, whileWashington was President, the Dismal Swamp CanalCompany was chartered by Virginia and NorthCarolina.

The first known colonywide drainage law wasenacted in New Jersey on September 26, 1772, andre-enacted in the new State constitution on July 2,1776. A drainage outlet for the City of New Orleanswas constructed around 1794 (Gain and Patronsky,1973). Early drainage works also were constructedin De1 "'are, Maryland, New Jersey, Massachusetts,South Carolina, and Georgia, under the authority ofcolonial and State laws.

American farmers increasingly found that largeoutlets beyond individual farm boundaries werenecessary to provide proper farm drainage. Theconstruction of such outlets has been facilitatedgreatly by the establishment of drainage districts,county drains, or other drainage enterprisesorganized under State laws. These outlets havebeen effective in draining large areas in the coastalplains, the upland prairies of the midwestern farmSte 'es, lake plains, and along many streams andriver bottoms.

LP I 15

The first onfarm drainage involved only small openditches. However, although ditches might make itpossible to cultivate the land, they did not lowerground-water tables fast enough after rains to per-mit the land to produce a maximum yield of crops.The shallow ditches were seldom deep enough tointercept hillside seepage. But if more ditches wereused they occupied too much land. The solution wasto have small covered drains emptying into openditches, thus permitting the land over the drains tobe cultivated.

Early settlers in New York and New England usedsubsurface drainage in addition to open ditches.Material used for buried drains prior to the use oftile included poles, logs, brush, lumber of all sortsincluding sawmill slabs, stones laid in various pat-terns, bricks, and straws. The latter was sometimestwisted into rope by a special machine. Logs wereeither bored or split with the inside scraped out.Concrete made of hydraulic cement, lime (whichhardens under water), and coarse sand was alsoused to shape a conduit. The only limit to the tyrwof material or method of use was the imagination ofthe user. Weaver's book (1964) has many sketcheson how these drains were constructed.

Drainage Moves West

By the 1850's, population pressure and a need formore and better farmland than was available on theeastern seaboard precipitated full-scale settlementof the Ohio and Mississipppi River Valleys. In itsnatural state, much of the fertile land in north-western Ohio, northern Indiana, north-centralIllinois, north-central Iowa, and southeasternMissouri was either swamp or frequently too wetto farm.

What these tracts were once like is - lescribed in thereport on Long's expedition to the source of the St.Peter's River in 1823. Sutton (1957) quoted from apart of this report as follows:

Near to this house we passed the state linewhich divides Ohio from Indiana . . . Thedistance from this to Fort Wayne is 24 miles,without a settlement; the country is so wet thatwe scarcely saw an acre of land upon which asettlement could be made. We traveled for acouple of miles with our horses wading throughwater, sometimes to the girth. Having found asmall patch of esculent-grass (which from itscolor is known here by the name of bluegrass),we attempted to stop and pasture our horses,but this we found impossible on account of the

16

immense swarms of mosquitos and horse flies.From Chicago to the place where we forded theDes Plaines, the country presents a low, flatand swampy prairie, very thickly covered withhigh grass, aquatic plants, and among othersthe wild rice.

Pickels (1925) noted that Government Land Officerecords show that one-fourth of Illinois and stilllarger portions of other States were swampland.Twenty-one counties in northwestern Ohio andnortheastern Indiana included much low landoriginally too wet to cultivate. At the time of settle-ment, much of the land in north-central Iowa was inshallow sloughs too wet for normal cultivation.Large areas in western Minnesota, northeasternArkansas, the gulf plains of Texas, and the deltaareas of Mississippi and Louisiana were originallyswamp and overflow areas. Drainage permitted cul-tivation of these areas (Wooten and Jones, 1955).

Hay and Stall (1976) reported on the development ofsurface drainage in east-central Illinois covering abasin of 1,250 square miles in parts of Ford, Cham-paign, and Vermilion Counties. To cote from theirreport on early conditions of areas in the north-central States:

"In its natural state, east-central Illinois was awide flat of gently rolling swampy expansecovered with tall bluestem and cord grass.Forested areas of various sizes were foundalong the three river channels, North Fork,Middle Fork, and Salt Fork in the Vermilionwatershed. Some trees also grew along thetributary creeks. All early settlements werelocated in these wooded areas along thestreams. The prairies were of little interest toearly settlers, but presented formidable bar-riers to be crossed. A Vermilion County history... describes the 'raw prairies with miles andmiles of swamps with a heavy wild grass, andthere was no drainage at all. Streams hadworn no channels for the water courses.' Theswampy land was considered worthless forfarming, but was grazed by cattle in dryseasons. It was only after outlet channels wereopened that the swampy areas could be tiledand cultivated.

"Life in the early settlements of this regionwas hard, especially near the swamps. Prob-lems of human health were frequently reportedin the records. There were epidemics ofmalaria with 'severe sickness and fatalitieswithout exception.' One senior citizen in Cham-

paign County told of illness due to malaria inher family every summer and fall as late as1900. Accounts also tell of cholera, milksickness, ague, and fever. Plagues of mos-quitoes and flies were also reported. It is easyto understand the account of the young manwho refused to trade his horse and saddle fora full section of swampy land in that period. At1976 prices a E40-acre tract would sell formore than a million dollars.

"Transportation at the time of the early set-tlements was extremely difficult. The earlytrails followed the glacial moraine ridgeswhenever possible. The lowlands were im-passable in wet seasons, and bridges acrossthe streams were few and far between. Reportstell of travel by boat across lower areas andskating for miles in winter. An 1867 map ofVermilion County, which was well settled atthat time, shows no 'through roads.' Theygenerally extended a few miles from a townpast several farmsteads, only to come to adead end at some farm...

"Thus problems of health and transportationas well as agriculture crippled by poorly drainedfields existed in this region through the earlyyears of settlement. Satisfactory solutions werenot achieved until 'hundreds of miles of ditchesand thousands of miles of tile drains' were in-stalled on the land. This area now ranks as themost productive land in Illinois and in the en-tire Cornbelt."

The Swamp Land Act

Beginning about 1830, increased public pressurewas brought on Congress to release for privatedevelopment large areas of swamp and wetlandsstill owned by the Government. After 20 years ofdeliberation, Congress passed the Swamp Land Actsof 1849 and 1850. These were the first importantpieces of Federal legislation relating to land drain-age. The Acts granted nearly 64 million acres toLouisiana in 1849, and to 14 other States in 1850and 1860. These vast areas of swampy and overflowlands went to the States on condition that fundsfrom their sale be used to build the drains andlevees necessary to reclaim them. No importantreservations were attached to this transfer, and theStates were free to dispose of the land as they sawfit (Wooten and Jones, 1955; Harrison, 1961).

The States did not immediately develop the lands asanticipated. State legislatures, facing the same

r

Figure 2-1The Little River Drainage District's flooding ditchesseen north from the Cotton Plant Road, Dunk lin County, Missouri.

dilemma as Congress, passed the holdings on to thecounties for sale to private owners and corpora-tions. After 20 years of experimenting, landownerslearned of the great costs in reclamation work. Lit-tle or no progress occurred in land sales until Statelaws permitted organization of drainage and leveedistricts, or allowed county governments toestablish projects with the consent of the majorityof beneficiaries.

An early example of such a project was the LittleRiver Drainage District in southeastern Missouri.This district, 90 miles long and from 4 to 30 mileswide, contained about 500,000 acres of rich alluvialland. The district provided outlets into the Missis-sippi River for an additional 614,000 acres and adiversion system for discharging runoff fromanother 750,000 acres of Ozark highlands.

First petitioned in 1905, the Little River District wasincorporated in 1907 after lengthy court litigation.Construction lasted from 1914 to 1929. A headwaterdiversion system with 50 miles of channel and 40miles of levees was built by dragline. The interiordrainage outlet channels, 887 miles in length, wereoriginally built with floating dredges and were latermaintained by draglines. Almost 88 million cubicyards of earth were moved in constructing the chan-nels and levees. The required $11-million construc-tion cost was raised by the sale of bonds, whichwere redeemed by taxes assessed on 436,000 acres.The Corps of Engincers provided protection from theMississippi River floods with levees and floodwaysalong the river (fig. 2-1) through which districtdrainage was discharged (Gain and Patronsky,1973).

17

In the lower Mississippi Valley States, administeringswampland funds was a major political, economic,and social issue for more than 30 years. State andFederal legislators alike underrated the complexityand cost of flood control and drainage in the area.Receipts from the sale of swamplands were a pit-tance compared with the cost of flood control anddrainage. The experience in flood control anddrainage engineering gained in trying to meet theprovisions of the grants formed the basis for largedrainage projects subsequently undertaken by localdistricts, the States, and the Federal Government.Many of tin legal and administrative concepts andprocedures developed under the Swamp Land Actsbecame imbedded in later flood control anddrainage projects (Wooten and Jones, 1955).

Reclamation and Other Federal Programs

With the Reclamation Act of 1902 began thegradual reversal of the Swamp Land Act precedentof only State and local involvement in land reclama-tion. The Reclamation Act, in setting up the Bureauof Reclamation, resulted in the establishment of adrainage specialist position and staff in USDA. Thisspecialist's first duty was to investigate drainagemethods to correct alkali damage caused by irriga-tion water seepage. Within 2 years, these dutieswere enlarged to include other drainage problems.Thus, what was USDA's Bureau of AgriculturalEngineering (BAE) became involved in agriculturaldrainage.

During the 1920's and 1930's, the Depression andunforeseen difficulties in developing lands forcedmany drainage enterprises to default on their debtsand generally neglect maintenance work. Thecapacity of many systems was insufficient to pro-vide good drainage. Many farms within projectareas were sold for taxes or mortgage foreclosure.

In 1935, Congress authorized the ReconstructionFinance Corporation to refinance drainage andirrigation districts in distress. This assistanceenabled districts in 26 States to continue operationsduring the Depression. Drainage enterprises alsoreceived assistance through Civilian ConservationCorps (CCC) camps and other Federal reliefagencies.

In 1935, the BAE became responsible for 46 CCCcamps involved in the rehabilitation and recon-struction of drainage improvements organized underState drainage laws. In December 1938, respon-sibility for the CCC camps as well as other drainageactivities in USDA was then assigned to the SCS.

184

a.

t

<,?

Figure 2-2Drainage rehabilitation work occurred during the De-pression thanks in part to the Civilian Conservation Corps.

Drainage work carried on by the CCC (fig. 2-2) andother public works programs played an importantpart in conditioning drained land for the neededgreat expansion in agricultural production duringand following World War II (Sutton, 1957). In 1941,drainage and irrigation work had been approved byUSDA as conservation practices to be included infarm conservation plans.

The Flood Control Act of 1944 authorized the Corpsof Engineers to construct major drainage outletsand flood control channels. This woik encouragedthe organization or reactivation of many drainagedistricts, particularly in the Mississippi RiverValley, in order to improve local drainage ditchesand reap the benefits of better outlet drainage. In1954, the Federal Watershed Protection and FloodPrevention Act (P.L. 83-566) authorized USDA toplan and construct various watershed works of im-provement, including drainage outlet channels, incooperation with State and local governments.Working through local soil conservation districts,SCS provided technical assistance on farm drainagemeasures and practices in farm conservation plans.These measures have included field ditches, sub-surface drains, structures to admit water into

ditches to prevent erosion, protection of tile outlets,and development of surface field drainage.

Drainage of Western Irrigated Lands

In personal communication (1984), William W.Dorman, consulting drainage engineer, Pasadena,California, offered this account of some of thehistory of drainage in the arid West:

"Drava ige problems were an almost inevitableconsequence of irrigation development in thearid west. One can trace the ancient irrigationcanals out of the Salt River in Arizona, nearpresent day Phoenix. These canals were builtby the Hohokam Indians in about 900 A.D.Their lands eventually became waterloggedand the only vestige of their occupation in thearea is the Casa Grande Monument. It is inter-esting to note that by 1911, with the completionof Roosevelt Dam, the Salt River Valley wasagain developed for irrigation. Drainage soonbecame a problem once more! In 1918, a studyby James Marr showed that pumping wouldlower the water table. By 1922 over 100,000acre feet of ground water was being pumpedand the drainage problem was eliminated.

"Other western irrigation projects quicklyevidenced a need for drainage remedialmeasures. The New lands Project it Nevada,the first project ever developed by the Bureauof Reclamation, became so waterlogged thatmuch of the land was unfit for cropping. M.R.Lewis and S;dney Harding made an investiga-tion which prescribed open drains to combatthe problem. Samuel Fortier and V.C. Conemade investigations of the drainage problemsin the San Joaquin Valley of California in 1905and 1906. As a result, from 1907 to 1922, theModesto Irrigation District spent $356,000 toconstruct an open, gravity system for 45,000acres. Later they resorted to pumping fordrainage, installing 77 wells. The pumpedwater was used to irrigate additional acres ofland. W. L. Powers made investigations ofmethods for draining the marsh lands ofWestern Oregon in 1916-18. At the same timeDean Bloodgood demonstrated that pumping fordrainage in the Mesilla Valley of New Mexicowas successful.

"Perhaps the grand-daddy of all drainage prob-lems in the early days of the irrigated westwas the Imperial Valley of California. Irriga-tion was first brought into the valley in 1901

v5

from the Colorado River. A U.S. Department ofAgriculture Soil Survey of 1902 called attentionto the potential drainage hazard. In 1908 C.E.Tait recommended the need for drainage reme-dial measures on some of the waterloggedareas. By 1919 some 200,000 acres were insome degree affected by high water tables andsalt accumulation. In 1921, the Imperial Irriga-tion District started construction on an opendrain system costing $2,500,000. This systemwas only partially successful but it did providean excellent outlet system for the subsequenttile drainage systems on the individual funs.In 1929 the District purchased a tile layingmachine and installed the first 5 miles of tiledrains. Subsequently drainage contractorscame into the Valley to perform this service.For many years over 200 miles of drains wereinstalled each season. Today over 80 percent ofthe cropland is tile or tube drained.

"Almost all of the Bureau of ReclamationIrrigation Projects have had to provide fordrainage remedial measures. Projects such asthe Columbia Basin in Washington, the GrandValley (Nebraska), Big Horn Basin (Montanaand Wyoming), Oahe (South Dakota), WeberBasin (Utah), Garrison (North Dakota), BigThompson (Colorado), have all had drainageproblems as a consequence of irrigationenterprise."

Materials and Methods forSubsurface Drainage

The first use of clay tile for underground farmdrainage in the United States is attributed to JohnJohnston, a native of Scotland who lived in theFinger Lakes region of New York State, nearGeneva. Weaver (1964) records that Johnston im-ported patterns for horseshoe-type drain tile fromScotland in December 1835. Tiles were made fromthese patterns at the B.F. Whartenby pottery atWaterloo, New York, in 1835. The first tiles weremade entirely by hand out of plastic clay rolled intosheets about a half-inch thick. These sheets werecut into rectangles of the desired size and bent overa pole in the shape of a horseshoe; they were allowedto air-dry and then baked in a kiln.

Clay Tile Fabrication

A crude molding machine installed in the Whartenbyfactory in 1838 made the process of making tilemuch cheaper and faster. Then, sometime after 1851,

19

John Dixon developed a much-improved machine formaking horseshoe tile. Dixon also introduced numer-ous other improvements in tilemaking. In 1866, heinvented the Down Draft Inside Flue tile kiln.

Another new method of tilemaking appeared in the1870's that did not use a conventional mold. Itemployed a rectangular slab of clay, which waspressed around the lower part of the workman's legto form a horseshoe tile. The piece was then air-dried and baked in a kiln. Quite naturally it came tobe called a shinbone tile.

Around 1875, pipe-tiles were made by forming theclay mortar around a pole. A pole of the desireddiameter for the inside of the pipe was covered byabout a half-inch layer of clay mortar and thensmoothed to a circular outside shape. The pole waswithdrawn and the resulting pipt,s then cut to thedesired lengths, cured, and baked.

The first tilemaking machine, the "Scraggs" wasbrought to America in 1848 from England. Thismachine operated on the extrusion process. Manylocally manufactured tilemaking machines followedthe Scraggs machine. Most of these early manufac-turers were located in New York State. These newmachines increased the efficiency of production ofclay tile and reduced its cost, an important factor inspreading the use of tile drainage. The manufac-tured clay tile might be a horseshoe tile; a circulartile called a pipe tile or pipe drain; or a sole tile.The latter was circular with an attached plate orsole. Tile lengths varied from 12 to 15 inches.Weaver (1964) listed advertised tile prices in theperiod 1849-62 for 1,000 pieces as follows: 3-inchhoresehoe tile at $10.00 to $12.50 and 4-inchhorseshoe at $12.15 to $15.00; 3-inch pipe tile at$14.00 to $15.00 and 4-inch pipe tile at $16.00 to$40; 3-inch sole tile at $16.20 and 4-inch sole tile at$20.25. The price of plates for horseshoe tile wasabout $6.00 to $8.00 per 1,000. These prices wereat the factory; when shipping charges were added,the average total cost was around $25.00 for 1,000pieces. Trenching costs generally varied from 12 to14 cents per rod (16.5 feet).

From these beginnings, the manufacture and installa-tion of tile spread westward. By 1882, the numberof tile factories had increased rapidly, with 486 inIndiana, 320 in Illinois, 230 in Ohio, 63 in Michigan,18 in Iowa, and 13 in Wisconsin. By 1867, thecenter of tile manufacture had moved from the eastto the Midwest (Weaver, 1964). By 1867, Ohio pro-duced over 2,000 miles of drain tile per year, mostlyfrom 500 steam-powered tile plants (Alpers andShort, 1966).

20

1

i

- -

e

Figure 2-3A Newton County, Indiana, farmer carefully positionsspade to take out the top cut in a drainage ditch.

Concrete Tile

Weaver (1964) also wrote of some early uses of con-crete for subsurface drainage. In 1862, DavidOgden developed a machine for making drain pipesfrom cement and sand, This machine could makepipe with an inside diameter of 2-1/4 inches to 24inches. Another idea used was to place concrete inthe trench around a glass liner. The liner was 1-3/4inches in diameter and 22 inches long. By 1881, con-crete tile was maunfactured in place by means of asimple machine operated in a properly graded ditch.Cement mortar was fed into the machine through ahopper. It came out of the machine as a continuouspipe, smooth inside and out. The pipe was cut intoany desired length in such a way that the bottomwas left continuous, yet sufficient crevices were leftfor the entrance of water.

Until 1900, concrete drain tile was used primarilywhere good clay was not available. A concrete tileplant could be built for a fairly small investment. Atfirst the industry was largely confined to scatteredplants operated by individuals. Some operators lackedprevious experience in drainage or in the manufac-ture of concrete products, and the result was poorquality tile. This was generally due to skimping on

j 6

the amount of cement, to using of dirty or improperlygraded sand and gravel, or to inadequate curingfacilities. However, many large manufacturers ofconcrete sewer pipe made good-quality drainagePipe.

In the 1950's, when ACP permitted cost-sharingpayments for underground tile drainage, the tilehad to meet American Society for Testing Materials(ASTM) specifications. This rule and related ed "a-tional activities were important in assuring themanufacture of good-quality clay and concrete tile.For example, Miller and Manson of the Universitycf Minnesota recommended that where soil acidsand sulphates were a problem, the concrete tileshould be made with a cement having high sulphateresistance. Figures 2-3, 2-4, and 2-5 show some tile-laying operations typical of 1940.

Fiber and Plastic Tubing

In the 1940's, bituminized fiber pipe was used insome locations, especially in the Eastern States.Early-generation plastic tubes were also introducedfor subsurface drains. But because these had to bethick-walled to provide proper bearing strength,their cost was not competitive with clay or concretetile.

Figure 24Workers lay 6-inch tile in New York State.

r:.,p7;r 'At4

.4

Figure 2.5With mechanical help, workers lay tile. Etc; is blinded overthe title joints to reduce siltation in sandy soil to improve drainage.

By the early 1960's, corrugated plastic tubing wasmanufactured from polyvinyl and polyethyleneresins. The corrugations provided sufficient bearingstrength to allow a thin-wall configuration, and alsoat a competitive cost. When buried, this tubing wasnot subject to deteriorction from ultraviolet rays,acids, or alkali solutions. It could De extruded in acontinuous tube and packaged into a lengthy coil.Very light and flexible, it drastically reduced han-dling and shipping costs, and tile alignment prob-lems were avoided.

As the demand for corrugated plastic tubing in-creased, many large tile manufacturing plantsclosed. Some converted to making tubing or brick.The high cost of operating and rebuilding thesmaller plants caused most of them to close or con-vert to making small-size corrugated plastic tubing.As most subsurface drainage systems presently be-ing installed involve the use of corrugated tubing,its evolution and uses ate discussed at more lengthby Fouss and Reeve in the next chapter.

Drain Envelope Materials

Soil particles entering and clogging subsurfacedrains have been a problem since the beginnings of

21

tile drainage. In an early drainage textbook byFrench (1859), a recommended method of preventingdraip sedimentation used double-walled or sheatheddrains with collars; a second method surroundedthe drain with clean, fine gravel. Over the years,envelope materials used for surrounding subsurfacedrainage conduits have included many kinds ofpermeable porous materials that are readilyavailable in large quantities and are relativelyeconomical.

According to Willardson (1974), the primary pur-poses for the drain envelope are: (1) to prevent themovement of soil particles into the drain which maysettle and clog the conduit; (2) to provide material inthe immediate vicinity of the drain-wall openingsthat is more permeable than the surrounding area;(3) to provide suitable bedding for the drainage con-duit; and (4) to stabilize the soil material on whichthe drainpipe is laid. Willardson also gives a detailedhistorical accounting of the various envelopematerials used and significant research findings.

The most common and widely used envelope materialsfor subsurface drainage are naturally graded coarsesands and fine gravels. Such materials are readilyavailable in many areas and are as permanent asthe soil particles themselves. Detailed proceduresfor designing gravel envelope filters for drains arespelled out in various standards and specifications,for example, Soil Conservation Service, Drainage ofAgricultural Land, USDA, SCS National EngineeringHandbook, Section No. 16, 1971; American Societyof Agricultural Engineers, Engineering Standard No.EP302.2 on Design and Construction of SubsurfaceDrains in Humid Areas (1983); and Land DrainageTechniques and Standards, U.S. Bureau of Reclama-tion, Reclamation Instruction Series 520 (1966).

Most of these standards provide criteria and pro-cedures to design a sand and/or gravel drain enve-lope with the proper particle size distribution toimprove permeability around the tile and to preventsedimentation for various soil types and installationconditions. For example, Section 16 in the SCSHandbook above recommends that all of the enve-lope material should pass through a 1-1/2-inch sieve,90 percent of the material should pass through a3/4-inch sieve, and not more than 10 percent shouldpass a No. 60 sieve. If the envelope also serves as afilter to stabilize soil material and prevent sedimen-tation, further specifications are given. These in-volve obtaining a sample of soil from the depth thatthe draintile is to be in-talled and conducting amechanical analysis to determine the distribution ofsoil particle sizes. Then the gradation of the designedfilter is made to match closely the base soil particle

22

size distribution. Much research has been conductedon this by the U.S. Bureau of Reclamation and theU.S. Army Corps of Engineers.

Some areas do not have natural sand and gravel foruse as envelope material. This has led to a searchfor manufactured materials that could be used assubstitutes. Fiberglass received the most attentionin research trials and field testing in the early1950's (Overholt, 1959). However, the fiberglasssheet had poor tear-strength properties and had tobe handled carefully during installation. In somesoils, the fiberglass material functioned more like afilter than an envelops, which resulted in the fabricclogging up with soil particles and prevented thedrain from functioning. Willardson noted that manyauthors used the word filter in referring to drainenvelopes. Willardson indicates "that a filter, bydefinition, would be self-defeating, because soilmatter will be deposited on or in the filter, therebyreducing the permeability." He said that porousmaterial placed around a subsurface drain shouldtherefore be referred to as a drain envelope(Willardson, 1974, p. 179).

Trenching for Subsurface Drains

Subsurface drains were first dug with show.its,followed by a combination of plowing and hand dig-ging (figs. 2-2 and 2-3). A breaking plow was used toplow a width needed for the trench depth, two fur-rows deep. The loose soil was shoveled out aftereach plowing. Next, a subsoil plow was used toplow to a depth of 24 to 36 inches, and the loosesoil was again shoveled out. This spading usuallybrought the trench to the required depth. With thismethod, two persons with a team of horses couldtrench 20 to 30 rods per day in good digging ground.

Probably the first revolving-wheel type trencherwas the Pratt Ditch Digger introduced around 1855.This horse-drawn machine consisted of a set ofblades mounted on a wheel, which elevated the soilloosened by a plow share and then discharged it toboth sides of the trench. Depending on ground con-ditions, this trencher could excavate 2 to 4 inches ineach pass of the trencher.

Following the Pratt machine, several other horse-powered machines were developed, but they all re-quired a number of passes over the trench to ex-cavate it to the required depth. Among these earlymachines were the Hickok and the Rennie elevatorditchers, patented in 1869. Another was the JohnsonTile Ditcher made in Ottawa, Illinois. It was drawnby eight horses, four abreast r revolving wheel

I$

Figure 2-3-0Id No. 88 proudlystands in retirement at GarwoodIndustries. Findlay, Ohio, as a re-minder of when the steam-powered Buckeye Ditcher cuttrenches throughout the Midwestand other States.

containing small spades first loosened the soil, thenelevated and threw it to one side of the ditch ateach pass of the trencher. It was claimed that thistrencher could cut from 100 to 150 rods of a 3-foottrench per day. By 1880. several types of theseditching machines were in use.

Single-pass machines powered by horses came next.One example was the Blickensderfer Tile DitchingMachine, manufactured in Decatur. Illinois. Thismachine consisted of a large revolving wheel withattached excavators or buckets mounted on a four-wheel frame. Curved steel teeth attached to, andprojecting beyond, the buckets loosened the soil.which was then lifted and worked out by a simplemanipulation of the revolving wheel. The power wasprovided by a single horse used upon a sweeparound the machine, which revolved the bucketsand at the same time moved the machine ahead.This ditcher could cut a trench 4 feet deep in onepass over the ground.

Another similar one-pass ditcher was the Heath'sDitching Machine that operated on a wooden track,powered by one horse on a sweep. There were alsoPaul's Ditching Machine and the Fowler DrainagePlow.

39

J. -t%3.*144.

The steam-powered Plumb Ditching Machine camein 1883, followed by the the Buckeye steam-poweredwheel-type trencher built in Ohio in 1892. It wascapable of cutting from 80 to 100 rods of a4-1/2-foot deep trench per day. Its cost was around$1,100. In 1908, steam power was replaced with a14-horsepower, one-cylinder horizontal gasolineengine with planetary reversing clutches. TheBuckeye Trencher (fag. 2-6) was doubtless theforerunner of the Cleveland (fig. 2-7) and today'shigh-speed trenchers and laser-controlled drainplows.

Mole Drainage

Mole drainage was another method of opening thesoil for subsurface drainage. This method wasrestricted to a relatively few locations wheremineral or organic soil conditions were mostfavorable for it, such as in Florida on fibrous peatsoils (Stephens, 1955). Various types of mole ditch-ers have been used but the early mole ditcherusually consisted of a steel cylinder (mole) with apointed end or nose. The mole was fastened to thelower end of a long sturdy cutting blade, much likethe standing colter of a plow. The upper end of thecutting blade was anchored to a plow-beam struc-

23

/111.-

Figure 2-7Capable of cutting a ditch 19 inches wide and 5.1/2feet deep, this Cleveland trencher works a 1940's farm in Maccles-field. North Carolina. Note the sight bar which helps the drivercontrol the grade.

ture attached to an axle with wheels. The moleformed a tunnel in the soil and packed the subsoilinto a fairly tight liner on mineral soils. Soil waterthat filtered in would often cause the wall to crum-ble and fill up the tunnel, requiring going over thefield again with the ditcher in orlar to provide con-tinued drainage.

According to Weaver (1964), the first mole plow inthe United States was introduced in 1867 in SteubenCouity, New York. However. in 1859. B. Briggs ofSharon. Ohio, used a machine much like a moleplow to lay tile without digging a ditch. Tile wasstrung on a rope and pulled into the mole tunnel asthe machine moved forward. This was probably thebeginning of today's mole-type machines that canpull in corrugated plastic tubing on grade.

Surface DrainageMeasures and Techniques

Surface drainage of fields, while commonplace. luisactually been one of the most neglected phases ofagricultural drainage. Shallow ditches have beenused since colonial days to remove surface waterfrom farm fields. However. the continuing problemhas been to get all the runoff water into the ditches.Even on subsurface drained fields, it has been

24

found that adequate surface drainage is alsonecessary. On flat. tight soils. v.here subsurfacedrainage is not practical or economical. completesurface systems are needed.

Bedding and Field Ditches

Methods of surface drainage have changed alongwith other farming practices. Early settlers in theUnited States used "bedding" extensively in the flateastern coastal and lake areas. Bedding. using verylittle planning or design. involves working the fieldin narrow beds in such a manner that surfacedrainage would first be to the dead furrows. thento a collection ditch into the ,nain outlet ditch.

With the migration of farmers from the Eastern tothe Midwest States. surface drainage was generallyaccomplished by bedding or random ditch systems.Little thought was given to individual field surfacedrainage. The early methods were geared tohorsedrawn plows. cultivators. and harvesters.Depressions slow to dry were skirted early in theseason. then plowed and planted later. Farms weresmall at the time so there was generally plenty oftime to cultivate and plant piecemeal. As farmsbecame larger and more mechanized. these oldpractices hampered operations. Large. fast equip-ment required a good, smooth roadbed without wetdepressions or potholes.

In Louisiana. surface drainage of sugarcane landhas been practiced since the 1860's. Improvementsin the practice have continued. The system ennerallyinvolves lateral ditches. known as split ditches. con-structed with the slope of the land and usuallyparallel. When the capacity of these ditches isreached, they are intercepted by a cross ditch. Croprows are laid off parallel to the split ditches. Waterfro!, the rows is carried by small plow-made crossditches or quarter drains to the split ditches.Research on this method, known as the sugarcanesystem. has produced many important results(Stewart and Saveson, 1955).

In the early 1940's, ideas began- develop for plan-ning complete surface drainage systems for farms.The principle involved was to avoid letting waterstand by providing farm ditches to collect waterfrom the rows on fields and to keep it moving to anoutlet. In this way, it was possible to prevent theland from becoming wet and soggy and to allow thesun and wind to dry the soil as soon as possible aftera rat,:. After evaluating various research and fieldapplications of surface drainage. four basic surfacedrainage systems with design criteria v . recom-

40

mended in 1950. These principal systems were bed-ding, random ditch. cross-slope ditch. and parallelditch (Beauchamp. 1952).

Land Forming and Smoothing

By the mid-1940's, it became apparent a system ofditches like those described above could not easilydrain land with numerous small pockets, where0.ater is likely to pond because it cannot get to thesurface drains. The answer was to allow each croprow to carry its runcff to its outlet without erosion,ponding, or overtopping. This led to the idea of landforming, whereby the entire land surfaces aremodified by grading and smoothing.

Row drainage and land forming were studied andcriteria suggested by the research work of A.J.Wojta of the University of Wisconsin; L.L. Savesonof USDA's Agricultural Research Service (ARS); L.F.Hermsmeier and C.L. Larson in the Red River Valleyof Minnesota; and W. Harris of the University ofArkansas. In 1947, the SCS conducted field trialsand demonstrations of land forming in many conser-vation districts of the North-Central States. After1950, there was a sloe, but definite acceptance ofthis practice in the Midwest, East, and South. In1952, the practice was included for the first time inthe ACP National Bulletin as "Shaping or LandGrading to Provide Permanent Slopes Needed forSurface Drainage."

Water Table Control

Draining peat and muck soils and high water tableson sandy soils has always been a major problem.Drainage studies on organic soils were initiated inthe early 1900's. Another problem was overdrainage,followed by subsequent settling of the organic soilswhen a low water table existed over an extendedperiod of time (Stephens, 1955). The practice of con-trolled drainage began about 1930. This generallyconsisted of installing check dams with stop logswhich were raised or lowered to control the waterlevel in open ditches. The attempt here was to takeoff only that amount of water that was detrimental,keeping the water table as high as possible for thegood of the crop. The success of this method variedwith the amount and distribution of rainfall and theseepage of water into the controlled area. Studies ofearly controlled drainage were reported by Claytonand Jones (1941) in the northern Everglades ofFlorida and by Harker (1941) on sand and mucklands in Indiana. Figure 2-8 shows a water controlgate used in South Carolina.

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,44

Figure 2-8A water-control gate operates at capacity after heavyrains near Neggetts, North Carolina.

Complete water table control then came into use.This is a combination of controlled drainage andsub-irrigation, where the water table is raised bypumping water into the system. This practice can beused only where there is a sufficient supply ofirrigation water. In controlled drainage, water ispumped into subsurface drains or into open ditcheswith water-level control gates in the drain. Theseditches serve both as drainage outlets and irrigationwater inlets to a parallel subsurface system. Pump-ing can remove excess drainage water and also sup-ply irrigation water, thereby mainte.ining watertables at correct levels for optimum crop growth.

By the late 1940's, water table control was used inMichigan, Indiana, and Ohio. The spread of thispractice was aided greatly by farm electrificationprograms, because automatic controls could then beused for pumping on individual farms.

An early example of group action for water tablecontrol was a project in north-central Ohio knownas "Marsh Run." Started in the late 1950's, thisproject involved a number of landowners growingtruck crops in organic soil. Irrigation water wasprovided by pumping high stages of flow fromMarsh Run Creek into an above-ground reservoir.Early development and use of this practice inFlorida is noted by Stephens (1955).

Excavating Ditches and Channels

Improved methods for constructing large outletditches were important factors in the spread andefficiency of drainage. Ditches and channels, even

25

Figure 2-9A Schield Bantam backhoe cuts new ditches in ex-tremely wet soils on Edisto Island. South Carolina, in 1958. Thewide tracks and shoes allow the machine to straddle the ditch whilecleaning it.

the large ones. were first excavated by handtools,such as the ditching spade, round point shovel.scoop, and the wheelbarrow. Then horse- or ox-drawn plows came into use. With such methods.only ditches up to 5 feet deep with a bottom widthseldom exceeding 4 feet could be constructedeconomically. Often ditches did not provide thedrainage desired.

A more economical means for constructing largeopen ditches was sought. It was only after the in-vention of power machinery, especially the dipperdredge. that land reclamation could be conductedon a large scale. Gain and Patronsky (1973) notedthat in 1883 the first mechanical excavator was usedby the Mason and Tazewell Special DrainageDistrict in western Illinois. A 14-1/2-mile main chan-nel was constructed with a steam-driven floatingdipper dredge. This dredge was similar in principleto a manpowered dredge used on the Seine River inParis some 200 years before. The steam-poweredshovel was mounted on a wide barge hull supportedby vertical spuds to prevent tipping. This equipmentwas said to have revolutionized drainage construc-tion methods.

A bank spud was developed later for this type ofdredge to reduce the required hull width. Orange-peel and clam-shell buckets replaced the shovelwhen dredges operated in soft material because ofthe longer boom that could be used for a widerreach. By 1900, steam-driven floating and landdredges had become the most economical ditch con-struction equipment.

26

Figure 2-10Ttis group drainage ditch, formed through draglineconstruction, replaces an inadequate and obstructed 24-inch tileoutlet. The new ditch serves 900 acres on seven farms nearGnffin, Ohio.

A drag-type scraper was first introduced in 1903 inthe construction of the Hennepin Canal nearChicago. In 1906, it was followed by the draglineexcavator. using a drag-type scraper. The draglinesoon became the universal ditch excavator becauseit could be made in many sizes for small or largeditch excavation and also permitted the use of wideberms (figs. 2-9 and 2-10). Later the dragline wasshifted from steam power and was mounted oncaterpillar tracks (Wooten and Jones. 1955).

The crawler tractor has played an important part indrainage work. The crawler was introduced inmany locations by the Civilian Conservation Corpsin about 1935. It quickly came Into common use fordrainage. The crawler was generally used for level-ing ditch spoil banks and in constructing V- andW-shaped and wide-bottom flat ditches for opendrainage systems. Bulldozers, large carryalls. andother similar tractor equipment have been used forlevee construction and foi land grading (Sutton.1957).

On 4 farm scale. figure 2-11 shows the constructionof a shallow flat-bottom ditch with flat backslopes,

5,4tV",77...kre

-Figure 2-11The author drives tractor-drawn scraper to shape a flat-bottomed farm drain in Wisconsin.

using a small carryall Scraper drawn by a farmtractor.

Pumping for Drainage

A most important and far-reaching advance indrainage technique was the development and use ofefficient equipment for drainage pumping and watercontrol. Pumping was essential where it was notpossible to have a complete gravity flow outlet.Pump projects have reclaimed much swamp andoverflow land which otherwise would be of littlevalue for farming. In coastal areas, pumping may beused in conjunction with tide gates (fig. 2-12).

The drainage wheel, operated by animal power,was first used on the plantations along the gulfcoast, especially on sugar plantations. At mit 1850,pumps began to be used. As the projects oecamelarger. low-lift centrifugal pumps gradually re-placed other types. The wood screw pump wasdeveloped in 1915. Other types of pumps were thepropeller or axial flow. mixed-flow pumps, centrifu-gal pumps, and the deep-well turbine pump used inirrigation (Wooten and Jones, 1955).

River bottoms, lake and coastal plains, peat land,and irrigated lands are the main types of landdrained by pumps. In the early 1900's, the Corps ofEngineers began constructing levees along manynavigable rivers on a district basis. This made itpossible to drain millions of acres of bottomlandalong the Mississippi, Missouri, Red, Arkansas,Illinois, and other major rivers. Levees were built toprotect the land or district facilities from river over-flow. Diversion channels and creeks with tie-backlevees diverted hill water from the bottomland.Open ditches and tile collected the interior waterand conducted it to the lower end of the district.

Pumping plants then lifted the water over the leveesinto the rivers (Sutton, 1957).

Pumping was used widely in the Mississippi Deltaand the coastal areas of Louisiana and Texas wherelevees and pumping lifts were lower than in theupper Mississippi Valley. Because of this, most ofthe pumps were axial-flow; some centrifugal pumpswere also used. The pumps were powered by inter-nal combustion engines or electrical motors. Pumpdrainage increased greatly after 1940. According tothe Census of Agriculture, 172,000 acres wereserved by pumps in Louisiana in 1950.

In Florida, most of the land served by pumps is inthe Lake Okeechobee-Everglades area. Prematureattempts at drainage began about 1880. Intensivedrainage operations began in 1906, and by 1928,

.nt

'4 V*

S.

Figure 2-12The tide is out in Seaside, Oregon, so the tide gatesopen to drain water off the land.

27

reversible pumps were necessary to pump waterfrom the fields in wet seasons and then from thecanals into the fields during dry seasons. Most ofthe pumps were of the axial flow or propeller type.In 1950, pumps served 293,000 acres in Florida(Stephens. 1955).

Most of the river drainage and levee districts in theupper Mississippi Valley also operated pumpingplants and found them to be essential to drainagework. Most of the pumping districts, particularlyalong the Illinois River, were established after 1905.The pumps of the early districts were generally toosmall and were supplemented or entirely replacedby new ones. By 1950, the area served by pumps inIllinois was 315,000 acres, in Missouri 67,000 acres,and in Iowa 82,000 acres (Sutton, 1955).

Before 1914, all pumping districts in the upperMississippi Valley used steam engines as a sourceof power. Between 1914 and 1918, all new pumpingplants were equipped with electric motors, andsome of the old steam plants changed to electricpower. The first diesel engine was installed in 1928.Diesel power was then used in most new installa-tions and in many old plants (Pickels, 1929).

Interest in small, individually owned pumping plantsincreased after the early 1940's. They were usedprimarily where there was no gravity outlet for sub-surface drains within the farm boundary. The outletditches in many locations were not deep enough toprovide adequate drainage. This type of pumpingcould often replace long tile mains or long deepoutlet ditches. In many cases, pumping allowedlandowners to proceed on their own without waitingfor district or group action. Individual farm pump-ing was also used in a water table control system.An example is the low land near the Great Lakes.High lake levels often kept outlets from functioningand caused crop losses. Because pumping lifts wereusually low, propeller-type pumps were generallyadequate. Progress in the development of onfarmpumping was due mostly to the wide availability ofelectricity on farms by the mid-1950's, along withimproved efficiency of tractors and internal com-bustion engines for power.

References

Alpers, R. J., and T. N. Short. 1966. Clay Draintileand Its Use. Proceedings of the ASAE NationalDrainage Symposium. Am. Soc. Agr. Engr., St.Joseph, Mich.

28 44

Beauchamp, Keith H. 1952. "Systems of SurfaceDrainage of Tight Soils," Agricultural Engineering.Vol. 33, No. 4 (April).

Clayton, B. C., and L. A. Jones. 1941. "ControlledDrainage in the Northern Everglades of Florida,"Agricultural Engineering. Vol. 22 (August).

Darby, H. C. 1940. The Draining of the Fens. Cam-bridge, England: Cambridge University Press.

Donnan, William W. 1976. An Overview of DrainageWorldwide. Proceedings of the Third National ASAEDrainage Symposium. Am. Soc. Agr. Engr., St.Joseph, Mich.

Gain, Elmer W., and Richard J. Patronsky. 1973.Historical Sketches on Channel Modification. ASAEPaper No. 73-2537. Am. Soc. Agr. Engr., St. Joseph,Mich.

Harker, David H. 1941. "Controlled Drainage," Agri-cultural Engineering. Vol. 22, No. 4 (April).

Harrison, Robert W. 1961. Alluvial Empire: A Studyof State and Local Efforts Toward Land Develop-ment in the Alluvial Valley of the Lower MississippiRiver. Little Rock, Ark.: Pioneer Press.

Hay, Ralph C., and John B. Stall. 1976. History ofChannel Improvements in an Illinois Watershed.ASAE Paper No. 76-2506. Am. Soc. Agr. Engr., St.Joseph, Mich.

King, James A., and W. S. Lynes. 1946. TileDrainage. (4th edition). Mason City, Iowa: MasonCity Brick and Tile Company.

Miles, Manley. 1892. Land Drainage. New York:Orange Judd Company.

Overholt, Virgil. 1959. "Fiberglass Filter for TileDrains," Agricultural Engineering. Vol. 40, pp.604-607.

Pickels, George W. 1925. Drainage and Flood-Control Engineering. New York: McGraw-Hill BookCompany.

Pickels, G. W., and F. B. Leonard. 1929. Engineeringand Legal Aspects of Land Drainage in Illinois.Bulletin No. 12. Illinois Geological Survey.

Soil Conservation Society of America. 1956. OurWater Resource. Des Moines, Iowa.

Stephens, John C. 1955. "Drainage of Peat andMuck Lands," Yearbook of Agriculture, 1955. U.S.Dept. Agr., pp. 539-557.

Stewart, K. V., Jr., and L. L. Saveson. 1955."Systems for Draining the Surface," Yearbook ofAgriculture, 1955. U.S. Dept. Agr., pp. 499-507.

Sutton, John G. 1955. "The Use of Pumps forDrainage," Yearbook of Agriculture, 1955. U.S.Dept. Agr., pp. 528-538.

Sutton, John G. 1957. "Drainage Developments Dur-ing the Past 50 Years," Agricultural Engineering.Vol. 8, No. 6 (June).

Sutton, John G. 1958. "Appraising Our DrainageJob," Land Improvement. Vol. 5, No. 4 (April).

van Schilfgaarde, Jan. 1971. Drainage Yesterday, .

Today, and Tomorrow. Proceedings of the ASAENational Drainage Symposium. Am. Soc. Agr. Engr.,St. Joseph, Mich.

van Veen, J. 1948. Dredge Drain Reclamation: TheArt cf a Nation. The Hague: Mortmas Nishoft.

Weaver, Marini M. 1964. History of Tile Drainage.Waterloo, New York: M. M. Weaver.

Wheeler, W. H. 1868. A History of the Fens of SouthLincolnshire. (Publisher unknown).

Willardson, Lyman S. 1974. "Envelope Materials,"Drainage for Agriculture (ed. J. van Schilfgaarde).Monograph No. 17. Am. Soc. Agronomy, Madison,Wisc.

Wooten, Hugh H., and Lewis A. Jones. 1955. "TheHistory of Our Drainage Enterprises," Yearbook ofAgriculture, 1955. U.S. Dept. Agr., pp. 478491.

Chapter 3

Advances in DrainageTechnology: 1955-85

James L. FoussAgricultural Research Service, USDABaton Rouge, Louisiana

Rona;d C. ReeveDrainage ConsultantColumbus, Ohio

Advances in agricultural drainage technology withinthe past 30 years are described in terms of changesand improvements in drainage conduit materialsand/or installation methods. Drainage technologychanged and modernized more during 1965-75 thanin the previous 100 years. Slow. inefficient installa-tion of heavy rigid conduit materials (clay and con-crete) gave way to light-weight flexible corrugatedplastic drain tubing installed with laser-beam-controlled high-speed trenchers and plow-typeequipment (Fouss, 1974; Reeve, 1978; Teach, 1972).

We accordingly review major technological develop-ments in materials and equipment, plus other tech-nology developed to design drainage and watermanagement systems through computerized simula-tion and design procedures (Skaggs, 1980).

Technological Challenges

The development of a rapid and low-cost techniquefor subsurface drainage has challenged engineersand inventors for centuries. Many ideas haveemerged, but very few have found widespread useor application. With the advent of the power trench-ing machine in about 1875, the goal of mechanizeddrain installation seemed to have been reachedandit lasted about 100 years. However, the extremelylarge amount of drainage work that was neededaround the world required even less labor, morespeed, and lower costs. Efforts to modify the moledrainage concept and installation methods wereparticularly important. The goal was to use the in-herent high speed of installation of mole drainage

30

r

and its elimination of relatively slow ditching andbackfilling operations associated with conventionaldrainage methods. Because the mole drain collapsedafter a short time in many soils, much of theresearch concerned stabilizing the mole channelwith structural support, using a tube or liner.

A second technological challenge involved develop-ing a means to design optimal agricultural drainagesystems on a probability basis that would properlyaccount for the spatial variations in the drained soiland the time variations in weather, as describedand rem mended by van Schilfgaarde (1965). Opti-mized drainage system design had long evadeddrainage engineers. With high-speed computers,substantial progress has been made in meeting thischallenge, thus providing another significant ad-vance in drainage technology.

Progress was also made possible in the drainageindustry because of technological developments inother industries and areas, such as plastic mate-rials, synthetic fabrics, construction equipment,electronic (laser) equipment, and computer Indus-tries. A number of the advances in these otherfields seer ngly came along just in time to meet theneeds of a developing new thrust in the drainagefield. Some of the innovations came about directlyin the drainage industry, but many were adoptedand/or adapted from developments originally in-tended for other purposes. Examples are heavyearth-moving machinery developed for construction,lasers developed for alignment tasks in civilconstruction, and synthetic fabrics developed by

Figure 3-1Eaton County, teshi-gan, workers haul palletize., liteon a "chariot" connected directlyto the tile machine.

the petrochemical industry for restraining land-fill areas and roadways in civil engineeringapplications.

Corrugated-wall plastic tubing, originally developedin the United States in the mid-1960's for under-ground electrical and telephone line conduit appli-cations was modified and perforated to serve as asubsurface drainage tube. Significant advanceshave been made in the manufacture and perforationof plastic tubing, especially as larger pipe sizeswere introduced. The high strength-to-weight ratioof the corrugated wall tubing, its continuous andcoilable length, corrosion resistance, nonbiodegrad-able characteristics, and structural performanceunder soil loading, made it an ideal and superiorproduct for the new subsurface drainage conduit.

Advances in Materials andMaterials Handling

Numerous innovations and improvements indrainage equipment and conventional draintilematerials handling were made during the 1960's.largely because of the rapid development of plasticdraintube products and the expected competition.Palletized handling was developed to replace piece-by-piece handling of clay and concrete draintile dur-

oi

-LS

ing manufacture, shipment, and installation. By themid-1960's, much of the clay, shale, and concretedraintiles installed (particularly in the midwesternUnited States) were handled on pallet, each contain-ing about 325 feet of tile. This packaging methodpermitted manufacturers to use forklift trucks tostore and load the tile for shipment, thus reducingcost and speeding operations.

Another improvement was t13 use of self-unloadingtrucks at the job site, thus reducing labor cost. Dur-ing installation, a chariot or wagon designed to haulone or more pallets was pulled alongside the movingtrenching machine. The tile sections were manuallyremoved from the pallet and placed into a tile-layingchute (fig. 3-1). The need for a person in the trenchcould be eliminated in some cases. Mechanized tilehandling reduced the work crew, but the maximumspeed of installation was still limited to the rate atwhich tile could be inserted into the tile chuteabout 25 feet per minute with one person and 50feet per minute with two people. The heavy weightof the loaded tile chariot also limited its use towhen the soil surface was fairly dry and tractionconditions good. Widespread ube of the palletizedtile handling decreased as plastic drain tubes wereintroduced and adopted in the early 1970's.

4731

SmoothWall Plastic Tubing

Polyethylene plastic tubing, a British development,was first manufactured in the United States inabout 1941. According to Schwab (1955), the Corpsof Engineers investigated the use of "perforatedplastic tubing" installed with cable-laying machinesfor airport drainage as early as 1946. Schwab'sresearch from 1947 to 1954 is the earliest knownuse of plastic draintubes for agriculture in theUnited States.' He conducted field experiments inIowa where smooth-wall polyethylene plastic tubesof various diameters and wall thicknesses werepulled into a mole-drain channel in clay soil with amole plow. Schwab indicated that it was necessaryto handle the smooth-wall plastic drain in 20-footstraight lengths because the tubing would kinkwhen coiled.

Fron: these early studies, Schwab developedguidelines on minimum tube-wall thickness forva:ious drain diameters to insure drain conduitdeflection of less than 20 percent of the originaldiameter. When inspected in 1966, 17 years afterinstallation, these drains remained in good condition(Fouss, 1968). The results from these pioneeringexperiments provided many of the technical back-ground data for the initial ASTM minimum re-quirements for plastic drain strength-deflectionstandards.

In the United States, smooth-wall plastic tubing wasnot used widely for agricultural subsurfacedi ainage, primarily because of its higher unit costand the greater material weight per unit length re-quirement as compared with other materials Endconfigurations. In the mid- 196')'s, limited use wasmade of 4-inch diameter, smooth-wall, polyethyleneplastic drain tubing in the Lower Rio Grande Valleyof Texas. The tubing was installed as deep as 6 feetwith a special narrow-wilnel trencher (Myers andothers, 1967; Rektorik and Myers, 1967).

In The Netherlands, De Jager (1960) conducted ex-periments with polyethylene tubas pulled into moledrains, but finally selected a narrow trenchingmachine to install 6-meter (19.7 feet) lengths of rigidvinyl plastic drain pipe. According to van Someren(1964), by the late 1960's, trenthed-in polyvinylchlo-ride (PVC) plastic drain pipes were used on up to COpercent of the installations in The Netherlands.

'The authors acknowledge this pioneering research of Professor

PlasticLined Mole Drains

Considerable international research was conductedfrom the late 1940's to the mid-1960's on the use ofplastic liner as a structural reinforcement for themole-drain channel. The results of this researchwere important in providing the foundation for sub-sequent investigative and developmental workleading to significant input to current drainagetechnology (Edminster, 1965). Janert (1952)developed a machine that formed and installed asemirigid vinyl plastic drain from rolls of sheet film.The plastic strip was heated to provide sufficientflexibility for forming it into a tubular drain. Theplow-type, drain-laying machine was constructedwith an inclined planelike digging blade whichopened a trench about twice the diameter of thedrain. Production models of this machine were soldin East Germany in the late 1950's, but its use wasnot widespread.

In the United States, Busch (1958) modified a moleplow for feeding a PVC plastic strip into a mole-drain channel and forming it into an arch-shapedmole liner. This research precipitated a series ofrefinements, modifications, and new developmentsby both American and British investigators. Atubular mole liner, formed from a PVC sheet, wasdeveloped in 1960 by a team at the CaterpillarTractor Company. Further studies led to the devel-opment and testing of the stronger zippered-typetubular PVC plastic mole liner (Fouss and Donnan(1962) in the United States and Ede (1963) and Boa(1963) in the United Kingdom).

Most of these early experimental plastic drainswere 2-1/2 to 3 inches in diameter. Materials han-dling for the plastic mole liner was exceptionally ef-ficient. For example, a 60-pound roll of 0.015-inchthick PVC sheet, 10 inches wide by 10 inches indiameter would form 600 feet of installed 3-inchdiameter drain (lined mole channel). This was atruly remarkable materials handling advantage overconventional practice. Ede (1965) and Fouss (1965)reported that thin-walled plastic liners, although of-fering significant materials handling advantages,were not strong enough to withstand deformationunder long-term soil loading. Thus, the plastic-linedmole drain concept was not pursued further,primarily because of the appearance of the superiorcorrugated-wall plastic tubing which could be easilyplaced in a trench or a subsurface channel formedwith plow-type equipment.

This early research on plastic-lined mole drainsSchwab and his generous help in reviewing this chapter. demonstrated the need for a systems approach in

32

4: 8

developing new drainage methods. The drainagematerials, materials handling, and installationequipment required integrated system developmentto minimize cost and also to ensure compatibilityand operational efficiency for high-speed installa-tion of subsurface drainage systems.

Corrugated Plastic Tubing

By the mid-1960's, almost all the research and develop-

merit on drainage materials and methods of materialshandling had begun to focus on corrugated-wallplastic tubing, primarily because of the advantagesof low material requirement versus high-strengthratio and flexibility for ease of handling. Continuousextrusion and molding machinery for manufacturingthe new plastic tubing had been perfected earlier inGermany. Underground drainage with the new conduit(about 2 inches in diameter) caught on rapidly inGermany and soon spread to other regions of Europe.The first U.S. uses of corrugated plastic tubing werefor underground electrical and telephone conduits.

Applications in Agriculture

Research in the United States on developing poly-ethylene corrugated plastic tubing, of 3- and 4-inchdiameters, for agricultural subsurface drainagebegan in 1965 (Fouss, 1965, 1968). The corrugated-wall tube structure developed for polyethyleneplastic (fig. 3-2) provided high strength to resistradial type loads such as from over-burden soil, butwith a considerably reduced requirement for wallthickness as compared with smooth-wall tubing.

Figure 3-2--Tube-wall corrugationfor polyethylene plastic drainagetubing.

Both tubing unit weight and unit cost are reducedsignificantly by corrugation.

The cost of corrugated tubing is almost directly pro-portional to tubing weight. The longitudinal flexibil-ity of the corrugated-wall tubing (a desirable quality)made it coilable for ease of handling, but the coil-ability characteristic also made it stretchable (likean accordion). Thus, a compromise in design of cor-rugation shcpe was necessary, and special mate-rials handling prccedures were needed. (The readeris referred to Fouss (1973, 1974) and Fouss andAltermatt (1985) for detailed discussions on optimaldesign procedures for corrugated plastic.drainagetubing for resistance to both deflection and stretch.)

By 1967, corrugated plastic drainage tubing wasbeing manufactured commercially in the UnitedStates for the agricultural market, and the new in-dustry grew rapidly (Fouss, 1974; Reeve and others,1981). By the mid-i970's, corrugated plastic drain-age tubing had wide acceptance for agriculturaldrainage, highway berm drainage, septic tank leachfield, and construction site applications. By 1983,95 percent of all agricultural subsurface drains in-stalled annually in the United States, and more than80 percent in Canada, were corrugated plastic tub-ing (Schwab and Fouss, 1985).

Tubing Standards

Specifications and performance standards weredeveloped during the early 1970's for these newdrainage products under the auspices of ASTM.

t tube

33

which involves voluntary and cooperative effortsamong industry, government, and public groups.This resulted in an ASTM Standard DesignationF405 entitled 'Standardization Specification for Cor-rugated Polyethylene Tubing" (ASTM, 1974). Amajor step in the development of this standard wasthe recognition by the cooperating groups that cor-rugated plastic tubing is a flexible-type conduit withproperties substantially different from the classicalrigid draintile such as clay, shale, or concrete.

Under field conditions, a flexible conduit gains moatof its vertical soil load-carrying capacity from thesupport provided by the soil compressed at the sidesof the conduit (Watkins, 1967). The density of thissidefill material is the key element in load-carryingcapability of the pipe-soil composite structure. Thesidefill material provides lateral support to the con-duit to give it more rigidity and acts in combinationwith the conduit to form a vertical load-carryingarch (Watkins and others, 1983).

During the early marketing stages of this new pro-duct in the United States, a sand-box test was de-vised as a quality standard (Herndon, 1969). Theinadequacy of this test as a product standard wassoon realized because of the interaction of the pipewith the sand envelope material. As recommendedfrom research (Sorbie and others, 1972), a parallelplate method for measuring the deflectionresistance of the corrugated plastic tube wasdeveloped as an integral part of the ASTM F405standard (fig. 3-3). This standard was developed toprovide minimum values for physical and chemicalproperties EtF.N-lated to product performance,including hanoung and installation. Minimum deflec-tion resistance is specified for 5- and 10-percentdeflection of tubing diameter. The staridard also in-cludes a requirement on elongatio,i (stretch) resis-

Figure 3-3Schernatc of parallel-plate, load deflection n'o,,P0,-.;testing flexible plastic drainagetubing.

34

tance, which limited elongation to 5 percent when aspecified tensile load is applied. Finally, in a 1978revision of the standard, a falling "Tup" impacttest, conducted at a cold temperature, was specifiedto detect brittle or poor-quality plastic resin.

Fabrication and Marketing

Water entry openings are made in the corrugateddramtube wall during the manufacturing operationby punching or drilling holes, sawing short narrowslots, or other means of perforation. Typically, theopenings are formed in the corrugation roots(valleys) rather than on the crowns (outside diam-eter), and are positioned in three or more rowsalong the length of the tubing. The cross-sectionalarea of openings for water entry to the drain variesamong manufacturers, but ranges from 1 to morethan 7 square inches per linear foot of drain. ASTMStandard F405 requires a minimum of 1 square inchper linear foot of pipe. Because the drainwall open-ings are controlled in the manufacturing operation,the quality of installation improved significantlywith corrugated tubing compared with ceramic tile.The crack spacing between ceramic draintile sec-tions had to be controlled during installation, thusgiving rise to great variability in drain qualityamong contractors.

The use of corrugated tubing greatly reduced laborand energy requirements in drainage materialshandling. Initially, the typical 4-inch diameter tub-ing used for laterals was supplied in 250-foot coiledlengths and weighed about 80 pounds. This com-pared with a weight of about 2,000 pounds for clayor concrete tile of the same size and length.

As the demand of, and use for, corrugated plasticdrainage tubing grew in the United States, contrac-tors desired larger and larger coils to make the

50

1.4- range of -1linear deflection

Figure 3-4It takes heavy-dutyhauling to move this 5,000-footjumbo-coil of 4-inch diameter cor-rugated plastic drainage tubing.Insert shows a 3,000-foot maxi-coil.

materials handling operation even more efficient. In1984, typical coil sizes available for 4-inch tubingwere 3,000-foot "maxi-coils" and 5,000-foot "jumbo-coils" (fig. 3-4). The 250-foot coil is still commonlyused for many small agricultural jobs, for industrialinstallations, and around housing projects. Severaltypes of self-loading trailers and wagons becameavailable to string tubing in the field (fig. 3-5). Asillustrated in figure 3-6, special reels were devel-oped for mounting directly onboard the drainageequipment to uncoil the tubing RS it was installed(Fouss, 1982; and Fouss and Altermat, 1982).

Most of the early corrugated plastic drainage tubingwas black, but by the mid-1g70's, tubing was pro-duced in lighter colors such as white, yellow, gray,and re i. Ultraviolet stabilizers and antioxidantswere incorporated in the plastic resin to increaseits resistance to weathering when tubing was stored

",'-,1_-,-;:dia.":7_=6-..--''''''''''' --""--

outside and exposed to sunlight. The lighter colortubing was developed partially for marketing pur-poses, but improved performance during handlingand installation was also realized because strengthand stretch resistance were maintained, even whenexposed to the hot sun. The darker tubing was moreprone to absorbing the sunlight which elevated thetube-wall temperature, thus reducing the tubing'sstretch resistance during handling and installation.

Use of the maxi-coils and special reels for stringingtubing reduced tubing stretch problems during in-stallation, even for black tubing on hot, sunny days.The 2-percent carbon-black used as the ultravioletlight inhibitor in black tubing is superior in perform-ance and lower in cost than the lighter pigments,permitting outdoor storage of the product. Thepower tubing feeder designed to eliminate thenatural stretch-producing drag at the top of the tub-

Figure 3.5(left) A farmer tows a trailer that uncoils 3,000-foot maxi-coils. A wagon stands readyto install 250-foot coils of 4-inch diameter plastic drainage tubing.

35

Figure 3-6Four-inch diameter plastic tubing is wound on its self-loading. machine-mounted reel.

ing chute was one of the most significant develop-ments in minimizing the adverse effects of stretch.

Diameters of corrugated plastic pipe increased fromthe original 4 inches in the mid-1960's to 24 inchesby 1982. Sizes up through 10 inches are commonlycoiled for shipment and handling. Drain sizes largerthan 12 inches are typically manufactured andshipped in 20-foot lengths. There is a noteworthymarket for 3-inch corrugated tubing, which istypically shipped in 350-foot standard coils, or5,000-foot coils. Interest in 3-inch diameter tubingwas greatest during the 1973 world oil shortage,but by 1984 the 4-inch tubing was considered theminimum tube size for lateral drains in many areasof the United States and Canada. A 5-inch diameteris specified as the minimum-size lateral drain inIowa; in Minnesota, a 6-inch drain is the preferredminimum.

Corrugated plastic tubing larger than 12 inches indiameter is generally more expensive than thesame-size clay or concrete tile, but the marketdemand and use for the lighter and easier to handlecorrugated plastic is increasing significantly. Theselarge-size corrugated concia!ts (12-24 inch) are alsoused extensively for culvert applications (Wctkinsand others, 1983), which was an area formt'rlythought to be reserved for concrete and steel pipe.The noncorrosive nature of the product and theadvances in the structural performance of plasticsfor this use are milestones in the drainage industry.

Synthetic Drain Envelope Itetarials

The technology of sand and gravel envelopes, in-cluding the particle size relationship betweenenvelope and base material had been developedduring 1930-60, and applied not only to minimizesedimentation, but also to drain stabilization and

36

alignment. Also, the machinery and the mechanicsof applying gravel envelopes of uniform thicknessaround the subsurface drains were developed andused extensively in the Western United States(Luthin and Reeve, 1957; Willardson, 1974).

There are distinct advantages in the pe:formance ofsand and gravel envelopes over thin membranes.Where envelopes are installed in very unstable basematerials, drain stabilization, as mentioned before,is a major advantage. The much greater thicknessof the granular envelope also provides free three-dimensional flow in the immediate vicinity of thedrain, thus minimizing entry head loss. Dutch scien-tists and engineers have used thick fabric and fibermaterials, but decreased flow resistance has oftencome at the expense of effectiveness in restrainingsediments.

Most of the synthetic materials that have been usedfor drain envelopes have been of the "thin-membrane"type. Ti. primary reasons for the development ofthin-membrane envelopes are: (1) the lack of readilyavailable and suitable sand and gravel envelopematerials in many of the drainage areas of thecountry, (2) the advent of strong durable, nonbio-degradable fiber materials, (3) the much reducedcost and reduction in labor-installed synthetics, and(4) the increased control of quality from preapplica-tion of the envelope to the pipe before installing inthe field.

Although gravel envelopes have distinct advantages,the cost is generally prohibitive in areas wherenatural gravels are not readily available. For thisreason and for the fact that thin-membrane fabricsare easily handled and installed, especially in con-junction with plastic corrugated pipe, syntheticenvelopes have become widely used throughout themajor drainage areas of the Midwest and East.

With the rapid and widespread use of corrugatedplastic drainage tubing in the United States andCanada, the development of synthetic fabrics asenvelopes to protect these drains against sedimenta-tion advanced rapidly. Because subsurface drainenvelopes are used primarily to protect the drainfrom the inflow of sediment and still maintain freeopen flow of gravity water into the drain, thedevelopment of envelopes has been mostly centeredaround the performance of thin membranes withfine sand and coarse silt-size particles (0.005-0.125mm). Understanding of the basics and developmentof improved practices in the use of drain-syntheticenvelopes have both advanced significantly in thepast two decades.

The terminology of drain envelopes is still in a stateof flux. But the term "envelope" seems to be pre-ferred to the term "filter" because filter commonlyrevers to a filtering action, where the associatedbuild-up of a "filter-cake" on the membrane woulddefeat the purpose of a drain envelope (Willardson,1974; Reeve, 1978b, 1979, 1982).

Fabrics that were developed by several major worldchemical and oil companies for other engineeringapplications were readily available from the 1960'sthrough the 1980's and thus gave a boost to the useof these materials for subsurface drain envelopes.From among the many materials that have beentested, polyester, nylon, and polypropylene werecommercially available in North America and havebeen used most widely for this application. Whilewoven, knitted, and spun-bonded productions of theabove materials have been used, the most commonlyused products from among these are knitted poly-ester (sock), spun-bonded nylon (CerexTh, Drain-guardTm), and spun-bonded polypropylene (TyparTM,Rema yTm).

By the late 1970's, as much as 8 percent of the cor-rugated plastic drainage tubing installed had a syn-thetic fabric envelope. These synthetic envelopesare light in weight and compact for ease of handlingduring transportation and installation. They arealso relatively low cost compared with sand orgravel envelopes. The synthetic fabrics may beplaced directly onto the tubing during manufactur-ing, or the envelope is placed on the tubing duringinstallation.

Standards end specifications for the syntheticfabric envelope or filter materials were still notdeveloped by late 1984, even though such productshad been in use for about 15 years. Developing suchstandards is complicated by the many variables in-volved in installation and hydraulic variables en-

countered in the field. Research has been condu.,..tedto determine why fabric materials plug up in somesoil types, particularly in clays and silty clay loams,but results have not been definitivt.. In other caseswhere the fabric mesh size is too large and the sedi-ments are extremely fine, such as in very fine sandandfor silt loams, envelopes fail by allowing excesssediment to pass through the fabric and into thedrain tubing.

In 1977, Broughton and others conducted extensivefield and laboratory tests on a large number of themajor commercial synthetic products, primarily :nsandy-type soils. They reported significant reductionin drain outflow during the first 1 to 3 months afterinstallation of most products and attributed theprobable cause to the "fine soil particles within thesand forming a filter cake in the soil outside thefilter material." A similar reduction in outflow ratewas reported for a coarse sand envelope, but thesustained peak flow rates after 2 years were muchhigher for the sand envelope than for the syntheticfabrics.

The performance of a thin-membrane envelopedepends primarily on the conditions of the soil atthe time of installation, the imposed hydraulics onthe system, and the installation practice itself.Failures are more likely where the conditions aree7 .nnely wet, where the soils are unstable andStx...Jet to "quick" conditions, and where the initialhydraulic head imposed on the drain is much higherat installation than will likely ever occur again oncethe drain is functioning and the water table hasbeen drawn down. Drains installed with envelopes,even in very fine sandy or silty soils, have per-formed satisfactorily when installed where thewater table had been low, the surface soil had beendry for better machine operation, and no excesshydraulic heads had been imposed on the systemduring installation. After the drain is installed andfunctioning, the soil in the vicinity of the drainstabilizes and the hydraulic head at the drain thenbecomes a function of head conditions as modifiedby the head loss or resistance to flow in the soil.

Experience and research have shown that favorableinstallation conditions and extreme care on the partof the contractor are both very important to thequality and proper functioning of drains with thin-membrane envelopes.

Willardson (1974, 1979) has advanced the conceptof excessive hydraulic gradients in the syntheticenvelope material as a contributing cause for plug-ging or sedimentation failure. Broadhead, Schwab,and Reeve (1983) have reported on a laboratory

5337

evaluation procedure that tested the soil particle-size distribution to determine the suitable openingsizes for tilt, synthetic drain envelope. They alsotested noncohesive sandy soils and showed thatdrain sedimentation can be prevented by selectingan envelope material with an effective opening ormesh size that is less than about 2.4 times thediameter of the 60-percent (D-60) size of the sandparticles.

An ASTM Task Force Committee used a laboratorytesting program with problem soils to evaluate thesuitability of various synthetic envelope materialsfor the purpose of developing a workable specifica-tion and standard. The Committee's work on com-mercial sy.:thetic envelope materials in the late1970's did not lead to conclusive results or a ten-tative standard, and thus the Committee wasdisbanded.

Drainage Equipment

Along with the rapid adoption of corrugated nlasticdrainage tubing worldwide, many significant La-provements and innovations were made in drainageequipment and materials handling methods. Of par-ticular significance was the development of newand improved methods for automatically controllingdepth and grade on modern high-speed installationmachines. By the mid-1970's, a totally new outlookwas given to installation and its cost, and many in-novative revisions were made in field operationalprocedures.

Trenching Machines

There are two basic types of trenching machinesused to install subsurface drainage: the wheel-type

Figure 3.7A high-speed trench-er on low-pressure rubber tireslays tubing.

38

54.

and the ladder- or chain-type. The wheel-typemachine remained essentially unchan, 4:1 in basicdesign for almost a full century (1850 to 1950) ex-cept for improvements in engines, power train.steering, and quality ana hardness of steel used inthe parts subject to wear. Drainage contractorsmade many of the design improvements to the dig-ging wheel mechanism, power plant, and tractionsystems. From about 1945 to 1960. almost al!trenching machines sold were first modified bycontractor-owners before they were put in service.Whereas track-type trenching machines were thestandard for many decades, rubber-tired. wheel-type trenchers were introduced in the early 1950'sand became popular among contractors. Therubber-tired machine could often travel, over publicroadways to the next job site, something not possi-ble with the earlier track-laying machines.

By thy 1960's, higher speed trenching machineswere :mend because of the greater ease ofhandlthe the corrugated plastic drainage tubing.The development of high-speed trenchers (those ca-pable of installing at least 50 feet cf drain per,ninute) became practical with the concurrent devel-opment of laser-beam automatic grade control.

The new generation of trenchers utilized super-charged engines and hydrostatic transmissiondrives. A modern high-speed wheel-type trencherand a high-speed ladder-chain-type machine areshown in figures 3-7 and 3-8. Figure 3-9 is abackfilling machine. There are several manufac-turers of thesG types of trenching machines (figs. 3-7to 3-12). Modern trenchers include five typicalfeatures: machine-mounted reels for coils of tubing,tube feeding and guiding devices, grooving devicesfor trench bottoms, blinding and backfilling attach-

3

Figure 3-8WorkerS place drainage tubing by using a high-speed,ladder-chain trenching machine.

Figure 3-10This trenching machine performs two jobs on a farmin Genessee County, Michigan. It installs drainage tubing and thenbackfills the soil.

r,

-ft

Figure 3.12This wheeltype trencher has an attached "shoe"which allows installation of deep drains, mainly for salinity control inCalifornia's Imperial Valley.

Figure 3.9A backfilling machine augers the soil back into theditch. A tile trencher had been used on this farm in EdgecombeCounty, South Carolina

Figure 3-11Wheel-type trenchers can lay tubing surrounded byan underground gravel envelope by using this machine.

Figure 3.13÷A California farm prepares for the installation of8 to 16-inch diameter drainage tile.

39

FigurW3-14:-A- drain ploW illit)Itilitalle corTugiieciplastic tubing in a gravel envelope. Coarse saidenvelope material is _recharged into a hopper at right

ments, and automatic laser-beam grade controlsystems. Special attachments have also beendeveloped to feed gravel envelope materials alongwith the corrugated plastic tubing (figs. 3-11 to3-13).

Estimates in the early 1980's indicate there weremore than 2,500 trenching machines installing sub-surface drainage in the United States. Several hun-dred more machines were reported to be operatingin Canada.

Drainage Plows

The concept of "plowing-in" subsurface drainageconduits dates back to at least the mid-1850's(French, 1859, p. 246; and Weaver, 1964, fig. 102).It became practical only in the mid-1960's with thedevelopment and introduction of corrugated-wallplastic tubing. Fouss (1965) reported on early U.S.field trials of 2-inch diameter corrugated plasticdrains installed with a tube feeder attached to amodified mole plow. The drainage tubing was fed in-to the ground through the slit opening created by

- ,

Figure 3-15This USDA research model of a long, float ng-beem drainage ploa was equipped with theleast laserbeam grade control system.

passing the plow blade through the soil, eliminatingthe slow, costly trenching operation.

The high installation speed possible with the plow(typically 80 to 150 ft/min ground speed) requiredan automatic means to control depth and grade.Thus, the laser grade control system was developedprimarily to meet the needs of the drainage plow(Fouss and Fausey, 1967; and Fouss, 1968). Drain-age plows were not used commercially in NorthAmerica until 1969, but their adoption and usesince then has increased steadily (Reeve, 1978). By1982, about 350 drainage plows were operating inthe United States and about 150 in Canada. Thetotal number of plows is small compared with thenumber of trenching machines, but, because of theirhigher ground speed, plows weie estimated to beused for 40-50 percent of the agricultural subsur-face drainage systems installed annually.

Several plow-type drainage machines have beendeveloped commercially, primarily in Europe andCanada. They fall into six classes as to the methodor mechanism of depth control: (1) depth-gauge

4056

eigure 3-16The principles oflaser-beam technology.

Mean OroundSurfaceReferencePlane

IF Laser BeamReceiver

wheels with fixed blade, (2) rigid floating beam withfixed blade, (3) floating rigid beam with hingedblade, (4) roller-link beam and floating blade, (5)dual-link floating beam, and (6) hinged cantilever-beam.

The depth-gauge wheel-type plow uses a constantplowing depth operation and is best suited wherethe land slope is uniform and/or pregraded to adesigned complex slope (fig. 3-14). For the irregularground surfaces commonly encountered on much ofthe Nation's farmland, a floating-beam-type plow isbetter suited. Most draintube plows are based onthe principle of a long floating beam to improve thedepth and grade control during drain installation(fig. 3-15).

The floating beam can be a rigid. physical beam (fig.3-16), where the hitch pin (H) is located several feetfoward of the plow blade (B). (Also, see fig. 3-15.)The counteracting rotational force provides themoments of force about the hitch pivot; that is, theplow weight (mg) and soil resistance or draft (R),balance each other, and the plow operates in afloating action mode. Change in the vertical positionof the hitch relative to the ground surface controlsthe grade. Such changes are not immediately re-flected in the plowing depth as the tractor pulls theplow forward. This delayed response allows time tocorrect the hitch height during forward travel tocompensate for ground surface irregularities, asdetermined in fundamental studies by Fouss andothers (1972). This function is performed by thelaser grade control system. The plow beam can alsobe virtual (imaginary), but still operating with thefloating-beam principle. Plows in classes (4) and (5)above have virtual beams formed by the linkagesysiem attached to the blade. (Also, see Reeve,1978.)

57

1:arcs

mg 14 Polygon

One of the first plows commercially available (about1969) in North America was the Badger Minor (fig.3-17), a production version of a design originallydeveloped by Ede (1961) in England. The blade andtractor are connected by a pair of rollers which runin a curved track or roller-track beam mounted onthe rear of the tractor. The center-of-curvature ofthe roller track acts as a virtual hitch point for thefloating blade. The virtual hitch was located at theapproximate center of the crawler tracks, isolatingthe blade from most of the pitching movements ofthe tractor.

Two units of similar design, the Zor Plow and theKrac Plow, developed in Canada in the early 1970's,used two nonparallel floating links instead of theroller track to make the connection with the blade.Figure 3-18 shows the Krac Plow mounted on arubber-tired, 4-wheel-drive (4WD) tractor. The 4WDtractor, with a special low-speed transmission,became popular with contractors during themid-1970's for operating draintube plows. These

Figure 3-17A Badger -Minor drainage plow lays roller-link cor-rugated plastic drainage tubing.

41

Figure 3-18--A rubber-tired, 4-wheel-drive tractor is mountedwith a dual-link Krac-Plow.

machines, like rubber-tired trenchers, can be drivento the next job site. Other nonparallel floating-link-type plows like the Link and RWF are manufacturedin Canada. The Wedge Plow is made in the UnitedStates.

The German-manufactured Hoes Plow (fig. 3-19) andthe Hollanddrain Plow from The Netherlands have afloating rigid beam with hinged blade. The physicalhitch points on these plows are mounted in a cen-tral location between the tracks, improving tractionby the downward component of the plow draft. Theclose-coupled blade and hydrostatic track drivesmake these plows easy to maneuver. The plowingdepth and grade are controlled during forwardmotion by hydraulically changing the angle between't,e rigid floating beam and the plow blade. The

th Plow, manufactured in The Netherlands, is anexample of the parallel-link beam; it can also beoperated as a hinged cantilever-beam plow. Specifi-cations and performance characteristics of mostdrainage machines available in the world, includingtrenchers, plows, and backhoes, are published inthe Drainage Contractor's Blackbook, prepared byAgri-Book Magazine of Exeter. Ontario. Canada.

Today's plows can generally install corrugatedplastic drains up to 6 inches in diameter and up to10 inches diameter for some plows. Drains 8 inchesand larger, if used for collector main lines, areoften installed with trenching equipment. Thus.many contractors who use plows also have atrencher to install the larger size main lines.

Soil type, soil moisture content, and buried rocksaffect the operation and field performance of mostdrainage plows. Operational problems with plowsusually differ from those encountered withtrenchers under similar conditions. For example, afew buried ricks that can completely immobilize a

42

58

Figure 3-19This tractor carries, at left. a Hoes Plow with a floatingrigid-beam and hinged blade.

trencher pose little, if any, problem for most plows.Rocks up to 12 inches in diameter are often merelylifted or pushed out of the way as the plow bladepasses through the soil.

The performance of most plows varies considerablywith soil moisture content, particularly for cohesive(clay type) soils. Because draft requirementsdecrease with increasing soil moisture, a moist soilis best for plowing-in drains. However, excessivelywet soils may cause a serious loss in traction forthe crawler tractor, and especially for the 4WD.rubber-tired tractor. For extremely dry cohesivesoils, draft requirements for the plow may becomevery high and make plow installation of drains im-practical. Some attention has been given tooscillating and/or vibrating plow blades to reducedraft requirements in dry soils (Child and others.1979).

The speed at which subsurface plastic drains canbe plowed-in ranges from 80 to 150 ft/min. Undermany field conditions. 2.000 ft of draintube can beinstalled per working hour: the typical range is1.500 to 3.000 ft/hr for many installation conditions.Plowing-in 20.000 to 30,000 feet of drain tubing perday is common practice. The high production (in-stallation) capabilities of the draintube plow make itwell-suited for large-scale projects. The farmer-customer often prefers that drainage installationsbe done with plow-type equipment, because the con-tractor can get into and out of the field much morequickly with a minimum of damage to crops and lit-tle soil disturbance.

The capital investment cost for most drainage plowsis somewhat greater than for the typical moderntrenching machine, but the installation charge perunit length for plowed-in drains !s typically 15-25percent less than the charge far trenched-in drains.

Figure 3-20Tile installation in-volves a laser beam to controltrench grade. A laser transmitter(foreground) sends a beam to aphotocell receiver on the trench-er. This 1968 Ohio State Unrversity photo shows one of V:: aarli-est field installations using laser-beam grade control.

Often farmers are willing to pay a unit chargeequal to Chat for trenching because the plow equip-ment can complete the installation faster and allowquicker access to the field for tillage and planting.Because of the increasing competition that haddeveloped by the early 1980's and the high capitalinvestment in drainage equipment, contractors withplows found it necessary to adopt improvedbusiness management techniques to schedule andutilize more effectively their equipment and thusstay competitive.

Several other improvements in the early 1980's further streamlined and improved the efficiency ofplow-in drainage. These included improved bladedesign, hydraulic blinder/backfillers, and onboardmaxi-coil reels (Fouss, 1982). The new design of theplow blade involved a soil-filling shaped bladecoupled with a special tube feeder boot to insuremore positive soil placement over and around thedrainage tubing as it is installed. The new discblinder/backfiller attachment is designed to com-plete the blinding and covering of the pipe. By useof onboard maxi-coils of corrugated tubing, thefeeding operation is more effectively controlled,thus minimizing stretch and preventing other instal-lation damage.

Laser Automatic Grade Control

The laser-beam automatic grade-control system wasdeveloped to meet the specific requirements of thehigh-speed drainage plows, because gradingmethods using sight-bars or stretched wires wereslow, costly, and/or unsatisfactory (Fouss and

Fausey, 1967; Fouss, 1968). Commercial versions ofthe laser-beam grade-con; -01 system were availableon the U.S. market in 1967, before operationaldi.;nage plows were fully developed for commercialuse. Those versions of automatic grading systemswere used on conventional tile trenching machinesby late 1968 (Studebaker, 1971; and Teach, 1972).An early installation is shown in figure 3-20. By theearly 1970's, many farmers expected or demandedthat their subsurface drainage systems be installedwith laser-controlled equipment. By 1970, almost allof the drainage plows introduced and sold in NorthAmerica were equipped with laser grade-controlsystems.

The basic principle of automatic depth and gravecontrol for drainage equipment, using a projec..edlaser-beam datum (grading reference line or plane)and an onboard laser tracking-receiver which auto-matically controls depth of drain installation, wasreported in detail by Fouss (1968) and Teach (1972).The typical laser used, for this application is thecontinuously emitting helium-neon gas laser, whichprojects a brilliant tail-light red be m of collimatedlight. Figure 3-16 shows the laser-beam receivermountod on the plow frame; and the laser-beamdatum projected from a remote source. Fouss andothers (1972) conducted computer simulation studiesand field testing to develop guidelines for the op-timum placement of the laser-beam receiver on-board the drainage plow (that is, distance "b-x" infig. 3-16) to ensure acceptable accuracy of auto-matic grade control for a wide range of field in-stallation conditions.

5343

Figure 3-21Pictured is anautomabc grade control systemon a trenching machine.A trencher and drainage plowoperate in the same field.

...........,

By 1971, three different types of laser-beam gradingsystems, based upon the projected 1, Hium-neon gaslaser, were in use and available from a number ofcommercial sources. The first laser type is a singlelaser light beam or line projected parallel to thedesired grade and along the direction of drainagemachine travel. The second type is a partial-planeor segment of circle (arc) projected parallel to thedesired grade in the direction of machine travel andalso parallel to the cross-slope level. The third typeis a circular laser plane reference created by rapidlyrotating the laser source (5 to 10 revolutions persecond), much like a lighthouse beacon, where oneaxis in the plane is aligned parallel with the desireddrain grade and the other axis aligned eitherhorizontally or parallel to the general land slope.The laser-plane reference system, shown schemat-ically in figure 3-21 for a trenching machine and

44

r GO

plow operating in the same field, became popularbecause the elevation or grading datum covered alarge field area, up to 100 acres, with each setup ofthe battery-powered laser transmitter unit. A heavy-duty car battery allowed it to operate for a fullwork day without a recharge.

Most of the laser tracking-receivers included a ver-tical array of closely spaced photocells connected toan electronic logic and controller circuit. Themachine hydraulics were operated by the controllerto provide the corrective feedback motion of theplow or trencher hitch (figs. 3-16 and 3-21), thusautomatically keeping the receiver unit centered"ON" the laser-beam or laser-plane datum. Formost tile trenching machines, a simple ON-OFF,stepwise hydraulic feedback correction has provenadequate. For the high-speed plows, a pure ON-OFF

and/or proportional corrective feedback motion hastypically been needed to maintain adequate gradecontrol (Fouss and others, 1972; and Teach, 1972).

As with the general pattern in any technologicdevelopment, the first 20 years of use for the laser-beam and laser-plane grade control systems on sub-surface drainage installation equipment has beenfilled with a series of important improvements andinnovations. The self-leveling laser-plane transmittergreatly increased the efficiency of the system andwas quickly adopted for general use by drainageand construction contractors. Several useful mech-anisms and techniques were developed for creatingand/or changing the desired drain grade, even dur-ing forward machine motion, without resetting theprojected laser-beam or laser-plane reference. Apopular approach involvas vertically moving the on-board laser receiver, relative to its machine mount-ing, as a selective function of ground travel dis-tance. Thus, any desired grade can be created for agiven (preset) or plane slope, even when thereference is projected horizontally. This approachalso permits chant; the drain grade at any pointof travel along the drain line, eliminating the needto reset the laser reference for each drain gradientchange.

With the development and successful commercializajon of the laser-beam and laser-plane automaticgrade control systems in the 1970's and 1980's, thelaser-beam-controlled di ainage plow for installingcorrugated plastic drainage tubing became an effec-tive and practical method of subsurfacing drainageinstallation. Laser-beam alignment and/or guidancesystems have found worldwide applications in otherareas, such as surveying, land grading, pipelines,tunnels, buildings, and other engineering and con-struction work, including military applications.

Drainage and WaterManagement Systems

Drainage has traditionally been consideredseparately from irrigation and other water controlpractices. We now recognize that these practicesshould be considered together in total water man-agement Qystems for agriculture.

In the mid-1980's, a significant amount of technicalinvestigative work and commercial market develop-ment in the broad area of agricultural watermanagement technology focused on combination (ordual-purpose) drainage and subirrigation systems,particularly in the humid climate regions of theUnited States. The development of the water man-agement simulation model, DRAINMOD, gave

61

engineers a practical and computerized means fordesigning agricultural water management systemsbased on the recorded variation of weather condi-tions over a long period of time (20 to 30 years).(See Skaggs (1980) and chapter 6 in this bulletin.)New approaches using computer simulations andfield testing were investigated to operate and/ormanage the dual-purpose drainage - irrigationsystems for humid climate conditions (Doty andothers, 1984; Smith and others, 1985; and Fouss,1985b).

The future promises that the farmer or farm man-ager can be provided with sufficiently sophisticatedmonitoring and control/management systems to fullyachieve onfarm water management, :So as to con-serve water resources, use natural rainfall effec-tively, reduce plant stresses from excess or defi-cient soil water, reduce energy costs, and maximizeoperating profits.

Computers are increasingly providing the neededcontrol for total water management. Significantadvances have been made in tt,e development ofsophisticated sensing equipment for monitoring andfeedback systems. Computer software is underdevelopment that will operate systems and dailymanagement decisions to make total water manage-ment an onfarm reality. These developments willalso help farmers make better risk and benefit deci-sions and will help them select managementoptions. These options will almost certainly includecurrent weather forecast information (Fouss, 1985a)down to the geographical coordinates of farms.

References

American Society for Testing and Materials(ASTM). 1974. Standard Specification for Cor-rugated Polyethylene Tubing (F405-74). ASTM Sub-committee F-17.65 on Land Drainage Systems.

Boa, W. 1963. "Development of a Machine forLaying Plastic Drains," Journal of AgriculturalEngineering. Vol. 8, No. 3, pp. 221-230.

Broadhead, R. G., G. 0. Schwab, and R. C. Reeve.1983. Synthetic Drain Envelopes and Soil Particle-Size Distribution. Transactions of the ASAE. Vol. 26,No. 1, pp. 157-160.

Broughton, R. S., and others. 1977. Tests of FilterMaterials for Plastic Drain Tubes. Proceedings ofThird National ASAE Drainage Symposium. ASAEPub. No. 1-77, pp. 34-39.

45

Busch, C. D. 1958. "Low Cost SubsurfaceDrainage," Agricultural Engineering. Vol. 39, No. 2,pp. 92-93, ff.

Child, Jr., J.L., J. L. Fouss, and E. K. Nowicki. 1979.Dynamic Plow Assembly and Methods of OperatingSame. U.S. Pat. No. 4,179,227 (12/18/79). Appl.825,192 (8117/77). Assignee: Hancor, Inc., Findlay,Ohio. (18 pages, 14 figures, 42 claims.)

De Jager, A. W. 1960. "Review of Plastic Drainagein The Netherlands," Netherlands Journal of Agri-cultural Science. Vol. 8, No. 4, pp. 261-270.

Doty, C. W., J. E. Parsons, A. N. Tabrizi, and R. W.Skaggs. 1984. Stream Water Levels Affect FieldWater Tables and Corn Yields. Transactions of theASAE. Vol. 27, No. 5, pp. 1300-1306.

Ede, A. N. 1961. "Floating-Beam Mole PloughTrials," Farm Mechanics. Vol. 13, No. 144, pp.274 -27&.

Ede, A. N. 1963. "New Methods of Field Drainage,"Agriculture. Vol. 70, No. 2, pp. 82-86.

Ede, A. N. 1965. New Materials and Machines forDrainage. Proceedings of ASAE Conference onDrainage for Efficient Crop Production. December,Chicago, pp. 58-61.

Edminster, T. W. 1965. The Challenge of NewTechnology in Drainage. Proceedings of ASAE Con-ference on Drainage for Efficient Crop Production.December, Chicago, pp. 43-45. .

Fouss, J. L., and W. W. Donnan. 1962. "Plastic -linedMole Drains," Agricultural Engineering. Vol. 43, No.9, pp. 512-515.

Fouss, J. L. 1965. Plastic Drains and Their Installa-tion. Proceedings of ASAE Conference on Drainagefor Efficient Crop Production. December, Chicago,pp. 55-57.

Fouss, J. L., and N. R. Fausey. 1967. "Laser BeamDepth Control for Drainage Machine," Ohio Report.Vol. 52, No. 4, pp. 51-53.

Fouss, J. L. 1968. Corrugated Plastic Drains Plowed-in Automatically. Transactions of the ASAE. Vol. 11,pp. 804-808.

Fouss, J. L., N. R. Fausey, and R. C. Reeve. 1972.Draintube Plows: Their Operation and Laser GradeControl. Proceedings of Second National ASAEDrainage Symposium. St. Joseph, Mich., pp. 39-42.

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Fouss, J. L. 1973. Structural Design Procedure forCorrugated Plastic Drainage Tubing. TB-1466. U.S.Dept. of Agr., Agr. Res. Serv.

Fouss, J. L. 1974. "Drain ube Materials and In-stallation," Drainage for Agriculture. (ed. Jan vanSchilfgaarde). Monograph No. 17, Am. Soc. Agron.Madison, Wisc., pp. 147-177, 197-200.

Fouss, J. L. 1982. Modernized Materials Handlingand Installation Implements for Plow-type DrainageEquipment. Proceedings, Second InternationalDrainage Workshop, Washington, DC. December,pp. 41-51.

Fouss, J. and W. E. Altermatt. 1982. Drainage-plow 'Boot' Design to Improve Installation of Cor-rugated Plastic Tubing. Proceedings of Fourth Na-tional ASAE Drainage Symposium. ASAE Pub. No.12-82, pp. 102-104.

Fouss, J. L. 1985a. Daily Weather Forecast RainfallProbability as an Input to a Water ManagementSimulation Model. ARS-30. U.S. Dept of Agr., Agr.Res. Serv. Proceedings of the USDA ARS/SCSNatural Resources Modeling Workshop, October17-21, 1983. Pingree Park, Col.

Fouss, J. L. 1985b. Simulated Feedback-Operation ofControlled-Drainage/Su birrigation Systems." Tran-sactions of the ASAE. Vol. 28, No. 3, pp. 839-847.

Fouss, J. L., and W. E. Altermatt. 1985. Strength vs.Stretch of Corrugated Plastic Drainage Tubing.Tech. Bull. 1H, Hancor, Inc., Findlay, Ohio.

French, H. F. 1809. Farm Drainage.'New York: A. 0.Moore and Co.

Jcnert, H. 1952. "Die Mechanisierung derDrainarbeiten." Wasserwirtchaft Wassertechnik,2, pp. 392-397.

Luthin, J. N., and R. C. Reeve. 1957. "The Design ofa Gravel Envelope for Tile Drains." In Drainage ofAgricultural Lands (ed. James N. Luthin).Monograph No. 7, Am. Soc. Agron. Madison, Wisc.,pp. 339-344.

Myers, V. I., R. J. Rektorik, and C. A. Wolfe, Jr.1967. Deflection Tests and Trench Conditions forPlastic Drain Pipe." Transactions of the ASAE. Vol.10, pp. 454-547.

Reeve, R. C. 1978a. Trenchless Drainage. Pro-ceedings of the International Drainage Workshop.(ed. Jans Wesseling). May 16-20, 1978, Wageningen,The Netherlands. Paper 3.09, pp. 571-589.

1978b. "Synthetics at Work,"Drainage Contractor Magazine. Vol. 5, No. 1, p. 80.Hensall, Ontario, Canada.

1979, Synthetic Drain EnvelopeMaterials Technical Information. Columbus, Ohio:Advanced Drainage Systems, Inc.

1981. Filter and Envelope Materials.Presented at Subsurface Drainage Workshop. ADSReprint, Univ. of Ill., February.

1982. Synthetic Envelope Materialsfor Subsurface Drainage. Proceedings, 2nd Interna-tional Drainage Workshop, Washington, DC.December 5-11.

Reeve, R. C., R. E. Slicker, and T. J. Lang. 1981. Cor-rugated Plastic Tubing. Proceedings, Am. Soc. Civ.Engr. International Conference on UndergroundPlastic Pipe. pp. 277-242.

Rektorik, R. J., and V. I. Myers. 1967. PolyethyleneDrainage Pipe Installation Techniques and Field Per-formance. Transactions of the ASAE. Vol. 10, pp.458-459, 461.

Schwab, G. 0. 1955. "Plastic Tubing for SubsurfaceDrainage." Agricultural Engineering, Vol. 36, No. 2,pp. 86-89, 92.

Schwab, G. 0., and J. L. Fouss. 1985. "Plastic DrainTubing: Successor to Shale Tile," AgriculturalEngineering. Vol. 66, No. 7, pp. 23-26.

Skaggs, R. W. 1978. A Water Management Modelfor Shallow Water Table Soils. Technical Report No.134, Water Resources Institute of the University ofNorth Carolina. N.C. State Univ., Raleigh.

Skaggs, R. W. 1980. A Water Management Modelfor Artificially Drained Soils. Technical Bulletin No.267, N.C. Agr. Serv., N.C. State Univ., Raleigh.

Smith, M. C., R. W. Skaggs, and J. E. Parsons. 1985."Subirrigation System Control for Water Use Effi-ciency." Transactions of the ASAE. Vol. 28, No. 2,pp. 489-496.

Sorbie, F. I., J. L. Fouss, and G. 0. Schwab. 1972.Comparison of Strength Test Methods for Cor-rugated Plastic Drainage Tubing. Transactions ofthe ASAE. Vol., 15, pp. 445-447.

Studebaker, D. C. 1971. "The Laser-plane System,"Agricultural Engineering. Vol. 53, No, 8, pp. 418-419.

Teach, T. L. 1972. Automatic Laser Grade Controls.Society of Automotive Engineers, Earthmoving In-dustry Conference, Central Illinois Section, Peoria,April 10-12. Paper No. 720386.

van Schilfgaarde, J. 1965. "Transient Design ofDrainage Systems," Journal of the Irrigation andDrainage Division. ASCE. Vol. 91 (IR3), pp. 9-22.

Van Someren, C. L. 1964. "The Use of PlasticDrainage Pipes in The Netherlands." (Translationsfrom Coltuurtechnik 1,2,3). Government Service forLand and Water Use, Maleibaan 21, Utrecht, TheNetherlands.

Watkins, R. K. 1967. The Development of StructuralConcepts for Buried Pipes Externally Loaded.Bulletin No. 7, Engineering Experiment Station, UtahState Univ., Logan.

Watkins, R. K., R. C. Reeve, and J. B. Goddard. 1983."Effect of Heavy Loads on Buried CorrugatedPolyethylene Pipe." Transportation Research Board,National Academy of Sciences, Washington, DC,pp. 99-108.

Weaver, M. M. 1964. History of Tile Drainage.Waterloo, N.Y. Private Publication. (ref. fig. 102),

Willardson, L. S. 1974. "Envelope Materials,"Drainage for Agriculture. Chap. 9. (ed, Jan vanSchilfgaarde). Monograph No. 17, Am. Soc. Agron.Madison, Wisc., pp. 178-200.

Willardson, L. S. 1979. "Hydraulic Gradients inEnvelope Materials," ARR-W-8/June. Utah StateUniv., Logan.

6347

Chapter 4

Purposes and Benefits ofDrainage

N.R. FauseyAgricultural Research S'ervice, USDAOhio State University

E.J. DoeringAgricultural Research Service, USDAMandan, North Dakota

M.L. PalmerDepartment of Agricultural EngineeringOhio State University

The importance of drainage to public health and theeconomic well-being of the Nation is generally notunderstood, we believe, because of a public percep-tion of drainage as only the process of convertingvaluable wetlands to other uses. We accordinglyreview the several purposes and benefits of drain-ing wet soils now in use for cropland, pasture,rangeland, and forestland. However, we do not con-sider the benefits of, or issues involved in, drainingwetlands for conversion to new cropland, develop-ment sites, and other uses. According to an Officeof Technology Assessment report cited earlier bySmith and Massey (OTA, 1984), agriculturaldrainage and clearing have been responsiblefor most wetland conversions since the mid-1950's,and there is still significant pressure to convertwetlands to other uses.

Although drainage is a mechanism by which thisconversion takes place, pressures for and againstconversion are exerted by competing economic andother public values. Competition issues are reviewedby Swader. But, our discussion focuses on the moreimmediate practical purposes and benefits of drain-ing wet soils now in agricultural or forest uses onfarms.

Purposes of Drainage

The underlying objectives in draining wet soils onfarms are to minimize risk, improve efficiency, and

48

C.

increase net income. Drainage is best viewed as awater management practice, whose practical pur-poses are different for different climatic regionsand land uses. A farmer may drain land for severalreasons: to reduce diseases of crops and livestock;to leach salt from irrigated land; or to removeexcess soil water, improving trafficability formachinery and the crop rooting environment.Figures 4-1 and 4-2 illustrate the effects of poordrainage on cotton and corn crops.

Another important purpose is to protect the soilfrom uncontrolled runoff and erosion. Closelyrelated farm or nonfarm purposes of drainage areto stabilize roadways and building foundations, toimprove the usefulness of recreation areas, toreduce flooding, and to facilitate land disposal ofwaste water.

Vow wet soils are drained depends on soil type,climate, topography, and intended land use.Grading, field ditches, swales, and other im-provements may be adequate for managing surfacewater (fig. 4-3). Subsurface drains must be used tomanage excess soil water and to remove excesssoluble salts from the soil (fig. 4-3). Both surfaceand subsurface drainage improvements are oftenneeded to properly manage the excess water. Whenproperly done, drainage has various primary andas ,:fated benefits.

,Figure 4 -t Colon plants sit unharvested in Randolph County, Arkansas, because of eloodina water. Locallandowners later organized a joint rural and urban project to drain the land.

Primary Benefits of Drainage

The, primary benefits of drainage go beyond the pro-.tection of irrigated land from excess accumulationsof undesirable salts and the improvement of plantgrowth by creating more favorable moisture en-vironments and protecting public health.

Vector Control and Public Health

Drainage eliminates diseases that harm people,crops, and livestock. The benefits for mankind aregreater life expectancy and improved'quality of life.The benefits for crops and livestock are healthier,more vigorous, and more productive plants andanimals, resulting in increased economic value.

Fkjure 4-2:Standing.w5ireesvoyed much of this corn crop inCarver County, Minneida.- tTile dralhage would have preventedthe loss.

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In developing areas of the world, health profes-sionals usually lead the effort to initiate drainageimprovements. Their concern is to eliminate stag-nant water which serves as breeding areas for mos-quitos or parasitic organisms that transmit or causedisease and illness. Mosquitoes and flies thrive inpoorly drained areas. Effective control methods formalaria and yellow fever rely on drainage to elim-inate mosquito-breeding areas.

Organisms causing foot-rot in large animals cannotsurvive in dry areas. The liver fluke snail flourisheson wet land; the only sure way to prevent the flukedisease is to destroy the snail's habitat by drainingwet areas. Drainage reduces or eliminates mildewinfections and various root rots of plants becausethe disease organisms cannot live and multiply indry conditions.

Figure 4.3Three years of good drainage management on sandyday soil help these citrus trees flourish in.Indian River, Florida.

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Figure 4-4Nearly 4,000 feet of tiling along Hardware Riverbottomland corrects poor drainage in Chewacla and Wehadkeesoils; Albemarle County, Virginia.

Salt Removal

Drainage is the key to successful irrigation agricul-ture. History clearly documents the demise of ad-vanced civilizations that did not realize the impor-tance of drainage to sustained irrigation in aridregions. The productive potential of irrigated soilcan be maintained for an indefinitely long timewhen drainage is instaaed and proper leachingtechniques control the salt content of the soil.

The dissolved salt content of soils may become quitehigh as a result of upward capillary flow of waterfrom a saline water table, or perhaps more impor-tant, because salt accumulates as water is tran-spired by plants. The effects on crops can be verysevere (fig. 4-5). The rate of capillary salinationdepends on the depth of the water table, the water-conducting properties of the soil, and the salinity ofthe ground water.

To counteract the accumulation of salts in the rootzone of irrigated soils, irrigation water in excess ofthe amount needed to satisfy crop needs is appliedto leach the salts down and uut of the root zone andinto the drains (fig. 4-6). The amount of excess ir-rigation (leaching) water needed depends primarilyon the tolerance of the crop to salt, on the quality ofthe irrigation water, and on the manner in whichthe irrigation water is applied. Frequent applica-tions that produce a steady downward flow of soilwater will require less leaching water than infre-quent applications, because the latter allows salinesoil :eater to rise toward the surface betweenirrigations.

In arid irrigated regions. drains are installed asdeeply as possible (often 8 feet or deeper) to

50

minimize the length of drain per unit of area andinsure that the midpoint water-table depth betweendrains is at least 4 feet below the ground surface.This practice minimizes the likelihood that thesaline ground water will rise into root zone bycapillary flow.

Increased Productivity

Drainage removes excess water from the soil andcreates a well-aerated root environment whichwarms up quickly in the spring and enhances theavailability of plant nutrients so plant growth canbegin early, continue vigorously, and achieve highproductivity. Early growth is important forestablishing an extensive root system which cansupply nutrients and water to the plant from a largevolume of soil. This can minimize the damagingeffect of drought during later growth stages.

Without drainage, crop growth may lag in thespring because wet soils warm slowly. Wet soilrequires five times more energy to raise its temper-ature than does dry soil, and the cooling effect ofthe greater evaporation from wet soils delays a tem-perature rise. Seeds will not germinate and rootswill not grow below a critical soil temperature(usually about 50°F), so rapid, early warming of bothsurface and subsurface soils is important. Plantroots do not function normally in saturated soil evenwhen adequate nutrients are present. Roots cannotabsorb water and nutrients under conditions ofoxygen stress or poor aeration.

Plant nutrient availability depends greatly on soilmicroorganisms that break down organic matter torelease nutrients or that fix nitrogen from the

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Figure 4.5This stunted ear of corn is dramatic evidence ofsalinization too much salt in tt .1 soil, at a farm in Grand Junction,Colorado.

Figure 44Bars soils' bespeak the damps of soil solidity.Proper water management and drainage could have saved thiscotton crop in"the Imperial Valley, California.

atmosphere. These organisms also require a well-aerated, warm environment to function normally.Without drainage, the microorganisms cannot supplynutrients for uptake by plants.

Drainage also stabilizes productivity by reducingthe variation in crop yields from year to year. Insome years, drainage may not be needed for goodyields on normally wet soils, but in other years, verylow yield. or no yields may result from poor drainage.Drainage can prevent these low yields, increasingthe reliability of crop production and minimizingrisk.

Associated Benefits of Drainage

The main associated benefits of drainage includeimproved trafficability for vehicles, implements, im-proved timeliness of farm operations, and reducedsoil erosion.

Trafficability and Timeliness

By removing excess water from the soil, drainageprovides a surface soil layer dry enough to handlefarm machinery, increasing the number of daysavailable for fieldwork and reducing or eliminatingproduction losses from the delays in planting orharvesting.

Delays in field operations can result in losses rang-ing from reduced yields to complete crop failure.Performing tillage, weed control, or harvestingoperations when the soil is too wet may be impossi-ble because the equipment cannot operate for lack ofsupport or traction. Soil compaction or soil struc-ture degradation are less obvious but more seriousproblems. Not only must the agronomic timelinessrequirements of the crop and soil conditions be met,but the physical integrity of the soil must bepreserved. Otherwise, a long-term loss in productionpotential may result from too much traffic or soilmanipulation at a time when puddling or compactionOccurs.

Drainage is important in all of trafficability forfarming operations. Subsurface drainage removesexcess water from the upper layers of the soil pro-file more rapidly than the natural processes ofevaporation and transpiration, Surface drainagecan prevent wet spots which often hold up opera-tions on low areas or cause inconvenience and lossof both time and productive area when they must beworked around. Rapid removal of surface water andrapid lowering of the soil-water content aidmaterially in providing soil moisture conditionssuitable for trafficability.

Reduced Erosion

Drainage reduces erosion by controlling thedischarge of excess water from the land. Surfacedrains and terraces are designed to remove waterwithout erosion. Subsurface drains remove waterfrom within the soil, providing storage that reducesthe amount of runoff from subsequent rainfall.Reduced erosion also means improved water qualityfor streams.

Drainage is very important to coil conservation ef-forts. conservation tillage systems do not performwe poorly drained soils; thus, drainage can bea Lance' element for conservation tillage systemsdesigned to control erosion. Drainage of grassedwaterways by subsurface drains is often essentialto dry the channel bottom so that protective vegeta-tion can be maintained, thereby preventing rills andeventually gullies.

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51

Chapter 5

Preserving Environmental Values

Carl H. ThomasSoil Conservation Service, USDAWashington, DC

Assessments of drainage needs are incompletewithout considering environmental ramifications.Farmland drainage may have both beneficial andadverse effects on the environment. These must berecognized along with any farm production benefitsand casts. Environmental components include suchitems as natural beauty; archeological, historical,biological, and geological resources; ecologicalsystems; and air and water quality. Although manyeffects of farmland drainage on the environment arenot economic in nature, they may provide importantevidence for judging the value of proposed plans.Farm drainage programs can benefit the environmentor have a neutral effect if multiobjective ormultipurpose projects include the management,preservation, or restoration of one or moreenvironmental components.

Identification and Measurement

Modern agriculture has grown more intensive anddependent upon an industeialized technology tomeet demands for food', fiber, and forest products.Water management through drainage is an impor-tant aspect of this technology. Conflicts often arisebetween drainage interests and ecological or en-vironmental interests.

The technical responsibility in this situation re-quires that ecological knowledge be blended withhydrologic knowledge and that both be responsive tothe objectives of private landowners and nationaltaxpayers, who subsidize drainage on privatelyowned lands to the extent that there is Federal par-ticipation or assistance. Realistic options can bedeveloped for the conservation, use, and manage-ment of all natural resources, including wetlands.The key to decisionmaking on wetlands use is tomaximize the well-being of people. In most in-stances, this happen: exolicitly recognizing thefunctions that w6tlauds perform and counting theloss as these functions ars) sacrificed or impaired.

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Functional Values of Wetgands

Wetlands are lands transitional between terrestrialand aquatic systems. The water table is usually ator near the surface, or the land is covered byshallow water. Wetlands must periodically supporthydrophytes, and the substrate must be predom-inantly undrained hydric soils. Examples ofestuarine as well as forested and emergentfreshwater wetlands are in figures 5-1 to 5-4.

Ten specific functional values of wetlands are gen-erally acknowledged: habitat for fisheries, habitatfor wildlife, water recharge and discharge, floodstorage and desynchronization, shoreline anchoringand dissipation of erosive forces, sediment and con-taminant trapping, nutrient retention and removal,food chain support, active recreation, passiverecreation, and heritage value. More completedefinitions of these functions follow, along withtheir economic and other values. The descriptionsare largely adapted from Adamus ar. tl Stockwell(1983).

Habitat for Fisheries. Fisheries are the fin fish andshellfish resources within the interior or coastalareas of the United States. The habitat includesbiological, physical, and chemical factors .r.tit affectthe food, cover, metabolism, attachment, predatoravoi'lance, and other life requirements of the adultor larval forms. The direct economic significance ofproviding habitat for fisheries is that fisheries areclearly vital to regional and national economies aswell as to the social well-being of people in pro-viding environmental amenities.

Habitat for Wildlife. Habitat pertains to thosefeatures which affect the food, water, cover, andreproductive needs for birds, mammals, reptiles,and amphibians in the place where they live. Thedirect economic significance of wetland habitat forwildlife includes consumptive and nonconsumptive

Figure 5 -1 These marshes are examples of estuarine emergent wetlands, where a river's current meetsthe tide. Pictured (clockwise, upper left to right) are: mixed plant community of an irregularly floodedmarsh, reed-salt hay cordgrass, regularly flooded cordgrass, black needlarush, Lynghye's sedge marsh,Alaskan irregularly flooded marsh.

6953

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It

31t4.,

4 ' J.Y

"k:-

-' -4

if

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Figure 5.2Example of forested 'wetlands (clockwise, upper left to right): red maple swamp, Atlantic whitecedar swamp, bald cypress swamp, bottomland hardwood swamp, riparian forested wetlands (those locatedon the banks of a natural water body), Alaskan forested wetlands mixed with scrub-shrub wetlands.

54

user days spent in birding, hunting, and otherwildlife-oriented recreational activities. Besides pro-viding year-round habitat for resident birds,wetlands are especially important as breedinggrounds, overwintering areas, and feeding groundsfor waterfowl and numerous other migratory birds(fig. 5-5). Both coastal and inland wetlands servethese valuable functions.

Besides waterfowl, wetlands also support otherspecies of birds, such as egrets, herons, gulls, shorebirds, some species of sparrows, an terns. Potholesand other inland emergent wetlands provide impor-tant winter cover and nesting habitat for ringneckpheasants.

Wetlands also provide valuable habitat for muskratsin coastal and inland marshes throughout the country.Other furbearers who depend on wetlands includebeaver, nutria, otter, mink, racc....on, skunk, andweasels.

m

?:4,4--1,8.jr."-H-;

Other dependent mammals include marsh andsin amp rabbits, numerous species of mice, blackbears, brown bears, caribou, moose, and severalreptiles and amphibians, such as turtles, alligators,frogs, and some species of snakes (fig. 5-6).

Figure 5-3Scrub-shrub wetlands emerge in this southern bog or"pocosin."

Figure 5.4Emergent wetlands (clockwise, upper left to right): northeastern sedge meadow, cattail marsh,prairie pothole wetlands, western sedge meadow.

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Figure 5.5Migratory birds find a home in wetlands (clockwise, upper left to right): an American avocetturns her eggs, a rednecked grebe settles onto her nest. a vigilant snowy egret guards the nest, andpintails flock to their feeding grounds.

Ground-Water Recharge and Discharge. Ground-water recharge is the movement of surface water orprecipitation into the ground-water flow system.Ground-water discharge is the movement of groundwater into surface water. Shallow recharge andminor ground-water discharges are sometimestermed seepage or leakage. When ground-water dis-charges into streams during dry periods, usually inconjunction with discharge to standing surfacewater. the process is termed low flow augmentation.Shallow and lateral recharge are local phenomena.They normally are of direr, value to fewer waterusers than deep recharge. because the latter ismore pertinent to regional ground-water systems.

56

I. 1

pp

.

Recharge is important for replenishing aquifers usedfor water supply, especially in those situationswhere aquifers are threatened by drought, overuse.or pollution from toxic waste or saltwater containedin adjoining aquifers. Discharge may also be criticalfor maintaining soil moisture in agricultural regions.Another advantage is that when floodwaters enter theground-water system via wetland basins capable ofrecharge. flood peaks can desynchronize significantly.thus reducing their potential for causing damage.

Discharge is important not only for maintaining lowflows essen`ial to fishejes but also for maintainingvegetation and providing drinking water for wildlife.

Figure 5-6WeUands abound with wildlife, like the beaver, moose, alligator, and spring peeper.

Seepage discharge through gravel is essential tospawning fish. Discharging springs often keep im-portant northern wetlands free of ice for longperiods during the winter, increasing their use bywaterfowl. Discharge of fresh ground water intoestuaries is vital to many commercially harvestedspecies, and discharges into prairie potholes main-tain the permanence of vital waterfowl breedinggrounds. A large number of rare plant species growin wetlands which receive ground -water discharge.

Flood Storage and Desynchronization. Floodstorage is the process by which peak flows enter aweiland basin and are delayed in their downslope,journey. Flood desynchronization is a pi -icess bywhich the simultaneous storage of peak flows innumerous basins within a watershed and theirsubsequent gradual release in a nonsimultaneous,staggered manner results in the containment offlows within the downstream channel and more per-sistent flow peaks downstream. Storage may bemeasured in fractions of an inch or in feet; reduc-tions in flooded areas are measured in square feet

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.11

or square miles. Flood storage greatly enhances theimmediate sediment-trapping capability of wetlands.Such storage also reduces the need for shoreline an-choring in downstream areas.

Shoreline Anchoring and Dissipation c f ErosiveForces. Shoreline anchoring, is the stabilization ofsoil at the water's edge or in shallow water byfibrous plant root complexes. It may involve long-term acc:etion of sediment and:3r peat, along withshoreline progradation. Dissipation of erosive forcesis the decline in energy associated with waves, cur-rents, ice, water-level fluctuations, or ground-waterflow.

The direct economic significance of shoreline an-choring and the dissipation of erosive forces is il-lustrated by millions of dollars spent annually forjetties, groin- , and other structures intended to stopshoreline erosion by waves and current. Such ero-sion may destroy inhabited structures, eliminateharvestable timber and peat, _dmove fertile soil,and alter local land uses. Eroded fine sedimentsmay be redeposited in navigable channels, ag-

57

gravating the need for costly dredging. Eroded finesediments may be redeposited in portions of a basinwhere ground-water exchanges occur, eventuallyslowing the rate of ground-water recharge ordischarge. Shoreline anchoring by wetlands mayminimize such erosion. Suspended sediment fromeroded shorelines may also inhibit the growth andsurvival of aquatic organisms. Erosion may alsodirectly threaten riparian wildlife habitat. Shorelineerosion is seldom aesthetically appealing, end theerosion of beaches may impair recreation.

Sediment Trapping. Sediment trapping is the pro-cess by which inorganic particulate matter of anysize is retained and deposited within a wetland orits basin. In practice, distinguishing inorganic fromorganic sediment may be difficult because organiccolloidal substances al e readily adsorbed onto in-organic part:les. Sediment trapping may be shortor long term. Short-term trapping may be definedarbitrarily as the retention of sediments for periodsof 30 days to 5 years: long-term trapping involvesretention for longer periods. Sediment trapping mayinvolve the retention of runoff-borne sedimentbefore it moves into ground-water aquifers or thedeep waters of a basin and the interception andretention of sediment before it is carrieddownstream or offshore.

The direct economic significance of sediment trappingis that sediment deposited in undesirable locationsmay require increased expenditures for dredging,channel modification, and water-treatment facilities.

Nutrient Retention and Removal. Nutrient reten-tion is the storing of nutrients, especially nitrogenand phosphates, within the substrates and vegeta-tion of wetlands. Nutrient removal is the purging ofnitrogen nutrients by conversion to gas. Nutrientretention may involve trapping both runoff-bornenutrients before they reach deep water and thenutrients borne by flowing surface water beforethey are carried downstream or to underlyingaquifers. Nutrients may be stored either short orlong term. Long-term storage is generally moresignificant to ecosystems. However, short-termstorage may also be significant if it helps maintainor improve downstream water quality, especially ifsuch storage occurs during seasons when plantsand algae are particularly nutrient-sensitive.

The direct economic effects are that nutrient reten-tion, by controlling eutrophica,:ion, may heil. maintainfisheries of economically important commercial orrecreational value. It may also reduce the need forcostly construction of waste treatment facilities.

58 r 4

Nutrient retention by wetlands can also enhancethis functional value by preventing downstreamnuisance algae blooms and associated fish kills.

Food Chain Support. Food chain support is thedirect or indirect use of nutrients, in any form, byanimals inhabiting aquatic environments. The use ofthe term food chain support pertains primarily tothe use by fish and aquatic invertebrates havingcommercial or sport value. Nutrient export is thenet movement of nutrients, particularly carbon,phosphates, and nitrates, out of particular wet-lands, but not necessarily out of the basin in whichthey are located. Movement may be to adjacentdeep waters (called inbasin cycling) and/or to down-current basins in wetlands. Nutrients may be eitherin particulate or dissolved form and either organicor inorganic.

The direr; economic significance of the food chainsupport function is that some regional economies de-pend almost exclusively on fisheries which, in turn,may depend heavily on wetlands for nutrient exportand habitat.

Recreational and Herit'ge Values. Active recrea-tion in wetlands refers to water activities and is akeystone of many local and regional economies.Passive recreation and heritage values includeaesthetic enjoyment, nature study, picnicking,education, scientific research, preservation of rareor endangered species, maintenance of the genepool, protection of archeologically or geologicallyunique features, maintenance of historic sites, andotaer mostly intangible uses. Rare botanicalfeatures also dot wetlands.

Progress in Evaluation

The importance of the various wetland valuesdescribed above are being recognized more widelyin political, economic, and ecologic& circles. Con-siderable research is being devoted to quantifyingsuch values for decisionmaking purposes. Alter-native methods for quantifying wetland values aredetailed in the following conference proceedingsand references:

Florida Conference. A National Symposium onWetland Functions and Values: The State of OurUnderstanding. Nov. 1978. (American WaterResources Association, 1979).

Evaluation Methods. In September 1981, theU.S. IN cater Resources Council issued a report thatevaluated various current methodologies for assess-

ing wetland values. (U.S. Water Resources Council,1981).

National Wetland Inventory. U.S. Fish andWildlife Service. (Frayer and others, 1983).

National Wetlands Workshop. A NationalWetlands Values Assessment Workshop was held inMay 1983. (U.S. Dept. Interior, 1984).

A Method for Wetland Functional Assessment.March 1983. Federal Highway Administration.(Adamus and Stockwell, 1983).

Many other technical publications on wetlands haveresulted from other symposia, seminars, andworkshops. However, generally acceptable methodsfor quantifying wetland values as marketable goodsand services have not yet been developed for manyof the wetland functions.

Ecological Concerns

Jahn (1978) wrote that a watershed can be subdivid-ed into three habitat units: freshwater, Faltwater,and terrestrial. The interrelationships among thesevaried aquatic and terrestrial habitats providestability to ecological systems and processes.

Cairns (1978) noted that any modification of inlandwater displacing or impairing ecosystem structureor function is a degradation of ecological integrity.Degradation occurs because plant and animalorganisms depend on a given set of environmentalconditions. When these conditions are disrupted orchanged, the dependent species must adjust, move,or die.

Wetland Resources and Losses

Wetlands exist in every State. Their abundancevaries with climate, soils, geology, land use, andother regional differences. Estimates of the area ofwetlands at the time of original settlement rangearound 215 million acres for the conterminous 48United States (Roe and Ayres, 19541. In 1955, anestimated 108 million acres of wetlands existed(Frayer and others, 1983). Today's wetlandresources in the conterminous 48 States cover about99 million areas, or 46 percent of our originalwetlands (Tiner, 1984). Tiner estimates Alaska'swetland resources at approximately 200 millionacres.

Palustrine wetlands (generally inland), includingfreshwater marsnes and swamps, constituted 94percent of the wetlands in the 48 States. In 1975,

41

about 93.7 million acres of palustrine wetlandsexisted, with over half the area forested wetlandsand a third emergent wetlands. By contrast, only5.2 million acres of estuarine wetlands the existed.This amounts to an area approximately the size ofMassachusetts, or 0.3 percent of the land surface ofthe conterminous 48 States (Tiner, 1984).

Small net ge'tis in deepwater habitatsartificiallakes. reservoirs, and coastal watersoccurred be-tween about 1955 and 1975 (Frayer and others,1983). Total lake area increased by 1.4 millionacres; about 94 percent of this gain was in theeaster', part of the country These lakes and reser-voirs were mostly created from uplands, althoughsome vegetated wetlands were destroyed in theprocess.

Some additional wetlands have also formed alongthe edges of new water bodies. During 1955-75,coastal open waters increased by 200,000 acres.Much of this gain was in Louisiana at the expenseof coastal wetlands, which were rapidly being floodedpermanently. During the same period, 200,000 newacres of unvegetated wetland flats and 2.1 millionacres of ponds were created.

Pond area nearly doubled between 1955-75, increas-ing from 2.3 milbun acres to 4.4 million acres,primarily because of farm pond construction in theadjacent Central and Mississippi waterflow flyways.Most of the pond acreage was on uplands, although145,000 acres of forested wetlands and 385,000acres of emergent wetlands were changed to openwater (Tiner, 1984). According to the most recent(1982) National Resources Inventory .(NRI) completedby USDA, there were about 78.2 million acres ofnonfederally owned wetlands in the United States.Of this total, 65.3 million acres (83 percent) wereprivately owned while 12.9 million acres (17 per-cent) were owned by State and local governments.

Tiner (1984) considers agricultural development tobe responsible for 87 percent of the recent wetlandlosses in the United States, while urban and otherdevelopments caused 8 percent and 5 percent of thelosses, respectively.

Monetary net worth does not describe the totalvalue of wetland protection, maintenance, and/orenhancement. The inability to quantify the fullmonetary value of wetlands, coupled with theoverestimate of monetary benefits, can often resultin decision(' to drain wetlands at the expense ofnumerous wetland values.

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Figure 5-7--An enlarged channel with vegetated side slopes im-proves drainage in the muck area of the Marsh Run Wastershed,Huron County, Ohio. The waterway alsc serves as an irrigationwater supply channel.

Coordination Mandates

During the past two decades, the terms wetlandsand drainage have stimulated varied and sometimesexcessive reaction from a variety of agricultural,wildlife, fishing, engineering, economic, watermanagement, and environmental interests. Such in-terdisciplinary interest and public concern hasdemanded coordinated action. Various laws, direc-tives, and regulations now mandate the coordinatedmanagement of wetlands.

The National Environmental Policy Act of 1969.This act authorizes and directs Federal agencies togive appropriate consideration to environmentalamenities and values along with technical con-siderations. The results of these analyses must beincluded in proposals for Federal action.

Executive Order on Protection of Wetlands. Ex-ecutive Order No. 11990 is reproduced in appendixA. Issued in 1977 by President Carter to comple-ment the National Environmental Policy Act of 1909,the order instructs Federal agencies to avoid, to theextent possible, the long- and short-term adverseimpacts associated with the destruction andmodification of wetlands and to avoid direct and in-direct support of new construction in wetlandswherever there is a practical alternative. It directseach Federal agency to provide leadership and takesuch action to minimize the destruction, loss, ordegradation of wetlands, and to preserve andenhance the national and beneficial values ofwetlands in carrying out agency responsibilities.

60

.._UltkA:

Figure 5-8This channel in the Boggs Creek Watershed, MartinCounty, Indiana, was improved by working just one side of thewaterway. Vegetation went undisturbed on one bank while theother side was seeded with Kentucky 31 Fescue.

The Clean Water Act, 1977 Amendments. The ob-jective of the 1977 amendments to the FederalWater Pollution Control Act (1972) now known asthe Clean Water Act is to restore and maintain thechemical, physical, And biological integrity of theNation's waters. The amendments established thefollowing six major goals, which have been only par-tially achieved:

That the discharge of pollutants into navigablewaters be eliminated by 1985;

That by July 1983 an interim goal of waterquality be provided for the protection and propaga-tion of fish, shellfish, and wildlife and recreation inand on waters;

That the discharge of pollutants in toxicamounts be prohibited;

That Federal financial assistance be providedto construct waste water treatment plants;

That areawide west. treatment managementplanning processes be developed and implemented;and

That major research and demonstration effortsbe made to develop technologies to eliminate thedischarge of pollutants into waters.

Channel Modification Guidelines. "ChannelModification Guidelines" is a good example of acooperative effort to emphasize wetland prote ionand maintenance. Jointly prepared by the SC andthe Fish and Wildlife Service, these guidelines helpagency personnel indentify when and where chan-nel modification may be used as a technique for im-plementing water and related land resource projects

under the authorities of the SCS for planning smallwatershed and resources conservation and develop-ment projects (figs. 5-7 and 5-8). The guidelinesstipulate that efforts will be made to maintain andrestore streams upon which fish and wildliferesources depend (U.S. Depts. Interior andAgriculture, 1979).

Comprehensive Evaluations

Despite current oversupply problems confrontingU.S. agriculture, it is unrealistic to assume that on apermanent basis significantly less land will bedevoted to agricultural production in theforeseeable future. However, food and fiber produc-tion should be balanced with the other ,noducts ofland, including those produced by wetlands. Allpossible measures should be incorporated inspecific drainage plans and designs to minimizedegradation of wetland values. Such evaluationsshould serve as a positive catalyst to pull togetherall interests and responsibilities. Mutual coopera-tion and understanding can lead to the planning andcompletion of only such added drainage as may beneeded in the public interest and within anstraintsthat maintain the important values associated withthe remaining wetlands.

This action supports USDA's policy which is toassure that the values of fish and wildlife arerecognized and that their habitats, both terrestrialand aquatic (including wetlands), are consideredwhen the Department carries out its missions. USDAsupports research and management programs thatrespond to the economic, ecological, educational,recreational, scientific, and aesthetic values of fishand wil&ife. Its goals are to imlrove, where needed,fish and wildlife habitats, and to ensure thepresence of diverse native and other populations ofwildlife, fish, and plant species (USDA, 1983).

References

11,:lamus, Paul R., and C. T. Stockwell. 1983. AMethod for Wetland Functional Assessment. U.S.Dept. Trans., Fed. Hwy. Adm. Rpt. Nos. FHWA-IP-82-23 and FHWA-IP-83-24.

'7'7

American Water Resources Association. 1979.Wetland Functions and Values: The State of OurUnderstanding. Proceedings of the National Sym-posium on Wetlands. Tech. Pub. No. TPS 79-2.Minneapolis.

Cairns, John. Jr. 1978. Wildlife and America. Councilon Environmental Quality. Govt. Print. Off.

Cowardin, Lewis M., Virginia Carter, Francis C.Golet, and Edward T. LaRoe. 1979. Classification ofWetlands and Deepwater Habitats of the UnitedStates. U.S. Dept. Interior, Fish and Wiidlife Serv.Rpt. No. FWS/OBS-79/31.

Frayer, W. E., T. J. Monahan, D. C. Bowden, and F.A. Graybill. 1983. Status and Trends of Wetlandsand Deepwater Habitats in the Conterminous UnitedStates: 1950's to 1970's. Fort Collins, Colo.: Depart-ment of Forests and Wood Sciences, Colorado StateUniv.

Jahn, Lawrence R. 1972). "Values of RiparianHabitat to Natural Ecosystems," Protection andManagement of Fluodplain Wetlands and RiparianEcosystems. Gen. Tech. Rpt. WO-12. U.S. Dept. Agr.,Forest Service.

Lonaid, Robert L., and others. 1981. Analysis ofMethodologies Used for the Assessment of WetlandValues. U.S. Water Resources Council, Washington,DC.

Roe, H. B., and Q. C. Ayres. 1954. Engineering forAgricultural Drainage. New York: McGraw-Hill BookCompany.

Tiner, Ralph W., Jr. 1984. Wetlands of the UnitedStates: Current States and Recent Trends. U.S. Dept.Interior, Fish and Wildlife Serv.

U.S. Congress, Office of Technology Assessment.1984. Wetlands, Their Use and Regulation. Rpt. No.OTA-0-207. Govt. Print. Off.

U.S. Department of Agriculture. 1983. U.S. Fish andWildlife Policy. Dept. Reg. 9500-4.

U.S. Department of the Interior and U.S. Departmentof Agriculture. 1979. Channel ModificationGuidelines (amended).

61

Chapter 6

Principles of Drainage

R. Wayne SkaggsDepartment of Biological and Agricultural

EngineeringNorth Carolina State University, Raleigh

A review of drainage principles appropriately beginswith the hydrologic cycle, the main components ofwhich are illustrated in figure 6-1. Precipitation fall-ing to the earth's surface either infiltrates into thesoil profile or moves from the area by overland flowwhich may eventually enter a stream or other surface-water outlet. The infiltrated water may be stored inthe unsaturated zone or percolate downward to asaturated zone. Water may be removed from theprofile by evapotranspiration (Ell and by naturaldrainage processes. These processes may includeground-water flow to streams or other surfaceoutlets, vertical seepage to underlying aquifers, orlateral flow (interfiow) which may reappear at thesurface at some other point in the landscape. Inmany soils, the natural drainage processes are suf-ficient for the growth and production of agriculturalcrops. In other soils, artificial drainage is neededfor efficient agricultural production.

Soils may have poor natural drainage for a numberof reasons. Lands with surface elevations close tothat of the drainage outlet (section D, in fig. 6-1)may have permanently high water tables. Land thatis far removed from the drainage outlet, such assections B and C may have high water duringcritical periods of the growing season. Other landsmay be poorly drained because of seepage fromupslope areas (section E) or because they are indepressional areas with in surface water outlet.Water drains slowly from soils with tight subsur-face layers, regardless of where these layers are inthe landscape; so soils may have poor naturaldrainage because of restricted permeability orhydraulic conductivity of the profile.

Climate is another important factor affecting theneed for artificial drainage. Natural drainage at a

62I 73

rate that may be sufficient for agriculture in a sec-tion of Nebraska where annual rainfall is 20 inchesper year, for example, may be inadequate in Loui-siana where the annual rainfall is 55 inches.Nowhere is this factor more evident than inirrigated semiarid areas. Lands that have beenfarmed for centuries under clryland cultures oftendevelop high water tables and become water-loggedafter irrigation is established. By contrast, naturaldrainage may be adequate in other soils and theseveral-fold increase in the amount of water appliedto the surface because of irrigation will not resultin poorly drained conditions. Seepage from unlinedirrigation canals or from reservoirs may also resultin poorly drained soils in areas where they did notpreviously exist.

All soils require satisfactory drainage for efficientagriculture.' production; many need improved c' ar-tificial drainage. Soils n ay be poorly drained becauseof climate and irrigatiol practices, position in thelandscape in relation to drainage outlets or irriga-tion canals, or low permeability and/or restrictinglayers in the soil profile.

In most cases, improved drainage practices can beused to satisfy agricultural requirements. These. willbe discussed first, followed by the factors control-ling the movement and storage of water in the soilprofile and methods that can be used to satisfydrainage requirements. Examples are given todescribe the design and operation of a drainagesystem and the concepts of controlled drainage andsubirrigation. The concluding section discussessome principles that can be used to consider offsiteimpacts of drainage and related water managementpractices.

i i

IINFILTRATION

INTERFLOW

I

i

B

PRECIPITATION

i

__ _WATER TABLE

i 1

C

i i

EVAPOTRANSPIRATION

I i fSURFACE

RUNOFF.._....

i

D ---1

4II

SURFACEWATER OUTLET.......1....

GROUND WATERFLOW

Figure 6-1Schematic of main components of the hydrologic cycle.

Drainage Requirements

There are basically three reasons for installingagricultural drainage systems: for trafficability sothat seedbed preparation, planting, harvesting, andother field operations can be conducted in a timelymanner; for protection of the crop from excessivesoil v. ater conditions; and for salinity control. Inspecial situations, drainage systems may be installedfor other purposes. An example is the use of drainageto increase the amount of wastewater that can beapplied and effectively tr sated on a land applicationsite.

Trafficability

The practical effects of poor drainage on timelinessof farming operations are outlined by Fausey andothers in chapter 4 and also by Reeve and Fausey(1974). Soils with inadequate drainage may ex-perience frequent yield losses because essentialfarming operations cannot be conducted in a timelyfashion. The result may range from complete cropfailure if planting is delayed too long, to reducedyields if tillage, spraying, harvesting, or otheroperations are not performed on time. The effects ofplanting-date delays on corn yield are shown infigure 6-2. Although the mechanisms causing re-duced yield because of delayed planting may be dif-ferent in North Carolina than in Ohio, results aresimilar. The results are based on data reported byKrenzer and Fike (1977) for North Carolina e-Nolte and others (1976) for Ohio. Yields are ._ .,dfor late-planted corn because of greater heat stress

( 79

during the pollination period, shorter day lengthduring yield formation, and increased susceptibilityto insects and diseases. Delays in planting may alsolead to increased stresses because of deficit soil-water conditions during the critical floweringperiod, which could cause even greater reductionsin yield than those shown in figure 6-2.

Protection from Excessive SollWaier Conditions

The major effects of excessive soil water on cropproduction are caused by reduced exchange of airbetween the atmosphere and the soil root zones.Wet soil conditions may result in a deficiency of ox-ygen (02) required for root respiration, an increasein carbon dioxide (CO2), and the formation of toxiccompounds in the soil and plants. Under field condi-tions, soil-water-plant systems vary continuously.Evaluating the effect of water content and aerationstatus on plant growth requires integration of theseconditions over time during the entire growing sea-son. One of the parameters that tends to integratethese factors in soils requiring artificial drainage iswater table depth (Wesseling, 1974). Although thedepth of the water table has no direct influence oncrop growth, it is an indicator of the prevailing soil-water status, water supply aeration, and thermalconditions of the soil.

Numerous laboratory and field experiments ha Jbeen conducted to determine the effect of watertable depth on crop yields. Probably the mainreason yield has been related to water table depthis that water table depth is easier to measure than

63

PLANTING DATE DELAY, DAYS

Figure 6-2--Effects of delayed plantings on corn yields in NorthCarolina and Ohio.

other variables such as the distribution of oxygen inthe profile. Most experiments have been directed atrelating yields to constant water table depths(Williamson and Kriz, 1970).

An example of the effect of water table depth on yieldis given in figure 6-3. The results were obtainedfrom Wesseling (1974) and are based on originalresearch conducted in The Netherlands by W. C.Visser. Both relationships show reduced yields atshallow water table depths because of excessivesoil-water conditions, an optimum range, and reducedyields at deeper water table depths because of defi-cient soil-water conditions. Although it may bepossible to define an optimum water table depth,the relative position of curves, such as those givenin figure 6-3, and thus the optimum depth, would de-pend on climate, soil properties, the crop, and alsocultural and water management practices. William-son and Kriz (1970) found that optimum water table

pths were greater when irrigation water wasapplied at the surface.

While cause-and-effect relationships for crop yieldsare easier to identify for constant water table depths,such steady-state conditions rarely occur in nature.The effects of fluctuating water tables and intermit-tent flooding on crop yields depend on the frequencyand duration of high water tables as well as thecrop sensitivity. Approximate methods have devel-oped to quantify the effect of excessive soil-waterconditions because of fluctuating water tables forcorn (Hardjoamidiojo and others, 1982) and grainsorghum (Rave lo and others, 1982). The method usesthe SEW30 concept (originally defined by Sieben inWesseling, 1974) to quantify stress caused by thewater table rising into the root zone. The stress-day-index method of Hi ler (1969) weights the stress by

64

80

crop susceptibility factors which depend on thestage of growth. The results are linear relationshipsbetween the percentage of optimum yield and thestress-day-index. Stress-day-index values may becomputed for a specific set of drainage designparameters, soil properties, weather data, and cropparameters with a simulation model that will bediscussed in a subsequent section of this chapter.

Salinity Control

It seems somehow unjust that dry lands of arid andsemiarid regions, when irrigated, often require ar-tificial drainage. Luthin (1957) documented drainageproblems that have beset irrigators since earliestrecorded times. The accumulation of salts in surfacesoil caused the once fertile Tigris and EuphratesRiver Valleys of ancient Mesopotamia to return todesert. Relics of abandoned irrigation systems,alkali flats, and saline accumulation throughout theNear East and Sahara Desert show how lack of properdrainage eventually caused economic ruin and prob-ably contributed to the destruction of ancientcivilizations. A present-day example is the annualloss of thousands of acres in the San Joaquin Valleyof California because of salt accumulation andwater logging.

Practically all irrigation water contains some salt.Evaporation and consumptive use of water by plantsconcentrate the salts in the residual soil water,causing a solution that is usually more saline thanthe irrigation water. Repeated irrigabifis continuallyincrease the salinity of the soil water even if theirrigation water is of relatively good quality.

.L.9 prevent the buildup of soil-water salinity to apoint that it harms plant roots and reduces produc-tivity, irrigation water in excess of the amountneeded for evapotranspiration is applied to teachthe concentrated soil solution from the root zone. If

010

20

30

40

50

60

LIGHT CLAY SOIL

SANDY SOIL

1 1 1 t 1 I I I 1 1

02 0.4 06 08 10 12 1.4 16 1.8 2.0

MEAN WATER TABLE DEPTH BELOW SURFACE. M

Figure 6-3Yield depression as a function of mean water tabledepth during the growing season for two soils.

Figure 6.4Subsurface drainateintensity Jepends on the spacingof the drain tubes, while the qual-ity of surface drainage is inverselyproportional to the depth of de-pression storage.

RAINFALL OR ET

VIII fitDEPRESSION STORAGE S RUNOFF (RO)

SOIL SURFACE

WATER TABLE

47/k/1,(4//fr//,#// ti/h/ittikti.ttlit/t.tti /AV/ XV/k/kii.tvRESTRICTIVE LAYER v DEEP SEEPAGE (DS)

drainage is adequate, the excess irrigation waterwin carry the concentrated salt solution out of therout zone. If it is not, the water table will rise inresponse to the excess irrigation water and thesalinity will continue to increase in the root zone, socror yields may then be reduced for two reasons,high salinity and high water tables.

When natural drainage is not sufficient, artificialdrainage systems are needed to remove the excessirrigation water from the soil profile. Because thesalinity below the water table is usually severaltimes that of the irrigation water, drainage systemsare normally designed to hold the water table wellbelow the root depth. The drains should be placeddeep enough to prevent salinization because of up-ward flux from the water table during the fallowperiod when irrigation water is not applied. Drainsare typically placed 2-3 meters (about 7-10 feet)deep in irrigated lands, compared with 0.75-1.5 m(2.5-5 feet) deep in humid areas.'

Drainage Theory and Practice

Both surface and subsurface drainage systems areused to meet drainage requirements of poorly drainedsites. A schematic of a drainage system is shown infigure 6-4. Subsurface drainage is provided by draintubes or parallel ditches spaced a distance, L,apart. Most poorly drained soils have a restrictivelayer at some depth, shown here as a distance, d,

'Both metric and U.S. units of measure are frequently given inthis chapter to help explain the theory of drainage for all readers.Units. abbreviations. and selected factors for converting to andfrom U.S. and metric measures are in appendix D.

below the drain tubes. When rainfall occurs, waterinfiltrates at the surface, raising the water contentof the soil profile. Depending on the initial soil-water content and the amount of infiltration, someof the water may percolate through the profile, rais-ing the water table and increasing the subsurfacedrainage rate. If the rainfall rate is greater thanthe infiltration rate, water begins to collect on thesurface. If good surface drainage is provided so thatthe surface is smooth and on grade, most of the sur-face water will be available for runoff. However, ifsurface drainage is poor, a substantial amount ofwater must be stored in depressions before runoffcan begin. After rainfall ceases, infiltration con-tinues until the water stored in surface depressionsinfiltrates the soil. Thus, poor surface drainage ef-fectively lengthens the infiltration event for somestorms, permitting more water to infiltrate and alarger rise in the water table than would occur ifdepression storage did not exist. Once excess waterenters the soil profile, it may be removed byevapotranspiration fron the surface and throughthe plants, by aatural drainage processes via deepand lateral seepage, and through artificial systemsconsisting of drainage tubes, ditches, or wells.

Subsurface Drainage Processes

The principal relationship used to describe watermovement in soil was derived experimentally byHenry Darcy in 1856. He found that the flow rate ofwater through sand beds of different thicknesseswas proportional to the hydraulic gradient. Darcy'slaw is illustrated in figure 6 -5 and may be written as:

I-H2Q = K A HL(6.1)

where Q is the flow rate through the soil column(cm' /hr, in3/hr), A is the cross-sectional area (cm',

Si65

Figure -1-5Water table profileshows Eteady-state drainage un-der a constant rainfall rate, R.

in2) L is the column length (cm, in) in the directionof flow, and H, and H2 are the hydraulic heads (cm,in) at the ends of the column. K is the proportionalityconstant which if; termed the hydraulic conductivity.K is also called peimeability in some references andhas units of cm/hr or in/hr. The flux, or dischargevelocity, is equal to the flow rate per unit of cross-sectional area of soil and may be expressed as:

H' -H2q 2 K HA

Although the soil-water flux has units of velocity (ascm/hr or in/hr), it is not equal to the velocity in in-dividual pores but is defined as the flow rate perunit area. The flux may be defined at every point asaturated zone in terms of the hydraulic gradient atthat point:

(6.2)

= -K dHdS

where s is the direction of flow and the negativesign indicates that flow is in the direction ofdecreasing hydraulic head. Flux should be regardedas 8 vector quantity having both magnit-ide anddirection. Then q, should be interpreted as the fluxcomponent in the S direction.

(6.3)

Uniform soils are soils in which K and other proper-ties, such as density and porosity, are constant.Although most natural soils are nonuniform, theyfrequently consist of relatively uniform layers. Soilsin which the hydraulic conductivity is independentof flow direction are called isotropic. A±,'sotropicsoils have K values which are dependent on theflow direction. (Refer to Childs (1969) for a completediscussion of anisotropy.) Buckingham (1970) showed

66

82

that, by expressing the conductivity as a iunction ofthe soil-water content, K = K(0), equation 6.3 is alsoapplicable to flow in the unsaturated zone.

When Darcy's law is combined with the principle ofconservation of mass, nonlinear partial differentialequations describing flow in both the saturated andunsaturated zones may be derived (Richards, 1931).Although numerical methorfs may be used to solvethese complex equations, simpler methods havebeen employed for design and analysis of mostdrainage priblems. Because the drain spacing isusually large. compared with ciepth to the restrictivelayer, flow to the drains is often primarily horizon-tal and the hydraulic gradient is approximatelyequal to the slope of the free surface. These approx-imations are referred to as the Dupuit-Forchheimer(D-F) assumption. When the D-F assumptions arecombined with Darcy's law and the principle of con-servation of mass. simplified solutions to certainproblems can be obtained.

Steady-State Drainage. The relation6hip t tweendrainflow rate and water table height for steadyrainfall can be obtained by using the D-F assump-tions. Drainflow rate per unit surface area equalsthe rainfall rate for steady-state conditions (fig.6-6)and may be expressed as:

8Kmd, + 4Km2R (6.4)

L2

where m is the midpoint water table elevationabove the drain tube and d is the effective depth tothe impermeable layer, which is less than the realdepth to compensate for conve.gence head losses in

the vicinity of the drain (van Schilfgaarde, 1974).The do value can be computed by equationspresented by Moody (1967), which may be writtenas follows for d/L < 0.3:

= K A d1 + d ( 8 In d - 3.4)

L Tr re

where re is the effective draintube radius (Skaggs,1978a). Another equation is used for d/L > 0.3.

(6.5)

Equation 6.4 is known as the Hooghoudt equationafter the Dutch scientist, Dr. S. B. Hooghoudt. Theequation for estimating drain spacings may be writ-ten as:

'/2

L = [ 8 K2 mdo + 4Ktm2 (6.6)

where Kt and K2 are the hydraulic conductivities ofthe soil layers above and below the drain, respec-tively. Although it is clear that water tables, rain-fall rates, and drainage fluxes vary with time undernatural conditions, equation 6,6 can be used to ap-proximate the required drain spacing if the ap-propriate m and R values are known. Thoseparameters are certain to depend on the crop andclimate, and therefore location, as well as on otherrut:nagement and cultural practices. A recentsimulation study on 12 North Carolina soils (Skaggsand Tabrizi, 1984) showed that an estimate of theoptimum drain spacing for corn production could beobtained with equation 6.6 by taking m correspond-ing to a midpoint water table depth of 0.3 m (12 in)from the surface, and the following design drainagerates:

1. good surface drainage: q = R = 5.4 mm/day (0.21in./day)

2. poor surface drainage: q = R = 6.2 mm/day (0.24in./day)

Figure 6.6-Water taU9 profileshows steady-state drainage un-der a constant rainfall rate, R.

Example-Initial and solution values will be given inU.S. and metric units; calculations and intermediatevalues are in metric units for simplicity.

A sandy loam soil with an impermeable layer 3 m(9.84 ft) deep has a saturated hydraulic conductivityof 0.75 m/day (29.5 in/day). How far apart shoulddrain tubes be placed such that a steady rainfallrate of 5.4 mmlday (0.2128 in/day) will result in amidpoint water table depth of 0.3 m (about 1 ft)?The drains are to be placed lm (3.28 ft.) deep andthe effective draintube radius is 1 mm (0.0394 in).

Using equation 6.6 with Kt = K2 = 0.75 m/day,m = 0.7 m, R = 0.005 m/day, and assumingdo= Jd = 1.4 m as a first approximation giveSL = 37 m. Because do depends on L which in turndepends on do, iteration must be used to obtain thecorrect L value. Substituting L = 37 in into equa-tion 6.5 gives a better estimate for de: do = 1.3 m.Solvinz ivation 6.6 again with the new de valueyie:ds L = 36 m. Substitution of this L into equation6.5 results in do = 1.3, which is the same as thevalue used to.obtain L. Therefore, drains placed 35m (118 ft) apart and 1 m (3.3 ft) deep will provide asteady drainage rate of 5.4 mm/day (0.21 in/day)with a midpoint water table 0.3 m (1 ft) from thesurface. Further examinatkn of the situation wouldshow that the steady state water table profile hasan elliptical shape as show. in figure 6-6.

The drain spacing given in this example is approx-imately the optimum drain spacing for corn produc-tion in eastern North Carolina for good surfacedrainage (that is, q = R = 5.4 mm/day or 0.21in/day). For poor surface drainage, q = 6.2 mm/day(0.24 in/day), and L = 33 m (i08 ft) is obtained fromequation 6.6. Although the effect of good surfacedrainage on the spacing required for optimum pro-

RAINFALL RATE, Rlilllll{I LL

RESTRICTIVE LAYER/Miltitti/M.f/W/,41/40//.4(1/P//k//1Y/1//k/JA//k//

8367

(a)SURFACE

(b) (c)

WATERTABLE

z

DATUM

Y1

Y2

h =pty

(e)

h=PPY

(f)

e

SANDYLOAM

JAV

WATER TABLE DEPTH, y

(d)

//LOAM

df= Vdy

Figure 6.7A soil column drained to equilibrium. With a water table (a), it has a linear pressure headdistribution (b). Given the pressure 119?^4 at each point, the soil water content. 0, can be determined (d)from the soil water characteristic (c). r characteristics for two soils are shown schematically in (c).The cross-hatched area in (e) represe olume of water drained when the water table falls from Y1 toY2. The drainable porosity, f, define, as dV/dy and is the slope of the curves shown in (f).

duction is relatively small for this soil, it may havea much more significant effect if subsurfiJedrainage is poor.

Soil-Water Distribution and Drainable Porosity_In most cases, drainage of water from the soil pro-file lowers the water table, reducing the hydraulicgradient and the drainage rate. The response of thewater table to removal or addition of a givenvolume of water depends on the soil's drainableporosity or specific- yield. Solutions to the Richardsequations (Skaggs mid TP ig, 1976) indicate that,except for the region ch., a to the drains, thepressure head distribution above and below thewater table during drainage may be assumed nearlyhydrostatic (figure 6 -7b) for many field-scaledrainage systems.

68

r,!

This situation happens because, in most fields withartificial drains, the water table drawdown is slowand the unsaturated zone in a sense "keeps up"with the saturated zone. As a result, verticalhydraulic gradients are small. Under these condi-tions, the soil-water distribution is approximatelythe same as in a column of soil drained to equilib-rium with a static water table. That distribution canbe obtained from the soil-water characteristic orsoil-water retention curve (fig. 6-7c), which is therelationship between the volumetric soil-water con-tent 0, and the pressure head, h = p/7, where p isthe soil-water pressure and y is the specific weightof water. As indicated in figure 6-7c, the soil-waterpressure is negative in the unsaturated zone; it iscommonly referred to as tension or suction in whichit takes a positive sign; that is, h = -25 cm (-9.8 in)would be a suction or tension head of + 25 cm (9.8

in). Water is held in the unsaturated soil matrix byadhesive and cohesive forces (Day and others, 1967;Childs, 1969; Kirkham and Powers, 1972). The watercontent at any given pressure head depends onseveral factors, including bulk density, texture,structure, and the existence of macropores fromroots, worms, or other causes.

Figure 6-7d shows the soil-water distribution for adrained-to-equilibrium profile with the water tableat depth d. The crosshatched area indicates thevolume of water per unit of surface area, which isactually a depth of water that would have to beremoved to lower the water table from the surfaceto depth y. The amount of water that would have tobe drained to lower the water table by a distanceAy is shown by the crosshatched area in figure6-7e. If we denote this volume (depth in cm or in) asAV, the drainable porosity is defined as f = AV/Az.If we start with the water table at the surface anddetermine the drainage volume for progressively in-creasing water table depths, relationships such asthose given in figure 6-7f can be obtained. Thedrainable porosity would then be defined as theslope of the curve at any giver water table depth.These relationships show that the drainable porositydepends on water table depth as well as soil type.Drainable porosity normally increases with watertable depth and it. higher for sandy soils than forclays. However, these relationships depend en soillayering, macropores in the surface horizons, andother factors.

Water Table Drawdown. Steady-state conditionsrarely exist in nature. In most cases, the watertable and the soil-water regime above the watertable are in a transient state, either increasing dueto rainfall or it ration or decreasing due todrainage and F. Because high water tables can betolerated for certain periods of time by most crops,the rate that a drainage system will lower thewater table after p-triods of high rainfall may bemore important than its operation under steady-state conditions.

Numerous methods have been developed for predict-ing water-table drawdown (for example, the Glovermethods (Dumm, 1954, 1964); Maas land, 1959; vanSchilfgaarrle, 1965; and Kirkham, 1964). Many ofthe methods are based on solutions to theBoussinesq equation which result from using the D-Fassumptions in combination with Darcy's law andthe continuity equation. Van Schilfgaarde's solutionwas for an initially elliptical water-table shape anddid not require linearizing the Boussinesq equation:

85

f 1,2

Kdt =

9In [me (2 d + m)/m (2 d + me)] (6.7)

In this equation, t is the time required for the mid-point water table to fall from its initial elevationabove the drain, roe, to m; f is the drainable porosity,and de is defined as in figure 6-6. To account forconvergence near the drains, d should be replacedby de in the equation. Numerical sol :ions to theBoussinesq equation have been used to determinethe effect of simultaneous drainage and ET onwater-table drawdown and the water-table responseto a transition from drainage to subirrigation bound-ary conditions (Skaggs, 1973 and 1975).

Bouwer and van Schilfgaarde (1964) proposed arelat../ely simple method for predicting water-tabledrawdown. They noted that the flux per unit of surfacearea in the steady rainfall case is approximatelyequal to the instantaneous flux during water-tabledrawdown, or

= - R.dt (6.8)

Bouwer and van Schilfgaarde used the Ilooghoudtequation (equation 6.4) to express R in terms=of mand obtained an equation similar to 5.7 for water-table drawdown. They also need that equation 6.8could be expressed as:

,ett = C (Am/Eif) (6.9)

where At is the time required to lower the midpointwater table by Am and C is the ratio of the averageflux per unit surface area, IT to the flux at the mid-point. In this formulation, tabulated values of T ver-sus m, rather than a closed form expression, couldbe used to compute time increments for successivem values to determine the midpoint water-tablenosition as a function of time. An advantage of thissimple formulation, not discussed by the authors, isthat variable drainable porosities may be consid-ered, and the effect of ET can be computed by simplysetting ir equal to the sum of the ET and drainagerates. Comparison of results obtairr by thismethod with numerical solutions to the Boussinesqequation have shos-:.1 good agreement for bothdrainage alone and for simultaneous drahiage andET (Skaggs, 1979).

Drawdown predictions for the example given in theprevious section are plotted in figure 6-8. Thewater table at time zero was assumed to have anelliptical shape with the midpoint coincident withthe sr -f a c e. The drainable porosity was assumed tobe f = 0.05. Solutions are presented for drainageonly and for drainage i combination with a steady

100

80

60

40

20

L 36mI.3m

K 0.75 m/df 005ET 4.9 mm/d

1 I I 1 1 I I I I 1 t I I I 11111_50 100 150 COt

TIME ,HOURS

Figure 6-8Shown is the predicted midpoint watt; table elevationfor the 36-meter (118 feet) spacing. The initial water table shapewas elliptical with the midpoint at the surface, 100 cm (25.4 inches)above the drains. Evapotranspiration may have a significant effecton water table drawdown for water tables dose to the surface.

ET rate of 4.8 mm/day [0.19 in/day). These resultsshow the significant Meet of ET on water-tabledrawdown. Without ET, 32 hours were required tolower the midpoint water table by 0.2 m for the36 m drain spacing considered. T..e same drawdownwould occur in only 20 hours i-ith an ET rate of4.8 mm/day. Because ET may be negligible duringcritical wet periods, it is usually neglected in thedesign of drainage systems so as to provide a con-servative design. However, the effect of ET may besubstantial, and .1t is an important component ofmodern,drainage simulation models.

Surface Drainage

Surface drainage is the rem. val of water that col-lects on the land surface. As noted earlier, watercollects on the surface becat.,a the rainfall rate isgreater than the infiltration capacity. In many flat,poorly drained soils, the most frequen* cause ofponded surfue2 conditions is the saturaion of thesoil profile with the water table rising to the surface.Under these conditions, the infiltration rate isreduced to the subsurface drainage rate, and pond-ing may exist for a long time if good surface drain-age is not provided. For this reason, good surfacedrainage must be provided for slowly permeablesoils and soils with fragipans or tight subsoils.

The next chapier co.f.rs the details of drainagedesign. Here, it is sufficient to note that a surfacedrainage system usually consists of an outlet chcamel,

70 (fit 88

lateral ditches, and field ditches. Water is carriedto the outlet channel by lateral ditches whichreceive water from field ditches or sometimes fromthe field surface. The system may include landsmoothing or land grading to eliminate surfacedepressior . and provide a continuous slope for theremoval of surface water. The outlet channel andlateral ditches may sometimes serve as outlets for asubsurface drainage system. Conversely, surface inletsleading to buried Milt.' may provide an outlet forlocal surface drainage.

Land grading or precision land forming is the shap-ing of land surface with scrapers and land planesto planned surface grades. Excellent surfacedrainage can be provided by land grading, but itsuse may be limited on lands where deep cuts thatexpose subsoils are required. Land smoothingremoves small depressions and irregularities in theland surface, normally after land grading.

Field ditches may be either random or parallel. Theradom ditch pattern is used in fields havingdepressions :' -areas that at too large to beeliminated oy land forming. Field ditches connectthe major low spots and remove excess water fromthem. If possible, the ditches s:iould be shallow6:laugh to permi',- crossing by machinery. If thetopography is sucl- mat deeper ditches are re-quired, a subsurface pipe with surface inlets in thelow areas may be preferred.

A parallel ditch pattern is frequently used in flat,poorly drained soils in humid regions. The land sur-face is graded toward the ditches. In many cases,the ditches are placed close enough together, nomore than 100 m (325 ft), to provide some subsurfacedrainage as well as surface drainage. Suilh ditchesare usually over 1 m (3.28 ft) deep and effectivelydivide the land area into narrow fields often inexcess of 800 m (1/2 miles mtg. A better system is toplace the parallel field ditches further apart withthe row direction perpendicular to the eitch. Byfollowing this pattern and using buried drain tubesfor subsurface drainage, field sizes can be increasedwith less land devoted to ditches.

The need for surface drainage depends very muchon the quality of subsurface drainage. The design oranalysis of a water management system shouldconsider both surface and subsurface drainagecompone.,ts.

Simulation of Drainage Systems

The design and operation of each component of awater management system should consider theclimate, soil properties, site conditions, and croprequirements. Further, the design of one componentshould depend on the other components. For example,a field with good surface drainage will require lessintensive subsurface drainage than if surfacedrainage were poor. This requirement has beenclearly demonstrated in both field studies of cropresponse (Schwab and others, 1974) and by theoret-ical methods. The relative importance of water-management components varies with the weather.In humid regions, a well-designed drainage systemmay be critical in some years yet. provide essentiallyno benefits in otters. Thus, methods for designingand evaluating multicomponent drainage and irriga-tion systems should provide a capability of identify-ing sequences of weather conditions that arecritical to cropproduction and of describing theperformance of the system during those periods.

An effective method of analyzing multicomponentdrainage and irrigation systems is the use ofcomputer-based models to simulate their perform-ance over several years of climatological record.Several models have been developed (Lagace, 1973;Belmans and others, 1983). DRAINMOD, a water-management simulation model deveL ped at NorthCarolina State University (Skaggs, 1978b, 1980), willbe used to demonstrate this approach and to furtherexamine the interactions and effectiveness of sur-face and subsurface drainage.

Inputs to the model include soil properties, cropparameters, drainage system parameters, andclimatological data. The model is based on a waterbalance in the soil profile which is computed on anhourly basis by using approximate methods tocalculate infiltration, drainage, subirrigation, andET (as liniited by both atmospheric and soil-waterconditions). The quality cf surface drainage dependson the depth of depressionai storage, which mayvary from about 1 mm (0.0394 in) for land-formedfields that have been smoothed, to greater than 30mm (1.18 in) for fields with numerous potholes anddepressions or that do not have adequate surfaceoutlets (Ge.yle and Skaggs, 1978). Thus, the effect ofimproving surface drainage can be simulated byvarying the average depth of depressional storage.The intensity of subsurface drainage depends on thedrair. depth and spacing as well as the hydraulicconductivity of the soil layers and depth to therestricting layer.

Approximate methods based on the stress-day indexconcept (Hiler, 1969) were incorporated in themodel (Skaggs and Tabrizi, 1983) to predict theeffect of excessive and deficient soil-water condi-tions on corn yields. The effect of trafficability andplanting date delay are also evaluated by usingrelationships such as those given in figure 6-2.

The simulation output includes daily infiltration,water-table depth, depth of surface, dry zone, sub-surface drainage, runoff, and ET. Monthly and yearlysummaries of these values, as well as the number ofdays suitable for fieldwork are also in the output.The corn yield response as a percentage of thepotential yield, which is defined as the averageyield that would be obtained if all soil-waterstresses were eliminated, is predicted for each yearof the simulation.

As an example of the use of simulation models forthe analysis of drainage systems, results for aneastern North Carolina soil, Rains sandy loam, willbe presented. This soil has a nearly level surfacewith a hydraulic conductivity of about 1 rn/day(39 37 in/day) and a profile depth of 1.4 in (55.12 in).It requires artificial drainage for trafficability andprotection from excessive soil water during wetperiods. Details of the soil properties and otherinput data are given elsewhere (Skaggs and Tabrizi,1983). Simulations were conducted for several drainspacings with both good and poor drainage usingweather data from Wilson, North Carolina.

Average predicted relative yields for the 26-yearsimulation period are plotted as a function of drainspacing in figure 6-9. Relationships for both good(depressional storage, s = 2.5 mm, 0.0985 in) andpoor (s = 25 mm, 0.9850 in) surface drainage arepresented. A maximum average relative yield (YR of0.78) Tas predicted for a spacing of L = 20 m (66ft) for good surface drainage and for L = 17 m (56ft) for poor surface drainage. Higher average yieldswere not obtained because of deficit soil-water con-ditions which caused drought stresses duringseveral years. Yields increased with better drainage(closer drain spacing) until the maximum was ob-tained. Further decreases in drain spacing causedthe average YR values to drop slightly, showing atende- ly for overdrainage if the drains were spacedtoo closely together.

These results showed clearly that the drain spacingrequired for a given level of production is depend-ent on the quality of surface drainage. The-bene-ficial effect of surface drainage increases withdrain spacing and is particularly important for poorsubsurface drainage. For example, the predicted

71

relative yield on the Rairis soil for a 100-meter (328ft) drain spacing, which is a typical spacing foropen ditch drains in eastern North Carolina, isYR = 0.48 for good surface drainage versusYR = 0.37 for poor surface drainage. Assuming anaverage potential yield (that is, the average yieldthat would be obtained in the absence of soil-waterstress) of 11,000 kg/ha (175 Wee), the predictedaverage yields would be 5,300 kg/ha (84 bu/ac) and4,000 kg/ha (64 bit/se), for good and poor surfacedrainage, respectively.

Economic analyses using present costs and pricesdetermined the drainage treatment that would pro-duce he maximum net profit. Results showed thatthe maximum profit for this soil would be obtainedfor a 24 m (78 ft) drain spacing with initial poorsubsurface drainage.

Annual relative yields predicted for years 1950-75are plotted in figure 6-10 for the Rains sandy loamwith drain spacings of 24 and 100 m (79 and 328 ft).Average predicted relative yields were 0.76 and0.47 for these two spacings, respectively. However,differences in the predicted yields between the twospacings varied widely from year to year. In wetyears, the closer drain spacing gave much higheryields. For example, in 1961, YR = 100 m. For thisyear, the closer spacing allowed planting on time (byApril 15), and the only decrease in yield was beccuseof a short period when the water table was highe:-rly in the growing season. However, planting forthe 100 m (328 ft) spacing was delayed until the lastof May. High water-table conditions after plantingand dry conditions later on durinr 'he delayed

DRAIN SPACING, ft.

150 450 750 900

RAINS SANDY LOAM

WILSON.14.C.

GOCO SURFACE DRAINAGE. 52.5mon

-------A1011 SURFACE DRA/NAGE Se 25fmn

Su 030 150 200 259 300

DRAIN SPACING,m

'Figure 6.9The effect of drain spacing on predicted averagerelative yields for a Rains sandy loam soil in Wilson, NorthCarolina.

72

t-)

growing season further reduced yields. The cumula-tive effect resulted in a relative yield of 0.23 for the100 m spacing.

During some years, when yields were limited bydeficient soil-water conditions, yields differed verylittle between the 24 m and 100 m drain spacings.Examples are 1952 and 1964 in some years, suchas 1956 and 1970, predicted yields for the 100 mspacing were higher than fcr the 24 In spacing. Thiswas caused by a sequence of wea.Aer events thatallowed planting to be completed on time for thecloser spacing but delayed planting 20-30 days forthe wider spacing. Subsequently, deficit soil-waterconditions occurred at a time when the early-planted corn was most susceptible to drought. Cornplanted later fared better because rainfall occurredbefore its period of maximum susceptibility.

Results given in figures 6-9 and 6-10 show thataverage yields are significantly increased by im-proved drainage. While the results showed that thebenefits of drainage varied widely from year toyear, improved drainage increases not only averageyields but also the reliability of production. Assam-ing a corn price of $2.50/bu and present costs forproduction and drainage materials, the yieldsshown in figure 6-10 were used to calculate netprofit for each of the 26 years for good drainage(L = 24 m, 328 ft). Re; lilts showed a net profit in 21of the- 26 years for good drainage compared withonly 11 out of 26 years for poor drainage. Gooddrainage improved the reliability of production andallowed a net profit, based on assumed prices andcosts, in ow,. 80 percent of the years. Yields werereduced b drought during the other 5 years,resulting in net losses.

Subirrigation

The same drainage system that removes excesswater during wet periods can also be used in somesoils for irrigation during periods of deficient soilwater. Subirrigation involves raising the watertable and maintaining it at a position that willsupply water to the growing crop. Subirrigation hasbeen practiced in scattered locations for manyyears (Clinton, 1948; Renfro, 1955). It has me .yadvantages over other alternatives under certainconditions. However, until recently, the method wasnot widely used because of the lack of establisheddesign criteria and information characterizing theoperation of systems in the field. Subirrigation isnow being promoted by the drainage industry andpublic agencies, and its use is increasing rapidly.

F-zC.)crLu

100

90

80 -

70

60

50

40

30

20

10

GOOD DRAINAGEL= 24mAVG. RELATIVEYIELD 4,76%

CONVENTIONAL DRAINAGEL = 100 mAVG. RELATIVEYIELD =476

ISX 52 54 56 58 60 62 64YEARS

Figure 6-10Yearly prrdicted relative corn yields for the optimum drain spacing, 24 meters (79 feet), andthe conventional open ditch spacing 0100 meters for a Rains sandy loam soil.

1

h I68 70

Figure 6-11 sketches both a drainage system and acombination drainage-subirrigation system. Drainslead to a ditch as shown on the right side of thedrawing, or to a head control tank. For conventionaldrainage, the water level in the outlet is maintainedat or below the tube. During subirrigation, thewater level in the outlet is raised to force waterback through the drains and raise the water tableas shown in the bottom part of figure 6-11.

For subirrigation systems to be practical, certainnatural conditions must exist: an impermeable layeror a permanent water table at a rather shallowdepth to prevent excessive seepage losses withinabout 7 m (23 ft) of the surface; relatively flat land,otherwise the water table might be maintained atan,optimum depth on one side of the field whileplants suffer from either toeinuch or too littlewater on the other sick:: a moderate to high soilhydraulic conductivity so that a reasonable spacingof ditches or drain tubes will provide subirrigationand drainage; and a readily available source ofwater. These topographical and soil conditions existfor several million acres in the humidregions of the United States.

Where suitable conditions exist, combined subir-rigation drainage systems offer a number of advan-tages and can play a significant role in watermanagement strategies. Probably the most outstand-

72 74 :975

ing advantage is the cost. Both drainage and subir-rigation can be provided in one system, often with aconsiderable cost reduction compared with separatesystems. Other advantages include low labor andmaintenance requirement° Ind no delay in cultivationpractices because of irrigation. Energy requirementsfor pumping irrigation water may be considerablylower-than for conventional irrigation systems.Massey and others (1983) showed that subirrigationrequired somewhat more water than conventionalirrigation but less than 10 percent of the energy forpumping when a surface-water supply was used.Salt buildup at the soil surface poses no problem in

DRAINAGE

WATER TABLE

' -DRAIN TUBES

OUTLETDITCH

//AY R //Mt //MAW AV/ 4s// k/.1 / #/ ki

SUBIRRIGATION

e

DRAINS

/1.(//kukiimAvAilit/Iiii.vi,efril.ty hp/Iv/et/Ai/h.-177'

Figure 6-11Schematic of a system used for both conventionaldrainage (top) and subirrigation (bottom).

89

73

humid regions because of high annual rainfall,whereas subirrigation is not feasible in arid andsemiarid areas because of salt buildup. Deteriora-tion of soil structure is a potential problem in humidregions when the water t tale is maintained at ahigh position for a long period of time.

Two basic design criteria must be satisfied in thedesign of subirrigation-drainage systems: first. thesystem must be capable of moving water to the cropfoot zone at a re;'s sufficient to supply plant re-quirements during peak use periods; second, thedrainage component must be designed to removevater from the soil at a rate that will prevent cropdamage during wet periods.

It is not always clear which of these criteria islimiting so far as design is concerned. Studies usingthe DRAINMOD simulation program indicate thatthe drainage requirement is usually limiting in theCaroline s. That is, drains that are placed closeenough together to meet the drainage needs willusually be close enough to supply the irrigationwater needs when the outlet water level is raisedfor subirrigation. On the other hand, simulations forconditions in the Midwest indicate that the irriga-tion requirement is usually limiting. In this case,drains placed close enough together to satisfy thedrainage requirements, even when the system is beingused for subirrigation, may not be close enough tosupply the irrigation requirements. Methods forpredicting the required drain spacing based onsteady-state conditions have been presented by Foxand others (1956) and Ernst (1975). Methods havebeen developed to characterize the rate of watertable rise during subirrigation (Skaggs, 1973).

The most critical Ewes', of design and managementof a subirrigation-drainage system is the interactionbetween the irrigation and drainage functions.Determining in advance what the movt criticalsequence of weather events might be for a givenmanagement strategy is nearly impossible. The mosteffective way of analyzir.g the performance of sachsystems is to use simulation methods suchDRAINMOD and other models discussed in the pre-vious section. SCS and others are using DRAINMODfor designing and analyzing subirrigation systems.

Research continues to develop better methodE formanaging or controlling these dual-purpose systems.Smith and others (1982) used both field experimentsand simulation methods to show that controllingsubirrigadon applications based on field waterlevels rather than outlet conditions reduced bothwater and energy requirements. Fouss (1983a,b)

74

modified the DRAINMOD model to analyze variouscontrol strategies for a subirrigation system. He isaiso investigating the use of weather forecast dataas a control variable, a subject studied earlier byWarner (1972). A research need in a slightly dif-fe-eent area involves drain-slope and enveloperequirements for subirrigation drainage systems.Present research data are not sufficient for deter-mining if envelope requirements are more criticalfor dual-purpose systems than for conventionaldrainage needs.

Offsite Effects

The preceding sections have discussed drainage andwater -table management in terms of agricultural re-quirements. Traditionally, the efforts of engineers,technicians, farmers, and contractors have beenaimed at one goal: to design and install systems thatwill satisfy agricvtnral drainage requirements atthe least cost. However, recognition in recent yearsof agriculture's role ia nonpoint source pollution ofsurface waters places additional constraints on thedesign and operation of drainage and related water-management systems, particularly where farms arelocated in environmentally sensitive areas, or wheredownstream users of water have stringent waterquality or quantity requirements. In most cases,several design and operational alternatives cansatisfy agricultural drainage needs. Same of thosealternatives have different effects on the rate andquality of water leaving the fields than others. Thechallenge is to identify those alternatives that willsatisfy agricultural requirements while minimizingdetrimental effects on the receiving waters.

Although research is by no means complete on thissubject, considerable work has been done to deter-mine water quality and hydrologic effects ofdrainage and associated water-management practices.In general, systems that depend primarily on sur-face drainage tend to have higher runoff rates wishmore sediment, phosphorus, and pesticides than dosystems with good subsurface drainage. However,good subsurface drainaga increases the outflow ofnitrates with the drainage water. Associated water-management practices, such as controlled drainageand subirrigation, will also have an effect on boththe rate and quality of drainage water leaving afield.

Figure 6-12 illustrates the effect sf subsurfacedrainage on peak outflow rates. T ae runoffhydrographs were measured on adjacent. almostflat 80-acre eastern North Carolina watersheds with

3.0

2.5

2.0

W,.cr

(..). 1.5

co Eo

1.0

0.5

OM QIN/ al.

POOR SUBSURFACE DRAINAGE, WATERSHED A

GOOD SUBSURFACE DRAINAGE, WATERSHED B

TOTAL RAINFALL 3.25 cm

TOTAL. RUNOFF FOR POOR s 2.74 cmSUBSURFACE DRAINAGE

TOTAL RUNOFF FOR GOOD 2.54 cmSUBSURFACE DRAINAGE

10 20 30 40 50 60 70

TIME (hr)Figure 6-12These runoff hydrographs chart a 3.25-centimeter (1.27 inches) rainfall in eastern NorthCarolina on February 28, 1983. The peak runoff rate for watershed A with poor subsurface drainage wasmore than twice that of the adjacent watershed B which had good subsurface drainage.

identical soils and crops. Watershed A has parallelditches spaced 100 m (328 ft) apart which providegood surface drainage but relatively poor subsur-face drainage. Watershed B has the same surfacedrainage system but drain tubes at 33 m (108 ft)intervals between the ditches which provide goodsubsurface drainage. The results show that, whiletotal drainage from the 3.25 mm (1.27 in) storm wasabout the same for both watersheds, the peakoutflow rate from the fields with good subsurfacedrainage was less than half of that from the fieldswith poor subsurface drainage. Good subsurfacedrainage removed excess water from the profileslowly over a lOnger period of time. It lowered thewatt.r table and provided more storage for in-filtrating rainfall than systems which dependedprimarily on surface drainage. Thus, in areas wherehigh surface runoff rates caused flooding andrelated problems, subsurface drainage tended toreduce the peaks. These effects may be very impor-tant in lands close to estuarine nursery areas where

91

high runoff rates may cause unnatural salinity fluc-tuations and consequently reduc4d productivity offish and shellfish.

The effects of subsurface drainage on water-qualityparameters for watersheds A and B a. e tabulatedbelow. Both have oaod surface drainage.

Concentration (milligrams per i;ter)Watershed Total Ortho

N^,-N TKN n P

A (poor subsurfacedrainage) 1.3 1.9 0.16 0.04

B (good subsurfacedrainage) 3.8 1.6 .08 .01

The tabulated values are mean concentrations ofnitrogen and phosphorus measured continuouslyover a year. These results showed that good subsur-

75

face drainage increased nitrate outflow but reducedthe loss of phosphorus (P) to drainage waters.Improvement of surface drainage has the oppositeeffect. Thus, if P concentrations in receiving watersare critically high, better subsurface drainagewould improve the situation. Improved surfacedrainage or the use of drainage outlet controls toincrease surface runoff would also reduce nitrateoutflow. Controlled drainage methods have been used(Willardson and others, 1972; Gilliam and others,1979) to promote denitrification and to reduce theamount of nitrate entering ground and surfacewaters. Skaggs and Gilliam (1981) used field resultsand simulation modeling to show the effects ofdrainage design and operation on nitrate lossesfrom a soil with poor natural drainage. Ths systemsconsidered satisfied agricultural drainage require-ments for corn. Results showed an annual averageloss of 39 kg/ha (35 lbs/ac) for a conventional systemwith poor surface drainage and good subsurfacedrainage. By improving the surface drainage andcontrolling the subsurface outlet during the wintermonths, the annual nitrate loss could be reduced to14.5 kg/ha (12.9 lbs/ac).

These examples emphasize that various drainageand associated water-management practices havedifferent effects on the r.. to and quality of runoffwater. By careful design and operation of water-management systc..2.as, agricultural managementrequirements may be satisfied while minimizingoffsite detrimental effects. To achieve this goal, theprinciples involved and the factors controlling off-site conditions and requirements as well as farmdrainage needs must be understood and considered.

References

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Bouwer, H., and J. van Schilfgaarde. 1963.Simplified Method of Predicting the Fall of WaterTable in Drained Lend. Trrinsactions of the ASAP.Vol. 6, No. 4, pp. 288-291, 296.

Buckingham, E. 1907. Studies of the Movement ofSoil Moisture. Bull. No. 38, U.S. Dept. Agr., Bureauof Soils.

Childs, E. C. 1969. Introduction to the Physical Basisof Soil Water Phenomena. London: Wiley-Interscience, pp. 125-128

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Clinton, F. M. 1967. "Invisible Irrigation on EginBench," Reclamation Era. Vol. 34, pp. 182-184.

Day, P. R., G. H. Bolt, and D. M. Anderson. 1.'d67."Nature of Soil Water," Irrigation of AgriculturalLands (ed. R. M. Hagan and others). Monograph No. '

11. Madison, Wisc.: Am, Soc. Agron., pp. 193-208.

Dumm, L. D. 1954. "New Formula for DeterminingDepth and Spacing of Subsurface Drains in Irrigated Lands," Agricultural Engineering. Vol. 35,pp. 726-730.

Dumm, L. D. 1964. Transient Flow Concept in Sub-surface Drainage: Its Validity and Use. Transactionsof the ASAE. Vol. 7, No. 2, pp. 142-146.

Ernst, L. F. 1975. Formulae for Groundwater Flow inAreas With Subirrigation by Means of Open Con-duits W th a Raise' Water Level. Misc. reprint 178.Wageningen, The Netherlands: Institute for Landand Water Management Research.

Fouss, J. L. 1983a. Simulated Controlled Operationof Subsurface Drainage - Irrigation Systems. ASAEPaper No. 83-2567. St. Joseph, Mich.: Am. Soc. Agr.Eng.

Fouss, J. L. 1983b. Daily Weo .-r Forecast RainfallProbability as an Input to a Water ManagementSimulation Model. Proceedings of the NaturalResources Modeling Sympok-um, U.S. Dept. Agr.,Agr. Res. Serv.

Fox, R. L., J. T. Phelan, and W. D. Criddle. 1956."Design of Subirrigation Systems," AgriculturalEngineering °ol. 37, No. 2, pp. 103-107.

Gayle, G. A;, and R. W. Skaggs. i978. SurfaceStorage on Bedded Cultivated Lands. Transactionsof the ASAE. Vol. 21, No. 1, pp. 102-104, 109.

Gilliam, J. W., R. W. Skaggs, and S. B. Weed. 1979."Drainage Control to Diminish Nitrate Loss fromAgricultural Fields,"Journal of EnvironmentalQuality. Vol. 8, pp. 137-142.

Hardjoamidjojo, S., R. W. Skaggs, and G. 0.Schwab. 1982. Predicting Corn Yiela Response to Ex-cessive Soil Water Conditions. Transactions of theASAE. Vol. 25, No. 4, pp. 922-927, 934.

Hi ler, E. A. 1969. Quantitative Evaluation of Crop-Drainage Requirements. Transactions of the ASAE.Vol. 12, No. 3, pp. 499-505.

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Kirkham, D., and W. L. Powers. 1972. Advanced SoilPhysics. New York: Wiley-Interscience.

Krenzer, E. G., Jr., and W. T. Fike. 1977. Corn Pro-duction GuidePlanting and Plant Population. NorthCarolina Agr. Ext. Serv., N.C. State Univ., Raleigh.

Lagace, R. 1973. "Mode le de Comportenent desNappe en Sol Agricola," Genie Rural Laval,(Quebec, Canada), Vol. 5, No. 4, pp. 26-35.

Luthin, J. N. 1957. "Drainage of Irrigated Lands,"Drainage of Agricultural Lands (ed. J. N. Luthin).Monograph No. 11. Madison, Wisc.: Am. Soc.Agron., pp. 344-371.

Massey, F. C., R. W. Skaggs, and R. E. Sneed. 1983.Energy and Water Requirements for SubirrigationVersus Sprinkler Irrigation. Transactions of theASAE. Vol. 26, No. 1, pp. 126-133.

Moody, W. T. 1966. "Nonlinear Differential Equa-tion of Drain Spacing," Journal of the Irrigation andDrainage Division. ASCE. Vol. 92(IR2), pp. 1-9.

Nolte, B. H., D. M. Byg, and W. E. Gill. 1976. TimelyField Operations for Corn and Soybeans in Ohio.Bull. 605. Coop. Ext. Serv., Ohio State Univ., Columbus.

Ravelo, C. J., D. L. Reddell, E. A. Hiler, and R. W.Skaggs. 1982. Incorporating Crop Needs intoDrainage System Design. Transactions of the ASAE.Vol. 25. No. 3, pp. 623-629, 637.

Reeve, R. C., and N. Fausey. 1974. "Drainage andTimeliness of Farming Operations," Drainage forAgriculture. Monograph No. 17 (ed. J. vanSchilfgaarde). Madison, Wisc.: Am. Soc. Agron., pp.55-66.

Renfro, George, Jr. 1955. "Applying Water Underthe Surface of the Ground." Water: Yearbook ofAgriculture, 1955. U.S. Dept. Agr., pp. 173-178.

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Richards, L. A. 1065. "Physical Conditions of Waterin Soil," Methods of Soil Analysis. Monograph No. 9,Madison, Wisc.: Am. Soc. Agron.

Schwab, G. 0., N. R. Fausey, and D. W. Michener.1974. Comparison of Drainage Methods in a HeavyTextured Soil. Transactior.3 of the ASAE. Vol. 17,No. 3, pp. a 24, 425, 428.

Skaggs, R. W. 1973. Water Table Movement DuringSubirrigation. Transactions of the ASAE. Vol. 16,No. 5, pp. 988-993.

Skaggs, R. W. 1975. "Drawdown Solutions forSimultaneous Drainage and ET," Journal of the Ir-rigation and Drainage Division. ASCE. 101(IR4),pp. 279-291.

Skaggs, R. W. 1978b. A Water Mancoment Modelfor Shallow Water Table Soils. Technical Report No.134. Water Resources Research Institute of theUniv. of North Carolina. N.C. State Univ., Raleigh.

Skaggs, R. W. 1979. Factors Affecting HydraulicConductivity Determinations from DrawdownMeasurements. ASAE Paper No. 79-2075,prerentedat the summer meeting of the Am. Soc. Agr. Eng.,Winnipeg, Manitoba.

Skaggs, R. W. 1980. A Water Management Modelfor Artificially Drained Soils. Technical Bulletin No.267. North Carolina Agri. Res. Serv., N.C. StateUniv., Raleigh.

Skaggs, R. W., and J. W. Gilliam. 1981. Effect ofDrainage System Design and Operation on NitrateTransport. Transactions of the ASAE. Vol. 24, No. 4,pp. 929-934.

Skaggs, R. W., and A. Nassehzadeh-Tabrizi. 1983.Optimum Drainage for Corn Production. TechnicalBulletin No. 274. North Carolina Agri. Res. Serv.,N.C. State Univ., Raleigh.

Skaggs, R. W., and A. Nassehzadeh-Tabrizi. 1984.Determining Design Drainage Rates for OptimumDrainage. ASAE Paper No. 84-1055, St. Joseph,Mich.: Am. Soc. Agr. Engr.

77

Skaggs, R. W., and Y. K. Tang. 1976. "Saturatedand Unsaturated Flow to Parallel Drains," Journalof Irrigation and Drainage Division. ASCE. Vol.102(1R2), pp. 221-238.

Smith, M. C., R. W. Skaggs, and J. E. Parsons. 1982.Subirrigation System Control for Water Use Efficiency.ASAE Paper No. 82-2520. St. Joseph, Mich.: Am.Soc. Agr. Engr.

van Schilfgaarde, J. 1965. "Transient Design ofDrainage Systems," Journal of the Irrigation andDrainage Division. ASCE. Vol. 91(1R3), pp. 9-22.

van Schilfgaarde, J. 1974. "Nonsteady Flow toDrains," Drainage for Agriculture. Monograph No.17. (ed. J. van Schilfgaarde). Madison, Wisc.: Am.Soc. Agron., pp. 245-270.

78

Warner, R. (.. 1972. A Management Model for aControlled Drainage and Subirrigation System. M.S.thesis, Clemson Univ., Clemson, S.C.

Wesseling, J. 1974. "Crop Growth and Wet Soils."Drainage for Agriculture. Monograph No. 17 (ed. J.van Schilfgaarde). Madison, Wisc.: Am. Soc. Agron.,pp. 7 -37.

Williamson, R. E., and G. J. Kriz. 1970. Response ofAgricultural Crops to Flooding, Depth of WaterTable and Soil Composition. Transactions of theASAE. Vol. 13, No. 1, pp. 216-220.

Willardson, L. S., and others. 1972. Nitrate Reduc-tion with Submerged Drains. Transactions of theASAE. Vol. 15, No. 1, pp. 84-90.

Chapter 7

Drainage System ElementsWalter J. OchsSoil Conservation Service, USDAWashington, DC

Richard D. WenbergSoil Conservation Service, USDAForth Worth, TexasGordon W. StroupSoil Conservation Service, USDAPortland, OregonA successful drainage system consists of a numberof elements or land-management practices. Theprimary elements are tha outlet, the collectionsystem, land-treatment measures, and land-protection measures. The design of each elementcan be related to the level of management desiredin an individual water-management system. Opera-tion, maintenance, cropping, and cultural practicesaffect the selection and design of individualelements.

Drainage investigations determine the extent ofproblems and the site conditions to ;a considered indesigning elements that will result in an OfeiAivesystem.

Outlets

The adequacy of outlets for a drainage syste,1 is animportant initial consideration. Outlet capacity canbe evaluated by careful analysis of design -dis-charges. The outlet is usually considered adequateif downstream flows in the receiving stream are notincreased by the design discharge from thedrainage system to the point where dainties are ex-pected. Outlets can be divided into two primarytypes: pumped or gravity. A comparison of relativeelevations will generally indicate whether a gravityoutlet is available or if pumping will be required.Special outlet structures may also be needed(fig. 7-1).

Gravity Out:Jts

Gravity outlets for drainage systems are usuallyconstructed channels or excavated ditches. but

9

rivers, streams, or lakes may be used. Large outletconduits are sometimes used when excavationthrough deep cuts would remove excessive amountsof land from production or when excavation wor:idcause serious aesthetic, safety, or environmentalproblems.

Open ditches or channels must be designed so thatdesign flow will not cause erosion. Channel banksor side slopes must also be stable. Depth and widthrequirement:, are based on the drainage systemdischarge rates, bank stability requirements, andthe elevation of inflow and outflow waters. Channeloutlet maintenance enhances the effective life ofmost drainage systems. Vegetation, phreatophytes,and sediment deposition must be controlled throughsound maintenance programs if an effective channel

Figure 7-1Two 24-inch tiles drain 1,200 acres to protect againsterosion in Miami, Ohio.

79

Trash Rock

MotorAir Relief ValveN---Siphon Breaker

Max. W.S.--Min. W. S.2

Fore 5a y.mixxxxxixiv

.0311117MICUImilF411117(:

ewasamar. ,Iiir

Discharge PipeW. S

Discharge Bay

Flap GateSubmerged Discharge

SURFACE AND SUBSURFACE WATER

Motor

iDischarge Pipe

Free Discharge

SUBSURFACE WATER ONLY

Figure 7.2A schematic of pumping plant :ayouts.

and drainage system is to continue to function(USDA, SCS, 1971).

Pumped Outlets

Pumps can be used for the discharge of water fromdrainage systems when a gravity flow outlet cannotbe obtained because of insufficient outlet depth, orif outlet capacity is restricted because of backwaterfrom storm or tidal flooding. Pumped outlets arenormally more expensive than gravity outlets whenthe entire life of a drainage system is consideredbecause of the initial equipment cost as well as themaintenance costs and energy requirements. Adetailed evaluation is often needed to datemine themost effectue and economical method of discharg-ing the drainage water. Pumped ot tlets may bepreferred in some systems to pioteOt wetland areaswhich are valuable wildlife habitats.

Pumping plants can include one or more pumps.power units, and appurtenances for lifting collecteddrainage water to a shallower gravity outlet (fig.7-2). Planning a pumped outlet requires considera-

800

tion of the entire drainage system so that diver-sions, storage areas, channels, and gravity outletsare used to the best advantage in determiningcapacity, size, and operation of the puilips. Somepump outlets operate for relatively short periodswhen high water levels.in the receiving streamwould restrict flow capacity enough to cause ex-cessive crop damage.

Collection Systems

A drainage system must include drains to collectwater from surface.dnr.ressions, very fiat itrfaco5.and excessive soil water in tho crop root zone. Thecollection system contains elements such as drain-age field ditches, subsui face drainage conduits,pumped well drains, and/or combinations of thethree. Subsurface drains and surface drainage fieldditches are often constructed on the same land.Both are often needed to provide the croppingenvironment desired for effective producti' collec-tion systems must be designed to remove excesswater from the surface of the soil and the crop root

zone in time to prevent damage to crops (USDA,SCS, 1971).

Drainage Field Ditches

Field ditches, normally shallow, graded collectionchannels with flat side slopes, allow farm equip-ment to cross. These ditches provide a specificwater removal rate for surface waters and arelocated °ad constructed so as to collect excesswater it: the field (fig. 7-3). The three types ofcollect ion systems using field ditches are parallel,random, and cross-slope or diversion, depending onthe way they are laid out.

Parallel Systems. Parallel systems usually drainflat, uniform land. The field ditches are establishedin a parallel but not necessarily equidistant patternand must have sufficient grade to prevent pending.Orientation of the field ditches depends upon thudirection of land slope and the location of otherfacilities in the field, such as diversions and outletchannels. The parallel field ditches usually runacross a field to discharge into outlet ditches on theborders of the field (fig. 7-4). The minor outletditches in a field are called laterals and should bedeeper than field ditches to provide free discharge(fig. 7-5).

Random Systems. Random systems drain irregularbut flat or gently sloping land where wet depres-

Figure 7-4A parallel drainagesystem.

Figure 7-3A surface drainage system carries water in PauldingCounty, Ohio.

sional areas occur randomly over the field (fig. 7-6).The field ditches transect as many depressions aspossible along a course through the lowest sectionsof the field (fig. 7-7). Two or more ditches may joininto a single field ditch as the water flows towardan available outlet. Deep earth cuts should beminimized when locating the field ditches (USDA,SCS, 1971).

Cross-Slope Systems. Cross-slope systems,sometimes called diversion systems, drain slopingland that may be wet because of slowly permeablesoil (fig. 7-8). Such a system prevents water ac-

97 81

Figure 7-5Tallulah, Louisiana, growers inspect a lateral outletditch in a parallel drainage system. Seeded to Kobe lespedeza, theditch is mowed 3 to 5 times a year.

cumulating from higher land concentrated inshallow pockets within a field. As water flowsdownhill. it is intercepted by the cross-slope system,then carried off by a field ditch. Field ditches inthese systems may be built to resemble a terrace ordiversion (USDA, SCS, 1971).

Subsurface Drains

Subsurface drains usually consist of undergroundpipe systems designed to collect excess soil waterfrom the root zone. These drains are normally in-

Figure 7-6A random systemdrains irregu .r but flat or gentlysloping land. =field ditches transectmany randa depressions alongtheir courses through the lowestsections of the field.

82

stalled to lower the water table and promote thedownward movement of water and salts in the croproot zone, especially if the land is being irrigated.Open channels can be used to provide subsurfacedrainage, but they must be deeper than closeddrains, which is a disadvantage because of the arearemoved from production and the division of fieldsinto small areas that are difficult to farm. Asillustrated in figure 7-9, ettbsurface drains are oftendivided into two classes: relief drains and intercep-tion drains (Ochs and others, 1980).

Relief Drainage. Relief systems lower high watertables which are generally flat or of very low gra-dient. Subsurface drainage conduits are generallyperforated pipe or tubing, or open joint tile or pipe.Common materials used for subsurface drainageconduits during the past 50 years have been clay,concrete, and plastic.

Relief drains (fig. 7-10) normally consist of a systemof parallel collection drains (open or closed) con-nected to a main drain located on the low side of afield or along a low waterway in the field. The maindrain transports the collected waters to the outletsystem. Subsurface collector lines used for reliefdrainage are approximately 3 feet deep in humidareas and 6-9 feet deep in arid and semiarid areas.Sometimes random subsurface drain lines providerelief drainage in areas where scattered isolatedwet soils are the problem. If individual wet areas

lasted SpoilIn Low Spots

Field lateral should be0.5' to l' deeper than thesurface field ditchesThis will provide completedrainage for random ditchesso they can be crossed withfarm, machinery. On soilssubject to severe erosionthe overlall should begraded back on a non-erosivegrade

or 98

Grade back small overfalls on anon- rosive grade. Where this isn'tpossible use a chute. drop spillwayor pipe

are large, a system of pattern parallel drains maybe used, with the random collection lines serving asan outlet.

Interception Drainage. Interception drainage ismost common where topography causes water-tablesurface gradients to slope and where lateralseepage occurs (fig 7-11). Collector lines intercept,reduce, and lower the surface level of ground-waterflows. Often an interceptor drain consists of asingle drain which intercepts the lateral flow ofground water caused by canal seepage, reservoirseepage, or levee-protected areas. These drains areusually perpendicular to the flow of ground waterthat is to be intercepted. Multiple tines are used ifwater quantities are high.

Pumped Well Drains

Pumped well drains can be used effectively as reliefdrains if an aquifer of deep sand and gravelunderlies the area to be drained and if there is goodvertical movement of water between the root zoneof the crops and the aquifer. Wells are spacedapart to create overlapping cones of depression,thus controlling the excess water in the root zone ofcrops (USDA, SCS, 1971). A line of pumped welldrains can also be used as an interceptor drain.

Land Treatment Practices

While they are not specifically drainage practices,various land treatment measures may be needed inconjunctica with drainage practices to ensure theproper, most advantageous functioning of thedrainage system (American Society of AgriculturalEngineers, 1979).

Clearing and Snagging

Clearing and snagging is the removal of snags,stumps, debris, or other obstructions from adrainage channel to establish suitable outlets for adrainage system, especially after a period of abnor-mally high flows or as periodic maintenance toremove accumulated growth and debris (figs. 7-12and 7-13). Failure to remove this material reducesflow capacity of the channel, promotes bank erosionfrom eddies, causes formation of silt bars, and in-creases the possibility of blockage by snow and ice.

Bedding

Bedding is a land-treatment measure used on veryflat cropland where normal cropping and tilling

99

Figure 7-7A random tile drain system cuts through Kewaimee-Manawa complex soils in Mantiwoc County, Wisconsin. Meantime,a grassed waterway for erosion control is under constructionthrough the middle of the farm.

operations interfere with the flow of surface waterfrom the field (fig. 7-14). Bedding is the grading of,aland surface to form a series of low, broad ridgesseparated by shallow, parallel drainage channels,.sent in the direction of greatest land slope. Thesechannels connect with field drains in the normaldrainage system.

Formation of the alternate ridges and channelscreates sufficient land slope so that excess surfacewater moves relatively quickly to the channelswhere it flows readily to the field drains.

Land Smoothing

Surface irregularities in the land surface can causetroublesome wet areas which.affect mtich-largerportions of a field. Such areas may be eliminated -with land smoothing, usually done with specialearthmoving equipment, such as land levelers orland planes (fig. 7-15). The soil surface irregular-ities may be dead-furrows, old field boundaries,fence rows, roadways, or similar features. Usuallyonly specific areas are treated without changing the,general topography of the field.

Land Grading

Land grading, the forming of land surfaces topredetermined grades so that each row or surfaceslopes to a drain, is used where natural slopes aretoo flat for.adequate surface drainage -and must beincreased, or for changing direction of surfaceSlopes to fit an overall farming-arrangement or

83:

After the ditches have beenconstructed, smooth or gradethe area between the ditches.This will eliminate all the minordepressions and humps that obstructthe free flow of surface water.

TYPICAL FLAT BOTTOM SECTION

Farming cperations up anddown slope across fieldditches up to approximately2% slope depending uponkrosion hazard and parallelto field ditches on slopesabove 2%

Fill depressions with materialexcavated from ditch Spread out excess excavated material

here so that ridge will not interferewith equipment

ground Level

Min. Osvo-9,

. -.0 .:. ," : . ,

. .

TYPICAL V-CHANNEL SECTION

Natural Ground Level

I p 118'

' : - '' . .:

Yin. Dspptt-

.

Figure 7-8Cross-slope systems drain sloping land.

84

too

WM?TABLE'

, % el c'sc_-I

..?." a'

/t . tIII

.4.. . '

Og/of/ '`

Ipo

.1 .< "

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c-<-1=b

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> ".%,:s , ,

' N''"P* 4'*. N

It

,

.00c=, W1 It

r4sLE

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41.

t?,

11.

Figure 7-9Relief and interception drains.

WATER TABLE, BEFORE DR 4/41.40e is TER TAW t, BEFORE 0,44tOGE

rf

Aoarew TABLE, AFTER Af/NAVE

Figure 7-10Relief drains.

ITE,4" 1A9LE, BEA-0.414" .0,94/4/.44',

more.? mete, iFTER omeimice-

Figure 7-11Inteception drains.

101

-----_,Q_--

w,47-ER meze, AFTER 12,04/4/46'e

k101:69 1:491 4 BEFORE 0,01/4.'4ae

WAVER 7-4471E, IFTE,4" ae4/4/4CE

85

drainage system (fig. 7-16). Farmers normally useland grading for higher value crops because thistreatment can be expensive. Excavations, fills, andland smoothing are all required to prepare the con-tinuous surface grades.

Leaching

Many drainage systems are installed in arid-regionsoil to control water-table problems or excessivesoil wetness, to remove accumulated salts (leaching),and to prevent excess accumulation of salts in theroot zone. Such leaching is accomplished by apply-ing water beyond crop needs so that water andsalts may be flushed out.

Figure 7-12Maintaining drain-age ditches is important for properconveyance of excess water.Here, a slope mower with a hy-draulic rotary blade cuts grass inSussex County, Delaware.

Figure 7-13Water hyacinth im-pedes free flow of water in Indian w*,

River County, Ronda.

86

The amount of water required for preventingsalinization may vary from 10 to 30 percent of thatused for irrigating a crop. When soils need to bereclaimed, however, substantially larger amounts ofwater may be needed. As much as 3 or 4 feet ofwater may need to be applied for such reclamationleaching.

The leach water moves downward through the soil^ofile, taking the salts with it. Some of this water

and some of the salts dissolved in it will be removedfrom the field through the drainage system. An ade-quate subsurface drainage system is a prerequisitefor a leaching program on saline soils.

411.11t

rt

I 102

Surface FieldDitch

Dead Furrows

End of Field

The U-shaped section in the bottomof the ditch is optional. It permitsmain part of ditch to .ry quickly sothat tractors can pass over oventhough the bottom of theU-section it wet.

S to 1 or flatterside slopes

(ismok

,1/41Z) Deadw,

o:L dr. . :pp-- A141!Ale N.... /J?

......111rwiwAVArnikti."Will2Z41"-41:1"1"L"135"161-le' to 20'

3 t

Width Varies Di root ion of ReddingTurn Strip Farmed

Separately

CROSS SECTION T END OF FIELD SHOWI NG COLLECTION DITCH AND TURN STRIP

Dead furrows must have acontinuous grad, without

//

any obstructions that mihtInterfere with the flow of water

- klf(w--str, ,...t, . I' - ...4,\--V9 ci $, ......4 to`

- a.:,- .. 44 ..... '

=L- Croon Ntiiht Min.

Width of led

Continuous Uniform Slope from Conter,cf led to Dead Furrow INDoad Furrow

CROSS SECTION OF BED SHOWING CROWN EFFECT AND PROPER SPACING OF CROP ROWS

Figure 7-14By bedding flat cropland, farmers can quickly channel excess water to field drains.

87

.103

TYPICAL CROSS SECTION OF GROUND SURFACE THAT HAS SOME GENERAL SLOPEIN ONE DIRECTION AND IS COVERED WITH MANY SMALL DEPRESSIONS AND POCKETS

Smooth or grade area between ditchesfilling depressions and removing barriers.

Uniform slope not necessary. Importantthat all rows drain from ditch toditch.

=ea

Use excavated material from ditchesto fill larger depressions or wasteon downhill side of ditch

_ .....cffewmr151,":".".71-1!;".1.. . ..e. -;.----:.:--:::-.--::::::::"......:-::::;:,f

,.: . .,......:.. ... :... .... ... :. .:41.07I;;;;;;,..:'....-a..

,',..v.--.:14:.--.-.,427zariz,Th .4.k.,_,.....sea, --A..:.....-, ....*Toz ft, r ...-- ev-

FinishedOitchsurface of landPrevious surface of land

TYPICAL CROSS SECTION OF GROUND SURFACE THAT HAS LITTLE OR NO GENERALSLOPE AND IS COVERED WITH MANY SMALL DEPRESSIONS AND POCKETS

Establish a continuous grade Use excavated material from ditchesby cutting on the lower and filling on the upper end. as fill for establishing gradeFill all depressions and remove all barriers. ,

41,:r1...ti cy,.;%.:*

Z..;:. r t -

4->: 1.?- .` I

.

Parallel ditches designed to carry drainage ru'off

Establish a continuous grade to a developed ridge midwaybetween field ditches by cutting from ditches ano fillingtoward center of land between ditches.

Ridge

Field Ditch--Field Ditch

TYPICAL CROSS SECTION OF GROUND SURFACE THAT HAS LITTLE OR NOGENERAL SLOPE AND iS COVERED WITH MANY SMALL DEPRESSIONS AND POCKETS

Figure 7-15Land surface irregularities can be overcome by theprocedures shown above.

Figure 7-16A tractor pulls a land

plane to precision-grade a

sugarcane field in Edgard, Louisiana.

88

Yak-1111111.

Figure 7-17A typical dike Erec-tion.

HIGHWATERLEVEL

CONSTRUCTED TC.7:

SETTLED TOP

ORIGINAL GROUND

CORE TRENCH/

Land Protection Practices

Various practices can protect land after a drainagesystem has been installed. Although these practicesare not a part of the drainage system, they may becritical to protect the land and enhance the value ofthe drainage component.

Conservation tillage is a cultural practice whichkeeps crop residues on the field surface to protectthe soil from wind or water erosion. Without thisprotection, soil surfaces and ditch banks may erodeor previously wet soils may dry and suffer wind ero-sion. Many soil conservation tillage systems requireadequate drainage to be fully effective. As higherpercentages of rainfall move through the soil pro-file, such soils require drainage intensities greaterthan previously used with conventional tillage.

Windbreaks are often needed in large, open areasof drained land, especially on organic soils wherethey may be closely spaced to prevent severe winderosion. Windbreaks may be either a strip of peren-nial or annual vegetation or a constructed barrieror fence placed across the direction of prevailingwind.

Flooding of farmland by surface waters may limitthe effectiveness of a drainage system or increasethe cost of the system needed to remove the addi-tional flood water. Diversions that intercept flowsfrom higher land and divert them to a safe outletare usually channels with a supporting ridge on thelower side built across the slope on a nonerosivegrade.

Dikes usually protect drained areas by preventingflooding from adjacent streams (fig. 7-17). Cautionmust be used in the design of dikes to avoid damage

105

from flooding of other areas by unduly restricting orincreasing natural stream flows.

Drainage System Combinations

The drainage system is an integral part of a watermanagement system in the fain' operation. For ex-ample, subsurface field drains provide an essentialelement of irrigation water management to controlsalinity in arid and semiarid regions.

Water table control systems that use either a sur-face or subsurface drainage system to supply ir-rigation water during dry periods are also becomingmore prevalent in humid regions (fig. 7-18). They areused mostly on porous high water-table soils or onorganic soils, and are likely to expand to other soils.Computerized simulation and design proceduresparticularly suit these more complex systems. The

4

Figure 7-18Carrots flourish on this 400-ecru tract of organic soilsin Highlands, Florida, because water control ditches at 100-footintervals both drain and irrigate.

89

Figure 7-19A contracting officerin the Celeryville ConservancyDistrict. Ohio. observes water ta-ble control whole perched on aFabndam on the Marsh Run Watershed; these rubberized fabricdams automatically inflate and de-flate.

water-table control systems provide an outstandingopportunity for improving water and energy conser-vation on farms in many watershed areas (fig. 7-19).Generally, costs are considerably lower than thecombined cost of separate drainage and irrigationsystems.

Waste-water disposal systems often require subsur-face drainage to provide time and space in the soilprofile for natural biodegradation to take place. Thesubsurface drainage system also provides an oppor-tunity to monitor the water-quality condition aftermovement through surface soils and before dis-charge into public waters.

Detailed design procedures for drainage systemsare included in USDA'S SCS Engineering FieldManual, drainage guides, technical guides, and inthe National Engineering Hondhook. section 16 titled

90

"Drainage of Agricultural Land." These documentscan be examined in SCS field offices.

References

American Society of Agricultural Engineers, SurfaceDrainage Committee (SW 233). 1979. "Design andConstruction of Surface Drainage Systems on Farmsin Humid Areas," Engineering Practices. ASAE EP302.2.

Ochs, W. J., W. R. Johnston, and others. 1980."Drainage Requirements and Systems," Design andOperation of Farm Irrigation Systems (ed. MarvinJensen). Monogr..ph No. 3, Am. Soc. Agri. Eng., St.Joseph, Mich.

U.S. Department of Agrkulture, Soil ConservationService. 1971. "Drainage of Agricultural Land,"National Engineering Handbook, section 16.

106

Chapter 8

Planning Farm and ProjectDrainage

Thomas C. G. Hodges and Douglas A. ChristensenSoil Conservation Service, USDAFort Worth, Texas

Because drainage usually involves substantial long-term investments of capital and other costs, theproper planning of farm and project drainagesystems is essential. Successful farm drainageresults in higher average and more stable farm in-come ,-;nce well-planned drainage systems ensure amore efficient use of resources.

General Design and EconomicConsiderations

Soils naeding improved drainage usually have thegreatest wetness problems during spring and fall.which cause planting and harvesting delays thatreduce crop yields. Even when crops are planted ontime. a high water table restricts root developmentand plant growth. As drier summer months approach.the water table level drops quickly and plantsbecome susceptible to drought stress because theroot system cannot reach the water table level.

Plants tend to respond to improved drainage quickly,so crop yields usually jump the first year afterdrainage systems are install'd. However, a numberof years of improved yields are necessary torecover the initial investment. Farm drainagesystems sometimes cost as much as or more thanthe land itself, especially when major outlet systemsare needed. Further, regular maintenance expend-itures are necessary to keep subsurface and sur-face drainage systems functioning well.

Farm drainage systems cannot function properlywithout adequate outlets or disposal works such asstreams, rivers, bays, or pumps. Drainage improve-ment may be as minor as installing a short field

drain to improve a wet spot on a farm field, or ascomplex as enlarging major channels and tributarieswith tile or open drainage ditches to remove excesswater from entire fields. The areas to be drainedmay range from less than an acre to thousands ofacres.

Drainage improvements are technically complex andmust meet proper design standards to be effective.In many cases, entire communities help plan anddevelop adequate drainage systems. Besides improv-ing farm systems, existing farm drain outlet systemsmay need to be enlarged and deepened. Majorsystems may require that highway and railroadculverts and bridges be reorganized or modified.Many States have passed laws that permit drainagedistricts or similar organizations to develop, plan,and install appropriate drainage works andsystems (see chapter 10).

Proper drainage systems can improve the localeconomy and environment of entire communities,with initial farm benefits spreading to agribusi-nesses and financial institutions.

In planning farm and project drainage systems,existing problems must be correctly identifiedbefore appropriate solutions can be designed. Someproblems involve excessive water seepage from ad-jacent hillsides. Other areas have pothole problemswhere surface water is trapped in dish-ahapeddepressions. Irrigation may aggravate drainageproblems when excess runoff and percolated watermust be carried away. In delta and coastal areas,drainage is essential to carry floodwaters caused byheavy rainfall from flatlands with fine texturedsoils, or from areas with perched water tableswhere water cannot move freely.

107 91

Various drainage problems and the damages theycause are prime economic considerations in thedesign of drainage systems. These damages oncropland are reflected in increases in productioncosts and reduced crop yields from excessive wet-ness. The design of the system takes into accountcost efficiency as well as maintenance of crop pro-ductivity and farm income. Important design factorsare proper ditch, tile, or channel depth and capacity,road culvert and bridge openings, geologic condi-tions, and downstream outlets which receive runoffwater while minimally affecting environmental andeconomic resources.

In a eGiind drainage design, installation and mainte-nance costs need to be balanced to ensure that thesystem will function properly through its expectedlifespan. Careful operation and maintenance of thesystem are necessary to attain the expected bene-ficial effects that justify the investment.

Drainage engineers have worked to balance fielddrain depth and capacity to fit the needs of cropproduction. As farming practices change, designcriteria Also change. For example, when farmingpm,...-essed from animal power to machine power,better drainage became necessary to support heavyequipment and provide proper traction. Tile orother pipe drains were buried deeper to avoid beingdamaged by heavy equipment, and surface drainswere designed to permit crossing by largemachinery.

Drainage systems must remove large volumes ofwater quickly fez plant survival and steady cropgrowth. Plant requirements dictate the degree ofdrainage that is justified. Field crops can usuallysustain wetter conditions than some specialty cropssuch as vegetables. Removing runoff from moderaterainfall episodes may suffice foi field crops, but forvegetable crops, quirk removal may be necessary.SCS has established aesign standards for variousresource areas and cropping systems within each Stete.

Total water management requires sophisticateddesign and operation; this provides better use ofresources and higher crop yields. Subirrigationhelps moderate water-table fluctuations during low-water periods frora spring to fall. En&ineers channe'.and the grab! water control devices inonfarm sysi.erwater maneg.monitor soiland to open,tures are inst.

92

channels. Such intensivemnre maintenance toL and runoff conditions

.as. Water control struc-irm drainage systems to

(2 a

reduce drainage when: soils are dry. Sometimesfarmers pump water into the blocked off channelsto increase flow into the fields. Vegetation control iseasier because water in the ditches inhibits plantgrowth.

Planning Farm Drainage

As a principle, the net economic benefit fromimproved onfarm drainage is the amount by whichnet income with the drainage system exceeds netincome without the System. The net income changemay come from increased crop production, reducedproduction costs, or both. Net income is the com-puted value of production less all associated costsof production, including cost of the drainage systemitself. The latter also includes the value of any landrequired by ditches or other improvements. Thegross value of crop production is the crop yieldtimes the price per unit of yield. Crop productioncosts include the cost of seed, labor, power, water,chemicals, and other materials plus prorated land,machinery, or management charges. Crop produc-tion costs with and without drainage systems maybe obtained from nearby farmers and local agri-cultural leaders.

Feasibility Calculations

Benefit-cost ratios are a relative measure of annualbenefits of a proposed improvement compared withits costs. Average annual installation cost is deter=mined by amortizing the initial cost of a drainagesystem at a current interest or other specified rateover Z:ge life of the investment. In SCS, farmdrainage systems are usually amortized over anexpected life of 25 years and project systems for 50years, assuming reasonable maintenance. The annualcost of operation and maintenance, plus any otherrecurring costs, are then added to amortized in-stallation costs to get total annual costs. Theaverage benefit-cost ratio, tot& annual benefitdivided by total annual cost, shows the benefitsexpected for each dollar of cost.

Many farmers encounter times when equipment getsstuck in wet areas during farming operations,resulting in lost time or the need to keep an extratractor nearby to pull the equipment out, 'Irons fre-quently need to be replanted. requiring more pro-duction inputs. Also, farmers may need to wait untilthe ground freezes before they can harvest crops. Ifthe ground does not freeze, the crop may be lost if itizt wet at harvesttime. The extent to which these

drainage problems are reduced or eliminated is aclear economic benefit of drainage systems.

Reliable information about changes in crop yieldwith and without drainage is not as available asthat for production inputs. Farmers' experience isone good source, although many do not keep in-dividual field records, and yield differences aremore varied than production inputs. Informationfrom farmers, supplemented by data from researchand agricultural leaders, can be used to estimateexpected changes in yields and costs under variousconditions. Computer simulation models are also usedfor estimating yield differentials.

Optimum Drainage Design

Drainage design decisions can be guided more effi-ciently by referring to research than by makingfield -by -field calculations. Farm operators can makea partial comparison of open or surface versus sub-surface drainage themselves when the soils andother conditions permit either method. The costs ofeach method and effects of open drains or reducingland in production can also be determined fairlyeasily. However, data are not always available forassessing the effect of alternative degrees ofdrainage on crop yields.

Researchers have more access to data, methods,and computer models to determine optimum drainspacings and types of drainage. For example, USDAscientists have developed an "Erosion-ProductivityImpact Calculator" (EPIC), a comprehensive mathe-matical model for determining the relationship be-tween rates of water-induced soil erosion and soilproductivity in different U.S. regions (Williams andothers, 1983). Drainage conditions are one elementof the hydrology submodel of EPIC, along with rain-fall, runoff, evapotranspiration, percolation, lateralsubsurface water flow, and irrigation. Other sub-models consider weather, erosion, nutrients, soiltemperature, tillage practices, and economics. TheEPIC model thus permits a simultaneous analysis ofhow crop yields, gross farm income, productioncosts, and net income may be affected by numerousphysical and economic variables, including drainage.

A planning and optimizing model more specific toquestions of drainage system design is DRAINMOD,developed by, agricultural engineers at NorthCarolina State University. This model encompassesmulticomponent water management systems involvingsurface drainage, subsurface drainage, subirriga-tion, and sprinkler irrigation. It considers theeffects of alternative system designs involving dif-

109

ferent depths and spacing of subsurface drains oncrop yields, production and investment costs, andfarm profits. (See the Skaggs segment for a detaileddescription and illustrated uses of DRAINMOD.)

A third model, combining a simulation model withan optimizing routine to minimize costs, has beendeveloped at Colorado State University (Durnford,1982). Its object is to identify economically optimumdrainage systems using open and closed reliefdi linage systems for arid irrigated areas. Thedrains facilitate proper leaching, thus limiting thenet buildup of the water table and reducing theaccumulation of salts in the root zone, especially ifthe ground water is saline. Durnford's model isadaptable to planning irrigation drainage in variousregions of the United States and other nations. Oneapplication has been to the Beni Magdoul area inMiddle Egypt.

Economic evaluations for project systems arebasically similar to those used for planning farmdrainage but naturally require a broader perspec-tive. Yield and production input data need to berepresentative, not site-specific. Alternativedrainage scenarios considering costs, productioninputs, and outputs are developed for each differentproject area. Net returns with and without improveddrainage are compared to determine net' benefits.The costs of the project and associated improve-ments are compared with all benefits in determiningnet benefits and benefit-cost ratios.

A final point to mention for farm drainage planningis that it often involves only one or a few decision-makersthe owner, manager, or renter. They makecapital investments considering their individual in-terests in the farm and its operations, accountingfor needs, costs, and effects. Detailed soil, croppingsystem, and engineering data are used to determinethe type and extent of the problems and neededtreatment measures. All decisionmake.s fit the costand expected benefits of drainage systems into theiroverall financial or management plans.

Planning Project Drainage

The proper functioning of farm drainage systemsdepends upon proper outlets. When several farmshave inadequate outlets, farmers need to plan asatisfactory outlet system together. Project drainageplans involve much the same basic information as farmplans, but because many farmers and other interestscan be involved, quick agreements are frequentlydifficult.

93

Information Needs

As the characteristics of decisionmakers in projectplanning are diverse, inventory data can be moregeneral and less site-specific. Project planning mustalso consider onfarm drainage needs. Reliable soilsand crop system data are necessary for both levelsof planning.

Engineering data ordinarily deal more with thehydraulics of stream systems rather than withsingle streams or specific farm situations. Engineersestimate costs for the main and tributary channel-work providing outlets for farm drainage. Theystudy alternate channel sizes to determine whichwill produce the most net benefits. Tributaries areevaluated separately to determine if improvementswithin them are justified in terms of producing netbenefits. Instream water control devices are ex-amined for any possible complementary irrigationbenefits.

Environmental considerations also become morecritical in project planning because outlet im-provements may disturb environmental resources,especially if they impinge on fish and wildlifehabitat. SCS and the Fish and Wildlife Service(FWS) have jointly developed and adopted uniformChannel Modification Guidelines to assist their per-sonnel in identifying when and where channelmodifications may be used as a technique for im-plementing drainage and other land and waterresource projects. These standards require effortsto maintain or restore streams, riparian vegetation,and wetlands as viable ecosystems for fish andwildlife.

Moving water in main and tributary streams andchannels to areas where discharge water can movefreely without causing downstre: In damages can bea different design problem. Proper planning of proj-ect drainage must include the analyses of flood-water from high direct precipitation which must becarried by the project systems. This is one respectin which project drainage is more complex than on-farm drainage. Road and railroad bridges andculverts may be modified, and utilities may need tobe altered or moved. Drainage water from one farmis channeled across another farm, sometimes fromone county to another county, and sometimes fromone State to another.

SCS provides technical assistance for farm and pro-,ject drainage planning, which must conform to Stateand local laws and follow approval standards andspecifications. SCS project drainage assistance is

941' 0-

authorized under the Watershed Protection andFlood Prevention Act (P.L. 83-566), which calls for acomprehensive approach toward solving floodprotection, water supply, drainage, and otherwatershed problems. SCS investigates hydraulicsystems, hydrologic effects downstream, economicand social impacts, and project feasibility. Studiesare made to evaluate environmental resources andtheir protection. Similar studies are undertaken bySCS in Resource Conservation and Development(RC&D) Projects involving drainage.

Cooperation in Drainage Planning

The Marshyhope Creek Watershed (100,600 acres)spanning the Delaware-Maryland boundary is agood example of how diverse environmental,political, and economic interests can be broughttogether to solve serious resource managementproblems. The project sponsors include theDelaware State Soil Conservation Commission, theCaroline County (Md.) Commissioners, the CarolineSoil Conservation District, and the town ofFederalsburg, Md. The headwaters are in KentCounty, Del. The main channel flows southwest-wardly into Sussex County, Del., then across theState border into Caroline County, and outlets atFederalsburg.

For more than 30 years, Kent County farmers hadtried to develop a drainage outlet system but hadfaced political and legal opposition by othermunicipal, county, and State interests. Federalsburg,subject to floodwater damage during large storms,feared additional damages if major upstream chan-nelworks were installed. Planning investigationsrevealed that 25 subareas in the watershed neededchannelwork. Each had adequate drainage outletsabove Federalsburg. Hydrologic studies showed that24 of the 25 subareas could be drained withoutadditional damage to Federalsburg. The largestsubarea that drained all of the Kent County portionof the watershed would cause a slight increase inflood stage at Federalsburg (in the event of a1-percent chance flood event). Such an event has astatistical probability of recurring once in 100years. It may actually recur more or less frequentlythan this.

Federalsburg rejected proposals for flood protectionother than channel enlargement to carry inducedflood flows caused by the upstream work. The finalwatershed plan included channelwork in the 25subareas and through Federalsburg. State andFederal agencies also helped protect fish habitats inSmithville Lake, Caroline County.

After reviewing several alternative solutions toflood problems, Federalsburg agreed to the enlarge-ment of the channel through town to carry increasedflows (assuming a storm equal to the 1935 storm)caused b channelwork upstream. The sponsors andfish and wildlife interests agreed to include a filterstrip and sediment trap above Smithville Lake. Thecost of the Federalsburg channel was included aspart of the cost of the work in the subarea, mostlyupstream, because hydrologic studies indicated thatthis area was the primary source of the Smiths illesubarea channel cost.

The general watershed plan was completed January1964 and subsequently approved for construction byCongress. It included 468 miles of channelwork in25 subareas and 9,000 feet of channel enlargementin Federalsburg. The sediment control devices wereincluded as part of the channelwork in theSmithville subarea.

Drainage in Irrigation Project Planning

The protection of irrigated soils from excessiveaccumulation of water (waterlogging) and salts is amajor initial consideration in planning irrigationprojects. Historic and probable declines in the pro-ductivity of irrigated soils arid regions can beattributed to soil properties that inhibit downwarddrainage, high rates of evapotranspiration, and poorwater quality. Proper recognition of these problemsand alternativo3 for preventing them with artificialdrainage systems is indispensable to the projectplanning process. Correcting them later can be ex-pected to be much more costly than initial avoidance.Moreover, the adverse effects of rising water tablesand soil salinity on irrigated land are not just long-term problems; they can become serious after only afew irrigation seasons. The project's economic justi-fication weakens in two major respects: additionalcapital is needed to solve the problem and/or lossesin productivity mean reduced benefits.

Strzepek, Wilson, and Marks (1982) indicate thatdrainage planning for irrigated areas involves threeinteracting planning levels: the overall feasibilitydetermination level (general economic justificationand essential irrigation and drainage facilities), theinfrastructural or collector drain level, and the fielddrain level. The field drains (surface or buried) con-trol soil water conditions, while the collectors

remove the drained water to the main drainagechannels. Strzepek and coworkers found, for example,that the location, size, and.type of collectors areeconomically interrelated with the spacing, size,and type of field draias. The design problem is todetermine the particular characteristics of collec-tors and field drains that will minimize total cost ofproviding required drainage, considering locationalvariations in soil permeability, uncertain cropyields, cropping patterns, and other factors.

Drainage planning for irrigated areas will increas-ingly require a fourth planning level and costelementone of designing project drainage systemsand arrangements that minimize or eliminate theadverse effects of chemical-laden waters on crops,wildlife, and human habitats, either within projectareas or on offsite areas. In this larger social con-text, the total project cost would be the sum ofwithin-project investment and operating costs plusoffsite damages or disbenefits. Adverse effects andalternatives for minimizing them are considered atmore length in the next segment.

References

Durnford, D. 1982. Optimal Drain Design: An In-cremental Net Benefit Approach. Ph.D. dissertation.Colorado State Univ., Fort Collins.

Strzepek, Kenneth M., John L. Wilson, and David H.Marks. 1982. Planning and Design of AgriculturalDrainage Under Uncertainty: A Dynamic Multi-LevelApproach. Rpt. No. 21, Dept of Civil Engineering,Massachusetts Institute of Technology, Cambridge.

U.S. Department of Agriculture, Soil ConservationService and Forest Service. 1964. Watershed WorkPlan for the Marshyhope Creek Watershed. (Cooper-ative report with the Delaware State Soil Conserva-tion Commission and local sponsors in CarolineCounty, Dorchester County, and the town ofFederalsburg, Maryland.)

Williams, J. R., K. G. Renard, and P. T. Dyke. 1983."EPIC: A New Method for Assessing Erosion's Effecton Productivity," Journal of Soil and Water Conser-vation. Vol. 38, No. 5, pp. 381-383.

95

Chapter 9

Drainage for Irrigation:Managing Soil Salinity and Drain-Water Quality.

Glenn J. HoffmanAgricultural Research Service, USDAFresno, California

Jan van SchilfgaardeAgricultural Research ServiceFort Collins, Colorado

SaliiJty control and the removal of excess waterare the major objectives of drainage in irrigatedagriculture. These objectives are related. Excesswater may induce high water tables which, if saline,contribute to the salination of soils. In humidregions, salinity control is of limited concernbecause rainwater is almost free of dissolved salts;thus, excess salinity occurs in rainfed areas wherethere is brine spillage, waste disposal, excess fer-tilization, or seawater intrusion in coastal regions.As supplemental irrigation increases in humid regions,soil salinity and water-quality problems like those inarid regions may become more prevalent.

Elements in Salinity Control

The key to salinity control is a net downward move-ment of soil water through the root zone. All soilsand irrigation waters contain a mixture of solublesalts, with the concentration of these salts in thesoil solution usually higher than that in the appliedwater. This increase in salinity results from planttranspiration and evaporation from the soil surface,which selectively remove water, thus concentratingthe salts in the remaining soil solution. To preventsoil salinity from reaching harmful levels, one mustdrain (leach) a portion of this concentrated soil solu-tion below the crop root zone. Salt will be leachedfrom the soil whenever water applications exceedevapotranspiratimi, provided soil infiltration anddrainage rates are adequate. Even in well-managed,high-yielding fields, however, the soil water may beseveral times more saline than the irrigation water.With insufficient leaching, this ratio can easilyincrease at least 10 times and damage crops. The

96 2

amount of leaching required depends on the qualityof the irrigation water, the crop grown, and theuniformity of irrigation. Subsurface drainage isessential for sustained irrigated agriculture wheresalinity is a hazard.

In areas where the ground water is deep or nonexis-tent, salts accumulated in the root zone can be forceddownward by irrigating if the substrata are perme-able. Of course, this leaching process can continueonly until the level of the ground water extends upinto the crop root zone. In some irrigated areas,rainfall is sufficient to leach the salts below theroot zone. In this case, extra irrigation water forleaching is not required and in fact will cause thewater table to rise unnecessarily. Without properdrainage, the water table may remain in the rootzone too long and reduce crop productivity.

Leaching

The amount of leaching required to maintain aviable irrigated agriculture depends upon severalfactors: the salt content of the irrigation water, soil,and ground water: the salt tolerance of the crop:climatic conditions: and soil and water management.If leaching is inadequate, harmful salt accumula-tions can develop within a few cropping seasons.The fraction of the applied water that must passthrough the root zone to prevent harmful saltaccumulations in the soil is the leaching require-ment. Once salts have accumulated to the maximumtolerable limit for the crop under a given set of con-ditions, any added salt from subsequent irrigations

must be balanced by a similar amount removed byleaching to prevent a loss in yield.

The optimum management strategy is to apply nomore water than is necessary for full crop produc-tion and leaching of salts. This leaching require-ment has been established for irrigation water ofvarious levels of sa;aity and for irrigated crops ofmajor importance (see fig. 9-1 and Hoffman, 1985).The salinity level of the applied water can beestimated by multiplying the salt concentration ofthe irrigation water times the amount of irrigationwater applied, and then dividing this product by thesum of irrigation and rainfall minus surface runoff.1This is shown as follows:

= (CI I) / (I + P - R),

where C. is the average salinity of the appliedwater that enters the root zone, CI is the salinity ofthe irrigation water (I), P is precipitation, and R issurface runoff. The amount of salt the crop cantolerate in the soil profile is the salt tolerancethreshold (Maas and Hoffman, 1977). The threshold(CI) is the maximum soil salinity permitted withoutcrop yield reduction.

Table 9-1 shows threshold values for a number ofcrops. As an example, if farmers use Colorado Riverwater for irrigation (Ct = 1.3 dS/m) and no rainfalls, a tomato crop (Ct = 2.5 dS/m) would requirean additional portion of water to be applied abovethat needed for evapotranspiration. If rainfall was250 mm, the depth of irrigation with Colorado Riverwater was 600 mm, and about 100 mm of the appliedwater was surface runoff, then the average salinityof the applied water would be 1.1 dS/m (accordingto the equation) and the leaching requirement (4)for tomatoes would be 0.08 (fig. 9-1). This meansthat 60 mm of the net amount of water applied mustdrain below the root zone to avoid losses in tomatoyields from excess salinity.

Additional Drainage

Not all the water requiring removal by drainagemay originate fro.-:. onfarm irrigation. In fact, asignificant part of the water input to the drainagesystem often results from seepage from irrigation

1For convenience, salt concentration in water is normallymeasured as the electrical conductivity of the water and reportedin units of decisiemens per meter (dS/m). The units of dS/m arenumerically equal to millimhos per centimeter (mmho/cm).

Table 9.1-Salt tolerance of crops as a function of theelectrical conductivity of the soil saturationextract (C), where relative yield (Y) in percent= 100 - S (C Ct), CCt.

Crop

Salttolerancethreshold

(A)(col

Percentyield

de(B)cline

(S)2

Qualitativesalt

toleranceratings3

dSIm4 Percentgann)

Alfalfa 2.0 7.3 MSAlmond 1.5 19.0 SApricot 1.6 24.0 SBarley 8.0 5.0Bean 1.0 19.0 S

Beet, red 4.0 9.0 MTBroccoli 2.8 9.2 MSCabbage 1.8 9.7 MSClover, red 1.5 12.0 MSCorn 1.7 12.0 MS

Carrot 1.0 14.0 SCotton 7.7 5.2 TCowpea 1.3 14.0 MSCucumber 2.5 13.0 MSDate palm 4.0 3.6 T

Grape 1.5 9.6 MSGrapefruit 1.8 16.0 SLettuce 1.3 13.0 MSOnion 1.2 16.0 SOrange 1.7 16.0 S

Peach 1.7 21.0 SPeanut 3.2 29.0 MSPepper 1.5 14.0 MSPlumPotato

1.51.7

18.012.0

SMS

Radish 1.2 13.0 MSSorghum 6.8 16.0 MTSoybean 5.0 20.0 MTSpinach 2.0 7.6 MSStrawberry 1.0 33.0 S

Sugar beet 7.0 5.9 TSugarcane 1.7 5.9 MSSweetpotato 1.5 11.0 MSTomato 2.5 9.9 MSWheat 6.0 7.1 MT

1Salt tolerance threshold is the mean soil salinity at initialyield decline.

2Percent yield decline is the rate of yield reduction per unitincrease in salinity beyond the threshold.

3Qualitative salt tolerance ratings are sensitive (S),moderately sensitive (MS), moderately tolerant (Ml), andtolerant (T).

4dS/m = decisiemens per meter = 1 millimho per cm,referenced to 25° C.

Source: Haas and Hoffman, 1977.

113 97

Crop salt tolerancethreshold value(C,), dS/m2

7

6

5

4

3

2

1

00

2.25 4.15i /

///

1_,. = 0.05 //

/

1_,. = 0.08

(2.5)

//

//

/

/ I

1

1(1.1)

///

9.10//

0.15

0.20

i /0.30

I I I

4

may be an economic optimal decision. The economiccriteria for optimal water application for leaching isto apply the amount of water where the cost of thelast unit of water applied equals the value of the

7.4 additional crop yield. If maximum possible yield issought, the cost of the last unit of water appliedmay exceed the value of the additional yield, andprofits may not be maximized (Fitz and others, 1980).

5.1

2.35

1 2 3 4 5 6

Salinity of applied water (C0), dS/M

Figure 9-1Solving for the leaching requirement from the salinity ofthe applied water and the salt tolerance threshold value for the crop,

canals or from areas irrigated some distance fromthe area under consideration, such as the desertarea west of the Nile Delta (Kirkham and Prunty,1977). However, water may leave the area throughavenues other than the drains. When Chang andothers (1983) attempted to match their computedwater table heights with measured ones for variousfields in California, they obtained their best matchwhen the assumed seepage rate was several timesthe rate of water removal through the drains.

The dominance of this deep seepage called attentionto the important difference between the naturaldrainage rate and the rate of drainage through in-stalled systems. When a new irrigation project iscontemplated for an area, the natural water tablemay be tens of meters deep, making the potentialrate of water removal from such a region difficultto estimate. The requirements of any drainagesystem, however, are obviously reduced by-theamount of natural drainage. If water supplies arerelatively expensive, and the spatial variation ofsoils, terrain, and water applications are minimal,applying less leaching water permits crop yields todrop below the maximum achievable yields, which

98

114

Drain Depth

Relatively deep drains are customary in irrigatedareas with arid climates. The U.S. Bureau ofReclamation, for example, typically specifies depthsbetween 2 and 3 meters. Such deep installations arecostly, and the question arises whether they areneeded. Doering and others (1982) concluded fromstudies in North Dakota that water table depths ofapproximately 1 meter provided maximum crop yieldwith minimal supplemental irrigation for severalcrops. In an evaluation of extensive field data fromPakistan, Oosterbaan (1982) found that the watertable depth required to prevent reduced yields ofsorghum and cotton was 60 centimeters. Such datasupport the contention (based on reasoning withlimited evidence) that the drain depth typicallyrecommended may be deeper than necessary. Recentchanges in installation techniques may support thiscontention. The equipment needed to install drainsto a depth of 1.5 meters by trenching is less cum-bersome and less expensive than that needed forgreater depths. Trenchless installations may bepractical at the shallower depths with significantcost reduction.

Drain-Water Disposal

Besides the benefits to the land being drained, oneneeds to consider disposal of drainage water. Thiscan be a matter of serious concern and high cost asillustrated by the as yet unresolved drainage prob-lems in California's San Joaquin Valley. An excellentonfarm drainage system has no value unless an ade-quate outlet exists for drainage water disposal.Depending on its quality, drainage water may be atotal or partial substitute source of irrigation water.

Drainage waters collected by tile lines and ditchesor removed by the pumping of wells can, in somecases, be disposed of in ways that do not reduce thequality of surface and ground waters. For example,the highly saline drainage water collected in ditchesfrom the San Juan irrigation project in Mexico andformerly discharged to the Rio Grande River is nowbeing conveyed directly to the Gulf of Mexico in aseparate channel. Also, a special channel has been

constructed for conveying the highly saline, drain-age water from the Wellton-Mohawk irrigation proj-ect in southwestern Arizona to a point on theColorado River below the last place where water istaken from the river for beneficial use. Conveyanceto sumps for evaporation or reclamation by desa-lination are other possibilities for disposal. In manycases, however, the disposal of drainage water in away that does not harm stream and ground water isnot practical or possible. There may be severalreasons for this: the cost is prohibitive; the drainagewater is neither collected nor pumped but moves byunderground flow to streams and ground-waterbasins; or the quality of the drainage water, thoughsomewhat diminished, is such that it still has valuefor irrigation or other purposes.

Where the flow of agriculture drainage water tobodies of surface and ground water cannot beeliminated, quality degradation can be reduced byminimizing the amount of salt leaving the root zone.That amount can be reduced by decreasing evapo-transpiration or by removing accumulated salts inthe smallest volume of water compatible with theleaching requirement. Simultaneously reducingevapotranspiration and the amount of water ap-plied decreases the amount of salt that must beremoved from the drainage water. This can beachieved in a variety of ways, such as using closedwater conveyance systems, eliminating nonbene-ficial vegetation, and growing crops with lowerevapotranspiration requirements as a consequenceof the season or length of their growth period.Removal of excess dissolved salts consistent withthe leaching requirement maximizes the salt concen-tration of the soil solution and drainage waters, andhelps produce harmless, slightly soluble salts, suchas lime and gypsum, in the soil. It also minimises thesolution of soil minerals and fossil salt depositswhich commonly occur in geologic materials belowthe root zone.

Unusually high and nonuniform soil permeability,and an excessive and nonuniform application of ir-rigation water are the chief causes of excessiveleaching. Minimizing the amount of salt leaving theroot zone in drainage water is, therefore, stronglyinfluenced by irrigation efficiency. The leaching ofdissolved salts is more efficient and the problems ofexcessively high and nonuniform soil permeabilityare reduced when applied water moves through thesoil by unsaturated flow. Irrigation by sprinkler andtrickle systems permits uniform and controlled ratesof water application.

Agricultural drainage waters sometimes containnutrients and chemicals in sufficient concentrations

1 1 3

to help or harm users of the water or the aquaticenvironment. Aside from the salts associated withsalinity, subsurface drainage may contain nitratesand trace elements that harm the environment.

Nitrogen in drainage effluent is normally in theform of nitrate because it is not adsorbed on soilparticles. After reaching surface waters, thesenitrates may contribute to eutrophication (a situa-tion where minerals and certain nutrients rob waterof oxygen, and thus favor plants over animal life). Inhigh concentrations, nitrates may cause or at leastcontribute to methemoglobinemia (a poisoning of theblood) in infants and certain disorders in ruminantanimals. High nitrate concentrations in subsurfacedrainage can originate from a number of sources:excessive fertilizer, geologic deposits, naturalorganic matter, decomposition of human or animalwastes, or possibly by deep percolation of nitratesbecause of a lack of complete efficiency of the rootsystem in absorption. The management goal indrainage and fertilizer practice is to minimize thenitrate concentration of drainage waters.

Minimizing Adverse Effects

In recent years, experts have become increasinglyconcerned with the significance of the degradationof irrigation return flows due to leaching of traceelements. Those elements have accumulated in thesoils, and the drainage waters have injured fish andwildlife and could potentially affect human health.As an example, the west side of the San JoaquinValley has serious drainage and salt managementproblems because the disposed drainage water isdamaging valley waterfowl, agricultural lands, andthe San Joaquin River. The original plan called forthe drainage water to be diverted from the valleythrough the San Luis Drain to the Sacramento-SanJoaquin Delta, and then into the San Francisco Bayand the Pacific Ocean. Construction of the drainbegan but it was not completed because of environ-mentally based objections and lack of constructionfunds in the mid-1970's. As a result, no acceptablereceiving water was identified, and most drainagewas discharged through the incomplete drain to theKesterson National Wildlife Refuge, where it wasexpected to evaporate. Deformities in waterfowlobserved at Kesterson have called attention to highlevels of selenium and other trace metals, such asboron, in drainage water from the valley.

Although continued operation of the current systemappears unacceptable, shutting down the system

99

appears equally untenable. Estimates indicate thatpossibly 500,000 acres (200,000 hectares) ofagicultural land could be lost over the next 30 yearsif drainage effluent containing salt or traceelements is not controlled, a loss that could cost theCalifornia economy $1.5 billion per year. TheDepartment of the Interior and the State of Califor-nia have initiated the San Joaquin Valley DrainageProgram to identify the magnitude and sources ofthe problem; the potential alternative bodies ofreceiving water; and options (including modificationof agricultural practices) available for resolving theissue without unacceptable effects on the environ-ment, agriculture, and the economy.

The potential damage from trace elements indrainage effluent is illustrated in table 9-2, wheretypical concentrations of a number of traceelements in the San Luis drain are compared withthe maximum recommended concentrations for ir-rigating sensitive crops (Pratt, 1973). The criteria onwhich these recommendations are based include:toxicities in crops grown in nutrient solutions; short-term soil culture experiments in which the amountof an element required to produce toxicities wasobserved; and soil-plant-animal relationships forelements that are toxic to animals through the foodchain at levels lower than those that produce tox-icities in plants. The levels of boron and selenium

Table 9.2Recommended maximum concontration oftrace elements in waters used to irrigatesensitive crops on soils with low capacity toretain these elements in unavailable formscompared with typical values from the SanLuis drain

ElementTypical concentrations

in San Luis drain1Recommendedconcentrationof irrigation2

mg/m3, (ppb) rn gftn3, (ppb)

Aluminum 100 5,000Arsenic 10 100Boron 14,000 750Cadmium 10 10Chromium 18 100Copper 10 200Iron 80 5,000Lead 10 5,000Lithium 2,5003Molybdenum 10Nickel 10 200Selenium 310 20Zinc 10 2,000

= not available.1Values reported by California Department of Water

Resources during first half of 1984 near Mendota, Calif.2Recommendations from Pratt, 1973.3Recomrnended maximum concentration for irrigated citrus

in 75 mg/m3.

100..1...1. 8

are of paramount concern. This points up how theconcentrations of trace elements in drainage ef-fluent is the most pressing new issue in drainage forirrigated agriculture.

References

Chang, A. C., R. W. Skaggs, L. F. Hermsmeier, andW. R. Johnston. 1983. Evaluation of a WaterManagement Model for Irrigated Agriculture. Trans-actions of the ASAE. Vol. 26, pp. 412-418, 422.

Doering, E. J., L. C. Benz, and G. I. Reichman. 1982.Shallow-water-table Concept for Drainage Design inSemi-arid and Sub-humid Regions. Proceedings ofFourth National ASAE Drainage Symposium, Chicago,III., December 13-14, 1982. pp. 34-41.

Fitz, Joseph C., Gerald L. Horner, and J. HerbertSnyder. 1980. The Economic Feasibility of InstallingSubsurface Tile Drainage in the Panoche WaterDistrict, San Joaquin Valley, California. University ofCalifornia, Div. of Agricultural Sciences Bul. No.1897.

Hoffman, G. J. 1985. "Drainage Required to ManageSalinity," Journal of the Irrigation and DrainageDivision. Am. Soc. Civ. Engr. Vol. 111, pp. 199-206.

Kirkham, D., and L. Prunty. 1977. Upslope Recharge,Downslope Waterlogging, and Interceptor Drains.Proceedings of Third National ASAE Drainage Sym-posium. ASAE Pub. No. 1-77, pp. 40-50, 54.

Maas, E. V., and G. J. Hoffman. 1977. "Crop SaltToleranceCurrent Assessment." Journal of The Ir-rigation and Drainage Division, Am. Soc. Civ. Engr.Vol. 103, pp. 115-134.

Oosterbaan, 0. J. 1982. Crop Yield, Soil Salinity, andWater Table Depth in Pakistan. Wageningen, TheNetherlands: Annual Report, International Institutefor Land Reclamation and Improvement. pp. 50-54.

Pratt, P. F. 1973. Quality Criteria for TraceElements in Irrigation Waters. Station Bulletin,California Agricultural Experiment Station, Davis.

Chapter 10

Drainage Institutions

Carmen SandrettoEconomic Research Service, USDAEast Lansing, Michigan

Early in the development of American agriculture,when good land was abundant and available forcultivation, areas with wet soils and naturalwetlands were often bypassed. Many farms containedtracts of land too wet for use even as pasture ex-cept during dry seasons, and large areas were tooswampy or frequently flooded to make regular cul-tivation practical. As tillable land became scarcerand higher in price, farmers began to explore waysof reclaiming lands with wetness problems throughimproved drainage.

Drainage for agriculture has traditionally beenrecognized as an endeavor beneficial to the publicbecause excess water can influence public health,farm production, farm income, and real estatevalues. A number of the States recognized early theright of every landowner to a drainage outlet, per-mitting an owner intending to drain to apply to adesignated official, pay any damages, and if thenecessity were proved, secure an easement to con-struct and maintain a private outlet for the drainacross a neighbor's land.

Agricultural drainage often needs an artificial drainconstructed or a natural watercourse improved,which in turn, may affect the land of other individ-uals. Efforts to improve drainage outlets oftenbenefit more than one farm and the cost is greaterthan any one individual wants to assume. These cir-cumstances have encouraged legislation permittingthe organization of public corporations or localimprovement districts to facilitate artificialdrainage activities.

Elements of Drainage Law

Drainage law focused historically on promotingdrainage for two purposes: removing excess waterfrom the land so it could be cultivated or otherwisedeveloped, and enhancing public health becauseswamps and low-lying areas were potential breeding

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places for malaria-carrying mosquitoes. These con-siderations were the basis for allowing privateindividuals to drain their lands (Beck, 1972).

The issues associated with drainage law deal withrepelling water at the boundaries of one's land aswell as with disposing of excess water once it hasentered. Because remedial actions taken by individ-ual landowners interfere with the natural processesof water arriving on or leaving their land, what land-owners do will likely affect someone else's land.

Over the years, the courts have molded a substan-tial portion of the common law of drainage and havefrequently quoted three Latin maxims in theirdeliberations (Beck, 1972). Translated, they are:

1. Water runs and ought to run, as it has used torun.

2. Whose is the soil, his it is even to the skies andto the depths below.

3. Use your own property in such a manner asnot to injure that of another.

Basic Drainage Law Doctrines

Given the background provided by the common lawof drainage and the modifications resulting fromcourt action, three rules concerning drainage of dif-fused surface waters have been identified. Follow-ing is a brief summary of them as drawn from Beck(1972).

The common enemy rule, or, as it is sometimesmistakenly called, the common-law rule, recognizessurface water as a common enemy which each land-owner may try to control by retention, diversion,repulsion, or altered transmission. The focus is ontwo points: the necessity of improving lands,recognizing that scme injury results from evenminor improvements, and a philosophical preferencefor the freedom of landowners to deal with theirown land essentially as they see fit.

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The common enemy rule permits landowners todrain or repel diffused surface water if they actreasonably under the circumstances. Collecting anddischarging large or unusual quantities of diffusedsurface water onto adjoining land who re it maycause damage is considered un:casonlble.

The natural flow rule, or, as it is sometimes called,the civil law rule, places a natural easement uponthe lower land for the drainage of surface water inits natural course. The natural flow of the watercannot be obstructed by the owner of the lower landto the detriment of the owner of the higher land.

Because there has to be some drainage rule, lookingto the law of nature for the rule is reasonable. TheSupreme Court of Illinois in 1869 stated:

The right of the owner of the higher land todrainage is based simply on the principle thatnature has ordained such drainage. ... As watermust flow, and some rule in regard to it must beestablished ... there can clearly be no other ruleat once so equitable and so easy of application asthat which enforces natural laws. There is no sur-prise or hardship in this, for each successiveowner takes whatever advantages or inconven-iences nature has stamped upon his land.

The need to drain h nd in order to develop it cer-tainly does not mean that a landowner should beable to force a neighbor or the public to pay for it.In the early development of this country, a presump-tion in favor of drainage existed because it wasviewed as a public benefit, but today policy mayfavor the retention of natural areas and wetlands.This policy consideration would reject the commonenemy rule and tend to support the natural flow rule.

L..The reasonable use modification in applying thenatural flow rule has been t^ promote drainage.However, the basic principle generally applicable tolandownership should apply: landowners should beable to use their property as they see fit as long asthey do not unreasonably injure someone else'sproperty. Certainly natural flow can be altered inmany instances without doing any injury or damageto another tract.

Under the reasonable use rule, landowners arelegally privileged to make reasonable use of theirland even though the flow of surface waters isaltered and causes some harm to others. Those land-owners incur liability when harmful interferencewith the flow of surface waters becomes unreason-able. The underlying philosophy of this approach is

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ci;ssatisfaction with rules that either favor theupper landowner, as does the natural flow rule, orthat envision conflict between adjoining land-owners, as does the common enemy rule.

Beck (1972) has identified the following questions asbasic to an analysis of a situation under thereasonable use rule:

(1) Was there a reasonable necessity for alteringthe drainage pattern to make use of the land?

(2) Was the altering done in a reasonable man-ner? That is, was due care taken to prevent in-jury to another's land? Was the natural drainagepattern followed as much as possible? Is theartificial system reasonably feasible?

(3j Does the benefit from the actor's conductreasonably outweigh the gravity of the harm toothers? This test is the traditional nuisancebalancing approach, which has the distinct ad-vantage of keeping tip to date.

All of the common-law rules concerning drainage ofdiffused surface waters involve elements of uncer-tainty. Under the natural flow rule, dominantowners must show that they are dominant and thatthe lower owner(s) obstructed the natural drainagepattern. The common enemy rule is uncertainbecause to permit one set of owners to get rid of dif-fused surface water as best they can may not be anoverall benefit if their action brings them into con-flict with neighbors who :lave the same rights. Thereasonable use test is uncertain because it dependsupon not only whether landowners make reasonableuse of their land but also whether it is reasonablein the larger setting.

The modifications of the common enemy and naturalflow rules have done much to alleviate the early at-tendant injustices. The reasonable use rule seemsthe most just because it considers the individual cir-cumstances of each case.

An inevitable consequence of a complex society isthe diminution in control that landowners have overtheir land. The public interest concept appears tobe expanding. In attempting to resolve problemsamong individuals, the reasonable use test seemsbest because it analyzes the gravity of harm versusthe utility of the benefit. An element of public in-terest is interjected in these cases in ascertainingnot just the utility to the individual but to the publicas well.

The question arises whether there is really any dif-ference between the independent reasonable userule and the reasonable use modifications of thecommon enemy and natural flow rules. In a growingnumber of jurisdictions, all conduct of a landownerwith reference to diffused surface waters is subjectto the reasonable use rule, whether as a modifica-tion of one of the other rules or as an independenttest (Beck, 1972).

The general rules formulated from a composite ofthe basic rules and their modifications with respectto the law of drainage of diffused surface waterscan be summarized as follows:

1. A landowner may not obstruct the naturalflow in a watercourse (liberally defined insome jurisdictions) to the injury of another.

2. A landowner may not collect unusual amountsof diffused surface waters and dischargethem onto adjoining land to its injury.

3. A landowner may not divert onto another'sland, to its injury, diffused surface watersfrom an area that did not naturally drain thatway.

4. A landowner may drain diffused surfacewater into a watercourse (liberally defined insome jurisdictions) subject to the overtaxingcapacity, the anticollecting-and-discharging,and the antidiversion rules.

5. In all other respects concerning their conductwith diffused surface waters, landowners aresubject to a rule of reasonable use of theirland, whether it relates to acceleration orrepulsion of flow.

Drainage Rights

Easements for a landowner to drain excess wateracross the land of another may be obtained the wayany other easement is, through grant, express orimplied, or through prescription. A number of Statesprovide for use of eminent domain power by privateindiv ivals to drain land. This individual exercise ofeminent domain is distinct and separate from theuse of the power by entities such as drainagedistricts. Eminent domain is limited to a public useor public purpose, which may create some difficultiesin use of the power for draining private lands.However, some State constitutions authorize use ofeminent domain for this purpose, and some courtsconstrue the benefit to the public health or economy

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arising from drainage as a sufficient public pur-pose. Also, it is possible to create a license fordrabage purposes (Beck, 1972).

Public Drainage Organizations

The expansion of agricultural development in manyparts of the Nation was accomplished throughcooperation among groups of landowners with com-mon drainage interests engaging in communityundertakings to remove excess water from theirholdings. These efforts eventually resulted in thecreation of public organizations to improve off-farmdrainage facilities.

Early attempts at drainage improvement by individ-ual landowners were often unsatisfactory becauseoutlets were inadequate to carry off the excesswater. Individual efforts to improve drainage werefollowed by cooperation between groups of adjacentlandowners to obtain effective drainage at lowercost. However, these attempts at cooperation in theconstruction of drains and the distribution of costsoften failed because of inherent weaknesses in suchvoluntary associations. Also, cooperating groups didnot possess the power to compel all landowners whobenefited from the drainage works to pay their fairshare of the costs, nor did they have a mechanismto permit construction of drains across the lands ofan owner who refused to consent when circumstancesmade such construction necessary to secure adequateoutlets.

Types of Drainage Organizations

The failure of individual and voluntary cooperativeefforts to establish economic drainage improve-ments led to legislation authorizing the formation ofpublic organizations with certain powers to allowimproved drainage of agricultural lands. Legislativeauthority for the creation of drainage districts as itexists today dates back to the 19th century.

The formation of public drainage organizationsusually involves a multistage process which variesin detail from State to State, but which containselements common to all. Enabling legislation sets outthe procedure for the formation of a drainagedistrict, indicates the powers it has, and imposes aduty on the district to keep drainage systems ade-quately repaired. Appendix B is a synopsis of lawsand regulations pertaining to drainage in selectedStates.

Drainage organizations have generally been referredto as public corporations or as quasimunicipal cor-

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porations. Drainage districts or close approxima-tions of them are authorized in 45 States. In 39States, entities actually denominated "drainagedistricts" may be formed for various drainage pur-poses (Beck, 1972). In some States, several types ofdrainage districts may be created. Many States alsoauthorize multipurpose districts to engage indrainage projects. One factor accounting for thediversity in public organizations has been thetendency to move from single-purpose to multipur-pose districts without doing away with the olddistricts.

The administrative structure established to provideunified action for handling a drainage problem iscommonly referred to as its organization; alldrainage activities under the direct managementand supervision of one organization constitute oneproject. Drainage projects are those activitiesundertaken to provide mew construction or replace-ment construction or to provide maintenance andoperation of existing drainage works, and are usuallyclassified into three groups:

1. Drains owned by one landowner; the land-owner may be an individual, a partnership, anestate, a private corporation, or an institution.

2. Cooperative or mutual drains that representundertakings by two or more landowners coop-erating without special organization underState drainage laws for the construction oroperation of drainage works benefiting theirlands. Many cooperative or group drainageprojects have received assistance andguidance from SCS.

3. Legally organized public drains that representcommunity or public drainage undertakingsaccomplished through some form of govern-mental organization. These organizations canbe administered by public officials of a county,a township, a State, an agency of the FederalGovernment, or by specially elected orappointed officials or boards. General orspecial State laws provide for equitablecooperation among landowners who willbenefit by a particular drainage undertaking.

A variety of drainage organizations have beenauthorized in nearly all States, with the corporatedistrict and the county drain constituting the twoprincipal types. A system of county drainage dis-tricts has been created in some States, whereas inothers, special drainage districts have been formed.

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Besides the two principal types of drainage organ-izations, some minor types exist: (1) township drains,which are generally similar in form to county drainsbut are controlled by officers of the townships; (2)State drainage projects controlled by State officials,usually embracing some State land; (3) irrigationdistricts, similar to drainage districts, that havedrained land within the irrigation districts; (4) com-mercial companies reclaiming and improving poorlydrained land for future sale; (5) cooperative ormutual undertakings without formal corporateorganization; and (6) individual landowners in-cluding farm partnerships and farm corporations(Bureau of the Census, 1961).

In several States, some difficulty exists in distin-guishing between drainage districts and countydrains. Many of the organizations classified ascounty drains were named "drainage districts" inthe law. District organizations, under the manage-ment of their own officials, were generally con-sidered better suited to larger and more costlyundertakings because they provided landownerswith a greater degree of local control. Countydrains administered by county officials weregenerally more economical for adniinistering smallenterprises with relatively simple engineering andfinancing problems and were most commonlyadopted in States where drainage improvementswere being provided to land already in farms.Drainage districts were generally confined to areaswhere reclamation end development of unimprovedlands for new farms had been an important con-sideration in establishing drainage organizations.

T1,3 1950 Census of Drainage treated the drainedlands of each county in States having predominantlycounty drains as a single drainage organization. TheStates were designated as "county-drain" States:Delaware, Indiana, Iowa, Kentucky, Michigan, Min-nesota, Ohio, Oklahoma, North Dakota, and SouthDakota. De law nre's predominant form of drainageorganization, however, is the drainage district. Thirtyother States were identified as "drainage-district"States. The six New England States, Pennsylvania,and West Virginia were determined, for the purposeof the Census, not to have drainage organizations(Bureau of the Census, 1952).

The geographic distribution of agricultural landsserved by organized drainage projects of 500 acresor more is presented in figure 10-1. The greatestconcentration of agricultural land within drainageproject boundaries is found in the Great Lakes, Up-per Midwest, Lower Mississippi Valley, Gulf, andDelmarva regions. California's drainage enterprisesare typically associated with irrigation projects.

Figure 10-1Land in organized drainage enterprises.

Creation of a drainage district begins with a peti-tion containing certain specified information, signedby the required number of people, and addressed toa designated court, board, or authorizing official.Frequently, a bond must be filed with the petition tocover the costs and expenses of the proceedings ifthe district is not established. Sometimes a mapmust accompany the petition.

The petition is usually referred to an engineer,surveyor, designated board, or some combination ofthese. A preliminary report is prepared that gives ageneral idea of the location, character, cost, andpotential feasibility of the proposed drainage proj-ect and indicates what lands would benefit.

Notice to interested persons or affected landownersis required, usually followed by a hearing and adeclaration of the establishment or nonestablish-ment of the district. In its declaration, the court orboard determines the technical sufficiency of thepetition and proceedings; it considers whether anybenefits will accrue, whether those benefitsoutweigh the costs, and whether public health orwelfare would be enhanced.

one do1.10,000 acres(aunty emit basis)

The procedure usually includes a provision forappeal from the board to a court or from theorganizing court to a higher court. Many Statecodes have provisions for voting by designated par-ties as an alternative method of forming districts oras a veto on any district formation. Sometimes theprocess is concluded with an assessment upon thoseto be benefited; but, in many States, the organiza-tional procedure is distinct from the assessmentprocedure.

The enabling legislation indicates the powerspossessed by a properly organized drainage district.These generally include the following powers: toacquire and own inivrests in real and personalproperty; to construct various works necessary toaccomplish the drainage improvements and anyother purposes for which the district is organized;to condemn property needed for carrying out thepurposes of the district (eminent domain); to makecontracts; to borrow money and issue bonds; to paydebts; to sue and be sued; to make an equitabledistribution of costs in proportion to benefits con-ferred; to levy and collect taxes against benefitedlands: to employ the necessary personnel; and toadopt regulations for administration of the com-

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Feted project or projects (Beck, 1972; Yohe, 1927).The codes usually impose on the district a duty tokeep the drainage and related works in repair.

What can be drained through the auspices of drain-age districts varies from State to State. The focus isusually on either the nature of the land, the purposeto be accomplished, or the nature of the water. Insome States, combinations of the foregoing ell_stated; a few States make no specific statements.The area of a drainage project is usually defined asthe area benefited by the drainage works. The areaimproved or benefited for agriculture as a result ofthe drainage facilities is what is considered in proj-ects undertaken by landowners, either individuallyor cooperatively (Beck, 1972).

Drainage district statutes normally do not specifyany particular geographic area to be included, butthey do require the petition to contain some descrip-tion of the proposed boundaries. Varie ts govern-mental bodies with final creative approval ofdistricts, or governmental officials such as Stateengineers, have differing degrees of control over theboundaries. In any case, the legal document estab-lishing the district defines its boundaries. In mostStates, if public drains are administered countywideor on the basis of established political boundaries,the boundaries are determined by the area directlybenefited. In special districts organized primarilyfor purposes other than drainage, the entire area inthe district defines the boundaries, even though onlypart may be benefited (Bureau of the Census, 1961).

Several States require the district land to becontiguous, while others specifically allow noncon-tiguous areas, and some States do not permitdistricts to cross county lines. Several States havelanguage relating to natural drainage basins, andmany States provide for mergers of two or moredistficts and for subdistricts or interstate districts(Beck, 1972).

After a drainage district is formed and certain landis included, the drainage activities of individuallandowners may be restricted. Essentially alljurisdictions give drainage districts the power ofeminent domain to foster their purposes, but its ex-ercise is usually limited in some way (Beck, 1972).

A project need not provide complete drainage forthe area served. Many projects, especially publicdrains, provide only the principal channel or outletdrain. The construction of laterals and field drainsrequired to provide optimum drainage may be left toindividual landowners. These drains and other water-

control works installed by farmowners on their ownfarms, either inside or outside the boundaries of anorganized drainage district, are probably eithersupplemental to or entirely independent of thedrainage works installed by a district organized toimprove lands for agriculture.

Administration and Financing

Public drainage projects are administered by aboard of drainage commissioners who are eitherelected by the residents or landowners of thedistrict (in some States, voting power is based onacreage), or are appointed by the organization'screative authority. In many States, board membersmust be real property owners in, and residents of,the county or district involved. In a few Sterns, ex-isting kcal officials supervise drainage projar.,a.Courts generally hold that a majority of the boardcan act to bind the district. Although commissionersmay usually exercise great discretion in carryingout the governing function, they can be challengedfor such improper activity as misapplication offunds (Beck, 1972).

Drainage improvements may be financed in severalways. An assessment against bane :tea land is mostcommon, but much discretion is often given to theassessing authorities in eateemining what consti-tutes a benefit and the procedures involved in theassessment process.

Many States have specific provisions dealing withorganizational costs, construction costs, andmaintenance costs. A uniform tax on all propertywithin the district is often used to cover organiza-tional costs, but construction and maintenance costsare generally recovered from tax levies based onassessed benefits to the respective tracts of land.Frequently, separate funds are maintained for eachcost category. Because expensive drainage projectscannot be financed through a single year's levy,provisions usually exist for a variety of borrowingand repayment methods (Beck, 1972).

As custodians of the project, the drainage commis-sioners are responsible for maintenance and repairof the drainage system. Deterioration of facilitiesand subsequent loss of efficiency in removing excesswater can occur rapidly if regular inspections andmaintenance are neglected. P-oper maintenance canyield substantial benefits through increased effi-ciency and extended life of the project (Yohe, 1927).

Man; public drainage organizations are establishedfor a specific purpose, such as to cnnstruct new

drainage facilities or to enlarge or renovatefacilities built by an earlier organization. Afteraccomplishing their immediate objectives, many ofthese organizations become inactive or dissolve, sowhen further work is needed, a new drainage organ-ization must be formed. Over the years, drainageorganizations have overlapped, and only a smallnumber of organizations may be currently active.Usually the functions of an inactive organization areassumed by a new organization, although controlsometimes passes from one organization to anotherthrough court action.

Many cases exist in which drainage districts havefailed, bonds have not been refunded, and ownersof assessed lands have not paid their assessments.The drainage codes of most States provide steps fordissolving defunct drainage districts which specifywho can initiate the procedure, where the dissolvingpower lies, and what conditions must exist before itcan be exercised. Lack of dissolution, however, hasbeen more of a problem than dissolution. Districtshave simply withered away, the commissioners ordirectors have disappeared, and projects have beenleft uncompleted and/or unmaintained (Beck, 1972).

The substantial amount of litigation in the courtsover the years demonstrates that many of thedrainage districts established years ago were ill-conceived; land was forfeited for failure to payassessments, and many bondholders could notrecover the full face value of their bonds. Recenttrends indicate a preference for multipurposedistricts (conservancy and water management, forexample). The result may be improved naturalresource management through emphasis on betterplanning and coordinating than occurred histori-cally with the single-purpose districts.

Multipurpose Districts

Several States have enacted legislation in recentyears authorizing the creation of general multipur-pose districts which are permitted to perform manyfunctions, including draining wetlands. Most ofthese have retained their statutes permitting thecreation and operation of separate drainagedistricts. Multipurpose districts have no primarypurpose except the very general one of promotingpublic welfare as it relates to the total waterresources. This differs from special-purpose

1This section on multipurpose districts was prepared by Dean T.Massey.

districts with a primary purpose. For example, mostirrigation districts can engage in some drainage;however, drainage is only incidental to the primarypurpose of irrigation.

Multipurpose districts that provide for wetlanddrainage as one function have different names indifferent States. For example, they are known asconservancy districts in Indiana, New Mexico,Montana, Ohio, and Oklahoma; as water conservancydistricts in Nevada and Utah; as watershed conser-vancy districts in Kentucky; and as river conservancydistricts in Illinois. Kansas and South Dakota havewatershed districts, Alabama has water manage-ment and drainage districts, North Dakota haswater resources districts, and Wyoming has water-shed improvement districts. Nebraska's naturalresources districts prob,ably have the broadestpowers of any multipurose districts. Minnesota hasboth conservancy and watershed districts that mayperform drainage functions. The relevant Statecodes are listed with other references to thisvolume.

Multipurpose districts generally perform severalfunctions, which may include preventing andcontrolling floods; constructing flood preventionstructures, including levees; improving stream chan-nels; preventing and controlling erosion andsedimentation; regulating stream flows and lakelevels and conserving water; improving drainageand reclaiming or filling wet or overflowed lands;diverting or changing water courses; proiri3tingrecreation; providing, developing, and conservingwater supply for domestic, industrial, recreational,and other public uses; providing for sanitation andpublic health, and regulating the use of streams,ditches, or water courses for the disposition ofwaste; relocating, extending, replacing, modifying,consolidating, or abandoning drainage systemswithin a multipurpose district; and operating andmaintaining drainage systems.

Multipurpose districts are generally initiated with apetition signed by a requisite number of landownerswhich is submitted to the county board of super-visors or county agency, officer, or court. After apublic hearing to determine the necessity of estab-lishing a district, the governmental authority willestablish a district. Sometimes a referendum is held.A board of directors, usually appointed by the sameauthority that established the district, governs thedistrict. Areas included in a district do not have tocoincide necessarily with county boundaries. Areascan be smaller or larger than a county.

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Multipurpose districts may purchase, lease, andown land, and, if necessary, may acquire suchinterests by eminent domain. They may enter intocontracts and construct and maintain structuresand facilities. Districts generally have power to levytaxes, borrow money, issue bonds, and levy specialassesiment of lands benefited.

References

Beck, Robert E. 1972. "The Law of Drainage," InWaters and Water Rights. Vol. 5. (ed. Robert EmmetClark). Indianapolis, Ind.: The Allen Smith Company.

Hannah, H. W., N. G. P. Krausz, and D. L. Uchtmann.1979. Illinois Farm Drainage Law. Coop. Ext. Serv.Circular 751, Univ. of Illinois, Urbana.

Indiana Farm Bureau, Inc. 1981. The CountyDrainage Board, Recodified 1981. Indianapolis, Ind.

Michigan Department of Agriculture, Division ofIntercounty Drains. 1984. Personal communication.

Nolte, Byron H. 1981. The Ohio Drainage Laws Peti-tion Procedure. Coop. Ext. Serv. Bulletin 482, OhioState Univ. and County Engineers Association ofOhio, Columbus.

Nolte, Byron H., and Eugene H. Derickson. 1976.Conservation Improvement Projects Through Soiland Water Conservation Districts. Coop. Ext. Serv.Bulletin 606, Ohio State Univ., Columbus.

North Carolina Department of Natural Resourcesand Community Development, Division of Soil andWater Conservation. 1984. Personal communication.

U.S. Congress, Office of Technology Assessment.1984. Wetlands: Their Use and Regulation. ReportOTA-0-206, March.

U.S. Department of Commerce, Bureau of the Cen-sus. 1932. Drainage of Agricultural Lands, 1930.

1952. "Drainage of AgriculturalLands," Census of Agriculture, 1950, Vol. IV.

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. 1961. "Drainage of AgriculturalLands," Census of Agriculture, 1960, Vol. IV.

1981. "Drainage of AgriculturalLands," Census of Ag-iculture, 1978, Vol. 5, SpecialReports, Part 5.

Yohe, H. D. 1927. Organization, Financing and Ad-ministration of Drainage Districts. Farmers' BulletinNo. 815., U.S. Dept. Agr.

State statutory references:

California Water Code, Secs. 8502, 8550, 8551,8750, 8751, 8758 (West 1971 and CumulativeSupplement 1984), Secs. 20700, 22095 (West 1984),Secs. 50110, 50300, 50932, 56010 to -014, 56018to -020, 56030, 56041 to -042, 56050, 56055, 56070to -071, 56074 to -076, 56083 to -084, 56095, 56104,56110 to -117 (West 1966 and Cumulative Supple-ment 1984), and Secs. 70150, 74522 to -525 (West1966).

Alabama Code, Secs. 9-9-1 to 9-9-80 (1980).

Illinois Annotated Statutes, Ch. 42, Secs. 383 to410.1 (Smith-Hurd 1976 and Cumulative Supplement1984-1985).

Indiana Code Annotated, Secs. 13-3-3-1 to 13-3-3-102(Burns 1981 and Cumulative Supplement 1984).

Kansas Statutes Annotated, Secs. 24-1237 (1981 andCumulative Supplement 1983).

Kentucky Revised Statutes, Secs. 262.700 to 262.990(1981 and Cumulative Supplement 1984).

Minnesota Statutes Annotated, Secs. 111.01 to111.82 and 112.34 to 112.86 (West 1977 andCumulative Supplement 1984).

Montana Code Annotated, Secs. 85-9-101 to 85-9-632(1983).

Nebraska Revised Statutes, Secs. 2-3201 to 2-3275(1977 and Cumulative Supplement 1982).

Nevada Revised Statutes, Secs. 541.010 to 541.420(1983).

New Mexico Statutes Annotated, Secs. 73-14-1 to73-14-88 (1578 and Cumulative Supplement 1983).

North Dakota Century Code, Sec. 61-16.1-01 to61-16.1-63 (Supplement 1983).

Ohio Revised Code Annotated, Secs. 1515.01 to1515.30 (Page 1978 and Supplement 1983) and Chs.6131, 6133, 6135, 6137 (Page 1977 and Supplement1983).

Oklahoma Statutes Annotated, Title 82, Secs. 531 to688.1 (West 1970 and Cumulative Supplement1983-1984).

South Dakota Codified Laws Annotated, Secs.46A-2-1 to 46A-2-37 (1983).

Utah Code Annotated, Secs. 73-9-1 to 73-9-43 (1980and Supplement 1983).

Wyoming Statutes Annotated, Secs. 41-8-101 to41-8-126 (1977 and Cumulative Supplement 111,93).

-7 0 ---1/,f3 109

Chapter 11

Economic Survey of Farm Drainage

George A. Pave lisEconomic Research Service, USDAWashington, DC

This overview briefly addresses a series of drainagedevelopment and economic questions: At what ratehave drainage organizations and individual farmersin the United States improved land by drainage?How has the cost of drainage changed over time?How have past investments in drainage added to theNation's agricultural capital and wealth? How doesdrainage capital relate to land and its value in dif-ferent States and regions? How does drainage con-tribute to farm production, and what is the sig-nificance of maintaining a productive irrigatedagriculture through proper drainage and relatedwater management strategies?

The density map in figure 11-1 indicates the generaldistribution of drained agricultural land in theUnited States. The total area drained in 1985 wasaround 110 million acres, of which about 70 percentwas cropped and 12 percent grazed. Woodlands ac-counted for 16 percent, with the balance (2 percent)in farmsteads and other miscellaneous uses.

Areas and Uses of Drained Land

Although poor drainage and its effects are evidenteven to the untrained eye, good natural drainageand functioning drain systems often go unnoticed.This unseen attribute of drainage is one reason whyreliable information on this important land improve-ment is difficult to obtain from landowners or farmoperators.

Another reason is that in its primary developmentalperiod, 1870-1920, and again in a secondary periodduring 1945-60, much new drainage occurred withinorganized drainage districts, or county and town-ship drains. These came to be called drainage"enterprises" (U.S. Dept. Commerce, 1961). Theycan be organized in several ways and can have

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multiple functions. They may engage in drainage onlyor in both irrigation and drainage. According to theBureau of the Census, 20 percent of the 840 or moreU.S. irrigation districts maintain about 14,000 milesof drains. Most of the drains serve projects originallyconstructed by the Bureau of Reclamation but paidfor and now operated by water users. Also, about15,000 miles (13 percent) of the irrigation canalsand ditches in the United States are lined tominimize conveyance losses and drainage problemsconnected with seepage (U.S. Dept. Commerce, 1982).

The connection between organized drainage and thedifficulty of obtaining reliable current information isthat many organizations have kept few records onproject activity within their areas and these maypertain only to the construction period. Organiza-tion officials may not have been replaced as theyretired or moved away, so it is difficult to locateresponsible individuals or otherwise gain access toavailable records.

The estimates on drainage compiled for this surveyare based on Bureau of the Census information, sup-plemented with data available from USDA agenciesand drainage specialists. The Bureau of the Censuscompleted a Census of Drainage Organizationsabout every 10 years between 1920 and 19,8 (13U.S. Code 142). It also collected some drainageinformation from farmers in its regular Censuses ofAgriculture for 1920, 1930, 1969, and 1974. TheReferences section contains numerous Departmentof Commerce publications on drainage and relatedagricultural topics dating from 1930 to 1985.

In 1978, the Bureau of the Census did not requestinformation on land drained from either drainageorganizations or farmers but rather compiled county-level estimates provided by local offices of SCS (U.S.Dept. Commerce, 1981). Also, no specific questions

78-M102

Figure 11-1Artificially drained agricultural land in the United States, 1985.

on drainage were asked of farmers or others in themost recent (1982) Census of Agriculture.

Procedures and General Estimates

A three-step approach was used to develop esti-mates of rural land drained in the United Statesfrom 1855 to 1985. The total area for which drain-age improvements had been installed at least oncewas determined first. As of 1985, the cumulativetotal since 1855 had grown to at least 150 millionacres. Useful information on drainage back to col-onial times is available in books by Harrison (1961)and Weaver (1964).

Determined next was the amount of land actuallydrained as of given years, using the abovecumulative figures in conjunction with areasreported drained in various censuses of agricultureand drainage and other available sources.

The third step was an effort to assess the conditionof farm drains, applying some simple assumptionsas to their expected service life. Average servicelives were assumed to be 20 years for field ditchesand other practices for improving surface drainage.A se:vice life of 40 years was assumed for tile and

1980United States

Total

107,483,000 ac.

1 Dot - 20,000 Acres

U S Department ot Camerae&sew ot The Grave

other subsurface drains installed since 1940 (30years if installed before 1940).

In the case of drainage organization facilities, grossand net capital values in a given period were con-sidered equal to accumulated investment. The yearlyinvestments were allowed to hypothetically "decline"over a period of 60 years to 50 percent of theoriginal cost, the decline being an approximation ofmaintenance allowances. This does not imply thatall organization outlets or other facilities, whichserved 65 million acres of drained land in 1985,were being maintained da needed. By 1920, main-tenance allowances represented 20 percent ofcumulative expenditures by drainage organizations.Comparable percentages for years since then were32 percent for 1940, and 55 percent for 1985. Mostcurrent organization expenditures are formaintenance and replacement.

The approximate areas of farm and other rural landdrained by 5-year or annual intervals between 1000and 1985 are in table 11-1. The areas are dividedbetween the land provided and not provided organiza-tion service. The areas are also divided between theland drained with o-len ditches or other surface im-provements and that improved with subsurface

111

Table 11.1 -Rural land drained with and without drainage organization service, United States, 1690435

Year

Net area drained Area sharesLandarea

drained'

Drainageorganization

service2

Independentfarm

systems

Drainageorganization

service

Independentfarm

systems

Million acres ---------- Percent--------1900190519101915

6.29511.67722.30535.045

6.26511.62022.19034.830

0.030.057.115.215

999999G0

1

1

1

11920 49.445 48.154 1.291 97 3

1925 47.563 45.185 2.378 95 51930 49.363 45.414 3.949 92 81935 45.850 41.265 4.585 90 101940 45.437 39.985 5.452 88 121945 50.324 39.203 11.121 78 221950 69.929 52.867 17.062 76 241955 78.865 57.809 21.056 78 221960 86.607 61.491 25.116 71 291965 93.643 64.333 29.310 69 311970 99.084 65.792 33.292 66 34

1975 103.400 66.279 37.121 64 361978 105.278 66.009 39.269 63 371980 106.286 65.685 40.601 62 38

1981 106.743 65.538 41.205 61 391982 107.200 65.392 41.808 61 391983 108.101 65.395 42.705 61 391984 109.002 65.401 43.601 60 401985 109.681 65.260 44.421 59 41

'The net areas of farmland drained are rounded to the nearest 1,000 acres. They are not estimates of wetlands drained butrather refer to the area of farm or other rural land benefitedjo some extent by water removal to improve the soil environment forplant growth (Bureau of Census definition). Both surface and subsurface drainage improvements are included, such as ditches,swales, tile or other subsurface drains, dikes, pumping plants, and land grading.

2The net area with organization or project service includes lands drained within organized drainage districts, county drains,other drainage enterprises, and irrigation enterprises active in special drainage, less those nonagricultural lands drained withinenterprises, and also farmsteads, roads, wasteland, and timber or brushlands within the farms serviced by drainage enterprises.As the censuses of agriculture and drainage were not the only sources of required information on drainage, particularly for yearssince 1959, the areas given may not agree completely with census data.

drains plus associated surface improvements (table11-2, fig. 11-2).

Beginning with 1950, the estimates of drained areainclude irrigated land where special drainage wasnecessary to control soil salinity and temporaryhigh water tables. In 1950, about 5.4 million acreshad been reported drained by irrigation enterprisesor by drainage enterprises organized specificallyfor controlling salinity and seepage on irrigatedland (U.S. Dept. Commerce, 1961).

The total area of rural land drained in 1985 wasabout 110 million acres, of which 75 million acres(70 percent) was cropland. About 20 percent of theNation's total cropland area is drained (for crop-land statistics, see Frey and Hexem, 1985). At least1 million acres of farm or other non-Federal ruralland were drained in 22 States. In decreasing order

112 12

of the approximate area of land drained, countingspecial drainage needs in irrigated areas, theseStates were: Illinois (9.8 million acres), Indiana (8.1),Iowa (7.8), Ohio (7.4), Arkansas (7.0), Louisiana (7.0),Minnesota (6.4), Florida (6.3), Mississippi (5.8),Texas (5.8). Michigan (5.5), North Carolina (5.4),Missouri (4.2), California (3.0), North Dakota (2.4),Wisconsin (2.2), South Carolina (1.8), Georgia (1.5),Maryland (1.2), Tennessee (1.2), and Nebraska (1.0).New York and Delaware followed with 915,000acres and 460,000 acres, respectively.

These 23 States had about 96 percent of all crop-land drained in the United States in 1985 andaveraged about 25 percent of their cropland drained.However, such general figures obscure the factor ofdependence on drainage. About 65 percent of allcropland in Arkansas and 60 percent in Louisianawas drained. Roughly 55 percent of the cropland in

Table 11.2 -Rural land drained with surface and subsurface drainage systems, and drainage for systems not fullydepreciated, United States, 1900.85

Land area drained Area shares Undepreciateddrainage'

Year Surfacedrainage

only

Subsurfacedrainagesystems

Surfacedrainage

only

Subsurfacedrainagesystems

Surfacedrainage

Subsurfacedrains

Million - Percent--------- - ------ - ----- Million acres ------ -- - ---acres

1900 5.271 1.024 84 16 3.975 1.0141905 9.775 1.902 84 1( 7.447 1.8771910 18.673 3.632 84 16 15.313 3.5721915 29.344 5.701 84 16 25.029 5.5411920 43.452 5.993 88 12 38.131 5.5731925 41.420 6.143 87 13 41.412 6.1431930 42.676 6.687 87 13 42.676 6.6871935 38.606 7.244 84 16 32.697 6.1181940 36.532 8.905 80 20 19.298 4.7111945 40.769 9.555 81 19 15.800 3.2911950 54.041 15.888 77 23 22.849 9.3321955 60.736 18.129 77 23 29.172 10.7681960 35.921 20.686 76 24 34.252 12.4121965 70.039 23.604 75 25 35.244 15.0211970 72.151 26.933 73 27 21.773 18.0221975 72.668 30.732 70 30 17.588 21.3261978 72.015 33.263 68 32 15.394 23.5571980 71.386 34.900 67 33 15.941 24.9941981 71.202 35.541 67 33 14.508 25.5051982 71.165 36.039 66 34 13.786 25.8731983 71.617 36.484 66 34 13.030 26.1881984 72.118 36.884 66 34 12.240 26.4581985 72.397 37.284 66 34 11.450 26.728

'Surface drainage improvement less than 20 years old; subsurface drains less than 30 years old if installed before 1940, and lessthan 40 years old if installed in 1940 or later.

Mississippi and 50 percent in Indiana and Ohio wasdrained. Other States with at least 25 percent of 120their cropland drained included Florida (45 percent),Illinois (35 percent), and Michigan (30 percent).Iowa, North Carolina, Missouri, South Carolina, andDelaware followed with around 25 percent of theircropland drained.

Mil. ac.

Uses of Wet Soils and Drained Soils

Information on the particular uses of wet soils anddrained wet soils on non-Federal rural land in theUnited States was available from a NationalResources Inventory completed by SCS in 1982. It isreviewed briefly because its distribution patterns ofdrained land use in 1982 were the basis for develop-ing comparable estimates for 1985.

A similar but less intensive sample inventory wascompleted by SCS in 1977. Field personnel of SCShad made county estimates of drained land for theBureau of the Census in the 1978 Census of Drain-age, but in the 1982 inventory they completed

100 -

80

-Total land drained/4#

///

60 /Surface drainage/

/- \ /40 -

/

/ 01101./.0°.20 ...

...0. Subsurface drains.0

-*..0 ....J.--- r - -1- 1 1 1 i 1 I

1900 1920 1940 1960 1980Year

Figure 11-2-Artificially drained land on U.S. farms, 1900.85.

2000

113

worksheets for about 1 million random samplepoints within about 350,000 primary sample units.The latter ranged between 40 and 640 acres; mostwere 100 to 160 acres. Observations for the 1million sample points covered land use, soil types,flood-prone areas, wetlands, irrigation, erosionrates, and conservation needs. Needs for drainagewere determined for nonirrigated cropland,irrigated cropland, pastureland, and rangeland.

The inventory sample points were also assigned aland capability class and subclass designation. Soilshaving a primary management problem of wetnesswere designated subclass "w." This designationapplies to several major capability classes, forexample, llw, IIIw, IVw, VIw, and VI Iw (USDA,1982). The non-Federal rural land in the UnitedStates having wet soils totaled over 233 millionacres, of which 45 percent was cropped and 30 per-cent forested. About 20 percent was in grazing uses.

In the 1982 as in the 1977 inventory, an effort wasmade to identify prime farmland. With respect todrainage, these are "not saturated with water orflooded during the growing season" (USDA, 1982,p.10).

For sample points designated subclass "w" and alsoconsidered prime farmland, one may reason that thebasic wetness problem did not seriously inhibit pro-duction, because it was removed or controlled bydrainage. The 1982 inventory identified about 107

million acres (46 percent) of the wet soils as beingprime or adequately drained, of which 72 percentwas then cropland (table 11-3). Such an indirectnational estimate for the area of land drained in1982 was about 2 percent higher than the 105 millionacres local SCS offices had reported to the Bureauof the Census in 1978.

Dideriksen and others (1978) showed that "w" soilsare not equivalent to wetlands as defined by theFish and Wildlife Service (FWS) and accepted byUSDA (Shaw and Fredine, 1956). FWS classes in-clude all wetlands, regardless of their agriculturalpotential. In 1982, USDA inventoried 78 millionacres of remaining non-Federal wetland (Heimlichand Langner, 1986), but 233 million acres of wetsoils existed, of which 107 million acres were drainedas noted above. The 126 million acres of undrainedwet soils in 1982 (233 less 107) exceeded theremaining area of wetlands (78 million acres) by 48million acres.

A special tabulation by Heimlich indicates thatabout 40 percent of the wet soils not cropland in1982 could also be classed as wetlands. Exc3sswater was the dominant restriction on crop use forabout 93 percent (65 million acres) of the 78 millionacres of wetlands remaining in 1982.

The 1982 inventory also provided information on theuses of drained soils that was not available ineither the 1978 or earlier drainage censuses. In the

Table 11.3-Major rural land uses, wet soils on farms, and prime or drained wet soils by land uses, United States, 1982

Land useTotalarea

Areahaving wet

soils'

Prime ordrained wet

soils2

Share oftotal acres

drained

Proportiondrained

each use

Million ------- Percentacres

Cropland in crops 421.4 106.9 77.0 71.7 72.0

Irrigated 60.53 14.4 8.4 7.7 58.3Not irrigated 360.9 92.5 68.6 64.0 74.1

Pastureland 133.3 26.2 11.4 10.7 43.5Rangeland 405.9 17.7 2.2 2.1 12.4Forest land4 393.7 70.0 15.0 14.0 21.4Other rural land 59.6 12.7 1.6 1.5

Total 1,413.9 233.5 107.2 100.0 45.9

'Wet soils induct:, land within major land capability classes II, Ill, IV, VI, VII designated subclass "w," as having a predominantwetness problem.

2Prime wet soils include prime farmland only in major land capability classes II, Ill, and IV designated subclass "w." Amongother favorable features prime wet soils are not saturated with water during the growing season and have low salt and sodiumcontent.

3The 60 million acres Included some land not irrigated in 1982 but irrigated in at least two of the years during 1979-81. The totalactually irrigated in 1982 was 49 million acres according to the Bureau of the Census.

4Forested wet soils include rural non - Federal land both in and not in farms in 1982, of which 6.5 million acres were grazed and63.5 million acres were not grazed. Forested wet soils drained, however, are estimated according to note2.

5Not estimated because this land drained was only 0.1 percent of total rural land inventoried in 1982.

114

130

1982 inventory, about 77 million acres (72 percent)of the 107 million acres of drained (prime) wet soilsin rural areas were in crops. Another 11.4 millionacres (11 percent) were in pasture and 2.2 millionacres (2.1 percent) in range. About 15 million acres(14 percent) were forestland.

About 75 percent of the wet soils in nonirrigatedcrops in 1982 were considered adequately drained.On the same basis, 8,4 million acres (70 percent) ofthe wet soils used for irrigated crops posed nodrainage problems (table 11-3). Census sourcesindicate that another 10.9 million acres of irrigatedcropland not having wet soils were also drained(U.S. Dept. Commerce, 1973, 1982). The total area ofirrigated cropland artificially drained in 1982 (19.3million acres) represented 43 percent of all irrigatedcropland (44.4 million acres). At least 2.5 millionacres of the balance (25.1 million acres) of undrainedirrigated cropland need drainage.

Because such statistics are subject to error, the in-ventory was designed to permit evaluation of theirreliability. For example, the 234 million acres of wetsoils and the 107 million acres of such soils drainedin the United States according to the 1982 inventoryare single-valued estimates. The true figures can beeither lower or higher than these estimates.

With about a 95-percent chance of being correct,the true figure for all wet soils on farms or othernon-Federal rural land can be estimated from the

1982 inventory to be somewhere between 232 millionand 235 million acres. The true figure for the frac-tion of we soils drained lies somewhere between106 million and 108 million acres. This and otherrange estimates of how wet soils and areas drainedwere used in 1982 are also in table 11-4.

In extrapolating 1982 inventory data on the uses ofdrained land and making State estimates to 1985,prime wet soils were regarded as a first approxima-tion of the total area drained, because other wetsoils, while not prime farmland, may also be drained.For cropland, the land likely drained in a State in1985 generally was taken as either (a) the primewet soils in crops, or (b) the wet soils in crops con-sidered to not need drainage in the 1982 inventory,whichever was greater. For pasture, forest, andother uses, the land likely drained was taken as theaverage of (a) prime wet soils in that noncrop useand (b) half the wet soils in that use not requiringspecial conservation treatment including but notlimited to drainage. This procedure recognizes, forexample, that many areas in the Southeast andDelta States have been drained as part of a perma-nent timber management program.

This procedure showed that the 109.7 million acresdrained in 1985 were distributed among land usesas follows: cropland, 75.5 million acres (69 percent);pasture or rangeland, 12.8 million acres (12 per-cent); woodlands or forest, 17.9 million acres (16percent); and miscellaneous uses, 3.5 million acres(3 percent).

Table 11.4-Ninetyfive (95) percent confidence interval estimates for all wet soils and drained wet soils in ruralareas, by different land uses, United States, 1982

Land usesAll wet soils Drained wet soils

Wet soilsby use'

Share ofinventory2

Intervalestimate3

Areadrained

Share ofinventory2

Intervalestimate3

Million acres Percent --------- Million acres Percent Million acres

Cropland in crops 106.9 7.1 106.1-107.8 77.0 5.1 75.6.78.0

Irrigated 14.4 1.0 14.1-14.7 8.4 .6 8.1-8.7Not irrigated 92.5 6.2 91.7-93.2 68.6 4.6 67.9-69.4

Pastureland 26.2 1.7 25.8.26.7 11.4 .8 11.1.11.4Rangeland 17.7 1.2 17.4-18.0 2.2 .1 2.1-2.4Forest land 70.0 4.7 69.2-70.7 15.0 1.0 14.7-15.3Other rural land 12.7 .8 12.3-12.8 1.64 4 4

Total 233.5 15.6 232.5-234.9 107.2 7.2 106.4-108.2

'Wet soils include land within major land capability classes II, Ill, IV, VI, and VII designated subclass "w," or as having apredominant wetness problem.

2Area in col. 1 as percent of all rural nonFederal land and small water areas (1.5 billion acres) sampled in the 1982 NationalResources Inventory. The larger (smaller) the percent of the total inventory acreage represented by the areas for each land use indata cols. 1 and 4, the narrower (wider) will be the range estimates in cols. 3 and 6.

3Ranges are for a 95percent statistical confidence Interval; that is, based on the inventory sampling procedures, there is a95percent probability that the true figures for wet soils or drained wet soils are within the interval given. Because each item in thiscolumn is estimated separately, totals may not be the exact sum of individual items.

4Share of total Inventory area only 0.1 percent; interval not estimated.

131115

Organized and Independent Drainage

Since about 1960, two major shifts appear ft, haveoccurred in drainage: one is a trend away fromorganizing new projects toward farmers independ-ently installing their own systems (Gain, 1967), andthe other is that the area with subsurface drainshas increased more rapidly than that improvedthrough open or surface drainage (table 11-1, table11-2, fig. 11-2). The changing condition of drainagesystems on farms and possible needs for redrainagewere approximated by analyzing these changes.

A rapid developmental period for organized projectdrainage began about 1870 and ended about 1920,by which time 48 million acres had been drainedwithin organization service areas. This area wasover 97 percent of all land then drained in theUnited States (table 11-1). The true organizationshare was likely less than this, however, because1920 was the first time farmers were asked toreport how much of their land was artificiallydrained. Before 1920, the Bureau of the Census andUSDA had cooperated in collecting drainagestatistics but only from drainage districts and otherpublic organizations.

A new surge of organized project drainage followedWorld War II and continued until the early 1960's.By 1965, the area of drained land served by organi-zations had grown to 64 million acres, but hadfallen to about 70 percent of all drained land. Thiswas because independent farm systems had expandedeven more rapidly during the same period. For ex-ample, between 1945 and 1965, nearly 42 percent,or 18 million acres of the 43 million acres of newlydrained land, did not rely on organization facilities.Since 1965, new drainage has primarily involved in-dependent farm installations. The area served bydrainage organizations within projects apparentlypeaked in 1978 at about 66 million acres.

Despite these changes, about 60 percent of thefarmland drained in the United States in 1985 stillrelied on arterial drains installed by townships,counties, special drainage districts, and otherorganizations. The proportion of drained land servedby drainage organizations is 80-85 percent in leadingdrainage States like Indiana, Ohio, Minnesota,Michigan, and California. Group or organized ef-forts are required for successful drainage of largeareas, especially if irrigated.

Another factor to consider is that much of the newinvestment in farm drainage will replace existingsystems using organization facilities. Also, whilelarger and fewer farms imply more freedom for

11613 2

owners and operators to drain independently ofother farms, that implication can be misleading.Enlarged farm units may encompass land alreadydrained and requiring group outlets. Also, what isreported as a large farm operating unit for censuspurposes may not be a single block of land but anumber of separated owned and/or rented tracts.

The need for cooperation in drainage tends toincrease with the intensity of drainage developmentwithin an area. Its success is determined byclimate, soils, topography, and other field condi-tions, as well as by economics. Any significantfuture expansion of project drainage may occur inconnection with new conversions of wetland forestsand other low-lying areas to agricultural, urban, orindustrial uses (U.S. Dept. Commerce, 1981, p. vi).But significant new organized activity may also bestimulated by an increasing concern with salinityand seepage in irrigated areas and the modernizationof existing drainage systems on farms, includingthose not now using organization outlets.

Drainage Methods

Surface improvements are still the predominantform of drainage on U.S. farms or other rural land.In 1985, at least 72 million acres (66 percent) weredrained with bedding, open ditches, or other surfaceimprovements. Complete data are not available, butup to 37 million acres (35 percent of the total) werepossibly drained with underground tile or the newertypes of plastic tube drains (table 11-2, fig. 11-2).Gains in subsurface systems in relation to surfacedrainage since 1960 can be attributed to muchimproved equipment and material, lower mainte-nance costs, and minimal land loss for undergrounddrainage. Other technological advances, like laser-beam grade-control devices, have made bothmethods of drainage and other land-shaping activ-ities more cost-efficient (van Schilfgaarde, 1971;Donnan and Schwab, 1974).

Information was inadequate to permit a breakdownof surface drainage improvements by whether theyare intended to simply dispose of excess precipita-tion and runoff or, as subsurface systems are usuallydesigned, to regulate water tables as well as improvesurface drainage. Program data from USDA agenciesgoing back to 1940 combined with general trendsnoted in historical census statistics were the mainbasis for separating and analyzing surface and sub-surface systems (USDA, 1981a,b,c). For this survey,deep ditches used for water table control, as in theMississippi Delta and coastal areas where tiling isnot feasible, were regardbd as surface drains.

Condition and Redrainage Potentials Mil. ac.80

Knowledge of the age and changing condition ofdrainage systems is as important as of the totalarea drained. The changing condition of artificialsurface and subsurface drainage was determined interms of "undepreciated drainage." That termrefers to surface systems (12 million acres in 1985)installed or reinstalled during the previous 20years, the assumed average useful life for surfacedrainage improvements. Undepreciated under-ground (subsurface) drains were regarded as thoseinstalled in the previous 40 years, the assumedaverage life for subsurface drains installed since1940. These benefited about 27 million acres in1985 (table 11-2).

One should not concludthan 20 years old and suthan 40 years old are noof no value to farmers or oample, the area drained in 1systems was nearly 72 millionparts: the 12 million acres witonly partly depreciated surfacemade since 1965), plus another 6fully depreciated improvements, orbefore 1965 (table 11-2).

e that surface drainage morebsurface systems moreonger effective and thusther landowners. For ex-

985 with surfaceacres. This had two

relatively new orimprovements (those

million acres ofthose made

Likewise, the area with subsurface drains in 1985was nearly 38 million acres, of which 27 millionacres represented systems installed since 1945. Theremaining 11 million acres with subsurface drainshad been drained before 1945. From the standpointof condition, therefore, the relatively new drainagesystems on U.S. farms are weighted more than 2:1in favor of subsurface drains (27 million acresversus 12 million acres).

Potential redrainage needs and opportunities forredesign change continuously over time (fig. 11-3).As of 1985, potential redrainage included 61 millionacres drained by surface improvements installedbefore 1965, plus the 11 million acres with subsur-face drains installed before 1945. Redrainage in-troduces additional questions, of course, such ashow to improve total water management on existingwet soils now in farms, as contrasted with naturalwetlands, with joint consideration of erosion con-trol, irrigation, and drainage and their economicbenefits and costs.

1_ 3

70

60

50

40

30

20

10

/Total redrainage potentials

iii/..,//

II

........0 ....1......10°T1111111900 1920 1940 1960 1980 2000

Year

Surface drainage

..I

Subsurface drains................ _

Figure 11-3Land potentially redrained on U.S. farms, 1900-85.

Investment and Drainage Cost

Tangibly and economically, drainage investmentsinclude: (a) depreciable land improvements made tofacilitate the removal of excess water from fields,either to simplify tillage operations or increase pro-ductivity, and with surface bedding, ditches, orburied concrete pipe, clay tile, or plastic and othertube drains; (b) durable equipment needed for drain-age, such as pumps and power units; and (c) anyother durable collection and disposal works likesumps, outlet ditches, main channels, and otherfacilities, regardless of where located or by whomfinanced and operated.

In examining capital growth, investments in drain-age were confined to initial equipment purchases,construction expenses, and other immediate costs.Future investments required along with maintenanceand operating costs should be included in determin-ing economic feasibility. The economic implicationsof "investment" applied to agriculture go farbeyond individual farms and localities and can beexplained in general terms.

117

Investment from both an overall economic viewpointand the viewpoint -f a farmer draining land can beexpressed in terms of national production during agiven year or other period of time. This productionconsists of all the newly available goods and serv-ices for which participants and production factorsin the provisioning process earn some income. Thevalue of the total output is represented by the totalincome thereby earned. Subtracting from the totaloutput and income the goods and services purchasedby consumers and government leaves three importantitems: net exports, newly available but unsold con-sumer goods, and newly available business goodsnot intended for individual personal consumption. Inagriculture, the latter include farm buildings,machinery or other durable equipment assets, andland improvements like drainage systems. Theincome-yielding or other benefits inherent in theseassets are deferred. They thus constitute investment(Stonier and Hague, 1956; Fox, 1964).

New buildings, equipment, and drainage improve-ments cause the net stock of agricultural capital toincrease if they more than make up for depreciationor the wearing out or using up of existing capital.Thus, depreciation is sometimes called capital con-sumption (Fisher, 1930).

An example of a governmental drainage activitycontributing to national income is a county's orpublic drainage district's acceptance of a contrac-tor's bid to rehabilitate drainage channels servingagricultural lands. This is an agricultural invest-ment, made by the community through its government.Individual farmers who install drains similarly in-vest. In addition to prospectively increasing farmproduction, reducing costs, and otherwise benefitingfarm operations, investments by farmers immediatelycontribute to national output and national income.

Drainage cost is the dollar investment or capitalexpenditure required to install, reinstall, or repair adrainage system. It represents the economic valueof the labor, materials, machine work, or otherresources expended on drainage rather than someother use. This expenditure is part of the basis fordetermining economic feasibility and, if made,becomes a capital asset. In the net prebent value(NPV) appraisal method, drainage is justifiedeconomically if installation cost is less than the dis-counted capitalized value of all expected futurebenefits of drainage less associated operating andmaintenance expenses. The discounting allows forrisk as well as time preference considerations.Skaggs illustrated earlier this kind of benefit-cost

1

118IS 4

analysis as applied to maximizing the expected netbenefits or profits from farm drainage.

Another way to determine economic feasibility is tofind which discount rate makes the expected futurebenefits of drainage exactly equal to the installationor investment cost. This rate is called the internalrate of return (IRR). If it is higher than known inter-est rates being earned on savings, paid on borrowedmoney, or possibly earned in some other investmentopportunity for the farmer, then the investment indrainage is considered justified.

Not all investments in drainage meet the test ofeconomic feasibility, especially if expected benefitsdid or do not materialize (Goldstein, 1971). Thehistorical investments is drainage discussed hererefer to actual investment.

Costs of Organization Service

Investment cost was explained above as the value ofthe resources needed to complete surface or subsur-face drainage improvements on a given tract of landor, more exactly, for an added acre of land if thequestion is how much more land to drain. Investmentby a drainage organization was regarded in thesame manner, as the value of the resources re-quired to extend project service to a given addi-tional area and number of farms.

Gross new investment in 1985 dollars for eachperiod beginning in 1855 W1.1.3 calculated by takingaverage investment costs pt,r acre (deflated to 1985price levels using available cost indexes) times thenumber of acres newly drained in each period, Thedeflated cost per acre is the "real" cost of investingh.; drainage.

The real investment required to provide an addedacre of drained land with organized project servicedid not appear to change much after about 1915.The real service cost in 1985 was $225 per acre.Project cost refers to the added gross investment,by drainage organization, historically associatedwith a 1-acre net increase in the area reporteddrained in a given year within project serviceareas.

In the primary developmental gage of drainage,1870-1920, the real cost of providing organizationservice was considerably higher than in 1985. In1900, it was $345 per acre. Project costs declinedbecause of scale economies and because of inprove-ments in ditching machinery and a more thorough

understanding of the physics of drainage (vanSchilfgaarde, 1971).

Costs of Drainage on Farms

The average investment cost of open or other sur-face drainage was about $140 per acre in 1985.About 72.4 million acres were then improved forsurface drainage. The real cost of surface drainageimprovements appears to have fluctuated over time,ranging from $225 per acre in 1900 to the low of$125 per acre in 1950. It rose to $210 per acre by1970 but by 1985 had again declined to $140 peracre. These costs exclude timber clearing or otherland reclamation activities often associated withdrainage development.

The investment needed to install subsurface drainson U.S. farms averaged about $415 per acre in1985. About 37.3 million acres were then drainedthis way. This cost was only about half the per-acrereal cost estimated for 1965. Notable declines in thereal cost of subsurface drains have resulted fromsuch technological advances as continuous cor-rugated plastic tubing, improved manufacturingmethods and materials, improved distribution andmarketing, and advances in field installation tech-niques and construction equipment. Laser-beamgrade-control devices on trenching and otherdrainage equipment are notable examples (Donnanand Schwab, 1974; van Schilfgaarde, 1971).

Investment Trends

For both organized and independent farm drainageactivity, long-term trends in investment parallelexpansions in the area drained, but only in ageneral way, because of changes in prices anddrainage technology. Nearly 46 million acres ofnewly drained land were added to organizationservice areas during 1900-20 (table 11-1). In 1985dollars, organization investment averaged $320million per year during this primary developmentperiod.

The rate of new investment by drainage organiza-tions peaked at $460 million per year during1905-10. During 1910-30, it dropped back to around$300 million per year. It was very low during theDepression through World War H. During 1945-60,investment by drainage organizations recovered toabout $75 million per year. It continued around thislevel until 1980. It fell to about $50 million per yearduring 1981-85.

Rather large areas were newly improved with sur-face drainage up until 1920 and again between

Th "*"10

1940 and 1970 (table 11-2, fig. 11-2). Investments inactual as well as real dollars increased sharplyafter World War II because of newly stimulatedproject activity, better yet more costly drainagemethods, and higher wsts for materials.

Excepting an apparent lull during 1915-25, farmersin the United States have installed new tile, plastic,or other subsurface drains at a steady rate. Asharp increase in both surface and subsurfacedrainage followed World War II. The area improvedbecause surface drainage increased by 875,000acres per year during 1945-80, compared with425,000 acres per year improved with subsurfacedrains (table 11-2). However, investments in subsur-face drains averaged $465 million per year during1945-80, compared with $190 million per year forsurface drainage. This increase occurred despitethe much higher per acre cost of subsurface drains.One factor was that subsurface drainage hadbecome more cost-effective, both absolutely andrelatively. Absolutegains in cost effectiveness forsubsurface drains occurred because their actual in-stallation cost did not rise as rapidly as prices ingeneral. Relative gains for subsurface drains oc-curred because their real cost per acre declined inrelation to the real cost of surface drainage.

Growth of Drainage Capital

The buildup of drainage investments over timebecomes a stock of drainage capital, much like anirrigation reservoir creates a stock of water by im-pounding runoff. Thus, any drainage improvementcan be regarded as involving prior investments andsacrifices in consumption in exchange for futureproduction and other benefits.

The accumulated real investments in drainage forthe United States were measured as accumulatedannual investments indexci (deflated) year by yearto a particular base year, chosen here as the year1985. The indexing was necessary to allow forchanges in investment rates due simply to changesin the prices of materials, labor, and other inputfactors. The indexed or constant-dollar investmentsrecognize that changes have occurred in materialsand methods as well as in the area drained.

Drainage works and improvements were also valuedterms of the hypothetical cost of replacing them at aparticular time, regardless of when they were builtor made. This concept of value is not as theoreticalas it may appear. It is a common basis for insurancecoverage and an important barrier to replacing ob-solete or deteriorated improvements.

119

Bil. dol.60

50

40

30

20

10

0

Investment to date*/

Net capital value

........ Replacement-cost valuelllllllll1900 1920

*In constant 1985 dollars.

1940 1960Year

"In current dollci3 for years Indicated.

1980 2000

Figure 1 1 -4 D rainage investment and capital in U.S. agriculture,1900-85.

Net capital value was also estimated. As the sum ofall past net investment, it grows or declines withthe yearly rate of net investment. The yearly net in-vestment rate is the yearly total investment lessdepreciation allowances. Calculated net capitalvalues for drainage improvements represent ai."talmarket value only to the sxtent a drainage marketexists. In practice, farm drainage improvements areessentially fixed to the land and become an integralcomponent of land value. Organization outlets orother community 'acilities may also be capitalizedinto the value of the benefiting private lands.

How historical investment and depreciation have af-fected the status of drainage capital from 1900 to1985 is shown in figure 11-4. One curve representsall accumulated U.S. investments in drainage as of1900 up to 1985, indexed to 1985 dollars. Anothercurve represents the cost of replacing all existingdrainage improvements as of any previous year, andat the costs prevailing in that year.

The third curve shows how aggregate net capitalvalues in constant (1985) dollars have changed dur-ing 1900-85. The aggregate net capital value of alldrainage capital is the value of organizationfacilities and farm drainage improvements still inuse after deducting all accumulated depreciation onfarm improvements from all accumulated in-vestmen::,. Changing net values of organization

120

136

Bil. dol.'50

40

30

20

10

0

An drainage capital!

Onfarm drainage improvements /

Drainage organization facilities/

//oir ...T. III!

I

1900 1920 1940 1960 1980 2000Year

in current dollars for years shown.

Figure 11.5The net value of U.S. organization and Warmdrainage facilities, 1900-85.

facilities and onfarm drainage improvements for1900-85 are in figures 11-5 and 11-6. Figure 11-7 isa similar division of replacement-cost values as ofthe years indicated.

During 1981-85, gross and net investment in drain-age in the United States fell off along with othertypes of agricultural investment. The area surface-drained increased an average 202,000 acres peryear. The average yearly increase for subsurfacedrains was 475,000 '.cres. In 1985 dollars, total rowinvestment declined to about $40 million per yearfor surface systems and $200 million per year forsubsurface systems. The average yearly investmentfrom 1981-85 for all new onfarm drainage ($240million) was less than half the average for 1976-80($508 million). For drainage organizations, invest-ment between 1981-85 averaged about $50 millionper year. This was assumed to be about the sr-zne asthe rate between 1976-80 and went mostly lb.maintenance.

Status of Drainage in 1985

The general status of drainage and capital valuesfor the United States in 1985 was as follows: thenet area drained for agriculture and forestry inrural areas was 110 million acres, of which about

Bil. dol. (1985$)12

10

8

6

4

2

0

..... ./

r I/ : Subsurf ace drains

1900 1920 1940 1960Year

1980 2000

Figure 11-6Net value of drainage improvements on U.S. farms,1900-85.

65 million acres were served by drainage organiza-tions and 45 million acres were drained independ-ently. Figure 11-8 shows percentages of all land andcropland drained in the various States.

The accumulated total investments in drainage since1855 were $56 billion (1985 dollars). The combinednet value of all drainage assets in agriculture in1985 was about $25 billion, $15 billion (60 percent)for organization property and $10 billion (40 per-cent) for onfarm systems (table 11-5).

Nearly 90 percent of the net value of farm drainageimprovements was represented by subsurfacedrains. They accounted for about 34 percent of alldrained land but for 70 percent of the 38 millionacres of land having relatively new drainage im-provements. The newer systems were on 16 percentof the land with surface drainage and on 72 percentof the land having buried drains. About 11 millionacres (28 percent) of the subsurface drains mayhave needed replacement and modernization while61 million acres (84 percent) of the surfacedrainage may have needed redrainage.

Having to replace all drainage works and improve-ments in the United States in 1985 would have costabout $40.3 billion, $14.7 billion (36 percent) foro :ganization works and facilities and $25.6 billion(1 .4 percent) for farm improvements. The $40-billionc,ist of reproducing all drainage assets in 1985 was,

1 "..) "1

Bil. dol. (1985$)30

25

20

15

10

5

0

.°°.All drainage capita/

/ Drainage organization./ I, fealties..........

Onfarm drainageimprovements

1900 1920 1940 1960Year

1980 2000

Figure 11-7Replacement-cost value (current dollars) of drainagecapital in U.S. agriculture, 1900-85.

numerically, nearly equal to the net cash incomefrom farming received by all farmers.

Potential redrainage cost, the cost of replacing fullydepreciated drainage improvements was about $12.9billion in 1985, including $8.5 billion for surface and$4.1 billion for subsurface drainage. As of 1985, fullydepreciated improvements included the surfacedrainage improvements made before 1965 and sub-surface drains installed before 1945.

Federal Financial Assistance

While the Federal Government actively aided in therehabilitation of major outlet ditches and otherdrainage organization facilities during the 1930's(see Beauchamp segment), the Federal role infinancing new drainage improvements on farms hasbeen relatively minor and declining. As of 1985, lessthan 10 percent of all existing surface or subsur-face drainage improvements could be attributed toFederal financing provided under the AgriculturalConservation Program (ACP) starting in 1944. Forthe years 1944-83, the area benefiting from ACPassistance was divided 80 and 20 percent betweensurface and subsurface drainage, while financialassistance was divided 40 and 60 percent betweensurface and subsurface drains (USDA, 1981b,c).

Financial assistance under the ACP as well as tech-nical planning assistance provided by SCS was cur-

121

Table 11.5 -Rural land drainage in the United States,1985; areas drained, capital values, and potential redrainage costs

Item

Onfarmdrainage

improvements

Drainageorganization

facilities

Allfarm

drainage

Dollar-

Average 1985 costs per acre 235 225 370Surface drainage on farms 140Subsurface farm drains 415

Thousand acres

Area drained or served 109,680 65,260 109,680Surface drainage 72,400 72,400Subsurface farm drains 37,280 37,280

Area potentially redrained 71,500 71,500Surface drainage 60,950 60,950Subsurface farm dr,...ns 10,550 10,550

Millions (1985 dollars)

Total investment, 1855-1985 41,400 14,7001 56,100Surface drainage 17,800 17,800Subsurface farm drains 23,600 23,600

Net capital value, 1985 10,000 14,7001 24,700Surface drainage 900 (900)Subsurface farm drains 9,100 (9,100)

Replacement-cost value, 1985 25,600 14,700 40,300Surface drainage 10,100 (10,100)Subsurface farm drains 15,500 (15,500)

Potential redrainage costs, 1985 12,900 12,900Surface drainage 8,500 8,500Subsurface farm drains 4,400 4,400

- = either not applicable, negligible, or not estimated in this and later tables.1lnvestment and capital values for organization facilities include $7.9 billion in maintenance allowances up to 1985.

tailed as early as in 1956 if new land was beingbrought into production. By the 1960's, Congress orUSDA agencies had ruled out assistance for drainingwetlands considered vital to waterfowl and otherw!ldlife. For the 1975-77 period, U.S. farmersreported that only 4 percent of the cost of installingnew or mainta.ning existing drainage improvementswas financed through ACP cost sharing or by FmHAloans. Further, about 82 percent of all drainageexpenditures were self-financed by farmers (Lewis,1982).

In 1983, Federal cost sharing for farm drainagetotaled only $75,000, down to 0.05 percent of allcost sharing provided under the ACP. Assistancewith drainage in 1983 went to 37 participatingfarmers in 12 States. Two-thirds of the paymentswere for underground drainage systems, mostly inNew York and Ohio. The remaining one-third wasnearly all for land shaping or grading to improvesurface drainage in Mississippi, Arkansas, Colorado,and Louisiana (USDA, 1984). Drainage assistanceunder ACP is now prohibited unless it is a

122

necessary element of an erosion control, water-quality, or environmental system of practices.

Drainage Capital in Land

In 1985, the estimated market or capital value of allU.S. farm real estate was $690 billion, about $90billion for farm homes or nonresidential buildingsand structures and $600 billion for land (Jones andBarnard, 1985). As estimated above, the net capitalvalue in 1985 of all agricultural drainage works andimprovements on and off farms was nearly $25 billion.Replacement-cost values totaled over $40 billion,$15 billion for drainage organization facilities and$25 billion for onfarm drainage systems.

Depending on whether investments in drainage areexpressed in terms of their net value ($25 billion) ortheir costs of replacement ($40 billion), they rangedbetween 4 and 7 percent of the market value of U.S.farmland in 1985. This supposes that sellers of farmor other rural real estate subjectively incorporate intheir asking prices at least the net or depreciated

Northern1 Plains

15/20 0

6/10Lake States

15/30

1-Mountain

1-

20/25

lr3nCo Belt

10/25

20/65

DeltaStates(20/55

25/60

Figure 11-8About 5 percent of all land and 24 percent of cropland is drained in the 48 contiguousStates. The first numeral is the percentage of all land drained in a State. The second numeral isthe percentage of all cropland drained in 1985 in the 23 drainage States.

value and perhaps the full replacement-cost value ofdrainage and other improvements, including acces-sible drainage outlets or other facilities belonging todrainage organizations.

Drainage needs, drainage methods, and drainageinvestments vary widely across regions among theStates. Accordingly, drainage capital values relativeto total land values and related economic data areestimated separately for 23 leading drainage States(table 11-6 and 11-7). These States had about 1million or mt,re acres of drained land in 1985, or atleast 25 percent of their total area of croplanddrained. Included are areas drained with open (sur-face) ditches only, areas having subsurface drainswith required surface improvements, and areasbenefiting directly from mains and laterals. Thetotal for New York also includes about 50,000 acresof wet cropland soils benefiting from diversion ter-races or similar improvements that serve a drain-age function (Stamatel, 1936).

Information on organized, independent, and surfaceand subsurface drainage on farms for the 23 leadingdrainage States and remaining States as a group is

139

20/50

Northeast

1

2115

9/25Southeast

1 4/8

36/25

19/25

in table 11-6, along with an estimated allocation for1985 of capital values between surface and subsur-face drainage systems. Proportions of croplanddrained are also based on data from the 1982 inven-tory. For example, roughly 50 percent (6.2 millionac 's) of Ohio's cropland (12.5 million acres) wasprime (drained) cropland having wet soils. The in-ventory also indicated that an additional one-third(4 million acres) of the cropland in Ohio neededdrainage improvements (Nolte, 1986). Nationalpotentials for additional drainage are not in table11-6 but are discussed further in the followingchapter.

In table 11-7, drainage capital values are estimatedand related to the value of farmland in differentStates. Drainage net capital as a percentage of thetotal value of farmland (col. 5) appeared to behighest in Michigan (20 percent), followed by Indiana,Ohio, Illinois, Louisiana, Iowa, Delaware, Minnesota,and Mississippi. The drainage improvements werefirst valued on a net basis and then a replacementbasis and compared with farmland values. On areplacement-cost basis, the relative percentages intable 11-7 are greater, but the State rankings arenot materially changed.

123

Table 114Rural land drained in the United States in 1985: Percentages of wet soils and cropland drained andpercentages by type of service and drainage methods

States'Totalland

drained

Cropland drainageOrganizeddrainageservice`

Subsurfacedrains5

Subsurfaceshare ofonfarmvalue

Shareof all

drainage2

Shareof all

cropland3

1,000 acres Percent

Illinois 9,795 90 35 50 85 95-99Indiana 8,085 85 50 80 70 85.95Iowa 7,790 90 25 60 85 95.99Ohio 7,400 80 50 85 65 80-95Arkansas 7,085 75 65 45 1 1-1

Louisiana 7,015 55 60 70 1 1

Minnesota 6,370 75 20 80 20 40-80Florida 6,290 45 45 60 5 20.60Mississippi 5,805 60 55 55 1 1-1Texas 5,760 55 10 65 10 25

Michigan 5,515 70 30 85 60 80.95North Carolina 5,400 45 25 25 15 35-75Missouri 4,240 70 25 65 10 10-25California 3,015 90 20 85 80 90.98North Dakota 2,365 95 6 65 10 15-30

Wisconsin 2,245 45 10 65 30 55-90South Carolina 1,755 60 25 20 10 15.50Georgia 1,545 35 8 20 15 40-80Maryland 1,210 75 30 35 20 40-80Tennessee 1,150 55 15 25 25 30-70Nebraska 1,005 80 7 45 10 10-40New York 915 90 15 10 5i, 75-95Delaware 460 70 25 55 10 20.60

Leading States 102,215 70 25 60 35 60.90

Other States 7,465 30 1 40 20 40-80

United States 109,680 70 20 60 34 60-90

'Leading States are listed separately, in decreasing order of the total land drained as estimated trom both the 1978 Census ofDrainage and the 1982 National Resources Inventory (NRI) and then adjusted proportionately to the national total for 1985 in tables11-1 and 11-5.-

2Cropland drained generally considers the greater of (a) cropland wet soils considered prime cropland or (b) wet soils in crop usenot considered to need drainage, as based on State totals in the 1982 NRI. This estimate for drained cropland in a State is thentaken as a percentage of all drained land in col. 1.

3Cropland drained in relation to all cropland in the 1982 NRI; cropland areas for 1982 closely approximate those also reported for1982 in Frey and Hexem (1985).

`Approximate percentage of the area drained on farms using drainage organization outlets or other disposal facilities; also seenote 2, table 11-1.

5Estimated as the maximum percentage of drained land having subsurface drains, based on 1982 NRI data for different landuses and wet soils drained. Pasture, forest, and mi.: cellaneous rural land are assumed to be essentially all drained with open (sur-face) systems; subsurface drainage systems are assumed to be limited largely to cropland, although surface systems are alsoused on cropland.

6The lower percentage is based on 1985 replacementcost values of subsurface in relation to all onfarm drainage improvements.The higher percentage is based on the net depreciated value of subsurface in relation to all onfarm drainage improvements in1985.

124

Table 11.7 -Land drained and drainage in the United States in 1985, with net and replacement values in relation toland values

Value of drainage capital Drainagecapital

Total Net Replacement Replacement in relationStates land value' value2 value to land

drained per acre2 value3

1,000 acres ---------- Million dollars -- ------- --- Dollars Percent

Illinois 9,795 3,155 4,775 485 10-15Indiana 8,085 2,825 4,095 505 15-25Iowa 7,790 2,655 3,940 505 8-12Ohio 7,400 2,420 3,540 480 15-25Arkansas 7,085 815 1,730 245 5-15

Louisiana 7,015 1,230 2,130 305 10.20Minnesota 6,370 1,490 2,350 370 7-10Florida 6,290 985 1,795 280 5-10Mississippi 5,805 805 1,550 265 8-15Texas 5,760 1,080 1,850 315 1-2

Michigan 5,515 1,880 2,725 495 20-30North Carolina 5,400 550 1,270 235 5-10Missouri 4,240 730 1,280 300 4-7California 3,015 1,120 1,605 530 2-3North Dakota 2,365 430 735 300 3.5

Wisconsin 2,245 500 815 365 4-7South Carolina 1,755 150 380 205 3-8Georgia 1,545 145 350 225 1-3Maryland 1,210 160 315 245 3-7Tennessee 1,150 150 305 265 1-3Nebraska 1,005 130 255 255 1-1New York 915 185 330 300 2-5Delaware 460 70 130 285 7-14

Leading States 102,215 23,660 38,250 375 5.9

Other States 7,465 1,040 2,050 275 1-1

United States 109,680 24,700 40,300 370 4-7

'Includes value of drainage works and facilities provided by drainage districts, county drains, and other organizations, and thenet depreciated value of all onfarm drainage improvements.

2AlI onfarm and organization drainage facilities and improvements are included in calculating replacement cost values andaverage replacement cost values per acre.

3Farmland values net of buildings are in Jones and Barnard (1985). The lower percentages are the net depreciated value of alldrainage facilities and improvements for the State(s) relative to total farmland value. The higher percentages value drainage capitalin terms of its replacement cost.

141 125

These indicators of the importance in 1985 of drain-age in the farm capital structure of individualStates are not claimed to be highly precise, norshould they be taken as measures of drainagebenefits as such. They do tend to be higher in Statesmore dependent on public drains and where onfarmsubsurface drains predominate, especially if theimprovements are valued on a net or depreciatedbasis.

The dependence on drainage organizations as wellas drainage methods used on farms differ by region,and also by States within regions. In terms of area,surface drainage was more common than subsurfacedrainage in 1985 in all leading drainage Statesother than Illinois, Indiana, Iowa, Ohio, andMichigan (table 11-6). However, because of theirlong life and greater installation cost, subsurface

rains accounted for most of the capital value of on-farm drainage, nationally and for most States.Notable exceptions are Arkansas, Louisiana, andMississippi. In these States, open and other forms ofsurface drainage were still the norm in 1985, interms of net and replacement values as well as area(table 11-6, col. 6).

Differences in Cost

Variations in capital values based on replacementcosts have some practical uses for anticipating theprobable cost (marginal cost) of addition& drainagein individual States. Costs can be expected to behigher if subsurface drains are involved and/orwhere organization outlets are necessary thanwhere surface drainage not using public outlets iscommon (table 11-7, col. 4). The average costs peracre given for various States would approach actualfield costs to the extent the probabilities of the addi-tional drainage being surface or subsurface orrequiring group outlets correspond to existing pat-terns of systems and drainage methods, such asthose indicated in table 11-6. But however figured,State averages are not substitutes for carefullydetermining marginal drainage costs in specificcases.

Drainage in the Humid East

Research by Irwin (1979), Skaggs and Nassehzadeh-Tabrizi (1983), van't Woudt and Hagan (1975),Smedema and Rycroft (1984), and numerous otherinvestigators indicates that correcting poordrainage condition improves the yield of nearly allfield and fruit crops. Broadly speaking, the ex-pected longrun benefits vary with expected farmprices, production costs, climate, soils, and

126

142

hydrology. Within a field to be drained, the benefitsor installation costs also depend on such design fac-tors as the depth and spacing of the drains andactual rainfall conditions.

Dideriksen and others (1978) have reported that 25percent of the value of all U.S crops sold comesfrom artificially drained land. At a regional level,some shares they gave for drained land were 75percent for cotton and soybeans from the DeltaStates, 40 percent for corn and soybeans from theCorn Belt, and 40 percent for oats, barley, and hayproduced in the Lake States. As these shares areequal to the shares of cropland drained, theypresume equal average productivity for drained andother cropland.

An important related question examined here waswhether localities in the generally humid EasternUnited States with fairly large fractions of theircropland drained tend to be more productive andexhibit higher real estate values than surroundingareas with smaller proportions of their land drained.Such economic differences cannot be credited en-tirely to differences in drainage intensity. Thedifferences favoring drainage are believed to be onthe conservative side, however, because the com-parisons are between different levels of drainageintensity, not between drained land and undrainedland with drainage problems. Such ideal comparisonson a broad scale were not feasible for this review.

To recognize various soil and climatic conditionsand numerous combinations of farming enterprises,the Lnalysis covered all 2,006 reporting counties inthe 31 Eastern States, for which necessary censusinformation was available on drained land, farmproduction, and land values.

The Census of Drainage for 1978 was used first toidentify those counties in the humid East with highconcentrations (percentages) of drained land (U.S.Dept. Commerce, 1981). The criterion for "highdrainage" varied rather arbitrarily from Stag; toState (fig. 11-9). It ranged from at least 5 percent ofa county's land area drained in New England andupper Northeast States like New York and Penn-sylvania to 40 percent of the land drained in heavilydrained States like Indiana, Ohio, Illinois, Louisiana,and Florida. On this procedure, 307 eastern countieswere identified as being highly drained. (See figure11-9.) A few counties were included where thepercentage of land drained was low but where theland drained in a State was most concentrated.

For 1978, an average of 44 percent of the land wasdrained in the 307 counties highly drained. Some in

Figure 11-9More than 300 eastern and Great Plains counties have relatively high concentrationsofland drained. Numerals show the minimum percentage of land drained in the counties designated by dots.

the Corn Belt and Delta regions were virtually100-percent drained. Collectively, the 307 countieshad 57 percent of all drained land in the 31 EasternStates, which in turn had 82 percent of all landdrained in the United States. The balance was mostlyin Texas (5 percent), California (3 percent), andNorth Dakota (2 percent).

The 1982 Census of Agriculture was then used toexamine land use, marketing receipts, and realestate values for the 307 highly drained countiescompared with the 1,699 other eastern counties,some of which also have substantial areas drained(U.S. Dept. Commerce, 1984). However, comparisonsof real estate values per acre between the highlydrained and other counties were restricted to 256predominantly agricultural counties to minimize thebiasing influence of nonagricultural factors on farmreal estate values near urban centers.

Crop and Livestock Enterprises

The 307 highly drained eastern counties included 15percent of the total land area in all the EasternStates. However, they contained 22 percent of theland in farms and 29 percent of the croplandharvested. In 1982, they accounted for 32 percent ofthe value of all crops sold on eastern farms, and for19 percent of the livestock or livestock productssold. Crop sales per acre of crops harvested for the307 highly drained counties averaged 67 percenthigher than for the other counties. An average of 44percent of the farmland was drained in highlydrained counties compared with 6 percent in theless-drained counties.

Crop and livestock production indexes for highlydrained counties in relation to other counties fordifferent Eastern States and regions were computed

127

Table 114Production and land values in highly drained counties in relation to other counties, in the EasternUnited States, 1982

Regions and States(total reporting

counties)'

Highlydrained

counties2

Production indexes Land value indexes4

Cropsales

Livestocksales

In relation toless highly drained

In relation toState average

Northeast (244)Maine (16)Vermont (14)New York (63)New Jersey (21)Pennsylvania (67)Delaware (3)Maryland (23)

Appalachian (469)Virginia (99)North Carolina (100)Kentucky (120)Tennessee (95)

Southeast (337)South Carolina (46)Georgia (159)Florida (65)

Delta (220)Mississippi (S2)Arkansas (75)Louisiana (63)

Lake (240)Michigan (83)Wisconsin (71)Minnesota (86)

Corn Belt (496)Ohio (88)Indiana (92)Illinois (102)Iowa (99)Missouri (115)

31 Eastern States(2,006 counties)

Number

34/284/24/47/74/04/42/29/9

47/438/6

17/1711/1911/11

32/238/68/7

16/10

49/4313/1318/1718/13

48/3616/1221/1311/11

97/3619/1523/2126/2014/1315/14

307/256

1466492

2111384183

159

175237151

195

202254115372

288316420166

132116168139

160150113130178323

167

Percent?

12355135767149

4,590198

7911143

64

58547472

2181

618

10785

12648

819293733855

78

Percent'

128129

88124

90

103

119127106128103

138126101114

12512313a104

117141140102

132127117126127146

127

12012497

132

91100106

115124105124103

131120101107

114116119102

113121126102

123118111117122136

120

= not available.'Regional totals include data for unlisted States and those with no highly drained counties.2The number before the slash is the total number of highly drained counties in the region or State as of 1978. The number

after the slash is the number of highly drained predominantly farm counties; it excludes highly drained counties classed asnonagricultural, urban, or agricultural-urban by the Bureau of the Census.

3Crop and livestock product sales per acre of land in farms computed from the 1982 Census of Agriculture. Indexes are peracre sales for the highly drained counties in relation to per acre sales for the less-drained counties in the State and region.

kand values per acre for highly drained farm counties in relation to average values for farm counties not highly drained andthen in relation to the average for all farm counties in the State and region.

128 144

(table 11-8). The production indexes indicate theextent to which gross farm income was derivedfrom crops and livestock products in the highlydrained counties compared with other counties.Average crop and livestock product sales per acrewere weighted by total sales volume as well as totalareas in farms.

In Arkansas, for example, crop sales for 1982 in 18highly drained counties averaged $168 per acre ofland in farms. The average for the 57 other countiesin Arkansas was $40 per acre, giving a ratio of 4.2($168/$40) or a 420-percentage index favoring drain-age. Sales of livestock and poultry products averaged$10 per acre in the highly drained counties com-pared with $162 per acre in the other counties, giv-ing an index of 6 percent ($103162). Crop productionin Arkansas is clearly concentrated in the countiesmost heavily drained, namely those toward theMississippi River. Other counties are geared moreto livestock and poultry production.

In 12 other Eastern States, crop sales per acre inhighly drained counties ranged from 105-370 per-cent of crop sales for the less-drained counties.These States were Florida, Missouri, Mississippi,South Carolina, Virginia, New York, Tennessee,Iowa, Wisconsin, Louisiana, Maryland, and Ohio(table 11-8).

Crop production in 1982 appeared to be less impor-tant in counties with more drained land than inother areas of Maine, Vermont, Pennsylvania, andDelaware. These States are important for dairy,poultry, and other livestock as well as crop produc-tion. The extreme livestock product index (4590) forthe two highly drained counties in Delaware (Kentand Sussex) can be attributed to their concentratedpoultry industry, which depends in part on locallygrown feed crops produced on drained land.

States where both crop and livestock productiontended to be concentrated in counties that have ex-tensive areas drained were Maryland, Virginia, andWisconsin. For these States, the crop sales andlivestock sales indexes in table 11-8 both exceeded100 percent.

Total Farm Production

Combined crop and livestock product salts per farmacre are a measure of average resource productivityamong different farms and producing areas. Compar-isons between highly drained and other counties inthe Eastern States suggest that total sales per acre

I

were greater for counties with larger amounts ofdrained land. Drainage appeared to be most cor-related with total farm output in 12 States:Delaware (index = 235), Maine (212), Mississippi(189), Maryland (184), South Carolina (161), Virginia(157), Missouri (146), Wisconsin (142), Vermont(132), and Ohio, Iowa, and Tennessee (122). Theseindexes express average total farm product salesper acre for the highly drained counties as apercentage of the average for counties with lessland drained.

A precaution on these indexes is that they do notfully allow for the fact that, in many localities,agriculture would not be possible without drainage.Wet soils are more productive when drained. Theymay be either more productive or less productivethan other soils with good natural drainage. Thisfactor partly explains the fairly low indexes forleading drainage States like Louisiana, NorthCarolina, Arkansas, Michigan, and Indiana. Theanalysis was conducted across regions and Statento compensate for limiting the comparisons to asingle crop year like 1982.

Land Value Influences

Real estate values are a measure of the capitalizednet economic returns expected from land as a factorof production, along with related buildings or otherstructures. Real estate values in 1982 for 256 highlydrained and predominantly agricultural counties inthe East averaged 27 percent more (index 127) thanvalues for the 1,422 other agricultural counties(table 11-8).

Real estate values per acre in the 14 most intensivelydrained farm counties in Missouri ran an averageof 46 percent higher than in Missouri's other 93agricultural counties. Additional States withrelatively high land value indexes for the countiesmost drained included Michigan (141), Wisconsin(140), Arkansas (138), Maine (129), New York (124),Kentucky (128), Virginia, Ohio, and Iowa (all 127),and Illinois and South Carolina (126). These indexesexpress average real estate values per farm acrefor the highly drained and predominantly agricul-tural counties as a percentage of the average foragricultural counties with less land drained. Allaverages were weighted according to total areas infarms and total farm real estate values for the twogroups of counties in each State.

Drainage appears to strongly influence farm realestate values in the Southeast. Values per acre in1982 in the 23 highly drained agricultural counties

129

in South Carolina, Georgia, and Florida ran 38 per-cent more than in their 252 other farm counties, 53of which are in Alabama. Alabama and some otherEastern States are not listed in table 11-8 becausethey have no counties with at least 5 percent of theland area drained for agriculture.

Drainage appeared to positively influence landvalues in all eastern regions and States listed intable 11-8, except Vermont and Pennsylvania. Farmreal estate values between highly drained and othercounties were not compared in New Jersey, becauseits four highly drained counties also happen to behighly urbanized.

Average real estate values per farm acre for thehighly drained farm counties as a percentage ofaverages for all farm counties in a State were alsocomputed (table 11-8). Because average land valuesfor States are published at fairly frequent intervals,these indexes would be useful for estimating landvalue differentials in dollars for highly drainedcounties under market conditions where their landvalues per acre tended to change proportionatelywith those for other counties

Separate iialues for land and buildings would im-prove these comparisons but were not available forcounties. This was possible earlier in relatingdraft:age invesonent to farmland values for leadingdrainage State:; (table 11-7). Irwin (1979) computednet land values in determining whether Ontariofarmers wishing to increase production shouldacquire additional land or should tile-drain existingwet soils. While the net ek.,;41e-nic benefits of theexpansion or drainage alternatives were notcalculated, Irwin found that tile drainage was only10-60 percent as costly as puzhasing additionalland in Ontario in 1979, depending on the county.

Changing Feasibility of Drainae,-

Commodity prices, production costs, drainage costs,and land values change both absolutely and in rela-tion to each other from year to year. The same istrue of associated environmental benefits ordisbenefits. Thus, the economic feasibility ofdrainage must be determined on a case-by-casebasis at a particular time by farmers and otherdecisionmakers, with respect to the benefits anddisbenefits or other costs of concern to them.

Data on production and land value differences forhighly drained counties or other areas are usefulfor explaining different rates of drainage develop-ment among regions. Those data also help identify

130 146

areas where economic pressures for added drainagemay be the greatest. For example, the ratio in 1985of added onfarm benefits to drainage per dollar offield installation cost (B/C ratio) averaged about0.90 for the 307 highly drained counties studied in25 Eastern States. In 1982 thA average B/C ratio forthe East was near 1.30; in 1978 it was 1.40.

These ratios take as added costs per acre averageU.S. surface and subsurlace drainage installationcosts in table 11-5 adjusted to the average Statereplacement costs in table 11-7. Added benefits areapproximated as average land value differentialsfrom the 1982 census (table 11-8) adjusted accord-ing to changes in yearly land values reported byERS (Jones and Barnard, 1985; USDA, 1986). Thedrop in the overall eastern B/C ratio from 1.30 in1982 to 0.90 in 1985, and to 0.75 in 1986 was mainlyattributable to falling land values.

Drainage costs increased by 10 percent from1982-86 while benefits fell by about 35 percent.Farm real estate values in the East had risen froman average of $935 per acre in 1978 to $1,360 peracre in 1982. By 1985, they had fallen by 25 percentand by 1986 by 35 percent (to $920 per acre) from1982 levels.

In 1985, there were nine Eastern States where thefarm-level B/C ratio for added drainage was at least1.0, including Arkansas (ratio = 1.90), Missouri(1.75), Kentucky (1.65), Virginia (1.37), Mississippi(1.32), South Carolina (1.30), Wisconsin (1.14),Michigan (1.07), and Florida (1.05). Note thepredominance of the Mississippi Valley and Sou'hernStates in this listing. In 1986 the B/C ratio was 1.0or more in only seven of these States: Missouri(1.60), Kentucky (1.60), Arkansas (1.55), Virginia(1.45b South Carolina (1.25), Mississippi (1.20), andFlorida (1.0).

Between 1982 and 1986, the "al ge" INC ratio fordrainage in Missouri fell from 2.85 to 1.60. It tellfrom 1.35 to 0.78 in Ohio, from 1.35 to 0.57 in Iowa,for 1.30 to 0.70 in Illinois, and from near 1.0 to 0.50in Indiana. Between 1982-86, the average B/C ratiofor the Corn Belt region dropped from 1.35 to 0.70,while in the Lake States it fell from 1.20 to 0.75.

Drainage and National Policy

Comparing production and land values for highlydrained and other counties in the Eastern Stateswas not an argument for converting remaining wet-lands to agricultural uses through drainage andassociated clearing or other land reclamation ac-

tivities. If economically feasible, drainage is still arecommended practice on wet soils, as contrastedwith wetlands. As already noted, the preservationof wetlands with their wildlife and other environ-mental values has been national policy in USDA andother Federal agencies since the 1950's.

The Food Security Act of 1985 denied price supportand other farm program benefits to producers whouse converted wetlands for producing annual crops.The possible effects of such legislation on conver-sion decisions by farmers and others were recentlyexamined by USDA in another report (Heimlich andLangner, 198F An earlier study by Goldstein (1971)dealt with siv alar questions.

Heimlich and Langner analyzed after-tax net incomein representative situations, considering conversioncosts, benefits with and without price supports,capital gains, and tax liability. They found, forexample, that withholding price supports maydiscourage decisions of farmers to drain wetlandsin some situations, but not if capital gains and othertax advantages are a primary motive for conversionby farmers or other owners of wetlands.

The Food Security Act of 1985 also required USDAto develop plans and give technical assistance toproperty owners, agencies of State and localgovernments, and interstate river basin commissionsfor the protection of both the quality and quantity ofsubsurface waters and also for the control of salinityin agriculture. The buildup of salts in poorly drainedirrigated soils, saline or contaminated drain watersleaving irrigated areas but used again elsewherefor irrigation or wildlife, and rising water tablesfrom irrigation demonstrate that irrigation anddrainage are interrelated aspects of water manage-ment in agriculture, especially in arid regions.

Drainage and Irrigation

Water management systems that can be used fordrainage as well as subirrigation as needed werestressed earlier as an important technologicaldevelopment, especially for organic types of soilscommon in the Southeast and Mississippi Deltaregions.

In addition to containing 57 percent of the drainedland in the East in 1982, the 307 highly drainedcounties discussed above also contained more thanhalf (3.9 million acres, 52 p:rcent) of the 7.6 millionacres irrigated in the East. Arkansas, Florida, Loui-siana, Missouri, Mississippi, Georgia, and New

Jersey have large areas drained and large areasirrigated (compare figs. 11-1 and 11-10). In 1978, theland reported drained plus that reported irrigatedP ,sily exceeded all the reported land in farms in 37of the 92 highly drained counties in these States.Data from the 1982 inventory indicate 'sat 85 percentof the cropland irrigated in Louisiana appears to beland that is also drained (fig. 11-10). Mississippi,Missouri, and Florida follow with 80 percent, 70percent, and 60 percent, respectively.

The Great Plains States present a contrasting situa-tion. Of the 649 counties in the six central PlainsStates, 37 are highly drained and comparativelyhumid (fig. 11-9). Note that 14 are in the gulf coastarea in Texas, where average annual rainfall variesbetween 25-50 inches. Average rainfall is at least20 inches for all of the 28 other highly drainedcounties in the Great Plains.

In 1982, crop sales per acre in farms for the 37highly drained counties in the Great Plains Statesaveraged 3.5 times the average for the 612 othercounties. Farm real estate values per acre tended tobe about 90 percent higher in Plains counties withsubstantial areas of drained land compared withother counties. Livestock product sales per acre forthe highly drained counties were only 55 percent asmuch as in the other counties. However, these com-parisons involve humid versus semi-arid climatesmore than different intensities of drainage underuniform climatic conditions.

Drainage and the Irrigated West

The Great Plains States are a transitional region inother respects. In 1985, they had almost 12 millionacres of drained land. This was over 10 percent ofthe national total of 110 million acres. California,North Dakota, Nebraska, and Texas were among the22 States leading in drainage (table 11-6, fig. 11-8).Drainage is mo ty on an organized basis in theseand other Wesvarn States, especially where it isnecessary to prevent or correct soil salinity andrising water tables in irrigated areas. Luthin andReeve (1957) indicate that the chief causes of salinityand drainage problems in irrigated soils and for af-fected local and other areas are unfavorable soilconditions restricting percolation, excess waterapplication, and seepage from irrigation canals,ditches, and rivers. They cite studies of the Bureauof Reclamation which indicated that 25 percent ofthe water entering unlined canals was lost beforereaching farmers' fields.

147 131

In 1978, about 400 of the 7,360 irrigation organiza-tions in the 17 Western States and Louisiana main-tained 17,500 miles of irrigation drains. Californialed with 4,400 miles, followed by Texas (2,500 mi.),Washington (2,100 mi.), Idaho (1,400 mi.), Montana(1,350 mi.), Wyoming (1,300 mi.), and Oregon (1,000ml) (U.S. Dept. Commerce, 1982). About 60 percentof the drains benefited irrigated lands within pro-jects originally constructed by the Bureau ofReclamation but paid for and now operated bywater users organized as districts.

Lining irrigation supply canals and ditches can alsocorrect or prevent seepage-related drainage prob-lems, in addition to conserving water and reducingmaintenance costs. Water savings result fromreductions in canal seepage and transpiration fromundesirable vegetation in or adjacent to ditches andcanals. In 1978, there were nearly 15,000 miles oflined irrigation canals in the West. This was an in-crease of nearly 25 percent since 1969 (U.S. Dept.Commerce, 1973, 1982). While 75 percent of thenewly lined canals were in California, lining activityincreased sharply in Oregon, New Mexico, Nevada,Nebraska, Idaho, and Colorado.

The drainage investment and capital estimatesgiven earlier (table 11-7) could be divided onlyroughly between drainage associated or notassociated with irrigation, based primarily onleading drainage States that also have large areasirrigated. These include California, Nebraska,Texas, Arkansas, Florida, and Louisiana. In 1985,these six States accounted for about 22 percent ofall U.S. land drained, and for at least $5.4 billion(22 percent) of the net national investment indrainage (table 11-7). They accounted for 70 percentof the cropland irrigated, and for nearly 85 percentof the 19.3 million acres of irrigated croplanddrained (1982 data).

The estimated capital value in 1985 of drains onirrigated farms and those drains managed by irriga-tion organizations in these six States was at least$2.5 billion; this was around 45 percent ref their in-vestment in drainage. The percentage for Californiawas over 90 percent. The U.S. investment in irriga-tion drainage was at least $2.9 billion. Thisrepresented an estimated 10 percent of all drainagecapital and an estimated 6 percent of all irrigationcapital. These tentative estirr 2tes consider the pro-portion of drainage capital specific to irrigation in aState to be at least equal to the proportion of alldrained land in irrigated crops in the 1982 inven-tory. (Also see tables 11-6, 11-7, and U.S. Dept. Com-merce, 1973.)

132

The percentages of irrigated cropland drained inthe leading irrigation and drainage States are infigure 11-10. The average was nearly 25 percent forthe 17 Western States and Hawaii. Percentages forthe Eastern States refer only to the proportion of allirrigated cropland having wet soils that have beendrained.

Drainage, water conservation, and related manage-ment needs on irrigated lands are not confined tothe States with established irrigation economies. Inthe 1982 inventory, drainage treatment or otherstrategies for better water nianagement were con-sidered primary treatment needs on 19.5 millionacres of irrigated land in the United States. Thiswas between 32-44 percent of all cropland irrigatedon U.S. farms in 1982 (table 11-9). About 16.3million acres (84 percent) of the irrigated landneeding treatment were in the 21 principal irriga-tion States.

The inventoried additional drainage and otherwater management needs on irrigated cropland aremost reliable for three particular States: California(4.3 million acres), Texas (2.5 million acres), andNebraska (1.8 million acres). Percentages of the ir-rigated cropland involved were 55 percent forCalifornia, 47 percent for Texas, and 30 percent forNebraska.

Estimates for the Great Plains, Mountain, andPacific regions each meet a similar reliability test;that is, the irrigated land requiring better watermanagement, including drainage, equaled or ex-ceeded 0.1 percent (1.5 million acres) of the nearly1.5 billion acres of U.S. rural land covered by the1982 inventory. Details for the U.S. productionregions are in table 11-9.

Irrigation in Farm Production

Maintaining the productivity advantages of irriga-tion through proper soil drainage, minimizing theneeds for scarce and costly water supplies, andcontrolling the off-site discharge of chemicals andother harmful agents in drainage effluent fromirrigated lands are important economic and environ-mental goals, within as well as outside ofagriculture.

Tradeoffs between these goals are inevitablebecause in many areas of the West irrigation isindispensable for sustained agricultural production.It is also an important contributor to the overallproductivity of U.S. agriculture. To illustrate thesepoints, information on land use and the value of

Table 114Drainage and other water management needs on irrigated cropland in the United States, by regions andselected State groupings, 1982

Regions Irrigatedcropland%

Drainagetreatment

needs2

Irrigationwater

management2

Total water managementneeds on irrigated landArea Range

1,000 acres Percent?

Northeast 275 1 34 35 11-12Appalachian 164 5 40 45 11-27Southeast 2,086 240 690 930 30.45Delta 5,695 1,170 535 1,705 30.33Lake States 845 15 110 125 11-15

Corn Belt 828 175 225 40C 32-48Northern Plains 9,182 40 3,165 3,205 29-35Southern Plains 5,695 150 2,445 2,595 25.46Mountain 11,660 100 5,060 5,160 35-44Pacific 10,885 580 4,755 5,335 43-49

21 irrigation States.% 41,190 870 15,435 16,305 29.40

Other States cl) 3,243 1,605 1,625 3,230 62.100

United States5 44,433 2,475 17,060 19,535 32-44

Ilrrigated cropland from the 1982 Census of Agriculture.2Reglonal estimates of drainage and other water management needs on irrigated land developed from data in the 1982National

Resources Inventory.3Except for the Delta region, the lower figures are total water management needs as percentages of irrigated cropland as

reported In the 1982 inventory. The higher figures are total water management needs as percentages of irrigated cropland asreported in the 1982 Census of Agriculture, or col. 41co1. 1. The opposite applies to the Delta region.

,The 21 irrigation States include the 17 western mainland States, Hawaii, Arkansas, Florida, and Louisiana.5lncludes Hawaii but not Alaska. The 1982 Inventory did not include Alaska.

agricultural products sold in 1982 has beenassembled for the United States as a whole, for 29States where irrigation is relatively less extensive,for the 21 principal irrigation States, and finally for71 leading producing counties in these States (table11 -10). The 71 counties were among the 100 leadingU.S. counties in the total dollar volume of farmproducts sold in 1978, but all land use and produc-tion data in table 11-10 are for the 1982 crop year.County rankings and county-level maps on total ir-rigated crops are available in special censusreports (U.S. Dept. Commerce, 1985a,b).

In 1982, the 71 leading producing U.S. counties inthe principal irrigation States accounted for nearlya third of the irrigated crops harvested in theUnited States. Recall that they were not chosen asleading in the area of irrigated land, yields poracre, or farm product sales per acre. Nevertheless,73 percent of the cropland harvested in these coun-ties was irrigated. In 1982, their crop sales aver-aged $625 per acre of crops harvested. This com-pared with averages of $135 per acre for othercounties in the principal irrigation States, and $185per acre for the 29 Eastern States where irrigationis less extensive. Livestock and livestock productsales per acre of cropland harvested were also

149

generally higher in irrigated areas, as were realestate values.

Livestock product sales per acre of croplandharvested are, of course, biased upward if croplandis limited or the livestock depend primarily on graz-ing or purchased food. Offsetting this, however, isthe fact that tame hays and other harvested feedsare important irrigated crops on many livestockranches. Wyoming and Nevada are prime examples.In 1982, even the highly irrigated farms (thosewhere all crops were irrigated) in Wyoming obtained72 percent of their gross income from livestockrather than crop sales. In 1982, farms and rancheswith at least some irrigated land accounted for 75percent of all livestock-related sales in Wyomingand for 60 percent of all livestock sales in Nevada.

Farms or ranches in the principal irrigated andother States as two broad groups appear to be com-parable in productivity as measured by crop salesper acre of crops harvested. The mix of livestockand crop enterprises in terms of dollar sales peracre of crops harvested is also about the sameunder irrigated and nonirrigated conditions,although, as observed above for Wyoming andNevada, areas can differ widely in this regard.

133

Table 11-10-Comparative land uses, market values of products sold, and product sales per acre for leading irrigationand other States, United States, 1982

ItemUnitedStates

21 irrigation States29

selected All 21States' States2

71 leadingcotint!ls3

Selected land uses:

Million acres

Land in farms 986.8 298.3 688.5 57.2Harvested cropland 326.3 166.1 160.2 19.4Irrigated land in farms 49.4 3.4 46.0 16.1Irrigated crops harvested 44.4 3.3 41.1 14.3Irrigated pasture and other land 4.6 4.6 1.8Drained land in farms 107.2 78.8 28.4 4.7Irrigated cropland drained 193 2.7 16.64 3.85

liars

Market value of products:Total farm products z)old 131.9 67.2 64.7 22.9Crop sales 62.3 31.1 31.2 12.2Livestock/livestock product sales 69.6 36.1 33.5 10.7

Percent

Irrigation and drainage percentages:Percentage of land irrigated on farms 5.0 1.1 6.6 28.1Percentage of harvested cropland irrigated 13.6 2.0 25.7 73.7Percentage ratio, drained to irrigated

cropland43.4 83.1 40.4 26.4

Dollars

Values and product sales per ace in farms:Value per acre of farm real estate5 825 1,340 595 1,468Total products sold per farm acre 135 225 95 400Crops sold per farm acre 65 105 45 215Livestock products sold per farm acre 70 120 50 185

Dollars

Product sales per acre of crops harvested:Total products sold per acre 405 405 4057 1,1805Crop sales per acre 190 185 195 625Livestock product sales per acre 215 220 210 555

- = not available.'Includes 29 States with relatively less irrigated land, such as Alaska and Eastern States other than Arkansas, Florida, and

Louisiana.2Leading 21 irrigation States Include the 17 western conterminous States, Hawaii, Arkansas, Florida, and Louisiana.3Leading counties are those 71 counties within the 21 irrigation States ranking among the 100 leading counties In the UP"

States in 1978 in the total value of farm products sold; however, all census o: other statistics are for 1982 (U.S. Dept. Commerce,1985). Eight of the 71 counties are In Arkansas, Florida, or Louisiana; the other 63 are in the 17 Western States or Hawaii. Data for"nonleading" counties in the 21 Irrigation States can be obtained by subtracting col. 4 from col. 3 in the first two sections andthen taking similar averages.

49.1 million acres for the 17 western irrigated States and Hawaii, or 25 percent of the irrigated .cropland.53.2 million acres for the 63 leading counties in the 17 western irrigated States and Hawaii, or 23 percent of the irrigated

cropland.°Real estate values per acre are weighted averages developed from total land values and total land in farms available by States

(Jones and Barnard, 1985).?Averages if limited to the 18 western irrigated States are about the same as these.°Respective peracre averages if limited to 63 leading counties in the 18 Western States are $1,145 .or total sales, $590 for crop

sales, and $555 for livestock sales.

134

1'3

Concluding Note

This descriptive overview of drainage development,capital growth, and related economic questions doesnot assume that the factors historically or recentlyaffecting drainage activities will hold in the future.However, the information is useful for severalpurposes:

Explaining major changes in technicalmethods and relating these to the responses offarmers and drainage organizations,

Estimating the costs and investmentrequirements associated with the redesign ofexisting drain systems,

Discussing the social costs and the role ofdrainage in agricultural production, as animportant element of land water resourcemanagement on farm as well as balancedenvironmental planning,

Assessing remaining potentials for drainageconsistent with public policy, and

Improving the quality of statistical informationabout drainage, including the quality of ad-ministrative arrangements for collecting it.

References

Doman, W. W., and G. 0. Schwab. 1974. "CurrentDrainage Methods in the USA," Drainage forAgriculture. Monograph No. 17 (ed., Jan vanSchilfgaarde). Am. Soc. Agron., Madison, Wisc.

Dideriksen, Raymond I., A. R. Hidlebaugh, and Keith0. Schmude. 1978. "Wet Soils for Crop Productionin the United States," Wetland Functions andValues: The State of Our Understanding. AmericanWater Resources Assoc.

Fisher, Irving. 1930. The Theory of Interest, NewYork: Kelly and Milliman.

Fox, Karl. 1965. Intermediate Economic Statistics.New York: John Wiley and Sons.

Frey, H. Thomas, and Roger W. Hexem. 1985. MajorUses of Land in the United States: 1982. AER-535,U.S. Dept. Agr., Econ. Res. Serv.

Gain, Elmer W. 1967. Land Drainage for Productionof Food and Fiber Crops. Proceedings, InternationalConference on Water for Peace, Wash., DC. Vol. 7,pp. 451-461.

Goldstein, Jon H. 1971. Competition for Wetlands inthe Midwest: An Economic Analysis. Resources forthe Future, Inc. Baltimore: Johns Hopkins Press.

Harrison, Robert W. 1961. Alluvial Empire: A Studyof State and Local Efforts Toward Land Develop-ment in the Alluvial Valley of the Lower MississippiRiver. Little Rock, Ark.: Pioneer Press.

Heimlich, Ralph E., and Linda L. Langner. 1986.Swampbusting: Wetland Conversion and Farm Pro-grams. AER-551. U.S. Dept. Agr., Econ. Res. Serv.

Irwin, Ross W. 1979. On-Farm Drainage Benefit.Final Report, OMAF Research Programs 39, ProjectA-39-742. Univ. of Guelph School of Engineering,Guelph, Ontario.

Jones, John, and Charles H. Barnard. 1985. FarmReal Estate: Historical Series Data, 1950-85. SB-738.U.S. Dept. Agr., Econ. Res. Serv.

Lewis, Douglas. 1982. Land Drainage InvestmentSurvey, 1975-77. ERS Staff Report No. AGES820525.U.S. Dept. Agr., Econ. Res. Serv.

Luthin, James N., and Ronald C. Reeve. 1957."Drainage of Irrigated lands," Drainage ofAgricultural Lands. Monograph No. 7 (ed. James H.Luthin). Am. Soc. Agron., Madison, Wisc.

Nolte, Byron H. 1986. Cropland Erosion andDrainage Status in Eastern Ohio. Ohio State Univer-sity, Columbus. Coop. Ext. Circular AGDEX 751/752.March.

Shaw, Samuel P., and C. Gordon Fredine. 1956.Wetlands of the United States. Circular 39, U.S.Dept. Interior, Fish and Wildlife Serv.

Skaggs, R. W., and A. Nassehzadeh-Tabrizi. 1983.Optimum Drainage for Corn Prodimtion. TechnicalBulletin 274. North Carolina Agri, Les. Serv. N.C.State Univ., Raleigh.

Smedema, Lambert, and David W. Rycroft. 1984.Land Drainage: Planning and Design of AgriculturalDrainage Systems. Ithaca, N.Y.: Cornell Univ. Press.

Stamatel, Henry. 1986. Assistant State Conserva-tionist, SCS/USDA, Syracuse, N.Y. Personalcommunication, May 7.

Stonier, Alfred W., and Douglas C. Hague. 1956. ATextbook of Economic Theory. London: Longmans,Green and Co., Ltd.

135, 151

U.S. Department of Agridulture. 1981a. StatisticalReporting Service. Agricultural Statistics. annual.

1981b. Agricultural Stabilization andConservation Service. Agricultural ConservationProgram: 45-year Statistical Summary.

1981c. Agricultural Stabilization andConservation Service. Practice Cost-Shares byStates: 30-year Summary, 1944-74.

1982. Soil Conservation Service, andIowa State University Statistical Laboratory. BasicStatistics, 1977 National Resources Inventory.SB-686.

1984. Agricultural Stabilization andConservation Service. Agricultural ConservationProgram: Statistical Summary, 1983 Fiscal Year.

1986. Outlook and Situation Summary:Agricultural Resources. April 9.

U.S. Department of Commerce, Bureau of the Cen-sus. 1932. Drainage of Agricultural Lands, 1930.

1942. Drainage of Agricultural Lands:Land in Drainage Enterprises, Capital Invested, andDrainage Works, 1940.

1943. Drainage of Alluvial Lands: AComparison of Agriculture Within and Outside ofDrainage Enterprises in the Alluvial Lands of theLower Mississippi Valley.

1952. "Drainage of AgriculturalLands," Census of Agriculture, 1950. Vol. IV.

136

1961. "Drainage of AgriculturalLands. 1960," Census of Agriculture, 1959. Vol. IV.

1973. "Irrigation and Drainage onFarms," Census of Agriculture, 1969. Vol. II.

1973. "Drainage of AgriculturalLands," Census of Agriculture, 1969. Vol. II.

1981. "Drainage of AgriculturalLands," Census of Agriculture, 1978. Vol. 5.

1982., "Irrigation," Census ofAgriculture, 1978. Vol. 4.

1984. "Geographic Area Series forStates and Outlying Areas," Census of Agriculture,1982. Vol. I, parts 1-54.

1985a. "Ranking of States and Coun-ties," Census of Agriculture, 1982. Vol. 2: SubjectSeries, part 3.

1985b. "Graphic Summary," Censusof Agriculture, 1982. Vol. 2: Subject Series, part 1.

van't Woudt, Bessel D., and Robert M. Hagan. 1957"Crop Responses at Excessively High MoistureLevels," Drainage of Agricultural Lands (ed., JamesN. Luthin). Monograph No. 7. Am. Soc. Agron.,Madison, Wisc.

van Schilfgaarde, Jan. 1971. Drainage Yesterday,Today and Tomorrow. Paper presented at ASAENational Drainage Symposium, Chicago, Dec. 6-7.

Weaver, M. M. 1964. History of Tile Drainage inAmerica Prior to 1900. Waterloo, N.Y.: Privatepublication.

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Chapter 12

Drainage Potential andInformation Needs

Arthur B. DaughertyNatural Resource EconomicsDivisionEconomic Research ServiceUSDAUniversity Park, Pennsylvania

Douglas G. Lewis*North Caroiina Department ofNatural Resources andCommunity DevelopmentRaleigh, North Carolina

Drainage is an important consideration whenexamining the quality of the land resource. Pros-pects for drainage are based on the drainage poten-tials or "needs" for various agricultural purposesas identified by SCS in its periodic inventories ofthe Nation's soil and water resources.

Remaining Drainage Potential

Major national data series do not contain a variablerepresenting the continuum of drainage opportu-nities at a particular location. For the most part,they must be evaluated on a field-by-field basis.However, some information is assembled at thenational level which gives an indication of addi-tional drainage potentials on existing and potentialcropland, but it is unclear at what points on thewater management continuum a drainage system iscalled for Etna when agricultural use is consideredinappropriate because of the degree of wetness.

The principal sources of information on remainingdrainage potential have been SCS'F periodic conser-vation and resource inventories (USDA, 1962 and

*Formerly the Economic Resep-ch Service, USDA, Raleigh,North Carolina.

1971 and USDA, SCS, 1980). The most recent ofthese surveys is the 1982 National Resources Inven-tory (NRI).

Inventories Before 1982

The 1958 Conservation Needs Inventory (CNI) didnot report drainage potentials as such. Instead, thearea of cropland having excess water as either adominant or secondary problem was reported.Excess water was defined as a high water table ortemporary flocding which prevented or limited theuse of conservation cropping systems or practices(USDA, 1962, p. 139). About 15 percent (60 millionacres) of nonirrigated cropland had excess water asa dominant problem (table 12 -1). Excess water wasa secondary problem on an additional 12.5 millionacres.

In the 1967 CNI, 43 million acres of nonirrigatedcropland in tillage rotation were considered to havedrainage problems. This area constituted about 10percent of all nonirrigated cropland in tillage rota-tion in the 48 conterminous States and Hawaii.

The 1977 NRI reported 357.2 million acres of nonir-rigated cropland in the same 49 States. Of thisnonirrigated cropland, 36.5 million acres or about

137

10 percent had drainage problems. So, in 1977, thesame percentage of nonirrigated cropland haddrainage limitations as in 1967, indicating that therelative potential for drainage remained as great in1977 as it was 10 years earlier.

The simple comparison in table 12-1 of the potentialfor drainage in 1958, 1967, and 1977 illustratessome of the definitional problems encountered whendetermining changes in drainage potentials overtime. The 1958 CNI reported excess water as thedominant or secondary soil and water problem af-fecting cropland, but we do not know if excesswater was comparable to requirements for adrainage system as assessed in the 1967 and 1977inventories.

In 1967, the potential for drainage was estimatedfor nonirrigated cropland in tillage rotation. Thisdefinition excludes orchards, vineyards, bush fruits,and open land formerly cropped (USDA, 1971, pp.10-11). However, the 1977 specification ofpossibilities for improving drainage on nonirrigatedcropland appeared to be related to all cropland, in-cluding the categories that were excluded in 1967.

The 1982 National Resources Inventory

In the 1982 NRI, drainage potentials were reportedfor a wider range of land uses than in earlier hiven-tories. About 25.2 million acres of nonirrigatedcropland, 2.5 million acres of irrigated cropland,

Table 12-1Nonirrigated cropland having drainage problemsinventoried in USDA surveys, 1958-771

Survey

Soil and water conservation problem

Excess water, Excess water,dominant secondary Drainageproblem2 problem potential3

Totalnonirrigated

cropland

1,000 acres

1958 CNI 59,918 12,526 399,6711967 CNI 43,004 420,8651977 NRI 36,511 357,166

= not available.IData represent 48 conterminous States and Hawaii.2Cropland with an excess water problem was defined as

"... land on which excess water caused by a high water table orby temporary flooding prevents or limits the use of conservationcropping systems or practices." (USDA, 1962, p. 139).

3Drainage potentials in 1967 were defined as "... cropland onwhich an adequate drainage system is needed to remove excesssurface or internal water" (USDA, 1971, p. 210). In the 1977 NRI, apotential for drainage was indicated where "... an adequatedrainage system is needed to control erosion and ')r) to removeexcess surface water or internal water" (USDA, SCS, 1977, p. 14).

4Data are for cropland in tillage rotation only (excludeorchards, vineyards, bush fruits, and other land formerlycropped).

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and 3.4 million acres not in crops had drainageproblems. The latter figure included 2.4 millionacres of pastureland, 300,000 acres of rangeland,and 700,000 acres of land in other minor uses inrural areas.

Of the total 31.1 million acres of potential newdrainage, 27.5 million acres, more than 88 percentwere classified as land capability subclass "w"soils, where water in or on the soil interferes withplant growth or cultivation. In some situations, thewetness could be partly corrected by artificialdrainage (USDA, Mar. 1981, p. 324). Of the nonir-rigated cropland with a drainage problem, 22.5million acres (89 percent) were subclass "w" soils.About 2.1 million acres (84 percent) of the irrigatedcropland with drainage problems were subclass"w" soils. The area of potential drainage treatmentmade up more than 25 percent of all wet soils incroplkAnd use in 1982.

Besides the 3.4 million acres in noncropland useswith drainage problems in 1982, additional drainagepotential may have existed if the land use changed.For example, the NRI did not assess drainage situa-tions for forestland in 1932. However, if forestswere cleared and converted to crop use, undoubtedlysome conversions would involve drainage of wet-lands. More than 14 million acres of forestland withmedium or high potential for conversion to croplandwere subclass "w" or wet soils, some of whichwould also be classed as wetlands.

The NRI did not evaluate drainage opportunities assuch for potential cropland. However, it consideredsoil and water problems which would inhibit or pre-vent the conversion of land to crop uses. Two suchproblems or limitations were "common flooding" (anNRI term), and also "wetland types 1-20," as definedby Shaw and Fredine (1956).

About 12.2 million acres that have medium or highpotential for use as cropland were wetlands and/orhad common flooding as the primary or secondarysoil and water problem. Table 12-2 presents thecombination of these problems of primary andsecondary importance. For this discussion, all othersoil and water problems were aggregated into onecategory. Nearly 10 million acres suffered commonflooding, and another 2.1 million acres werewetland types 1-20. In addition, 241,000 acres hadcommon flooding as a secondary soil and waterproblem, and 239,000 acres were classified aswetland types 1-20 as a secondary problem, eachwith some other primary problem.

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About 500,000 acres of the 12.2 million acres ofmedium- and high-potential cropland, which hadeither a flooding problem or were wetlands, neededdrainage treatment in their present, noncroplanduse (pasture, range, or other minor u.1). 1 tis left11.7 million acres of medium- or high-potentialcropland with a possible potential for drainage.

About 1.6 million acres were in 1 of the 20 wetlandtypes but had no secondary soil and water problemaffecting conversion to and use as cropland. Thisarea, about 1 percent of the medium- or high-potential cropland, seemed to have the greltestpotential for drainage. While land with combina-tions of problems and/or suffering from floodingmay benefit from drainage, the net benefits may beless relative to areas suffering from only a wetnessproblem.

The NRI showed that the remaining potential fcrfarm drainage in the United States ranged between31.1 and 42.8 million acres. In the lower range wasinventoried land drainable in its use at the time.The upper range included land having medium andhigh potential for conversion to cropland that wasone of the wetland types and/or land that had acommon flooding problem but was not identified asrequiring drainage in its use at the time.

Table 12.2 Soil and water problems with all land ofmedium and high potential for croplandinventoried in the 1982 National ResourcesInventory

Primary soiland

water problem

Secondary soil and water problemWetlandtypes Common Other Total

None (1-20) flooding problems

1,000 acres

None 91,165 0 0 0 91,165Wetland types 1,605 77: 211 224 2,112

(1.20)Common

flooding7,571 1,112' 57 868 9,603

Otherproblems

34,714 239 241 14,614 49,837

Total2 135,056 1,422 509 15,736 152,722

'This figure indicates that about 12 percont of the 9.6million acres of convertible land with common (frequent)flooding can also be considered to be 1 of the 20 wetlandtypes. Frequent flooding in itself is not an identifyingcharacteristic of wetlands. The total area of land where awetland designation is either a primary or secondary problemit; conversion is thus about 3.5 million acres (2.112 + 1.422mil. ac.).

2ltems may not sum due to rounding.

Achieving new drainage depends on a number ofeconomic and institutional factors. Some of thesecan be estimated by or for the individual farmowneror oper itcr, such as the benefit from a positive pro-duction response or a reduction in production costs.Other factors may not be determined so specifically.These include the necessity for group action fordrainage water removal and tho acquisition of anypermits from Federal or State agencies needed forinstalling drainage improvements. Any drainage ofpotential cropland must be consistent with presentand prospective public policies concerning produc-tion levels and resource conservation, includingwetland preservation.

Drainage Information

Examination of drainage accomplishments and pros-pects is constrained by the availability of reliabledata relevant to drainage of agricultural land. Vir-tually all historical drainage information c 'mesfrom three primary sources: the Census of Agricul-ture; program reports of USDA agencies; andperiodic special surveys of drainage. Drainage datafrom the Census of Agriculture reflect two generalsources: data collected directly from farm operatorsand data collected from organized drainage dis-tricts. SCS and ASCS publish program reportswhich summarize their technical assistance andcost-sharing on drainage.

Census of "luiculture Data

Census data on drainage date from 1920. Drainagedata were collected from farm operators and frompublic or private organizations engaged in coop-erative drainage enterprises. Drainage enterpriseswere defined as "... public and private corpora-tions and local improvement districts organized tosecure the drainage of land for agricultural pur-poses...." (U.S. Dept. of Commerce, Bureau of theCensus, 1922, p. 348). Drainage enterprises weregenerally synonomous with drainage districts, aterm more commonly used in recent censuses.

In 1920 more than 53 million acres out of a total of956 million acres of U.S. farmland were providedwith some form of drainage. An additional 39million acres were reported to have drainage prob-lems. Data were also collected on the number offarms reporting drainage, land use on land indrainage enterprises, miles of ditches and tiledrains in drainage enterprises, and total capitalinvested in drainage enterprises.

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Data collection in the 1930 Census of Agriculturewas comparable to the 1920's except for the changein land use information on drained land. Farmoperators reported drainage on 44.5 million acres, adecline from 1920's levels. However, over 66 millionacres within drainage enterprises were drainedsufficiently to produce a normal crop, more thancompensating for the derline reported by farmoperators.

The 1940 Census of Drainage was the first whichexcluded individual farm operators and focuseddata collection entirely on cooperative drainageenterprises. The number of reported projects declinedfrom 1930 to 1940, but the area within their bound-aries increased slightly to 87 million acres. Morethan 75 million acres received sufficient drainagefor a normal crop at a capital investment of $692million. The slight increase in total investment andthe facilities of ditches and tile drains representedby that investment was made despite the generaleconomic depression of the time.

Data on drainage enterprises are relatively consis-tent regarding method of collection and contentfrom 1920 through 1940. However, several pro-cedural changes began in 1950. The main changeswere: drainage enterprises under 500 acres wereexcluded, drainage enterprises absorbed by a laterproject were not enumerated, and the data on enter-prises under common management were consolidatedinto one report. The geographic area consideredexpanded with each Census.

Comparability of data was probably significantlyaffected by the addition or deletion of Slates, whichcan be accounted for, and by excluding enterprisesof 500 acres or less, which can only be estimated.About 5 percent of the land in drainage enterpriseswould have been deleted from the 1940 total hadthis rule then applied. The number of separatedrainage enterprises would have decreased by 53percent.

Almost 103 million acres were reported as net landdrained in 1950 within drainage enterprises. Whilepublished on the same line as land in drainageenterprises from the previous three Censuses ofDrainage, the reports are not necessarily compar-able because not all land within the boundary of adrainage enterprise was artificially drained. Thelands may have received some benefit, however,when artificial drainage on adjacent land enhancedthe natural drainage patterns.

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The 1950 Census marked a change in the financialdata collected. In Censuses before 1950, all capitalinvestment accumulated prior to the census datewas requested. Investment data for the 1950 Censusreferred only to investments made during thepreceding decade. Annual revenue data were alsocollected and combined with beginning and endingindebtedness and operation and maintenance coststo construct an approximate equation of the finan-cial status of drainage enterprises for the decade.This was an effort to separate new capital invest-ment from operation and maintenance costs and toidentify total tax revenue.

The 1960 Census of Drainage did not include datafrom projects where land was drained solelybecause of irrigation. The total area in drainageprojects serving agricultural lands was 101.9million acres in 1960. This total excluded about 3million acres of drained irrigated land and 6 millionacres of swamp and wasteland counted in 1950.Thus, the remaining 92.3 million acres werepredominantly agricultural lands benefiting fromartificial drainage within drainage projects.

Drainage data collection in the 1970's marked apartial return to earlier procedures. Data werecollected from farm operators in the 1969 Census ofAgriculture and from drainage projects via the 1972Census of Governments. Data covered all 50 Statesfor both censuses and were reported as part of theCensus of Agriculture. Farm operators respondingto the 1969 Census reported draining nearly 60million acres. Analysts agree that the 1069 and the1974 estimate (42.8 million acres) greatly under-sta-ed the total drained. Considerable dataavailable from the Census of Governments detailedthe number of project employees, debt, expendi-tures, and revenues.

The most recent published data on drainage comefrom the 1978 Census. Data on land drained werecollected in yet another manner because of the poorquality of the 1974 Census reports. State and countySCS officials estimated land benefiting from artifi-cial drainage for individual counties which wascombined with financial and employment data fromdrainage districts obtained in the 1977 Census ofGovernment. The 1978 estimates of land drainedwithin each county totaled about 105.3 millionacres. Financial data were shown for only onefiscal year in both the 1972 and 1977 Census ofGovernments.

Table 12-3 summarizes the geographic coverage anddata acquisition of the Census Bureau from 1920 to

I.'IOU

Table 12.3 Sources of Census Bureau drclnags.i dataand States, per selected year

Number Source of drainage dataYear of Census of Census of Census of Cooperation

States drainage Govern. Agricul with SCSenterprises ments ture

1920 341930 351940 381950 40

1960 3937

1969' 501974 50

291978 50 X

X = Drainage data available by year and source.'Census of Governments data are for 1972 but are used in

conjunction with data from the 1969 Census of Agriculture.

1978. This is widely regarded as the current bestsource of data regarding land drained in the UnitedStates.

Sources of drainage data and coverage are notconsistent nor are methods and procedures of datacollection. Another problem is that specific dataitems have changed from one Census to the next.The total information from these data resembles amosaic with missing parts. Analysts must use thesedata with caution because perceptions about thestatus and trends of artificial drainage ofagricultural land are necessarily a function of thedata. Poor data can lead to poor perceptions andfaulty conclusions.

Agency Feogram Reports

ASCS has administered the Agricultural Conserva-tion Program (ACP' since 1936. The objective of theACP had been to encourage adoption of approvedconservation practices by providing cost-sharingincentives to landowners. Cost sharing is based onthe judgment that the benefits tend to be widelydispersed while the costs are borne by the land-owner. Local SCS technicians provided landownerswith the technical assistance necessary to installthe approved conservation practices.

Each year, ASCS and SCS compile a summary oftheir cost sharing and technical assistance activ-ities. During 1944-73, the total acreage drained topermit conservation farming under ACP was 54.1million acres. Funds used for cost sharing fordrainage for the same period totaled $356.7 million.These data are incomplete because not all onfarm

drainage was installed under the ACP program.Further, the cost share total reflected only anunknown proportion of the total cost of the installa-tion of facilities. Landowners provided the balanceof funds necessary to complete the project fromtheir own resources. Cost-sharing proportions wereusually unavailable in aggregate form for theperiod.

SCS data were limited to miles of open ditches andtile drains installed each year. The exception wasthe cooperation given to the Census of Agriculturein 1978 when local SCS personnel estimated thetotal land drained in their county. It is difficult tocombine miles of tile and ditches with other data todescribe in a meaningful way the status ofagricultural land drainage because the data do notdefine quantity, quality, or cost of the investmentwithout making some arguable assumptions.

Periodic Special Surveys

SCS conducted national inventories of soil andwater conservation problems and possible tredt-ments in 1958 and 1967. Similar data were collectedin the 1977 and 1982 NRI's. ERS used a subsampleof the 1977 NRI to estimate the extent of drainageinvestments during 1975-77.

The objectives of the SCS inventories differed fromthe previously described data sets. While the Censusdata and agency reports painted a ph.:ture of whathad been accomplished regarding agricultural landdrainage, the inventories described what remainedto be done. Land capability is described in terms oflimitations, such as excess water. This limitationhas a presumed but not a necessary relationship todrainage, for example, drained lands do not havethe limitation of excess water. These data helpassess the potential for drainage but cannotdescribe the current status of agricultural landdrainage.

The 1982 NRI will facilitate estimates of subsurfacedrains, field ditches, and main ditches installed as aconservation practice. Only three practices perpoint can be listed, so drainage may be deleted infavor of three other practices. It is not clear howthe existence of underground drainage is to bedetected or if only drainage as a "conservationpractice" is counted. No provision is made for thecollection of collateral economic data.

ERS's Land Drainage Investment Survey was afollow-on survey to the 1977 NRI. ERS collected dataon land drained, type of drainage, and total invest-

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ment for 1975-77. About 29 million acres wereaffected by drainage investments in the UnitedStates during the 3-year period. Almost 6.5 millionacres were drained by new systems and 22.5 millionacres were drained by additions to existingdrainage during the 3 years.

Conclusions on Drainage Information

Perceptions about the status and trends of artificialdrainage of agricultural land are a function of theextent and quality of drainage data. Existing infor-mation tends to give an incomplete picture of landdrainage. Although Census data are widely used asthe authoritative source of drainage information,such information has been based at various timeson the Cenms of Agricuture, the Census ofDrainage, the Census of Governments, and SCSestimates. Not all farm operators know what part oftheir land is drained, nor do drainage district orSCS personnel. Published Census reportsacknowledge the double counting of some drainagewhile some land is overlooked. Although the defini-tion of drainage has changed little over time,specific data items have changed as have defini-tions of the relevant universe, such as what con-stitutes a farm, whether to include drained irrigatedland, and public versus private drainage enter-prises. It is not possible to assess the effectivenessof existing systems so it is implicit in the data thatall systems remain equally effective in removingexcess water.

Another problem i., that new drainage investmentscannot be separated from maintenance expenditures.Some data, the number of drainage district employ-ees, for example, are of questionable usefulness inevaluating the status or trends of agriculturaldrainage.

ASCS and SCS reports are limited to programparticipants and include only the cost-sharing por-tion of total investment. Some data are reported inunits which cannot be meaningfully integrated withother data sets. The periodic surveys tend toaddress drainage remaining to be done rather thandrainage which has been done. The exceptions arethe 1982 NRI and the 1975-77 trend data from the1978 Resource Economics Survey.

Given these limitation::, use agricultural landdrainage data with caution. Changes in policies andinstitutions affecting drainage certainly change thebenefits and costs of draining, both to the individualand to society at large. Greater attention to societal

142

interests mikes the information needed for decision-making more complex. In short, increased effortsand expenditures to improve data collection areneeded to ensure a more accurate "mos' c"describing agricultural land drainage, and thusmore rational private drainage investments andpublic policy decisions.

References

Shaw, Samuel P., and G. Gordon Fredine. 1956.Wetlands of the United States. Circular 39. U.S.Dept. Interior, Fish and Wildlife Serv.

U.S. Department of Agriculture, AgriculturalStabilization and Conservation Service. 1981.Agricultural Conservation Program, 45-yearStatistical Summary, 1936-1980.

1975. Practice Cost-shares by States:30-year Summary, 1944-1974.

Agricultural Conservation Program:Statistical Summary, annual.

, Economic Research Service. 1982.Land Drainage Investment Survey, 1975-77: A Reporton Landownership Follow-on Survey. ERS StaffReport AGES820525.

, Soil Conservation Service. 1977. Ero-sion Inventory, Instructions for the PSU and PointData Collection. June.

1980. Basic Statistics-1977 NationalResource Inventory.

1962. Basic StatisticsNational Inven-tory of Soil and Water Conservation Needs. SB-317.August.

1971. Basic StatisticsNational Inven-tory of Soil and Water Conservation Needs, 1976.SB-461. January.

1981. "Soil and Water Resources Con-servation Act, 1980 Appraisal." Soil, Water andRelated Resources in the United States: Status, Con-dition, and Trends. March.

U.S. Department of Commerce, Bureau of the Cen-sus. 1922. "Irrigation and Drainage," U.S. Census,1920, Vol. VII.

158

1930. "Drainage of AgriculturalLand," U.S. Census, 1930.

1942. "Drainage of AgriculturalLands," U.S. Census of Agriculture, 1940.

1952. "Drainage of AgriculturalLand," U.S. Census of Agriculture, 1950, Vol. IV.

1961. "Drainage of AgriculturalLand," U.S. Census of Agriculture, 1959, Vol. IV.

1973. "Drainage of AgriculturalLands," U.S. Census of Agriculture, 1969, Vol. IV.

1977. "Irrigation and Drainage onFarms," U.S. Census of Agriculture, 1974, Vol. II,part 9.

1981. "Drainage of AgriculturalLands," U.S. Census of Agriculture, 1978, Vol. 5,special reports, part 5.

1.59143

Chapter 13

Drainage Challenges andOpportunitiesFred SwadecExtension Service, USDAWashington, DC

George A. Pave lisEconomic Research Service, USDAWashington, DCLand drainage has its roots in antiquity. Its extentand persistence document its relevance to pre2ent-day agriculture. Substantial changes and progressin technique have occurred, especially followingWorld War II. Uncertainties exist about the prof-itability of using drainage to improve existing or todevelop new cropland, and these uncertainties arelinked primarily to the prevailing cost-price situa-tion for specific commodities, not to the concept ortechnologies of land drainage.

Drainage challenges and opportunities exist intechnical and operational matters as well as in thepolicy arena. These challenges and opportunitiesare likely to be perceived differently by differentaudiences. At the operations levels, concerns offarmers and their related agribusiness institutionsmay differ from those of other private interests andgovernment. We outline some tit these concerns to illus-Irate the complexity of their mutual accommodation.

Preservation of Wetlands

The preservation of wetlands is an excellent exam-ple of the intermixture of views at various levelsand by various audiences. This is no longer adebatable issue at the Federal level. ExecutiveOrder 11990 issued in 1977 (appendix A) detailsand codifies policy. This policy directive and similarformal legislation on the preservation of wetlandsclearly sets policy at the Federal level. Federalagencies have implemented the necessary adminis-trative procedures to comply. Executive Order11988 on Flood Plain Management (May 1977) coverswetlands within flood plains. Other pertinentlegislation includes the Fish and Wildlife Act of1958, the Drainage Referral Act of 1962, the

144

National Environmental Policy Act of 1969, theEndangered Species Act of 1972, section 404 of theClean Water Act of 1972, and the "anti-swamp-busting" provisions of the Food Security Act of1985. Various State and local policies have similarobjectives.

Many people, farmers included, appreciate water-fowl and the recreational and general environmentalvalues of wetlands (figs. 13-1 and 13-2). But also,many people appreciate these values from anabstract rather than personal economic perspective.Those who actually own or manage land must weighthe !..nited economic and potential nonmonetarybenefits of leaving a wetland area undisturbedagainst the potential economic benefits of adaptingit to their operations by draining it. This very prac-tical contrast of values is the point of departure ina major National Geographic article on waterfowlprotection needs (Madson, 1984).

Wetlands may be considered a liability for a num-ber of reasons. They may impede farming opera-tions and farm expansion. They may be assessedand taxed the same as productive farmland, or evenassessed the same as waterfront property. Wet-lands may attract waterfowl, which can damagecrops, or less desirable blackbirds and muskrats.

In his earlier chapter, Thomas writes "....generallyacceptable methods of quantifying wetland valuesas marketable goods and services have not yet beendeveloped...." In their chapter, Smith and Masseyalso allude to the level of abstract appreciation ofwetlands when they note that "...The demands forenvironmental p_ .ducts of wetlands are largelyexpressed through governmental organizations."

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Figure 13-1Spring migrating geese flock to the 25 -acre Wilson Creek Wa Swelled, 0109 County,Nebraska.

These differences in perception can deter theacceptance of Federal and. State policies to protectwetlands. Such policies often embrace the ideal ofpreservation of wetlands without addressing thepragmatic concerns of the landowner.

There have been, and continue to be, Federal, State,and private programs that address these pragmaticconcerns. An excellent example is the FederalWater Bank Program. administered by USDA underthe Water Bank Act of 1970 (P.L. Law 91-559, asamended). Under this program, wetlands alongwaterfowl flyways are withheld from farm useunder long-term rental agreements with landowners.Financial assistance can also be provided for in-stalling habitat and water-quality improvementmeasures. As of 1995, USDA had negotiated about7,500 Water Bank agreements witE landowners,covering 720,000 acres of wetlands

An important USDA disaster assistance provisionallows CCC grains to be donated to the Departmentof the Interior for feeding migratory waterfowlwhen threatened with starvation or for preventingcrop damage. Such assistance requires that the Sec-retary of the Interior finds that an emergency exists.

CCC grain stocks may also be donated by USDA toState agencies for feeding resident wildlife threat-ened with serious damage or loss from starvation,upon requests of appropriate State agencies andauthorization by the Secretary of the Interior(USDA, 1983).

Other Federal agencies also assist and cooperate inthe preservation of wetlands and the managementof wildlife refuges along the major waterfowlflyways. Flyways are general migration routes.Private organizations, notably Ducks Unlimited,

161145

'..t:114

Figure 13-2Wild ducks and geese feed on annual lye grassplanted for them in Dare County, North Carolina.

have active programs to preserve wetlands aswaterfowl breeding areas. Several Stafos have theirown programs to encourage farmers to maintainand manage wetlands for waterfowl habitat.

The Function of Wetlands

Wetlands are purported to be and often are wildlifehabitat, flood storage areas, ground-water rechargeareas, ground-water discharge areas, siltationbasins, ecological filters, and unique ecological andeducational areas. Except for wildlife production,market values cannot yet be assigned to these func-tions. If there are no market values or arrangementsfor compensating landowners for income given up bymaintaining wetlands, landowners resist protectionby regulation as a "taking" of traditional propertyrights.

The desirability of expanding current cost-sharingand cost-transferring programs to protect wetlandsdepends upon one's niche in a spectrum, rangingfrom detached conceptualist to threatened land-owner. The existing programs appear to have beenwell-received and effective. But, it is not knownwhether enough wetlands can be purchased to ade-quately sustain an as yet unspecified optimumwaterfowl population. Market values have not beenestablished for wetland functions other than water-fowl production. Jther wetland functions are notwell understood, much less appreciated. This mayhelp explain why no programs for purchasing orleasing wetlands exist except those associated withwaterfowl production.

146 16

Increased public education may help landownersaccept the importance of wetlands for functionsother than waterfowl habitat. If landowners under-stand that wetlands within their holdings servesome valuable function, such as ground-waterrecharge, the understanding will translate intowider acceptance of the need to preserve ormanage such areas for multiple purposes. Thisbehavior presupposes that ecologic or hydrologicfunctions are known, or can be reliably identified,and can be related to something of importance tothe landowner. Educational programs based onsound, reliable information are beginning to appearin the Southeastern Coastal Plain Region, address-ing the problems of Bottomland Hardwoods (Harrisand others, and Florida Cooperative Extension Serv-ice, 1984).

Note that even such functional information may notbe sufficient. A study of farmer attitudes towardsoil conservation practices found that "Stewardshipof the Soil" (moral) arguments are not perceived tobe particularly effective in promoting soil conserva-tion. Economic considerations are significantly moreimportant in this regard, based on farmers' beliefs,perceptions and past behavior (Pioneer, 1982). Thisis so despite a 50-year effort by USDA agencies topromote conservation. It suggests that cost sharingand technical assistance, coupled with conservationeducation programs, will probably be more effectivepromotional devices for preserving wetlands thanthose based on the premise that farmers have amoral duty to conserve or leave untouched naturalresources for the benefit of others.

Rates of Wetland Conversion

Until Acent studies of the Fish and Wildlife Serviceand USDA, there was little data on the area of wet-lands or rates of conversion to other uses (Frayerand others, 1983; USDA, 1982). Earlier estimateswere largely approximations from independentstudies which contained different concepts andbaseline data. While the estimates are largely ofhistoric interest, there is no argument that largeacreages have been converted from wetlands toother uses, and a primary end use was agriculture.The more important issues are whether such con-versions are likely to continue, whether the projec-tions like those of the National Research Council arelikely, and whether new policies are needed to limitsuch conversions.

Little eressure currently exists for a ..ditionalconversions to produce agricultural products. The

current surpluses, the depressed farm economy, andthe weakened competitive position of the Americanfarmer in world markets seem to make large-scaleconversions unlikely in the short run.

At the same time, however, domestic and worldsupplies of corn, soybeans, and feed grains mayfluctuate greatly. Supply-demand relationships arelikely to swing again toward increased demand forthe products of U.S. agriculture, including corn,soybeans, and feed grains.With large increases indemand, there is little doubt U.S. farmers wouldlikely respond by increasing their acreages at theextensive margin, including moving into heretoforeunprofitable wetlands.

The effects of shifts in world supply/demand rela-tionships may be mitigated by the continued intro-duction of bio- and other technologies into farming.Clearly, if per acre yields, especially of soybeans,could be doubled by genetic engineering, thenecessity of expanding cropland acreage by variousmeans, including drainage, would greatly decrease.At the same time, however, intensive water manage-ment, including controlled drainage systems for wetsoils, may be a profitable component of using newtechnologies to their best advantage.

Continued educational programs are needed. What-ever the likelihood of expanded demand and in-creased prices for agricultural crops, the absenceof awareness of the importance of wetlands willmake those wetlands situated within the intensivemargin vulnerable. When demand is strong andcommodity prices are increasing, such areas aremore likely to be regarded as obstacles to increas-ing income.

Supply of Wet lano, Products

There is a presumption of a shortage of wetlandproducts. Smith and Massey state that "Because ofthe increasing scarcity of wetland products and theheightened public valuation, private decisions at theextensive margin increasingly face a public choicetest." Whether this perception is supported by pres-ent inventory data is not clear.

It appears that most presumptions of a shortage ofwetland products are based on waterfowl numbers.There have not been detaili3c1 estimates of the extentandlocation of wetlands that perform other specificfunctions, except perhaps the acres of hardwoodbottomlands, which do play a role in floodwaterstorage.

i$

-

Figure 13-3Pines we able 0 grow because of woodland ditchdrainage in Brunswick, Georgia, where once the soil was toowaterlogged to support trees.

In its National Wetlands Inventory, the Fish andWildt:te Service is producing detailed wetland mapsfor the rInited States. These maps will help quantifythe extent and location of wetlands that performvarious specific functions.

Do Wetlands Need More Protection?

The present demand for cropland is not likely to re-quire draining large areas of wetlands. The Nationis not in imminent danger of exhausting its availablecropland (Crosson, 1982). Farmers who survive thecurrent crisis in agriculture will likely concentrateon intensifying their operations to optimize growingconditions for "hi-tech crops." Their land improve-ment efforts are likely to focus on existing cropland.Much of this cropland has already been drained;the maintenance of existing drainage systems wilibe required. There will also be some expansionwithin pwtially dra'ned fields. The aggregateimpacts vi these ?Wes upon wetlands will prob-ably be small.

It is not clear, however, that other primary in-dustries will limit land drainage to the intensivemargin. Relatively large acreages of wetlands havebeen drained in the Southeastern Coastal Plain forsubsequent intensive forestry production. Such landtreatment changes large acreages from wetlands ofsome classification and some hydrologic functions toother productive functions.

Such conversions are usually made by are cor-porations as part of their long-range productionplans. These companies have sufficient capital to

163 147

retain engineering services, to contract for landimprovement, to harvest and process existing timberstocks, and to clear the remains in preparation forintensive forestry production. Such conversions aresubject to State laws. They may be influenced moreby national export policies and by State employmentgrowth policies than by wetland preservationpolicies at either level of governments.

The purpose of these corporate efforts is sometimesconfused by short-term intervening uses. If theprices for farm commodities are relatively highthere will be incentives and local pressures to leaseor use such newly drained lands to produce high-value cash crops. In the early 1970's, large areas ofyoung pines were cleared by bulldozers, convertingeventual pine forests to soybean fields.

The immediate returns from such cash cropping maywell recoup the costs of conversion and also returnsome additional benefits to the land developmentcompany. The use of chemicals to produce cashcrops discourages forest regrowth and suppressesthe populations of subsequent weed species. It maynot be good wetland management, but the short-termcropping of cleared coastal plain forestlands maymake good economic sense to landowners (fig. 13-4).While agriculture has played a significant role inthe drainage of wetlands, this scenario illustrateshow the role may sometimes be incidental to theoriginal purposes of drainage. It also challenges acandid consideration of the possible scope ofwetland conversion potentials in different regions,and in industries other than agricultrua.

National and Regional WetlandConversions

More information on the extent of wetlands of dif-ferent types and suitability for wildlife, hydrclogicfunctions, and agricultural use is becomingavailable from various Federal and State studies.Recent national assessments include the WetlandsStatus and Trends Study by FWS in the Departmentof the Interior, and the 1982 NRI, completed by SCS(Frayer and others, 1983, and USDA, 1982).

The Wetlands Trends Study of FWS photo-interpretedland use changes between the mid-1950's andmid-1970's for about 3,600 randomly selected sampleunits (each 4 square miles). On the other hand, the1982 NRI identified land uses along with many othercharacteristics as of 1982 for about 1 million ran-domly selected sample points examined in the field.

Agricultural Conversions

According to ale Wetlands Trends Study, agricul-ture was the observed end ;Ise of about 87 percentof the wetlands developed between 1954 and 1974(USDA, 1085, and Frayer and 'Finer, 1984). Nearly 98percent of the conversions to agriculture involvedPalustrine wetlands. Broadly speaking, Palustrinewetlands are inland freshwater or water-saturatedareas more than 30-percent covered by trees,shrubs, or mosses. If not meeting these conditions,they can ba small areas (under 20 acres) withfreshwater regimes, with any standing water lessthan 2 meters (6.6 feet) deep. Complete scientificdefinitions of Palustrine and other major wetlandsystems and classes are in Cowardin and others(1979).

Figure 134Sottomiend vollands are Wing cawerM to agricultural use in many arms of the Southeastqhannelizing (left) and clearcutting.

148

The Wetlands Trends Study also indicated thatgross conversions of Palustrine wetlands toagriculture were limited almost entirely to onlythree of six recognized broad classes of Palustrinewetlands. The three classes and their relative im-portance include: Palustrine Forested (53 percent),Palustrine Emergent (39 percent), and PalustrineScrub/Shrub (8 percent). Examples are in figures 5-4to 5..6.

While USDA's 1982 NRI employed a detailed wet-lands classification developed earlier by FWS(Shaw and Fredine, 1956), it also broadly classifiedwetlands as to whether they were in the Palustrinesystem or the four other major wetland systems nowused by FWS: Marine, Estuarine, Lacustrine, andRiverine.

PACIFIC

Another important feature of the 1982 NRI was thatit encompassed all non-Federal rural land. State,county, municipal, Indian, and private ownershipcategories were recognized. Privately owned andvegetated Palustrine wetlands not in agriculturaluse, whether or not now in farms, are the wetlandsmost rele "ant to questions of agricultural conver-sion. This Leaves aside conversion costs, othereconomic factors, and management requirementsthat determine the actual feasibility of conversionand likely environmental impacts.

Four major waterfowl flyways are recognized byFWS and others for the United States. Each is dividedinto north and south sections (fig. 13-5). For theseflyway areas, table 13-1 contains estimates as of1982 of all non-Federal wetlands, non-Federal

MISSISSIPPI

Note: Shaded portions Incorporate general wetland areas. Each dot represents about 10,000 acres.

SOURCE: Adapted from Samuel P. Shaw and C. Gordon Rodin'. "Wetlands of the United States: Their Extent and Their Value to Waterfowl and Other Wildlife."Fish and Wildlife Service, U.S. Department of the Interior, Circular 39. 1656.

*Counties in the Mississippi Flyway more'than 75 percent drained.

Figure 13.5Waterfowl flyways and wetlands of the United States.

165 149

publicly held wetlands, privately owned wetlands,and the private Palustrine wetlands vegetated andnot currently cropped or permanently grazed. Rangeestimates of the convertibility of such wetlands tocropland through drainage and associated develop-ment measures are also included in table 13-1. Ourlow estimate (2.5 million acres) is based on directjudgments made in the 1982 NRI of medium or highpotentials for conversion to cropland of privatelyowned vegetated Palustrine wetlands not currentlyin agriculture. Our middle estimate (7.5 millionacres) includes all such wetlands fairly easilysuitable for crops (land use capability IIw and Il Iw).Our high estimate (12.9 million acres) then adds inwetlands marginally suitable for crops (capabilityclass IVw).

In their analysis of the NRI data, Daugherty andLewis (chapter 12) indicate that the total remainingpotential for farm drainage in the United States in1982 was between 31.1 and 42.8 million acres. Thelower figure included land already in crop use orgrazed and considered to need drainage. The added11.7 million acres were noncropland with at least a

medium potential for conversion to cropland. For3.5 million acres was a designation as wetlands(types 1-20) under the Shaw/Fredine system (1956),either a primary or secondary soil and water prob-lem limiting conversion. A later analysis byHeimlich and Langner (1986) indicates that 5.1million acres of wetlands were rated in the inven-tory as having at least a medium potential for con-version. Their figure covered all non-Federal

Table 13-1-Nonederal wetlands in the 48 conterminous United States in 1982, with estimates of wetlands convertible tocrop production'

Flyways(figure 12-1)

Totalnon-Federalwetlands2

Non-Federalpublic

wetlands3

Totalprivate

wetlands'

Wetlandsconvertibleto crops5

Estimates ofagricultural conversions

Lowestimate

Middleestimate

Highestimate

Thousand acres

Pacific: 4,390 635 3,755 584 35 56 150North 1,623 73 1,550 301 34 45 109South 2,767 562 2 205, 283 1 11 41

Central: 10,378 799 9,579 2,120 53 250 538North 6,693 536 6,157 704 13 36 74South 3,685 263 3,422 1,416 40 214 464

Mississippi: 34,577 7,763 26,814 19,638 1,477 2,657 4,810North 19,191 6,929 12,262 8,967 556 1,141 1,518South 15,386 834 14,552 10,671 921 1,516 3,292

Atlantic: 28,884 3,708 25,176 20,425 950 4,544 7,370North 8,239 1,009 7,230 5,655 262 1,164 1,706South 20,645 2,699 17,946 14,770 688 3,390 5,664

United States 78,229 12,905 65,324 42,767 2,510 7,517 12,868

'Basic data for this table were compiled by Ralph E. Heimlich, ERS, USDA, from the 1982 National Resources Inventory.2Wetland system types with nonFederal U.S. totals include: Palustrine, 70.564 million acres (90.2 percent); Estuarine, 5.985

million acres (7.7 percent); Lacustrine, 1.508 million acres (1.9 percent); Riverine, 144,000 acres (0.2 percent,; and Marine, 28,000acres (len than 0.1 percent).

3NonFederal public ownership categories with U.S. totals include: State, 10.292 million acres (79.7 percent); county, 1.518 millionacres (11.8 percent); Indian, 800,000 acres (6.2 percent); and municipal, 295,000 acres (2.3 percent).

4Includes all privately owned rural wetlands because wetland conversions to agriculture as the end use are not limited to areaspresently in farms. In 1982, about 16.3 million acres (25 percent) of the privately owned U.S. wetlands were used for grazing orcrops.

5lncludes Palustrine wetlands not grazed or cropped in 1982, having either forest, scrublshrub, or emergent vegetation char-acteristic of saturated soils. Loosely corresponds to wetland classes 1, 2, 3, 6, and 7, as defined by Shaw and Fredine (1956).

6Minimum conversion estimate represented by private Palustrine vegetated wetlands not used for agriculture in 1982 that, in thejudgment of conservatio-, specialists completing field observations for the National Resources Inventory, had eithera medium orhigh potential for conversion to cropland.

'Middle conversion estimate represented by private Palustrine generally vegetated wetlands not used for agriculture in 1982 thatwere designated land use capability classes Ilw and II lw in the NRI. These are lands that are suitable for crop production only withappropriate conservation management and if the wetness (w) plus the secondary limitations that restrict the choice of plants arecorrected. Acres by class are: Class Ilw (2 million acres) and class 111w (5.5 million acres). Capability classification systems aredetailed in Agricultural Handbook 210 (USDA, 1961).

8Conversion estimate as in 7 but with land use capability class Ilw also added. Class IV lands have severe limitations thatrestrict the choice of plants andlor require very careful conservation management. Class IVw lands account for about 5.4 millionacres (42 percent) of the maximum estimate for agricultural wetland conversions in the United States.

150

166

"Palustrine" wetlands as defined by Cowardin andothers (1979), including 1.3 million acres ofwetlands that could be brought into crop productionwithout drainage. About 95 percent of the 5.1million acres were Shaw/Fredine wetland types 1, 2,3, 6, and 7; nearly 80 percent were types 1 and 2.

The Daugherty/Lewis and Heimlich/Langner anal-yses thus suggest that an estimate of wetlands mostfeasibly drained and converted to cropland couldrange from 3.5 to 3.8 million acres. The flyway-based estimates in table 13-1 (total 2.5 millionacres) are lower because they are limited toprivately owned and to at least partially vegetatedPalustrine wetlands nut currently cropped or grazed;they are considered the wetland areas mostvulnerable to being converted from waterfowl

12

2

Ct

habitat to agriculture by drainage. The middle andupper estimates in table 13-1 (7.5 and 12.4 millionacres) cpply basic land-use capability considera-tions rather than convertibility judgments of techni-cians completing the 1982 NRI.

Waterfowl Values

In their 1956 study, Shaw and Fredine qualitativelydetermined areas having primary and secondaryvalue to waterfowl, for each of their 20 definedtypes of wetlands. Waterfowl habitat areas ofprimary concern are identified in figure 13-6.Weighting the Shaw-Fredine primary value percent-ages for types 1, 2, 3, 6, and 7 by the area in thesetypes in the 1982 inventory indicates that, for theUnited States as a whole, about 22 percent (9.4

18

0

Figure 13.6Major waterfowl habitats.

GULF OF MEXICO \'4

F..

.4

0

Priority Area Name1 Prairie Potholes and Parklands 12 Middle-Upper Pacific Coast2 Central Valley of California 13 Klamath Basin3 Yukon-Kuskokwim Delta 14 Upper Alaska Peninsula4 Middle-Upper Atlantic Coast 15 Copper River Delta5 Lower Mississippi River Delta and Red Riser Basin 16 West-Central Gulf Coast6 lzembek Lagoon 17 Upper Cook Inlet7 Upper Mississippi River and Northern Lakes 18 San Francisco By8 Northern Great Plains 19 NE United States - SE Canada9 Yukon Flats 20 Sandhills and Rainwater Basin

10 Intermountain West (Great Basin) 21 Playa Lakes11 Teshelpuk Lake

167 151

million acres) of the 42.7 million acres of remainingprivate t'alustrine vegetated wetlands theoreticallyconvertible to crop production are of primary valueto waterfowl, although Shaw and Fredine consideredall wetlands to have at least a "lesser" value forwaterfowl. Under the minimum conversion estimatein table 13-1, between 550,000 acres and 700,000acres (22-28 percent) of the wetlands drained andconverted to agriculture could be regarded as havingprimary value to waterfowl. For the middleestimate, the amount would be between 1.6 and 2.1million of the 7.5 million acres converted. The max-imum conversion would involve between 2.8 and 3.6million acres of wetlands having a primary value towaterfowl.

This brief examination of wetlands from the view-point of wildfowl and conversion questions alsoreveals that States within the Mississippi and Atlan-tic Flyways contain 81 percent of all non-Federalwetlands, 89 percent of State, county, and othernon-Federal publicly owned wetlands, and 80 per-cent of all privately owned wetlands (table 13-1).More important, these two humid-area flywaysapparently contain 92 percent of the vegetatedPalustrine wetlands not currently, in agriculture.

Smith and Massey observed that pressures for com-plete evaluation of-all wetland benefits for wildlife,hunters, farmers, and other interests will increasewith wider public recognition of their alternativeuses and their reduction to a remnant level. Someproducts of wetlands, such as waterfowl hunting,are more readily evaluated than others. Pending thecompletion of coordinated studies, opportunities forcombining information on the value of different usesdeveloped in separate studies and from independentsources should not be overlooked. The next sectionoutlines some of these possibilities.

Balancing Competing NaturalResource Values

Miller and Hay (1981) have studied the relationsh-pbetween wetland habitat availability, hunter success,and the level of duck hunting in the MississippiFlyway. This is a 14-State area extending throughMinnesota, Wisconsin, and Michigan, the entireCorn Belt, and the Mississippi Delta, plus Kentucky,Tennessee, and Alabama (fig. 13-1). Other approachesto determining waterfowl habitat values in theUpper Midwest were examined earlier by Goldstein(1971). Miller and Hay estimated that in 1975waterfowl habitat had a value (consumer surplusvalue) to duck hunters of $29 per day of hunting per

152

year, based on cited earlier work of Hay with Char-bonneau. Capitalized into the indefinite future at a7-3/8-percent discount rate in 1984 prices, thisamounted to $160 per acre of rost wildlife habitat.

A similar study for the Pacific Flyway by Hammackand Brown (1971) was based not on days hunted,but on the value hunters placed on a duck bagged,estimated at $9.80 per duck at 1984 prices. This con-verts to a capitalized value of about $220 per acreof habitat, assuming an average of 1.6 birds peryear are bagged per acre of habitat and again capi-talizing into the indefinite future at 7-3/8 percent.

These two research studies suggest that an acre ofwetlands available for duck hunting in 1984 had amarket value ranging from $160 to $220 per acre,for an average of $190 per acre. It is not advisableto relate precisely such wide-area values to themarginal values of particular wetlands if convertedto agriculture, so only broad estimates can be made.According to the 1978 Census of Drainage, therewere 20 predominantly agricultural counties withinthe 14-State Mississippi Flyway with 75 percent ormore of their land area drained (U.S. Dept. of Com-merce, 1981). The 20 counties are listed in table13-2. Figure 13-5 shows their general location. Fiveof the 20 counties are more than 90-percent drained:Mississippi County, Arkansas (59 percent);Mississippi County, Missouri (98 percent); HancockCounty, Ohio (96 percent); Dunklin County, Missouri(96 percent); and New Madrid County, Missouri (94percent).

The rationale for looking at counties already inten-sively drained is that, if not in agriculture, largeareas in these localities would have remained as orwould revert to wetlands and waterfowl habitat.Their present market values in agricultural use areguides to the market value of an additional acre ofwetlands converted to farming, though not neces-sarily in the same county. This value, less the netcost of conversion, can be related to waterfowlhunting values as an opportunity costone of aclass of benefits given up when draining wetlands.

Net conversion costs are actual draining and/orassociated clearing costs less the value of wood orother products removed in the process. For the ninecounties of table 13-2 located in the northern sectionof the Mississippi Flyway (Michigan, Ohio, Indiana,and Iowa), net conversion costs in 1984 averaged anestimated $550 per acre. Conversion costs for the11 counties located in the Southern section averaged$435 per acre (Herrington and Schulstad, 1978).

lCd

The next step is to subtract conversion costs frommarket values of farmland. According to the mostrecent Census of Agriculture and USDA sources, in1984 the market value of farmland withoutbuildings for: the 20 high-drainage counties withinthe Mississippi Flyway averaged $1,105 per acre(U.S. Dept. Commerce, 1983; Jones, 1985). This pro-vides a rough measure of the market value in 1984of an added acre of remnant wetlands within theMississippi Flyway converted to agriculture bydrainage and/or necessary clearing. Deducting a netconversion cost of $477 per acre, the added netagricultural market value would be $628 per acre.This is a farm use value to compare with the abovevalues of $160 to $220 per acre associated with notconverting additional wetlands to agriculture.

For situations similar to those in the 20 MississippiFlyway counties more than 75-percent drained,waterfowl hunting values in 1984 averaged 25 to 35percent of net agricultural values, depending onwhether the above Miller-Hay waterfowl huntingvalue of $160 per acre or the Hammack-Brownvalue of $220 per acre is compared with the netagricultural value of $628 per acre. If the twowaterfowl habitat value estimates are given equalweight (averaged to $190 per acre), the 1984 water-fowl values of wetlands within the MississippiFlyway were about 30 percent of the correspondingagricultural value of drained wetlands (table 13-2).But, this percentage ranged from 63 percent forconditions represented by Sharkey County,Mississippi, to 21 percent for conditions

Table 13.2 Waterfowl hunting values compared with agricultural values for the 20 agricultural counties in theMississippi Flyway where at least 75 percent of the farmland area is drained

Counties (States),Farmland

areadrained

Farmland value, 1984Relative

waterfowlvalues4

1984 1986

Salevalue2

Netvalue3

Percent Dollars per acre PercentSharkey (Mississippi) 80 735 300 63 124St. Francis (Arkansas) 85 760 325 58 140Clinton (Michigan) 88 875 325 58 154Shiawassee (Michigan) 86 890 340 56 141Mississippi (Arkansas) 99 960 525 36 67

Duni,:in (Missouri) 96 965 530 36 79Washington (Mississippi) 75 990 555 34 53Crittenden (Arkansas) 85 1,015 580 33 58New Madrid (Missouri) 94 1,045 610 31 64Mississippi (Missouri) 98 1,040 605 31 64

Paulding (Ohio) 86 1,225 675 30 62Crawford (Ohio) 83 1,250 700 27 58Hancock (Ohio) 96 1,305 755 25 52Jefferson Davis (Louisiana) 49 1,190 755 25 42Henry (Ohio) 86 1,345 795 24 49

East Carroll (Louisiana) 79 1,230 795 24 39Wells (Indiana) 75 1,385 C35 23 50Adams (Indiana) 82 1,400 850 22 49Pocahontas (Iowa) 80 1,475 925 21 69Acadia (Louisiana) 80 1,335 900 21 34

Average, 20 counties5 86 1,105 628 30 58

1Counties listed according to highest waterfowl hunting values re:ative to agricultural land values in 1984.2Land without buildings, based on Census of Agriculture for 1982 and Jones (1985).3Sale value less average net costs of draining or clearing and draining. Net drainage costs for listed counties in Mississippi,

Arkap'as, Missouri, and Louisiana averaged $435 per acre. These costs exceed drainage costs in chapter 11, averaged for thesefour States, by about 60 percent, indicating that substantial clearing and other preparation costs are lik.rly in converting southernwetland to agriculture. Costs for the remaining listed counties in the Northern States within the Mississippi Flyway (Michigan,Ohio, Indiana, Iowa) averaged $550 per acre. These costs exceed drainage costs in chapter 11, averaged for these four States, byabout 10 percent.

4Ratio of average waterfowl hunting value per acre ($190) to net farmland values for 1984 or 1986. The $190 per acre is theaverage of $16t) per acre and $220 per acre. See text.

5Averages based on 5.7 million acres in farms and 4.9 million acres drained in the 20 counties. Drainage intensities are assumedto be approximately the same in 1984 and 1986 as reported in the 1978 Census of Drainage (U.S. Dept. Commerce, 1981).

169 153

represented by Pocahontas County, Iowa, andAcadia County, Louisiana. It is interesting to notethat nearly the same fraction (80 percent) of thefarmland in these three counties is drained, butagricultural land values differ considerably.Excluding buildings, in 1984 values were $735 peracre in Sharkey County, $1,335 per acre in AcadiaCounty, and $1,475 per acre in Pocahontas County.

Waterfowl habitat values relative to the potentialagricultural values of remnant wetlands change asthe demands for and supplies of waterfowl habitatand farmland change. Lacking actual data, assumethat between 1984-86 habitat values and drainageconversion costs in the Mississippi Flyway werestable. Between 1984 and 1986 average farmlandvalues did fall except in New Jersey, Virginia. andNew England (USDA, 1986). Per entage decreases inaverage farm real estate val....1s per acre for theeight Mississippi Flyway States represented in table13-2 were: Iowa (-44 percent), Indiana (-34 percent),Ohio (-30 percent), Mississippi (-23 percent), andMississippi (-20 percent). The relative waterfowlvalues in table 13-2 were approximated by applyingpercentage statewide decreases in land values be-tween 1982, 1984, and 1986 to county land valuesreported in the 1982 Census.

The sensitivity f relative waterfowl values tochanging farmland values can be shown by compar-ing waterfowl .,alue indexes for 1984 and 1986.Between 1984 and 1986, the waterfowl value indexrose from 63 to 124 percent for Sharkey County,Mississippi. It rose from 58 to 154 percent forClinton County, Michigan. The relative value ofwetlands for waterfowl habitat increased more inthe northern than in the southern States of theMississippi Flyway because agricultural land valuesfell more in the northern States. For example, be-tween 1984 and 1986 the relative waterfowl valuepercentage rose from 21 to 69 percent for PocahontasCounty, Iowa, but from 21 to only 34 percent forAcadia County, Louisiana.

The average waterfowl value index for wetlands forthe 20 highly drained counties in table 13-2 as agroup rose from 30 to 58 percent between 1984 and1986. For all counties in table 13-2, nonagriculturalbenefits of wetlands other than waterfowl huntingvalues woulu need to be less significant in 1986than in 1984 to justify wetland preservation. Preser-vation of waterfowl habitat alone would be ;ustifiedfor the first four county situations in the table,although the situations are not necessarily typicalfor the entire county.

154 1 70

Under such conditions, the incentive to drain addi-tional wetlands is reduced in two ways: (1) Foroperators wishing to expand operations, the cost ofSimi iy purchasing additonal cropland as againstdraining wetlands for crop use would fall, and(2) existing landowner options for marketing water-fowl hunting values and/or other beneficial qualitiesof wetlands to hunters or public agencies, by meansof purchase, lease, or easements, would be moreattractive. How well the agricultural, nonagri-cultural, and environmental benefits of wetlandsare quantified or otherwise identified will determinethe ultimate success of such institutional arrange-ments for optimum wetland use.

The research opportunity suggested by these possibleoutcomes is to periodically update information likeCult in tables 13-1 and 13-2 for all flyways asfarmland values and recreational demands change.The fact that State Experiment Stations and USDAalready monitor land values on a regular basis formany other purposes would facilitate this workconsiderably.

Such research would enable environmentalists andpublic officials to identify localities where lease andpurchase of remaining true wetlands to farming in-terests would likely be the least costly. It would alsoimprove predictions on the future rate of wetlandconversions, based on anticipated waterfowl hunt-ing demands as well as anticipated demands for tilt:products of competing industries. These include notonly agriculture, but also forestry, resort, andresidential community development, and other activ-ities like airport construction. More specificanalyses of farm drainage adoption and optimumdesign decisions have been completed by Goldstein(1971), Irwin (1980), and Skaggs and Nassehzadeh-Tabrizi (1983).

Improving Drainage Information

Perceptions on the status and trends of wetlandsdepend on the amount and quality of data concern-ing the current extent of drainage. Governmentstatistics have tended to give an incomplete pictureof land drainage. Census-type data have been widelyused as the most authoritative sourca of information.However, they have been based at various times onthe Census of Agriculture, the Census of Drainage,the Census of Governments, annual SCS planningassistance progress reports, and ASCS cost-sharingreports. Not all farm operators know what part oftheir land is drained.

'Douglas Lewis contributed information for this section.

Although the definition of drainage has changed littleover time, specific data items have changed, ashave definitions of the relevant universe, such aswhat constitutes a farm, how drained irrigated landis considered, and what constitutes public versusprivate drainage enterprises. Moreover, it has notbeen possible to assess the effectiveness of a fferentdrainage improvements in different regions. As aresult, in official reports, all systems appear to beequally effective in removing excess water or soilfaits in the case of irrigation-associated drainage.

Another problem is that new drainage investmentshave not been reported separately from expendi-tures for maintenance. The 1983 Farm ExpenditureSurvey, conducted by NASS, was a first effort topick up both kinds of financial information.

A SCS and SCS reports are also limited to programparticipants and typically give only the cost-sharingportion of total investment. Some information isgiven in units sot easily integrated with other datasources. Periodic agency surveys have tended toaddress additional drainage needs rather than im-provements already in place. The 1982 inventoryconducted by SCS and a 1978 Resource EconomicsSurvey conducted by ERS attempted to correct thisproblem.

Given these limitations, caution is recommended inusing histo:ical agricultural land drainage data.Changes in policies and institutions affectingdrainage certainly change the benefits and costs ofdraining, both to individual farmers and society atlarge. Greater attention to societal interests meansthat the information needed for decisionmakingbecomes more complex. In short, increased effortsand expenditures to improve data collection areneeded to ensure a more accurate mosaic ofagricultural land drainage, thus permitting morerational private drainage investments and publicpolicy decisions.

USDA's role in farmland development throughdrainage has diminished considerably since itsagricultural conservation and resource improvementstarted in the 1930's. In 1960, drainage accountedfor about 9 percent of all conservation cost-sharingassistance to farmers; about 40 percent of thisassistance went for open drains compared with 60percent for subsurface or pipe drains. By 1983,drainage accounted foi only $51,(,00, or 0.02 percentof all ACP assistance. Also, in 1983, only 8 percentof the ACP assistance was for surface or opendrainage systems.

The minor USDA role in current drainage activitieswas also indicated in a 1978 Resource EconomicsSurvey (Lewis, 1982). During 1975-77, cost sharingand loan programs of USDA represented only about4 percent of the capital funds spent for onfarmdrainage improvements. Nearly 82 percent camefrom farmers' own funds. The remaining 14 percentwas obtained from loans.

The basic drainage information challenge, however,comes from another quarter. Legislation has beenpassed to discontinue the Census of DrainageOrganizations taken every 10 years since 1920 bythe Department of,Commerce. As already noted,USDA has eliminated drainage as a practicequalifying for cost-sharing assistance. USDA doesprovide technical assistance for draining wat soilsbut not for land classified as wetlands.

Governmental agencies unquestionably have beenone of the primary users of the information theydevelop at public expense for public use. But, as anagency's own drainage program activities are scaledback, its capacity to produce and even its interestin statistical information tend to weaken. Thechallenge, therefore, is to develop plans to acquirecoordinated information on farm and other drainageactivities, including wetland conversions, withoutrelying on Census-type and other formal data-gathering programs. This is an opportunity forwildlife, agricultural, forestry, and other commer-cial interests to pool their knowledge and resourcesfor research, management, and policymaking. Suchefforts will require the participation of allinterested sectors of the economy, including Federalagencies.

Maintenance and Repair Challenges

Open drains traditionally have not been maintainedin a timely manner which decreases their effective-ness. This is especially true for open drains used asoutlets for numerous onfarn*. drainage systems.Studies by Burris and others in Ohio (1985) showedthat the net benefit of an effective annualmaintenance program over periodic reconstruction(15-year cycle) averaged $12.70 per acre.

A good maintenance program for any type of drain-age system is just as necessary as proper designand constr-ntion. Sound maintenance plans shouldbe deveh,ped that consider system effectiveness aswell as environmental concerns. When systemsinvolve more than one landowner, the assignment ofresponsiblility for maintenance should be outlined

171 155

and agreed upon by the concerned parties in theoriginal plans.

Salinity and Water Quality Control

Drainage systems can help maintain salinity levelsin crop root zones within safe limits for cropproduction. Sound irrigation water management canreduce and, in some cases, eliminate the need forartificial drainage systems. Using drainage water asa supplemental source of irrigation is now receivingspecial attention. If successful, drainwater use forirrigation will reduce drainwater flow and thusease discharge problems that now exist or coulddevelop in arid and semiarid climates. Drainwaterquality is a growing concern, particularly for traceelements and the salt load. Efforts to handle theseproblems must be considered in all system designsand farming operations in these climates.

Drainage is Water Management

Agricultural drainage always has been viewed as aprocess of land conversion, improvement of the soilenvironment for plants either with or without irriga-tion, and elimination of operational hazards andnuisances. Drainage is now seen as a key aspect ofwater management, not as a purpose or activity initself. Water is the resource basically involved,whether the purpose is to remove or otherwise con-trol it on cropland, to avoid offsite wildlife andother environmental disbenefits from chemicallypolluted drain waters, to control salinity on irri-gated soils, or to limit the intrusion of agricultureand other land uses into wetland areas. No onedenies that large areas of former wetlands are nowin urban and agricultural uses (Shaw and Fredine(1955), Tiner, (1984), and U.S. Congress,(3984).T But,it is also true that neither surface nor subsurfacedrainage improvements, nor provisions for properdrainage on irrigated lands, necessarily mean a lossin wetlands as conventionally defined.

cite concept of drainage as water management haseven stronger support in new drainage systems basedon rainfall probabilities and in water controlsystems usable either for water removal or subirri-gation, depending on grcwing-seas-m variations insoil moisture conditions. Such systems are alreadyviewed as the best context for anticipating thefuture character of water management on farmsand for agriculture generally.

To consider drainage as water management is toadvocate a complete analysis of drainage benefits,

156

17 2

costs. and environmental impacts in particularcases. Nonagricultural aspects are acknowledged tobe very significant aLd variously include hydrologic,water quality, climatic, recreational, and educa-tional values (Thomas, chap. 5, and Bardecki, 1984).This does not mean such values have an importanceoverwhelming all others, although they maysupersede all others for prescribed areas orwetland types. It may be more meaningful as wellas less controversial to quantify these values from awater-resource rather than from a wetland vantagepoint.

As true wetlands are drained and converted toagricultural or other uses, most of the values said tobe lost are associated with a changed or impairedwater and aquatic plant environment, not withdrained land as such. Similarly, benefits from im-proved drainage in wet soils not consideredwetlands are associated with improved moistureand other soil conditions for crops and more effi-cient field operations. The result is essentially thesame when irrigated lands are adequately drained.

Within these newer concepts, several additionalchallenges call for policy attention and study of thefuture of farm drainage.

Agricultural drainage can have positive andnegative consequences, both on farms and offsite.The problem is that the consequences are fre-quently not associated with the original decision-maker, beneficiary, or loser. Further, some drainageactivities on farms are clearly neutral in theirconsequences. They may involve nonirrigated soilsor irrigated soils but not hurt wildlife and wetlands,at least not as generally defined. Separating theneutral from known or potentially controversialsituations is one way to simplify matters for policy-makers as well as for other scientists.

Fausey and colleagues observed that by increasingmoisture storage capacity, good drainage can re-duce runoff and erosion damage, thus improving theeffectiveness and durability of soil conservationmeasures like minimum tillage and grassed water-ways. Their observations illustrate how watermanagement strategies can have multiple onsite andoffsite benefits as well as costs and particular detri-mental effects. While many of the various purposesand effects of soil and water management asdescribed by agronomists, soil scientists, andengineers seem readily usable for structuring com-plete benefit/cost studies, not much economicresearch of this kind has.been done. It is importantbecause farm output-increasing or cost-decreasingstrategies like irrigation and drainage ar3 some-

times questioned as perhaps benefiting agricultureat society's expense, especially when water suppliesare being diminished and crops are in surplus.

Challenges for Research and Education

A first research and educational challenge is to in-crease our understanding of how all drainage bene-fits and costs, in both a direct and opportunitysense, can be related to each other in the sameframework in analyzing alternative private deri.-sions and public policies. In effect, this will removepotential market-failure situations as described byLangner (1985). It will also improve predictions onthe and location of additional drainage andthus on the likely nature of possible controversies,providing a rational basis for actually resolvingdisputes. It will require cooperation amongengineers, biologists, extension specialists, andsocial scientists throughout the research process,especially in the planning stag-%

Surveys and inventories are an important statisticalresource in benefiticost studies, but analysts needto proceed from similar definitions. The economicevaluation of the environmental costs of agriculturalactivities-requires survey data developed on an inter-disciplinary basis (Miranowski, 1983). Just as it ispossible to define away problems, it is also possibleto provoke them by arbitrary definitions and classi-fications tilting toward a particular but not agreed-upon point of view. Agricultural and environmentaladvocates can be expected to cooperate in examin-ing drainage if they agree, at least in principle, onthe expected costs and benefits of drainage, on thekinds of lands and soil conditions involved, and onthe environmental benefits or disutilities createdelsewhere.

Another research opportunity is implied in theSmith and Massey observation that past agri-cultural productivity projections were based onassumptions of competition. This is a situation inwhich there are many farms, with none individuallyhaving an appreciable influence on product pricesand input costs. P:T the most part, this stillcharacterizes A...ierican agriculture. A researchchallenge here is to study technological andmarketing activities in the drainage industry itself,given the reduced number of farmers, overcapacityproblems in agriculture, and concern over losses ofwetlands. The size, location, form of businessorganization, and probable public agriculturalpolicies for remaining farms, plus any remainingnatural limitations to production, will be the keys toanticipating where additional drainage will likelyOccur.

We close with a few recurring ideas. We do notknow enough about most of the real functions ofwetlands, especially noncoastal wetlands, to predictthe specific effects of either maintaining or drainingsuch wetlands for agriculture and other uses. Drain-ing hardwood bottomlands is an exception, becauseflood storage capacities of such wetlands can becalculated within reasonable limits of accuracy.

It follows that if the functions are not known andthe effects of wetland preservation or drainage arcnot known, it is difficult to formulate new drainagepolicies or develop programs to inform farmers,landowners, or policymakers about the value of re-taining wetlands. The same difficulties apply in in-creasing public awareness of the contributions ofagricultural drainage to public health, land settle-ment, and eccnomic development.

Efforts should be made to identify and measure allfunctional values of wetlands. Meanwhii.), real oppor-tunities exist for developing educational programsof more immediate interest to, and effectiveness for,farm operators and wildlife interests.

Many landowners attach no intrinsic value towetlands but view them as any other pieces of prop-erty. If the property has no intrinsic value and noapparent functional value, it must either be writtenoff as having no value or converted to something ofvalue. It follows that, in the absence of existingfunctional values, or the opportunity to developsuch values, conversion to other uses becomes theonly rational option. This challenge to researchersand educators can be expressed as a series of frankquestions.

Can programs be developed to manage wetlands toprovide some incentive for wetland retention and toprovide some tangible benefits to the farm oper-ator? Are there things that farmers themselvesmight do to increase the returns from retained wet-lands? Can their wetlands and those of other pri-vate landowners be managed to prods r,3 economicreturns in the form of trappable furbearers or leasedhunting rights? Can the waterfowl hunting valueslike those in table 13-2 be converted to landownerincome to maintain wetlands? Such programs wouldtake the question of wetland retention, at least insome cases, from the realm of abstract values totangible returns. The potential for such programshas been acknowledged within various Federalag3rcies (Tiner, 1984), but there is little identifiablemovement toward such programs.

Some recognition is beginning to emerge at the Statelevel (Harris and others, 1984; Malecki, 1985;

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Davidson, 1984). But, much of the literature con-tinues to deal with the generalities or potential fordrainage impacts on wetlands (Redelfs, 1983;Sullivan, 1985). They do not address the highlytechnical matters of actual impacts. Other studiesdiscuss the potential for legislative solutions ratherthan opportunities for enlisting the assistance oflandowners in protecting wetlands for their func-tional values (Kusler, 1983; Bell, 1981). Drainageand wetlands preservation of natural resource man-agement as a stable element of both depends onpublic policies and private actions that accom-modate both landowner and public interests.

References

Bardecki, Michael T 1984. "What ValueWetlands?," Journal of Soil and Water Conserva-tion. Vol. 39, No. 3, May-June, pp. 166-169.

Bell, H. E., II. 1981. Illinois Wetlands: Their Valueand Management. Illinois Institute of NaturalResources, Chicago.

Burris, Robert L., Dana C. Chapman, and Gary L.Overmein. 1985. Economics of Ditch Mainten ince inNorthwestern Ohio. Presented at Am. St.., of CivilEngineers Irrigation and Drainage Specialty Confer-ence, San Antonio, Tex., July 16-19.

Cowardin, Lewis F., Francis C. Golet, and Edward T.LaRoe. 1979. Classification of Wetlands and Deep-water Habitats of the United Str-tes.FWS/OBS-79/31. U.S. Dept. of the Interior, Fish andWildlife Serv.

Crosson, P. R. 1982. The Cropland Crisis - Myth orReality?. Resources for the Future, Inc., Wash., DC.

Davidson, B. 1984. "Texas Wetlands--A ValuableResource," Texas Water Resources,. Vol. 20, No. 1.Texas Water Resources Institute, College Station.

Frayer, W. E., T. J. Monahan, D. C. Bowden, and F.A. Graybill. 1983. Status and Trench of Wetlandsand Deepwater Habitats in the Conte:: urinous UnitedStates, 1950's to 1970's. U.S. Dept. of the Interior,Fish and Wildlife Serv., and Department of Forestand Wood Sciences, Colorado State Univ., Ft.Collins.

Goldstein, Jon H. 1971. Competition for Wetlands inthe Midwest: An Economic Analysis. Baltimore:Johns Hopkins Press for Resources for the Future,Inc.

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Hammack, Judd, and Gardner. Mallard Brown, Jr.1974. Waterfowl and Wetlands: Toward Bioeco-nomic Analysis. Baltimore: Johns Hopkins Press forResources for the Future, Inc.

Harrington, Billy E., and Robert N. Schulstad. 1978.Conversion of Delta Woodland and Pasture to Crop-land: Economic Feasibility and Implications. Bulletin858. Arkansas Agr. Expt. Sta., Fayetteville.

Harris, L. D., R. Sullivan, and L. Badger. 1984. Bot-tomland Hardwoods: Valuable, Vanishing,Vulnerable. Florida Coop. Ext. Serv. SP-28. Univ.Florida, Gainesville.

Heimlich, Ralph E., and Linda L. Langner. 1986.Swampbusting: Wetland Conversions and Farm Pro-grams. AER-551. U.S. Dept. of Agr., Econ. Res. Serv.

Irwin, Ross W. 1980. On-Farm Drainage Benefit.Final Report Project A-39-742. Univ. of Guelph,School of Engineering, Guelph, Ontario.

Jones, John F. 1985. U.S. Dept. Agr., Econ., Res.Serv. Special data developed for authors.

Kusler, J. A. 1983. Our National Wetland Heritage:A Protection Guidebook. The Environmental Law In-stitute, Wash., DC.

Langner, Linda L. 1985. Economic Perspective onthe Effects of Federal Conservation Policy on Wild-Life Habitat. Transactions, North American Wildlifeand Natural Resources Conferences, Wa3h., DC.March 18-20.

Lewis, Douglas. 1982. Land Drainage InvestmentSurvey, 1975-77. ERS Staff Report No. AGES820505.U.S. Dept. Agr., Econ. Res. Serv.

Madsen, John. 1984. "American Waterfowl:Troubles and Triumphs," National Geographic. Vel.166, No. 5, pp. 562-599.

Malecki, R. 1985. "Agriculture and Wetlands: ANew Perspective," New York Food and Life ScienceQuarterly. Vol. 15, No. 3, pp. 11-13. New York StateAgri. Exp. Sta., Ithaca.

Miller, Jon R., and Michael J. Hay. 1981. "Deter-minants of Hunter Participation: Duck Hunting inthe Mississippi Flyway," American Journal of Agri-cultural Economics. Vol. 63, No. 4, pp. 677-684.

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Miranowski, John A_ 1983. "Agricultural Impacts onEnvironmental Quality," Water Resources Research:Problems and Potentials for Agriculture and RuralCommunities. Ankeny, Iowa: Soil Conservation Societyof America.

Pioneer Hi-Bred International, Inc. 1q82. Soil Con-servation Attitudes and Practices: The Present andthe Future. Des Moines, Iowa.

Redelfs, A. E. 1983. Wetlands Values and Lossef., inthe United States. M.S. thesis, Oklahoma StateUniv., Stillwater.

Shaw, Samuel P., and C. Gordon Fredine. 1956.Wetlands of the United States. Circular 39. U.S.Dept. Interior, Fish and Wildlife Serv.

Skaggs, R. W., and A. Nassehzadeh-Tabrizi. 1983.Optimum Drainage for Corn Production. TechnicalBulletin No. 274. North Carolina Agri. Res. Serv.,State Univ., Raleigh.

Sullivan, J. D. 1985. Stream Channelization in NewYork: Impacts on Agriculture and the Environment.M.S. thesis. Cornell University, Ithaca, N.Y.

Tiner, R. J., Jr. 1984. Wetlands of the United States:Current Status and Recent Trends. U.S. Depi. In-terior, Fish and Wildlife Serv.

U.S. Congress, Office of Technology Assessment.1984. Wetlands: Their Use and Regulation. March.

U.S. Department of Agriculture, Economic ResearchService. 1986. Outlook and Situation Summary;Agricultural Resources, April 9.

U.S. Department of Agriculture, Soil ConservationService. 1961. Land Capability Classification.AH-210.

U.S. Department of Agriculture, Soil ConservationService and Iowa State University. 1982. BasicStatistics, 1977 National Resources InventorySB-686. (Statistical Bulletin in process for 1986 In-ventory; wetland data retrievable from computerfiles).

U.S. Department of Commerce. 1981. "Drainage ofAgricultural Lands," Census of Agriculture, 1978.Vol. 5: Special Reports, part 5.

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Appendix A

Executive Order 11990:Protection of Wetlands

(Federal Register, Vol. 42, No. 101,Wednesday, May 25, 1977)

By virtue of the authority vested in me by the Con-stitution and statutes of the United States ofAmerica, and as President of the United States ofAmerica, in furtherance of the National Environ-mental Policy Act of 1969, as amended (42 U.S.C.4321 et seq.), in order to avoid to the extent possiblethe long and short term adverse impacts associatedwith the destruction or modification of wetlandsand to avoid direct or indirect support of newconstruction in wetlands wherever there is a prac-ticable alternative, it is hereby ordered as follows:

.Section 1. (a) Each agency shall provide leadershipand shall take action to minimize the destruction,loss or degradation of wetlands, and to preserveand enhance the natural and beneficial values ofwetlands in carrying out the agency's responsibil-iths for (1) acquiring, managing, and disposing ofFederal lands and facilities; and (2) providingFederally undertaken, financed, or assisted con-struction and improvements; and (3) conductingFederal activities and programs affecting land use,including but not limited to water and related landresources pla 'ning, regulating, and licensingactivities.

(b) This Order does not apply to the issuance byFederal agencies of permits, licenses, or allocationsto private parties for activities involving wetlandson non-Federal property.

Sec. 2. (a) In furtherance of Section 101(b)(3) of theNational Environmental Policy Act of 1969 (42 U.S.C.4331(b)(3) to improve and coordinate Federal plans,functions, programs and resources to the end thatthe Nation may attain the widest range of beneficialuses of the environment without &gradation andrisk to health or safety, each agency, to the extentpermitted by law, shall avoid undertaking or provid-ing assistance for new construction located in wet-lands unless the head of the agency finds (1) thatthere is no practicable alternative to such construc-

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tion, and (2) that the proposed action includes allpracticable measures to minimize harm to wetlandswhich may result from such use. In making this find-ing the head of the agency may take into accounteconomic, environmental and other pertinentfactors.

(b) Each agency shall also provide opportunity'or early public review of any plans or proposalsfor new construction in wetlands, in accordancewith Section 2(b) of Executive Order No. 11514, asamended, including the development of proceduresto accomplish this objective for Federal actionswhose impact is not significant enough to requirethe preparation of an environmental impact state-ment under Section 102(2)(C) of the National En-vironmental Policy Act of 1969, as amended.

Sec. 3. Any requests for new authorizations orappropriations transmitted to the Office of Manage-ment and Budget shall indicate, if an action to beproposed will be located in wetlands, whether theproposed acts )11 is in accord with this Order.

Sec. 4. When Federally-owned wetlands or portionsof wetlands are proposed for lease, easement, right-of-way of disposal to non-Federal public or privateparties, the Federal agency shall (a) reference inthe conveyance those uses that are restricted underidentified Federal, State oz local wetlands regula-tions; and (b) attach other appropriate restrictionsto the uses of properties by the grantee or pur-chaser and any successor, except where prohibitedby law; or (c) withhold such properties fromdisposal.

Sec. 5. In carrying out the activities described inSection 1 of this Order, each agency shall considerfactors relevcnt to a proposal's effect on the sur-vival end quality of the wetlands. Among these fac-tors are:

(a) public health, safety, and weilare, includingwater supply, quality, recharge and discharge; pol-lution; flood and storm hazards; and sediment anderosion;

(b) maintenance of natural systems, includingconservation and long term productivity of existingflora and fauna, species and habitat diversity andstability, hydrologic utility, fish, wildlife, timber,and food and fiber resources; and

(c) other uses of wetlands in the public interest.including recreational, scientific, and cultural uses.

Sec. 6. As allowed by law, agencies shall issue oramend their existing procedures in order to complywith this Order. To the extent possible, existing pro-cesses, such as those of the Council on Environ-mental Quality and the Water Resources Council,shall be utilized to fulfill the requirements of thisOrder.

Sec. 7. As used in this Order:

(a) The term "agency" shall have the samemeaning as the term "Executive agency" in Section105 of Title 5 of the United States Code and shall in-clude the military departments; the directives con-tained in this Order, however, are meant to applyonly to those agencies which perform the activitiesdescribed in Section 1 which are located in oraffecting wetlands.

(b) The term "new construction" shall includedraining,, dredging, channelizing, filling, diking, im-pounding, and related activities and any structuresor facilities begun or authorized after the effectivedate of this Order.

(c) The term "wetlands" means those areasthat are inundated by surface or ground water witha frequency sufficient to support and under normalcircumstances does or would support a prevalenceof vegetative or aquatic life that requires saturatedor seasonally saturated soil conditions for growthand reproduction. Wetlands generally includeswamps, marshes, bogs, and similar areas such assloughs, potholes, wet meadows, river overflows,mud flats, and natural ponds.

Sec. 8. This Order does not apply to projectspresently under construction, or to projects forwhich all of the funds have been appropriatedthrough Fiscal Year 1977, or to projects and pro-grams for which a draft or final environmental

impact statement will be filed prior to October 1,1977. The provisions of Section 2 of this Order shallbe implemented by each agency not later thanOctober 1, 1977.

Sec. 9. Nothing in this Order shall apply toassistance provided for emergency work, essentialto save lives and protect property and public healthand safety, performed pursuant to Sections 305 and306 of the Disaster Relief Act of 1974 (88 Stat. 148,42 U.S.C. 5145 and 5146).

Sec. 10. To the extent the provisions of Sections 2and 5 of this Order are applicable to projectscovered by Section 104(h) of the Housing andCommunity Development Act of 1974, as amended(88 Stat. 640, 42 U.S.C. 5304(h)), the responsibilitiesunder those pnvisions may be assumed by theappropriate applicant, if the applicant has alsoassumed, with respect to such projects, all of theresponsibilities for environmental review, decision-making, and action pursuant to the NationalEnvironmental Policy Act of 1969, as amended.

The White House Jimmy CarterMay 24, 1977

Protection of Wetlands

(Statement by the President Accompanying ExecutiveOrder 11990. May 24, 1977)

The Nation's coastal and inland wetlands are vitalnatural resources of critical importance to the peopleof this country. Wetlands are areas of great naturalproductivity, hydrological utility, and environmentaldiversity, providing natural flood control, improvedwater quality, recharge of aquifers, flow stabilizationof streams and rivers, and habitat for fish andwildlife resources. Wetlands contribute to theproduction of agricultural products and timber, andprovide recreational, scientific, and aestheticresources of national interest.

The unwise use and development of wetlands willdestroy many of their special qualities and impor-tant natural functions. Recent estimates indicatethat the United States has already lost over 40percent of our 120 million acres of wetlands inven-toried in the 1950's. This piecemeal alteration anddestruction of wetlands through draining, dredging,fill:ng, and other means has had an adversecumulative impact on our natural resource and onthe quality of human life.

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The problem of lost of wetlands arises mainly fromunwise land use practices. The Federal Governmentcan be responsible for or can influence thesepractices in the construction of projects, in themanagement of its own properties, and in the provi-sions of financial or technical assistance.

In crder to avoid to the extent possible the long andshi:rt term adverse impacts associated with thedestruction or modification of wetlands and to avoidat set or indirect support of new construction inwetlands wherever there is a practicable alternative,I have issued an Executive Order crti the protectionof wetlands.

Appendix B

Selected State DrainageAuthorities

Carmen Sandretto and Dean T. Massey

For all States with established public drainageorganizations, the basic enabling statutes determinethe types of organization permitted. In some States,the authority to establish drainage districts isconferred by the legislature on the governing bodyof the county in which the largest portion of theaffected area is situated. In other States, theauthority is vested in counties, or in district orcircuit courts. The clerk of the superior court isvested with this authority in some jurisdictions(North Carolina is one example). Boards of drainagecommissioners have jurisdiction in others.

Drainage authorities for California, Illinois, Indiana,Michigan, North Carolina, and Ohio are herein sum-marized and provided as examples of differentsystems. (References consulted appear at the end ofthe basic text chapter on Drainage Institutions).These six States account for about one-third of theagricultural land drained in the United States(Bureau of the Census, 1081).1 While the statutesare somewhat similar for any public drainage orga-nization, they reflect adaptation of general prin-ciples to the particular needs of individual States.Several uniform requirements are: (1) the drainageactivity must, in addition to improving or reclaimingagricultural land, be beneficial to the public health,utility, or welfare; (2) the cost of the drainage worksmust not exceed the estimated benefits to be derivedby the land affected; and (3) the indebtednessincurred must not exceed the actual assessmentslevied for the purpose of liquidating such debts.

1References cited in app-iidix B are listed in the References

In some States, a system of county drainage districtshas been created; in others, special drainagedistricts have been formed (Illinois has the largestnumber of these organizations). Of the six Statesdiscussed here, California, Indiana, Michigan; andOhm ht. a county drainage districts, and also haveprovisions for intercounty or interstate drainagedistricts if circumstances warrant such ,ointventures. California permits the formation ofdistricts with a primary purpose other thandrainage, such as irrigatim, but the districts maycarry out drainage as a secondary purpose. Illinois,Indiana, and Ohio authorize multipurpose districtsthat include agricultural drainage as one of theirfunctions. In Indiana, separate funds are employedto finance the various functions carried out by thedrainage organization. In Ohio, soil and waterconservation districts can also implement drainageimprovements. Several types of cost-sharing arrange-ments are available in Ohio, including provisions forState help in financing.

California

California authorizes the creation and operation ofcounty drainage districts, of special districts withdrainage as a secondary purpose, and of theSacramento and San Joaquin Drainage District.

The creation of a county drainage district is initiatedsection of chapter 10. by a petition signed by at least 100 owners or at

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least 50 percent of the owners of real propertywithin the proposed district. This petition is submit-ted to the county board of supervisors, which thenadopts and publishes a resolution stating its intentionto create a district and setting a date for a publichearing on the petition.

After the public hearing, the board of supervisorsmay issue an order forming a district. That ordernames the district and describes its boundaries,which may be set to include areas within a villageor city if the governing boards of those areasapprove. However, if 10 percent of the district'sregistered voters so request, the county board ofsupervisiors must first submit the -..eation of adistrict to a vote.

The governing body of a district is a board of direc-tors consisting of at least five members. If thedistrict does not inch,de any incorporated areas,the county board of supervisors serves as the boardof directors. Boards of directors of districts con-taining incorporated areas are comprised of thepresiding officer of each city or village within thedistrict, the chairperson of the county board ofsupervisors, a member of the governing body ofeach city or village within the district (other thanthe presiding officer), and two members of the countyboard of supervisors (other than the chairperson).

A county drainage district in California has theauthority to acquire, hold, and use real and personalproperty whin the dist.xt; to exercise powers ofeminer domain; to make and accept contracts; toemploy personnel; to acquire, construct, andoperate all types of land drainage systems; and tosell property. District directors can also adoptordinances relating to the operation of a district inthe same manner as a county board of supervisors.

Before constructing a drainage system or holding avote on the issuing of bonds, a general survey mustbe prepared on any problems anticipated in protect-ing the land within the district from storm, overflow.or waste waters. Survey documents include a gen-eral description of the work to be performed,general plan and general specifications of theproposed work, any property to be acquired, andestimated cost for the proposed work. If the generalsurvey is approved, precise plans and specificationsare prepared. Work may begin after the final plansare adopted by a four-fifths majority of the board.

District boards are empowered to levy and collecttaxes, borrow money and incur indebtedness, and

direct payment of all lawful claims against thedistrict. Taxes may be levied on the equalizedassessed value of all taxable real property in thedistrict to assist in repaying bonds, as well as thecost of maintaining, operating, extending, or repair-ing any work or improvements.

Special assessments to cover the costs of drainageconstruction may be levied against the property inthe district benefited if approved by four-fifths ofthe district board of directors. County drainagedistricts are also empowered to charge and collectfees for providing and operating storm drainagefacilities.

Bonds may be issued after the district board liasapproved the general survey and after the issuancehas been approved by two-thirds of the registeredvoters in the district casting votes in a specialreferendum. A district may not incur an indebted-ness exceeding 15 perce.z. of the assessed value ofall taxable real property in the district. Proceedsfrom the sale of bonds can only be used for acquiringproperty and performing construction work.

California also permits the formation of spe-ialpurpose districts that may have a primary purposeother than drainage, but that can also carry outdrainage as a secondary purposo. Irrigation dis-tricts, for example, are permitted to provide fordrainage made necessary by irrigation. Suchdistricts may be created upon petition by owners ofland irrigated from a common source and by thesame system of works.

Special purpose districts include reclamationdistricts empowered to construct, maintain, andoperate drains, canals, sluices, water gates, levees,pumping plants. dams, aiversion works, or irrigationworks. The purpose of these districts is to reclaimland subject to ove:flow or to incursion from tidalor inland waters. These districts are created uponpetition of owners of one-half or more of any landssubject to flood or overflow, susceptible to reclama-tion and who desire to reclaim the land. Anotherspecial purpose district, the levee district, operatesto protect land from overflow. Drainage is also oneof the several special purposes of water conserva-tion districts.

The Sacramento and San Joaquin Drainage District,located in the 5-million-acro San Joaquin Valley,was formed under California statutes in 1913, andis managed and controlled by a seven-memberreclamation board appointed by the governor. Thedistrict constructs, maintains, and operates ditches,

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canals, pumping plants, and other drainage works.The board adopts plans for a project, estimatescosts and expenses, and may then levy assessmentsupon lands benefited within the district for workperformed.

Illinois

The civil-law principles of natural drainage apply toall Illinois farmlands, regardless of whether theyare in drainage districts. However, natural drain-age rules do not adequately meet the needs of land-owners in many parts of the State. To cover theinadequacies of natural drainage rules and to pro-vide landowners with a means for securing properdrainage, the legislature passed laws p.:oviding fordrainage districts based on a system of assessmentswhich permit districts to include only lands bene-fited (Hannah, Krauz, and Uchtmann, 1979).

All drainage districts in Illinois are subject to thefollowing general principles:

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1. Assessments can be levied only against landwhich is benefited.

2. Assessments on land cannot exceed thebenefits which the land will receive.

3. Drainage districts are public corp-rationscharged with specific governmental functions.If necessary, the districts may acquire rightsin land by instituting eminent domainproceedings and paying just competratirn tothe owner.

4. Assessments are not limited tc, land alonebut may be levied against improvements,provided that there are benefits to theimprovements.

5. Benefits, or the estimated value of theproposed drainage works to a particularproperty, are not limited to agricultural orsanitary benefits, but may include otherkinds, such as those for a railroad ormanufacturing concern. The efore, a0000-ments may be levied against such property.

6. Landowners are entitled to a hearing on thequestion of benefits before tl. iy can be com-pelled to pay drainage assessment

7. Drell ge districts are dependent solely uponstatute, and these statutes must be fulfill 4:1to make their organization legal.

In Illinois, landowners in the proposed drainagedistricts initiate organization by filing a petition inthe circuit court of the county in which most of theproposed district lies. The petition must be signedeither by a majority of the landowners who ownone-third of the land, or by one-third of the land-owners who own a majority of the land. A petitionsigned by one-tenth of the landowners who own atleast one-fifth of the land is also valid, but then areferendum is also required.

Any petition must include the name of the proposeddistrict, a statement showing its necessity, adescription of the proposed work, a description ofboundaries and approximate area of the lands thatwould -be affected, +he names of landowners, and aformal request for the organization of the districtand appointment of commissioners.

After the court finds for the petitioners, the countyboard or chief executive officer appoints three com-missioners. These commissioners must examine theland and prepare a report showing the feasibility ofthe proposed project, its probable annual cost, whatlands will be benefited and the F -gregate benefits,whether aggregate benefits equal or exceed costs,and whether the proposed district includes all thelands benefited. The commissioners may alter theplan in the petition to secure maximum benefits andminimize damages.

The activities of Illinois drainage districts may befinanced through assessments, loans or grants,notes, or bonds (with specific limitations on bondingauthority). The scop of activities for drainagedistricts includes drainage planning as well as theconstruction and maintenance of improvements forflood control, conservation, regulation, utilization,and disposal of water and water resources.

In carrying out their activities, drainage districts in'ninth: lay cooperate aria enter into agreementswith other kinds of districts, proper Federal orState agencies, and municipal corporations. Provi-sions exist for annexation or detachment of landsand for the consolidation of drainage districts. Thedissolution of drainage districts may be initiated bypetition from at least three-fourths of the adult land-owners who own not less than three-fourths of theland or by a majority of the drainage commis-sioners. The court may order dissolution after ahearing, provided that the district is free of debt,that no contracts will be impaired, and that thecosts of dissolving the district are advanced by thepetitioners.

tEO

Indiana

Indiana has a system of county drainage boards.Each board consists of three appointees who mustbe resident freeholders of the county andknowledgeable in drainage matters. In addition, theelected county surveyor serves on the board as anex officio, nonvoting member.

Each regulated drain in a county is under thejurisdiction of the board, but private and mutualdrains are handled separately. However, landdrained by a private or mutual drain is subject toassessment for construction, reconstruction, orMaintenance as a regulated drain if any part of theland is drained by a regulated drain.

The county surveyor is the technical authority onthe construction, reconstruction, and maintenanceof all regulated drains or proposed regulated drainsin the county. The county surveyor classifies allregulated drains in the county as drains in need ofrecorstruk " a, maintenance, or abandonment, andsubmits a written report setting forth the classifica-tion of regulated drains in order of priority foraction by the toard.

In determining the benefits of drainage, thesurveyor and board may consider a number of fac-tors, including the charac:aristics of the watershed,soil type, land use and number of acres in eachtract, and the increased value accruing to eachtract from the construction, reconstruction, ormaintenance of drains.

Each county has a general drain improvement fundto pay the cost of constructing or reconstructing aregulated drain. A meint mauce r -id for eachregulated drain is used for the ne 3sary repair ormaintenance of that particular drb.n.

If the board determines that the cost of constructingor reconstructing a particular drain is in excess ofthe amount that assessed landowners may conven-iently pay in installments over a 5-year period, itmay authorize the sate of bonds to finance the proj-ect. A redemption fund is then established for eachproiect for vhich the board authorizes the sale ofbonds.

Indiana drainage codes also contain provisions forhandling situations involving more than one county,municipalities, interstate drains, and cooperativeprojects with State or Federal agencies.

Michigan

Michigan has a system of drainage organizationsbased on individual counties plus a number of inter-county drainage districts. Of the 83 counties in theState, approximately 70 have an elected countydrain commissioner. In the remaining counties(usually those with small populations, littleagriculture, and limited drainage problems), thecounty road commission handles the drainagematters within its jurisdiction.

Intercounty drainage districts exist in places wheredrains ::ross county boundaries. In these cases, adrainage board is organized to administer the inter-county drainage district. The board is composed ofa representative from the Michigan Department ofAgriculture and of drain commissioners from theaffected counties.

County drainage systems in Michigan are supportedthrough special taxes levied on properties thatbenefit from the drp',iagc facilities. The countydrain commissioners assess the tax on the basis of adetermination of the beneficial effects to individualproperties.

No4h Carolina

In North Carolina, drainage districts are consideredpolitical subdivisions of the State. They areestablished by petitioning the clerk of court, withthe petition specifically, identifying the lands involvedand the proposed drainage or reclamation activity.All landowers in the district must be notified ofthe proposal. The c:erk, upon receipt of the petition,appoints a disinterested board of viewers to examinethe land and project, and to report back to theclerk. The feasibilLy, benefits, and necess_cy of theproject are all determined.

After the district is formally established, the boardof viewers classifies the lands therein according tofive types based upon the extent of benefits. Afternotine And hearing, this ...,yva 'so clip ,ubjeut-toclerk of court approval. It may be further appealedto superior court.

After the district is established, it is operated by anelected board of drainage commissioners, with atreasurer appointed by the clerk of court. Theboard is the central decisionmaking authority,although some items are subject to approval by beclerk of court.

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The construction or improvement process iscontrolled by an appointed superintendent of con-struction or engineer. The contract-letting is subjectto public notice and sealed bidding, with thecontract tvised upon the board of viewers' finalreport, which is fixed with the clerk. The drainagecommissioners have control of the maintenance Lndrepair of the project after completion.

Because the establishment of new districts hasdecreased over time, organized drainage activitiesin North Carolina are currently concerned mostlywith the improvement, renovation, enlargement, andextension of canals and other existing works. Theprocedure for improving and enlarging the originalproject is again a step-by-step process involving thecommissioners, the clerk of court, a separate boardof viewers, notice of and hearing on any proposal,and the opportunity for appeal to the superiorcourt. The feasibility, benefit, and necessity of theimprovement or enlargement is determined onlyafter notices and hearings.

The authority for the collection of costs is specified.Initially, the cost of the projects plus 3 years'maintenance is certified to the clerk. placed in a'drainage record, and collected on annual basis.An assessment roll is :o be prepared by the boardof drainage conunissimors, specifying the owners ofland and the amount of assessment.

The commissioners may levy annual maintenanceassessments based upon the previous classificationsof land. The amount of assessment is subject toclerk of court approval, and collection is the respon-sibility of the county tax collector.

Ohio

Drainage laws in Ohio are broad in scope and areadmiestered by the boards of county commissioners.A wide variety of drainage-related improvementsmay be planned, financ-id, and constructed, usingeither the petition procedure or the mutual agree-ment procedure. When drainage improvement af-fects land in two or more coui:ties, the proceedingsAre conducted by a.inint hoard of county conunmis-sioners. A representative of the director of the OhioDepartment of Natural Resources is an ex officiomember of the joint board but able to vote only inthe case of a tie.

The petitioning procedure may be initiated by anybenefiting owner(s) or public body and filed with theboard of county commissioners. The Loard of county

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1b2

commissioners, the county engineer, and otherinterested parties view the proposed drainage im-provement. The first hearing is held after propernotification of affected owners, and the county thenfiles a proliminim report, including an estimate ofcost, comments on feasibility of the project, and theengineer's opinion as to w)- ither benefits from theproject are likely to exceed the estimated cost.

If the board of county commissioners grant; thepetition, the county engineer is respowible for mak-ing surveys, developing plans, and estimating thecost of construction. The plans must provide for ero-sion and sediment control measures as part of thepermanent improvement. If the land requiredexceeds specified amounts, the owner(s) shall becompensated by removal of the extra land from thetaxable valuation of the property. A schedule ofassessments of benefits and damages may be pre-pared, but as an alternative, the boa& countycommissioners may pass a resolution to levy a taxon all the property listed and assessed for taxationin the county to cover the construction and main-tenance costs of a drainage improvement (Nolte,1981).

All landowners wl. 3e name._ in the countyengineer's schedule of assessments and damagesmust receive proper notice of the final hearing. Theboard determines when assessments are to be paidand whether bouis are to be issued, and orders thecounty engineer to let contracts ;or, r-nstruction.Upon completion of construction, Ce assessmentsare adjusted pm rata from the estimated to thefinal cost. This assessment plus maintenance costsfor 1 year are levied upon each parcel of land.

The board of county commissioners establish9s andmaintains a fund for the repair, upkeep, and perma-nent maintenance of each drainage improvement,obtained through an annual assessment upon thebenefited owners. Any owner may apply for areduction in the maintenance assessment to allowfor work the owner proposes to do on any portion ofa public ditch, watercourse, or other improvement.The cow / engineer recommends the reduction inthe maintenance assessment, and the board confirmsor rejects the allowances.

The board of county commissioners may grant anyowner a reduction of not more than 50 percent ofthe annual maintenance assessment provided thatsuch owner has filed with the county engineer pro-per certification from the board of the soil andwater conservation district r the county where theland is located. Such an owner must follow certain

practices in the cultivation or management ofagricultural land, practices that are designed toreduce surface water runoff and erosion of sedimentand silt into drainage channels. The county engineer:las the right to inspect the premises of any ownerclaiming assessment reduction and to ask the soiland water conservation district to review any cer-tificate on file. Such a certificate remains in effectuntil canceled by the board of county commissioners(Nolte, 1981).

The board of county commissioners, with the adviceof the county engineer, may also enter into agree-ments with local soil and water conservationdistricti for the purpose of planning, constructer -',or maintaining drainage improvements. Certaintypes of drainage improvements cue eligible for Statefinancial assistance (Nolte and Derickson, 1976).

The legislature has established a rotary fund tohelp pay initial expenses, including the costs ofsurveys, plans, and appraisals for soil and waterconservation. Applications ,for -a repayable advancefrom the rotary fund are submitted to the Ohio Soiland Wafer Conservation Commission by the boardof county commissioners.

Applications for cost-share funds are submitted bythe board of county commissioners to the Ohio Soil

Appendix C

Acknowledgments andContributors

This cooperative publication was planned by an adhoc committee including James L. Fouss, Agri-cultural Research Service; Walter J. Ochs, Soil Con-servaton Service; George A. Pavelis, EconomicResearch Service; Paul E. Echleusener, CooperativeState Research Service; Fred Swader, ExtensionService; and Jan van Schilfgaarde, AgriculturalResearch Service. Raymond L. Brkige, Division ofInformation, Economics Management Staff, assistedwith eaely editork! suggestions. James R. Carlin andother staff of the Infor.nation Division assisted withedi..ing, design, art preparation, slid publication.

and Water Conservation Commission. Agreementsmay be authorized to provide up to 50 percent ofthe non-Federal cost of construction of an approvedimprovement.

The mutual agreement procedure applies in Ohiowhen one or more owners desire to join in theconstruction of a drainage improvement and arewilling to pay the cost of construction. The mutualagreement, with plans approved by a registeredprofessional engineer and with construction sched-ules, is submitted to the clerk of the board of countycommissioners, and iareviewed by the county engi-neer. The county engineer prepares benefit assess-ment schedules for maintenance purposes, and theboard of county commissioners holds a hearing toapprove the schedules.

The landowners contract for and pay the cost of theconstruction plus the estimated cost of maintenancefor 1 year. The construction must be acceptable tothe county engineer and certified to be in accord-ance with the plans. The improvements and mainte-nance are under the direction of the board of countycommissioners and are funded by an annual assess-ment upon the benefited owners (Nolte, 1981).

The various chapters of this publication were exten-sively reviewed and discussed by authors andothers at a Drainage Workshop in Denver, Colorado.April 11-12, 1984. Woi.shop Advisors wereProfessor David J. Allee, Department of AgriculturalEconomics, Cornell University; Professor Glenn 0.Schwab, Department of Agricultural Engineering.Ohio State University; Dr. Gerald B. Welsh,SCS/ARS Research Coordinator, Soil ConservationService, USDA; and Professor Lyman S. Willardson,Department of Agricultural and Irrigation Engineer-ing, Utah State University.

183 167

Courtesy copies of most chapters in draft wereinformally provided staff from the Fish and WildlifeService (,FWS), U.S. Department of the Interior, whodiscussed their National Wetlands Inventory andrelated activities at the workshop in Denver. GaryL. Hickman provided helpful comments on the initialmanuscript in June 1984. This USDA project wasreviewed further with FWS personnel in Washing-ton, DC, September 1984, and the completedpublication was reviewed by Dr. William 0. Wilenand other FWS staff. A number of photographs forthe work have been generously provided by FWSthrough Dr. Wilen, Coordinator of its NationalWetlands Inventory.

Others providing reviews, information, or editorialsupport included Professors Robert E. Beck ofSouthern Illinois University and Byron H. Nolte, Ex- Arthur B.tension Agricultural Engineer, Ohio-State University; Daughertyalso Susan Collins, Carla Eakins, Jane Kohlwey, andMarc Robertson of the University of Wisconsin-Madison. Swayne F. Scott, National IrrigationEngineer for the Soil Conservation Service, HenryStamatel, Assistant State Conservationist for NewYork (SCS), and Donald McCandless of the NortheastTechnical Center, SCS, provided reviews or specialinformation, as Economic Research Service staffDwight M. Gadsby, Ralph E. Heimlich, Gerald L.Horner, John E. Hostetler, and Gary C. Taylor.

James R. Carlin(Editorial Advisor)

Douglas A.Christensen

Division of InformationEconomics Management Staff,

USDAWashington, DC

EconomistSouth National Technical

Cen'3rSoil Conservation Service,

USDAFort Worth, Texas

Ann M. Crowell Federal Aviation Agency(Word-processing Washington, DC

assistance) (Formerly with EconomicResearch Service, USDA)

The present affiliations of authors and othersdirectly involved in the publication follow:

David J. Allee Professor of Economics(Advisor) Department of Agricultural

EconomicsCornell UniversityIthaca, New York

Eugene T. Doering

William E. Donnan

James L. Fouss

Linda G. Allen Bureau of Censur(Word-processing U.S. Department of Commerce

assistance) Washington, DC(Formerly with Economic Thomas C. G.

Research Service, USDA) Hodges

Glennis J. Beaird(Word-processing

assistance)

Resources and TechnologyDivision

Economic Research Service,USDA

Washington, DC

Keith H. Soil Conservation ServiceBeauchamp Engineer (ret.) Enid

ConsultingDrainage Engineer

605 Webster AvenueJacksonville, Illinois

168

184

Glen L. Hoffman

Agricultural EconomistResources and Technology

DivisionEconomic Research Service,

USDAWashington, DC

Agricultural EngineerNorthern Great Plains

Research CenterAgricultural Research

Service, USDAMandan, North Dakota

Consulting Drainage Engineerand former AgriculturalResearch Service Engineer

Pasadena, California

Agricultural EngineerAgricultural Research

Service, USDALouisiana State UniversityBaton Rouge, Louisiana

head, Economics, SocialSciences and EvaluationStaff

South National TechnicalCenter

Soil Conservation Service,USDA

Fort Worth, Texas

Research LeaderWater Management Research

LaboratoryAgricultural Research

Service, USDAFresno, California

Doug la:. Lewis

Dean T. Massey

Walter J. Ochs

Melville L. Palmer

George A. Pavelis

Ronald C. Reeve

Carmen Sandretto

Paul E.Schleusener

Divisions of Soil and WaterConservation

Department of NaturalResources arid CommunityDevelopment

State of North CarolinaRaleigh, North Carolina

Agricultural Economist andAttorney

Law School, University ofWisconsin

Madison, Wisconsin

Agricultural and RuralDevelopment Department

The World BankWashington, DC

Extension Agricultural- 'EngineerOhio State UniversityColumbus, Ohio

Resources and TechnologyDivision

Economic Research Service,USDA

Washington, DC

Drainage ConsultantColumbus, Ohio

Agricultural EconomistResources and Technology

DivisionEconomic Research S 3rvice,

USDAWashington, DC

Agricultural Engineer (ret.)Cooperative State Research

Service, USDAWashinpon, DC

Glenn 0. Schwab Professor of Soil and `mater(Advisor) Engineering

Department of Agi 'ulturalEngineering

Ohio State UniversityColumbus, Ohio

1 85

R. Wayne Skaggs

Stephen C. Smith

Gordon W. Stroup

Fred Swader

Jan vanSchilfgaarde

Carl H. Thomas

Profess, of Soil and WaterEngineering

Department of Biological andAgricultural Engineering

North Carolina StateUniversity

Raleigh, North Carolina

Associate DeanSchool of Natural ResourcesCollege of Agricultural and

Life SciencesUniversity of WisconsinMadison, Wisconsin

Drainage EngineerWestern National Technical

CenterSoil Conservation Service,

USDAl'ortland, Oregon

National Program Leader forWater ,lesources

Extension Service, USDAWashington, DC

Director, Mountain StatesArea

Agricultural ResearchService, USDA

Fort Collins, Colorado

Chief Biologist (ret.)Soil Conservation Service,

USDAWashington, DC

Gerald B. Welsh Research Coordinator,(Advisor) SCSIARS

Soil Conservation Service,USDA

Washington, DC

Richard Wenbw.g

Lyman S.Willardson

(Advisor)

National Drainage EngineerSoil Conservation Service,

USDAWashington, DC

Professor of IrrigationDepartment of Agricultural

and Irrigation EngineeringUtah State UniversityLogan, Utah

169

Appendix D

English and Metric Conversion Equivalents

English or metric units Multiplied by Gives

acac-ftcmcm2cm3cmIhrcir13/hrcm3/cm2ft3ft3/secgalgpmhahamkgkmkm2Itrmm/daym3mm/daymimi?yd3

170

acre 0.4047 haacre-feet 0.1233 ha-mcentimeter 0.3937 insq. centimeter 0.1550 in2cu. centimeter 0.0610 in3cm. per hour 0.3937 in/hrcu. cm. per hour 0.0610 in3/hrcu. cm. per sq. cm. 0.3937 in3/in2c l! . feet 0.0283 m3

cu. ft. per second 28.32 Itr/secgallon (U.S.) 3.7853 Itrgallons per minute 3.7853 Itr/minhectare 2.4710 achectare- meters 8.1080 ac-ftkilogram (1,000 g) 2.2046 lbskilometer (1,000 cn) 0.6214 misq. kilometer 0.3861 mi2

liter (1,000 cu. cm.) 0.2642 galmeter 39.3700 inmeters per day 39.3700 in/daycu. meters 1.3080 yd3millimeters per day 0.0394 in/daymile 1.6093 kmsq. miles 2.5900 km2cu. yard 0.7646 m3

186