use of enhanced ditch plugs

Hey and Associates, Inc.

Use of Enhanced Ditch Plugs andRiparian Wetlands to Reduce Nitrogenand Phosphorus Export from Small

Agricultural Watersheds

Neal O’Reilly, Ph.D., PHConservation and Environmental Studies

University of Wisconsin - Milwaukee


Partners

UWM- Conservation and Environmental Studies


“A Lake is A Reflection of its Watershed”

Source: Primary Components of a Watershed (Heathcote, 1998). Conservation and Environmental StudiesUWM- Conservation and Environmental Studies


“A Lake is A Reflection of its Watershed and Characteristics of its Floodplains and

Riparian Wetlands”

O’Reilly’s Corollary Conservation and Environmental StudiesUWM- Conservation and Environmental Studies


Water Quality Benefits of Floodplains

• Copper, J. R, J. W. Gilliam, R. B. Daniels, and W. P. Robarge. (1987). Riparian areas as filters for agricultural sediment. Soil Science Society of America Journal. 51:416‐420.

• Copper, J. R. and J. W. Gilliam. (1987). Phosphorus redistribution from cultivated fields into riparian areas. Soil Science Society of America Journal. 51:1600‐1604.

Conservation and Environmental StudiesUWM- Conservation and Environmental Studies



• Cooper et al (1987) monitored two small watersheds to determine the sediment and nutrient removal efficiencies of stream buffers.

• Copper found that stream buffers can reduce sediment delivery from cultivated fields between 84% and 90%and phosphorus by 50%(Copper et al, 1987, and Copper and Gilliam, 1987).




• Wetland Treatment for Water Quality

Wetland Type

Suspended Solids

Total Phosphorus NH3 Lead Zinc

Constructed 80 58 44 83 42

Natural 76 5 25 69 62

Source: (Strecker et. al. 1992)




• As we have developed the landscape into agriculture and urban areas we have not only modified the land use but also the drainage system and floodplains through ditching and tiling.




• In many watersheds most small storms do not even over top the banks of the stream and have limited contact with riparian vegetation.



Typical Stream Floodplain

Source: NRCS

1.7 to 2.0 year Storm

2 to 10 year Storm



Fox Lake, Wisconsin

• Fox Lake Inland Lake Protection and Rehabilitation District

• Wisconsin Department of Natural Resources

Fox Lake



Fox Lake, Wisconsin

Surface area = 2,525 ac Conservation and Environmental StudiesUWM- Conservation and Environmental Studies


Fox Lake, Wisconsin

• In the 1950’s mean total phosphorus levels in Fox Lake were less than 50 ug/l.

• Today total phosphorus ranges from 150 to 400 ug/l



Fox Lake, Wisconsin

90% of Drainage Area is in agricultural Conservation and Environmental StudiesUWM- Conservation and Environmental Studies


Elements of the Fox Lake Restoration Plan

1. Shoreline Stabilization

2. Watershed Protection3. Aquatic Plant

Management4. Fishery Management5. Dam Replacement6. Public Education



Fox Lake Watersheds

Total Watershed = 35,574 acWatershed to Lake Ratio 14:1

3,894 ac

13,693 ac

14,900 ac



Sediment and Phosphorus Inputs to Fox Lake

Sub-watershed Land Area (ac)

Sediment Load

(tons/yr)

PhosphorusLoad

(lbs/yr)

% total Phosphorus

Load

% of TotalLoad Due to

Cropland Alto Creek 13,693 6,477 23,859 45% 98 Cambra Creek 14,900 4,156 18,530 35% 96 Drew Creek 3,894 1,861 6,834 13% 96 Fox Lake 3,087 1,000 3,845 7% 97 Total 35,573 13,494 53,068 100%

Sub-watershed Land Area (ac)

Sediment Load

(tons/yr)

PhosphorusLoad

(lbs/yr)

% total Phosphorus

Load

% of TotalLoad Due to

Cropland Alto Creek 13,693 6,477 23,859 45% 98 Cambra Creek 14,900 4,156 18,530 35% 96 Drew Creek 3,894 1,861 6,834 13% 96 Fox Lake 3,087 1,000 3,845 7% 97 Total 35,573 13,494 53,068 100%


Based on WinHUSLE Modeling


Strategy to Reduce Sediment and Phosphorus Inputs to Fox Lake

• Conservation practices on agricultural fields and barnyard management systems

• Buffers and grass waterways on tributary drainage channels

• Improved water filtering through riparian wetlands on main channels



Alto Creek Wetland Project

Purpose: To reduce sediment and nutrient loadings to Fox Lake during moderate storms.Approach: Series of low‐head control structures to cause moderate storm events to spill over into existing riparian wetlands to filter nutrients.




Date TSS (mg/l)

TP (mg/l)

SRP (mg/l)

TKN (mg/l)

NO2/ NO3 (mg/l)

5/18/2006 19 0.192 0.131 1.45 7.475/25/2006 66 0.061 0.035 0.92 8.425/31/2006 34 0.157 0.083 1.58 5.966/13/2006 20 0.084 0.042 0.54 10.86/19/2006 19 0.092 0.045 0.71 11.512/8/2009 10 0.050 0.022 0.4 11.25/5/2010 12 0.078 0.051 0.91 7.888/2/2010 20 0.237 0.217 1.16 7.298/22/2010 14 0.149 0.107 0.62 9.56Mean 23.78 0.122 0.081 0.92 8.90St. Dev. 17.27 0.06 0.06 0.41 1.96

Conservation and Environmental Studies

SRP = 66% of Total P



Alto Creek Wetland ProjectDesign Criteria:

• Reasonable access• Low maintenance• Low cost• Potentially constructable by untrained labor, such as

“Secured Work Force”• Does not impact on regulatory flood elevations• Does not cause prolonged flooding of adjacent crops• Allows fish passage• Requires minimal wetland disturbance




• The process was started with detailed mapping of the watershed.




• A 1‐foot contour map was created from a aerial fly over.




• Selection of potential restoration sites based on topography and potential for maximizing the spread of storm water into the floodplain wetlands.



Mapping of Soils and Land Use in GIS



Alto Creek Land Use and SoilsLand use Soil group Area(acres)Water B 32.1Water D 139

Commercial B 1.7Agriculture A 9.6Agriculture B 4322.5Agriculture C 8.1Agriculture D 890.6

HD‐Residential B 110.1HD‐Residential D 14.8LD‐Residential B 173.3LD‐Residential D 37.5Grass/Pasture B 1056.9Grass/Pasture D 58

Forest B 52.1Forest D 17

Total Area 6923.3



Runoff Curve NumbersWater B 98Water D 98

Commercial B 96Agriculture A 67Agriculture B 76Agriculture C 83Agriculture D 86

HD‐Residential B 87HD‐Residential D 93LD‐Residential A 54LD‐Residential B 70LD‐Residential D 85Grass/Pasture B 68Grass/Pasture C 78Grass/Pasture D 83

Forest B 61Forest D 80




• Developed a hydrology model using HEC‐HMS.




Water Level Control StructureHEC-RAS Cross-sections

• Developed a hydraulics model using HEC‐RAS to understand the potential areas of inundation and impact on regulatory floodplains.




• Selection of design storms.

~ 5 year 24-hr Storm Conservation and Environmental StudiesUWM- Conservation and Environmental Studies

Accumulative. Total P Load (%)



• Ecological assessment of each potential site.




Reed Carney Grass

Cattails




CTH F



Water Resources, Wetlands and EcologyWater Resources, Wetlands and Ecology

Conservation and Environmental Studies

Plan View

Cross-Section



Alto Creek Wetland ProjectDrawdown

notch and fish passageway



Stream Flow



Area of Groundwater Discharge

Weir Structure (AC‐1)

Upstream Sample Site (AC‐2)

Groundwater Discharge Area


Hey and Associates, Inc. Conservation and Environmental Studies

Groundwater Discharge Area



Total Suspended Solids (TSS)



Total Suspended Solids (TSS)

61.1%



Total Kjeldahl Nitrogen (TKN)

76.8%



NO2/NO3

35.9%



Total Phosphorus

61.1%



Dissolved Phosphorus

65.5%

67% of the total phosphorus is in the form of soluble reactive phosphorus


Total Phosphorus



Dissolved Phosphorus



Total Kjeldahl Nitrogen (TKN)



Nitrite/Nitrate




• Conclusions:– Use of low‐head dams can be used to enhance the connectivity of stream flow with riparian floodplain wetlands.

– Increasing this connectivity can improve the trapping of sediment and nutrients.




• Conclusions:– Because Alto Creek carry's little suspended sediment and most of the Total Phosphorus is in the dissolved form, I believe here biological uptake is a more important factor for nutrient removal than sedimentation.



Questions


use of enhanced ditch plugs

Environment

ac conservation

ph conservation

agricultural conservation

publiceducation conservation

year storm conservation

partners uwm conservation

total load

total phosphorus load