volumetric survey of medina lake and ... survey of medina lake and diversion lake prepared for:...

VOLUMETRIC SURVEYOF

MEDINA LAKE ANDDIVERSION LAKE

Prepared for:

BEXAR-MEDINA-ATASCOSA COUNTIES WATER CONTROL ANDIMPROVEMENT DISTRICT NUMBER ONE

Prepared by:

The Texas Water Development Board

March 10, 2003

Texas Water Development Board

Craig D. Pedersen, Executive Administrator

Texas Water Development Board

William B. Madden, Chairman Noe Fernandez, Vice-ChairmanCharles W. Jenness Charles L. GerenLynwood Sanders Elaine M. Barrón, M.D.

Authorization for use or reproduction of any original material contained in this publication, i.e. notobtained from other sources, is freely granted. The Board would appreciate acknowledgment.

This report was prepared by the Hydrographic Survey group:

Scot Sullivan, P.E.Duane ThomasSteve Segura

Marc RobichaudWayne Elliott

For more information, please call (512) 936-0848

Published and Distributedby the

Texas Water Development BoardP.O. Box 13231

Austin, Texas 78711-3231

TABLE OF CONTENTS

INTRODUCTION ............................................................................................................................1

HISTORY AND GENERAL INFORMATION OF THE RESERVOIR ...........................................1

HYDROGRAPHIC SURVEYING TECHNOLOGY ........................................................................3GPS Information...................................................................................................................3Equipment and Methodology ................................................................................................4Previous Survey Procedures.................................................................................................5

PRE-SURVEY PROCEDURES .......................................................................................................6

SURVEY CONTROL SETUP ..........................................................................................................7

SURVEY PROCEDURES................................................................................................................8Equipment Calibration and Operation..................................................................................8Field Survey.........................................................................................................................9Data Processing..................................................................................................................10

MEDINA LAKE SURVEY RESULTS...........................................................................................12

DIVERSION LAKE SURVEY RESULTS......................................................................................13

SUMMARY....................................................................................................................................14

APPENDICES

APPENDIX A - DEPTH SOUNDER ACCURACYAPPENDIX B - MEDINA LAKE VOLUME TABLEAPPENDIX C - MEDINA LAKE AREA TABLEAPPENDIX D -AREA-ELEVATION-CAPACITY GRAPH - MEDINA LAKEAPPENDIX E - DIVERSION LAKE VOLUME TABLEAPPENDIX F - DIVERSION LAKE AREA TABLEAPPENDIX G - AREA-ELEVATION-CAPACITY GRAPH - DIVERSION LAKEAPPENDIX H - MEDINA CROSS-SECTION PLOTS

LIST OF FIGURES

FIGURE 1 - LOCATION MAPFIGURE 2 - LOCATION OF SURVEY DATAFIGURE 3 - LOCATION OF SURVEY CONTROL POINTFIGURE 4 - SHADED RELIEFFIGURE 5 - DEPTH CONTOURSFIGURE 6 - MEDINA LAKE 2-D CONTOUR MAPFIGURE 7 - DIVERSION LAKE 2-D CONTOUR MAP

MEDINA LAKE AND DIVERSION LAKE

HYDROGRAPHIC SURVEY REPORT

INTRODUCTION

Staff of the Hydrographic Survey Unit of the Texas Water Development Board (TWDB)

conducted hydrographic surveys on Medina Lake and Diversion Lake in July, 1995. The purpose of

the surveys was to determine the capacity of the lakes at the conservation pool elevation and to

establish baseline information for future surveys. From this information, future surveys will be able

to determine sediment deposition locations and rates over time. Survey results are presented in the

following pages in both graphical and tabular form. All elevations presented in this report will be

reported according to the Medina datum. The Medina datum is approximately 7.8 feet below mean

sea level based on the National Geodetic Vertical Datum of 1929 (NGVD '29). Based on a survey

made prior to 1912, the surface area of Medina Lake at the conservation pool elevation of 1,072.0 feet

was calculated to be 5,575 acres with a corresponding capacity of 254,000 acre-feet. There was no

previous information for Diversion Lake. Information presented in the following report will deal

mainly with the Medina Lake survey. Information regarding the procedures and processing of data for

the Diversion Lake survey will be presented in the section, "Diversion Lake Survey."

HISTORY AND GENERAL INFORMATION OF THE RESERVOIR

Medina Lake is located on the Medina River approximately 16 miles southeast of Bandera,

Tx. The lake and dam facility are owned by the Bexar-Medina-Atascosa Counties Water Control and

Improvement District Number One. Inflows to the lake originate over a 634 square mile drainage

area. At the conservation capacity pool elevation of 1072.0 feet, the lake is approximately 18 miles

long and about 3 miles wide at it's widest point.

Originally the project was built by the Medina Valley Irrigation Company. The water rights

were conveyed by the State Board of Water Engineers under Certificate of Filing # 18 on February

14, 1914. The Medina Valley Irrigation Company went into receivership in 1917 and several years

later became Bexar-Medina-Atascosa Counties Water Improvement District Number One. On

November 1, 1979, a resolution was passed, broadening its powers as a water district and changing

3

its name to the presently known Bexar-Medina-Atascosa Counties Water Control and Improvement

District Number One (BMA). On August 1, 1981, a Certificate of Adjudication # 2130 was issued

by the Texas Water Commission to BMA authorizing the owner to maintain an existing dam and

reservoir known as Medina Lake and to impound not to exceed 237,874 acre-feet of water. BMA was

also authorized to maintain an existing dam and reservoir, known as Diversion Lake and impound

therein not to exceed 4,500 acre-feet of water. Authorization was granted to BMA to use, not to

exceed, 66,000 acre-feet of water per annum from both Medina and Diversion Lake for irrigation of

a maximum 33,000 acres of land within the boundaries of the Bexar-Medina-Atascosa Counties Water

Control and Improvement District Number One. It also authorized the BMA to use , not to exceed 750

acre-feet of water per annum by the residents of the district for domestic and livestock purposes.

Certificate of Adjudication # 2130 was amended several times. The latest amendment, # 2130C, was

filed September 3, 1993 for the purpose to clarify all use authorizations. The total amount of water

for usage did not change but the purpose was changed to include irrigation, municipal and industrial

purposes.

Medina Dam construction commenced in 1912 and was completed in 1913. Deliberate

impoundment of water began on May 7, 1913. The project was designed by Bartlett and Ranney of

San Antonio, and the total cost of Medina and Diversion Dams was $2,739,300.

Medina Dam is a gravity-type concrete dam with a length of 1,580 feet, rising 164 feet above

the natural stream bed to an elevation of 1084.0 feet. The uncontrolled spillway is a cut through

natural rock and is 880 feet long with a 3 foot wide cutoff wall located near the right end of the dam.

The water supply outlets consist of 3 steel pipes, 5 feet in diameter, with lift type gates. The invert

elevation of these outlets is elevation 966.5. The low flow outlets consist of 2 steel pipes, 2.5 feet

in diameter, with lift type gates. The invert elevation of these pipes is 920.0

HYDROGRAPHIC SURVEYING TECHNOLOGY

The following sections will describe the equipment and methodology used to conduct this

hydrographic survey. Some of the theory behind Global Positioning System (GPS) technology and it’s

4

accuracy are also addressed.

GPS Information

The following is a brief and simple description of Global Positioning System (GPS)

technology. GPS is a new technology that uses a network of satellites, maintained in precise orbits

around the earth, to determine locations on the surface of the earth. GPS receivers continuously

monitor the broadcasts from the satellites to determine the position of the receiver. With only one

satellite being monitored, the point in question could be located anywhere on a sphere surrounding the

satellite with a radius of the distance measured. The observation of two satellites decreases the

possible location to a finite number of points on a circle where the two spheres intersect. With a third

satellite observation, the unknown location is reduced to two points where all three spheres intersect.

One of these points is obviously in error because its location is in space, and it is ignored. Although

three satellite measurements can fairly accurately locate a point on the earth, the minimum number of

satellites required to determine a three dimensional position within the required accuracy is four. The

fourth measurement compensates for any time discrepancies between the clock on board the satellites

and the clock within the GPS receiver.

GPS technology was developed in the 1960s by the United States Air Force and the defense

establishment. After program funding in the early 1970s, the initial satellite was launched on

February 22, 1978. A four year delay in the launching program occurred after the Challenger space

shuttle disaster. In 1989, the launch schedule was resumed. Full operational capability will be

reached when the NAVSTAR (NAVigation System with Time And Ranging) satellite constellation is

composed of 24 Block II satellites. At the time of the survey, the system had achieved initial

operational capability. A full constellation of 24 satellites, in a combination of Block I (prototype)

and Block II satellites, was fully functional. The NAVSTAR satellites provide data based on the

World Geodetic System (WGS '84) spherical datum. WGS '84 is essentially identical to NAD '83.

The United States Department of Defense (DOD) is currently responsible for implementing

and maintaining the satellite constellation. In an attempt to discourage the use of these survey units

as a guidance tool by hostile forces, the DOD has implemented means of false signal projection called

Selective Availability (S/A). Positions determined by a single receiver when S/A is active result in

5

errors to the actual position of up to 100 meters. These errors can be reduced to centimeters by

performing a static survey with two GPS receivers, one of which is set over a point with known

coordinates. The errors induced by S/A are time-constant. By monitoring the movements of the

satellites over time (one to three hours), the errors can be minimized during post processing of the

collected data and the unknown position computed accurately.

Differential GPS (DGPS) can determine positions of moving objects in real-time or "on-the-

fly." One GPS receiver was set up over a benchmark with known coordinates established by the

hydrographic survey crew. This receiver remained stationary during the survey and monitored the

movements of the satellites overhead. Position corrections were determined and transmitted via a

radio link once per second to a second GPS receiver located on the moving boat. The boat receiver

used these corrections, or differences, in combination with the satellite information it received to

determine its differential location. The large positional errors experienced by a single receiver when

S/A is active are greatly reduced by utilizing DGPS. The reference receiver calculates satellite

corrections based on its known fixed position, which results in positional accuracies within three

meters for the moving receiver. DGPS was used to determine horizontal position only. Vertical

information was supplied by the depth sounder.

Equipment and Methodology

The equipment used in the performance of the hydrographic survey consisted of a 23-foot

aluminum tri-hull SeaArk craft with cabin, equipped with twin 90-Horsepower Johnson outboard

motors. Installed within the enclosed cabin are an Innerspace Helmsman Display (for navigation), an

Innerspace Technology Model 449 Depth Sounder and Model 443 Velocity Profiler, a Trimble

Navigation, Inc. 4000SE GPS receiver, a Motorola Radius radio with an Advanced Electronic

Applications, Inc. packet modem, and an on-board computer. The computer was supported by a dot

matrix printer and a B-size plotter. Power was provided by a water-cooled generator through an in-

line uninterruptible power supply. Reference to brand names does not imply endorsement by the

TWDB.

The shore station included a second Trimble 4000SE GPS receiver, Motorola Radius radio

6

and Advanced Electronic Applications, Inc. packet modem, and an omni-directional antenna mounted

on a modular aluminum tower to a total height of 40 feet. The combination of this equipment provided

a data link with a reported range of 25 miles over level to rolling terrain that does not require that

line-of-sight be maintained with the survey vessel in most conditions, thereby reducing the time

required to conduct the survey.

The GPS equipment, survey vessel, and depth sounder combine together to provide an efficient

hydrographic survey system. As the boat travels across the lake surface, the depth sounder gathers

approximately ten readings of the lake bottom each second. The depth readings are stored on the

survey vessel's on-board computer along with the corrected positional data generated by the boat's

GPS receiver. The daily data files collected are downloaded from the computer and brought to the

office for editing after the survey is completed. During editing, bad data is removed or corrected,

multiple data points are averaged together to get one data point per second, and average depths are

converted to elevation readings based on the daily recorded lake elevation on the day the survey was

performed. Accurate estimates of the lake volume can be quickly determined by building a 3-D model

of the reservoir from the collected data. The level of accuracy is equivalent to or better than previous

methods used to determine lake volumes, some of which are discussed below.

Previous Survey Procedures

Originally, reservoir surveys were conducted with a rope stretched across the reservoir along

pre-determined range lines. A small boat would manually pole the depth at selected intervals along

the rope. Over time, aircraft cable replaced the rope and electronic depth sounders replaced the pole.

The boat was hooked to the cable, and depths were again recorded at selected intervals. This

method, used mainly by the Soil Conservation Service, worked well for small reservoirs.

Larger bodies of water required more involved means to accomplish the survey, mainly due

to increased size. Cables could not be stretched across the body of water, so surveying instruments

were utilized to determine the path of the boat. Monumentation was set for the end points of each line

so the same lines could be used on subsequent surveys. Prior to a survey, each end point had to be

located (and sometimes reestablished) in the field and vegetation cleared so that line of sight could

7

be maintained. One surveyor monitored the path of the boat and issued commands via radio to insure

that it remained on line while a second surveyor determined depth measurement locations by turning

angles. Since it took a major effort to determine each of the points along the line, the depth readings

were spaced quite a distance apart. Another major cost was the land surveying required prior to the

reservoir survey to locate the range line monuments and clear vegetation.

Electronic positioning systems were the next improvement. If triangulation could determine

the boat location by electronic means, then the boat could take continuous depth soundings. A set of

microwave transmitters positioned around the lake at known coordinates would allow the boat to

receive data and calculate its position. Line of site was required, and the configuration of the

transmitters had to be such that the boat remained within the angles of 30 and 150 degrees in respect

to the shore stations. The maximum range of most of these systems was about 20 miles. Each shore

station had to be accurately located by survey, and the location monumented for future use. Any errors

in the land surveying resulted in significant errors that were difficult to detect. Large reservoirs

required multiple shore stations and a crew to move the shore stations to the next location as the

survey progressed. Land surveying was still a major cost.

Another method used mainly prior to construction utilized aerial photography to generate

elevation contours which could then be used to calculate the volume of the reservoir. Fairly accurate

results could be obtained, although the vertical accuracy of the aerial topography was generally one-

half of the contour interval or + five feet for a ten-foot contour interval. This method could be quite

costly and was only applicable in areas that were not inundated.

PRE-SURVEY PROCEDURES

The reservoir's surface area was determined prior to the survey by digitizing with AutoCad

software contour 1064.0 (the equivalent conservation pool capacity elevation in NGVD datum used

by the USGS) upstream from the dam on two USGS quad sheets. The names of the quad sheets are as

follows: MEDINA LAKE, TX 1964 (Photorevised 1982) and PIPE CREEK, TX 1970 (Photorevised

1982). The graphic boundary file created was then transformed into the proper datum, from NAD '27

8

datum to NAD '83, using Environmental Systems Research Institutes's (ESRI) Arc/Info project

command with the NADCOM parameters. The area of the lake boundary was checked to verify that

the area was the same in both datums.

The survey layout was designed by placing survey track lines at 500 foot intervals across the

lake. The survey design for this lake required approximately 258 survey lines to be placed along the

length of the lake. Survey setup files were created using Coastal Oceangraphics, Inc. Hypack software

for each group of track lines that represented a specific section of the lake. The setup files were

copied onto diskettes for use during the field survey.

SURVEY CONTROL SETUP

The first task of the Hydrographic Survey field staff after arriving at Medina Lake was to

establish a horizontal reference control point. Figure 3 shows the location of the control point

established. This location was chosen due to the close proximity to the reservoir and the security of

the area.

Prior to the field survey, TWDB staff had researched locations of known first-order

benchmarks and requested BMA staff to physically locate the associated monuments. Of the

monuments found, the one chosen to provide horizontal control for the survey was a U. S. Geological

Survey first-order monument named SCHMIDT located approximately 10 miles east of Hondo, Tx..

The coordinates for the monument are published as Latitude 29° 22' 14.23872"N and Longitude 99°

00' 14.54646"W.

On July 5, 1995, TWDB staff performed a static survey to determine the WGS'84 coordinates

of the lake survey control point. The control point used for the shore station was a nail set in concrete

at the west end of the dam's crest. The GPS receivers were set up over each point and satellite data

were gathered for approximately one hour, with up to six satellites visible at the same time to the

receivers.

Once data collection ended, the data were retrieved and processed from both receivers, using

9

Trimble Trimvec software, to determine the coordinates for the control point. The WGS' 84

coordinates were determined to be North latitude 29° 32' 27.28214" and West longitude 98° 56'

12.47555".

Using the newly determined coordinates, a shore station was set up over the control point to

provide horizontal control during the survey. The coordinates from the static survey were entered into

the GPS receiver located over the control point to fix its location. Data received during the survey

could then be corrected and broadcast to the GPS receiver on the moving boat during the survey.

SURVEY PROCEDURES

The following procedures were followed during the hydrographic survey of Medina Lake

performed by the TWDB. Information regarding equipment calibration and operation, the field survey,

and data processing is presented.

Equipment Calibration and Operation

During the survey, the GPS receivers were operated in the following DGPS modes. The

reference station receiver was set to a horizontal mask of 0°, to acquire information on the rising

satellites. A horizontal mask of 10° was used on the roving receiver for the purpose of calculating

better horizontal positions. A PDOP (Position Dilution of Precision) limit of 7 was set for both

receivers. The DGPS positions are known to be within acceptable limits of horizontal accuracy when

the PDOP is seven (7) or less. An internal alarm sounds if the PDOP rises above seven to advise the

field crew that the horizontal position has degraded to an unacceptable level.

Prior to the survey, TWDB staff verified the horizontal accuracy of the DGPS used during the

Medina Lake survey to be within the specified accuracy of three meters by the following procedure.

The shore station was set up over a known United States Geological Service (USGS) first order

monument and placed in differential mode. The second receiver, directly connected to the boat with

its interface computer, was placed over another known USGS first order monument and data was

10

collected for 60 minutes in the same manner as during a survey. Based on the differentially-corrected

coordinates obtained and the published coordinates for both monuments, the resulting positions fell

within a three-meter radius of the actual known monument position.

At the beginning of each surveying day, the depth sounder was calibrated with the Innerspace

Velocity Profiler. The Velocity Profiler calculates an average speed of sound through the water

column of interest for a designated draft value of the boat (draft is the vertical distance that the boat

penetrates the water surface). The draft of the boat was previously determined to average 1.2 ft. The

velocity profiler probe is placed in the water to moisten and acclimate the probe. The probe is then

raised to the water surface where the depth is zeroed. The probe is lowered on a cable to just below

the maximum depth set for the water column, and then raised to the surface. The unit displays an

average speed of sound for a given water depth and draft, which is entered into the depth sounder.

The depth value on the depth sounder was then checked manually with a measuring tape to ensure that

the depth sounder was properly calibrated and operating correctly. During the survey of Medina Lake,

the speed of sound in the water column varied daily between 4,936 and 4,942 feet per second. Based

on the measured speed of sound for various depths, and the average speed of sound calculated for the

entire water column, the depth sounder is accurate to within +0.2 feet, plus an estimated error of +0.3

feet due to the plane of the boat for a total accuracy of +0.5 feet for any instantaneous reading. These

errors tend to be minimized over the entire survey, since some are plus readings and some are minus

readings. Further information on these calculations is presented in Appendix A.

Field Survey

Data was collected on Medina Lake during the period of July 18-20, 1995. Approximately

57,570 data points were collected over the 92.47 miles traveled along the pre-planned survey lines

and the random data-collection lines. These points were stored digitally on the boat's computer in 234

data files. Data were not collected in areas of shallow water (depths less than 3.0 ft.) or with

significant obstructions unless these areas represented a large amount of water. Random data points

were collected, when determined necessary by the field crew, by manually measuring the depth with

a surveying rod and entering the depth value into the data file. As each point was entered, the DGPS

horizontal position was stored automatically with each return keystroke on the computer. The boat

11

was moving slowly during this period so positions stored were within the stated accuracy of + 3

meters to the point poled. Figure 2 shows the actual location of the data collection points.

The collected data were stored in individual data files for each pre-plotted range line or

random data collection events. These files were downloaded to diskettes at the end of each day for

future processing.

Data Processing

The collected data were down-loaded from diskettes onto the TWDB's computer network.

The diskettes were then stored in a secured, safe location for future reference as needed. To process

the data, the EDIT routine in the Hypack Program was run on each raw data file. Data points such as

depth spikes or data with missing depth or positional information were deleted from the file. The

depth information collected every 0.1 seconds was averaged to get one reading for each second of

data collection. A correction for the lake elevation at the time of data collection was also applied to

each file during the EDIT routine. During the survey, the water surface elevation ranged daily from

1,056.37 to 1,056.40 feet. After all changes had been made to the raw data file, the edited file was

saved with a different extension. After all the files were edited, the edited files were combined into

a single data file, representative of the lake, to be used with the GIS software to develop a model of

the lake's bottom surface.

An aerial survey was flown by Tobin Surveys, Inc. of the lake in 1984 and 1985. Information

from this survey was used to supplement the TWDB survey for the area from elevation 994.88 to

elevation 1080.0. 39,947 data points inside the lake below elevation 1080.0 feet were determined

from the aerial photos using photo-metric processes.

The resulting DOS data file was imported into the UNIX operating system used to run

Environmental System Research Institutes's (ESRI) Arc/Info GIS software. The latitude and longitude

coordinates of each point were then converted to decimal degrees by a UNIX awk command. The awk

command manipulates the data file format into a MASS points format for use by the GIS software. The

graphic boundary file previously digitized was also imported.

12

To develop a model of the lake using both the TWDB and Tobin data, a new boundary was

digitized from the maps used to create the survey lines file in the Pre-survey Procedures. Contour

elevation 1080.0 was digitized upstream from the dam. The file was then converted from NAD ‘27

to NAD ‘83. The NAD ‘83 file was then converted to the Medina datum by adding 7.8 feet to the

contour elevation or elevation 1087.8. This file was then down-sized to elevation 1080 based on the

location of any of the Tobin data that was at elevation 1080 or less. The Board does not represent any

of the contour lines developed in this report to be actual land versus water boundaries. Instead, it is

a graphical approximation of the actual boundary used solely to compute the volume and area of the

lake.

The edited MASS points and modified boundary file were used to create a Digital Terrain

Model (DTM) of the reservoir's bottom surface using Arc/Info's TIN module. The module builds an

irregular triangulated network from the data points and the boundary file. This software uses a method

known as Delauney's criteria for triangulation. A triangle is formed between three non-uniformly

spaced points, including all points along the boundary. If there is another point within the triangle,

additional triangles are created until all points lie on the vertex of a triangle. All of the data points

are preserved for use in determining the solution of the model by using this method. The generated

network of three-dimensional triangular planes represents the actual bottom surface. Once the

triangulated irregular network (TIN) is formed, the software then calculates elevations along the

triangle surface plane by solving the equations for elevation along each leg of the triangle. Information

for the entire reservoir area can be determined from the triangulated irregular network created using

this method of interpolation.

There were some areas where values could not be calculated by interpolation because of a

lack of information along the boundary of the reservoir. "Flat triangles" were drawn at these

locations. Arc/Info does not use flat triangle areas in the volume or contouring features of the model.

These areas were determined to insignificant on Medina Lake. Therefore no additional points were

required for interpolation and contouring of the entire lake surface. The TIN product then calculated

the surface area and volume of the entire reservoir at one-tenth of a foot intervals from the three-

dimensional triangular plane surface representation. The computed reservoir volume table is

13

presented in Appendix B and the area table in Appendix C. An elevation-area-volume graph is

presented in Appendix D.

Other presentations developed from the model include a shaded relief map and a shaded depth

range map. To develop the shaded relief map, the three-dimensional triangular surface was modified

by a GRIDSHADE command. Colors were assigned to different elevation values of the grid. Using

the command COLORRAMP, a set of colors that varied from navy to yellow was created. The lower

elevation was assigned the color of navy, and the lake upper pool elevation was assigned the color

of yellow. Different color shades were assigned to the different depths in between. Figure 4 presents

the resulting depth shaded representation of the lake. Figure 5 presents a similar version of the same

map, using bands of color for selected depth intervals. The color increases in intensity from the

shallow contour bands to the deep water bands.

The DTM was then smoothed and linear smoothing algorithms were applied to the smoothed

model to produce smoother contours. The resulting contour map of the bottom surface at ten-foot

intervals is presented in Figure 6.

MEDINA LAKE SURVEY RESULTS

Medina Lake is located on the Medina River in Bandera and Medina Counties. The major

tributaries that flow into the main body of the lake are Mescal and Elm Creeks. This pristine lake with

it's clear waters lies west of San Antonio in the limestone outcrop of the Texas Hill Country. Over

one dozen coves and hollows with steep canyon walls are located along the shoreline from the dam

upstream to Turks Head on the west bank and Goat Hill on the east bank. The elevation relief

becomes more gentle in the upper reaches of the lake's head waters. While collecting data the field

crew rarely encountered any navigational hazards such as stumps. The crew did locate a few sand

bars in the flats and upper reaches. Lake grasses were also encountered in the shallow areas at the

upper end of the lake.

Results from the 1995 survey indicate Medina Lake now encompasses around 6,066 surface

14

acres and contains a volume of 254,843 acre-feet at the conservation pool elevation of 1072.0 feet.

The volume at elevation 1080.0 was 305,784 acre-feet and the surface area was 6,742 acres. The

shoreline at conservation pool was calculated to be 71.09 miles. The shoreline for elevation 1080.0

was calculated to be 87.76 miles. The lowest elevation encountered was around elevation 933.2 feet,

or 138.8 feet of depth when the lake is at the top of the conservation pool. This point was found 1,800

feet north of the dam.

The storage volume calculated by the 1995 survey is approximately 2.5 percent less than the

previous record information for the lake. The lowest gated outlet invert elevation is at elevation 920.0

feet. There is no dead storage volume at this elevation so the conservation storage capacity for the

lake is 254,843 acre-feet.

DIVERSION LAKE SURVEY RESULTS

The field survey on the Diversion Lake was performed on July 12, 1995. The method used

to performed the field survey was a modified range line survey. Cross-sections were located and an

electronic distance measuring device was used to determined the lengths of the cross-sections. A 14

foot boat with a recording fathometer was then driven at a constant speed across the lake to create a

bottom profile. The survey of Diversion Lake consisted of a total of 13 cross-sectional lines. After

the survey, the data was processed and coverages were created in ArcInfo. A TIN model similar to

the model created for Medina Lake was created. Additional data points were interpolated in between

the cross-sections for contouring purposes. An area-elevation-capacity table was created from the

resultant model. Figure 7 shows the cross-section locations and the contour lines that were created.

The volume of the Diversion Lake was calculated from this survey to be 2,555 acre-feet at elevation

926.5 and the surface area was 169 acres.

SUMMARY

Medina Lake and Dam were completed in 1913 and deliberate impoundment of water began

on May 7, 1913. Initial storage calculations estimated the volume of the lake at the conservation pool

elevation of 1072.0 to be 254,000 acre-feet with a surface area of 5,575 acres. There was no prior

15

information on the capacity of the Diversion Lake.

During the period July 18-20, 1995, a hydrographic survey of Medina Lake was performed

by the Texas Water Development Board's Hydrographic Survey Program. The water elevation of the

lake during this period ranged from 1056.37 - 1056.40 ft., or about 16 ft below the conservation pool

elevation. Additional data from an aerial survey performed by Tobin Surveys, Inc. in 1984 and 1985

provided additional information from elevation 994.88 to 1080.0. The Tobin data was merged with

the TWDB data at the request of BMA from which the TWDB developed a model of the entire depth

range of the lake up to elevation 1080.0. Results from the survey indicate that the lake's capacity at

the conservation pool elevation of 1072.0 feet was 254,843 acre-feet and the lake’s capacity at

elevation 1080.0 was 305,784 acre-feet. The previous storage capacity for Medina Lake, based on

a survey made prior to 1912, was estimated at 254,000 acre-feet for elevation 1072.0 and 300,000

acre-feet at elevation 1080.0. The storage information generated by the TWDB and Tobin Surveys,

Inc. shows no loss of storage during the last 84 years in Medina Lake.

In addition to the survey on Medina Lake, TWDB staff performed a modified range line

survey of Diversion Lake on July 12, 1995. From this survey, the capacity of Diversion Lake at

elevation 926.5 was determined to be 2,555 acre-feet.

It is difficult to compare the original design information and the information generated from

the TWDB and Tobin Surveys, Inc. because little is know about the original survey procedures and

data. However, the TWDB considers the 1995 survey to be a significant improvement over previous

survey procedures and recommends that the same methodology be used in five to ten years or after

major flood events to monitor changes to the lake's storage capacity. The second survey will remove

any noticeable errors between the previous survey and the 1995 survey and will facilitate accurate

calculations of sedimentation rates and storage losses presently occurring in Medina Lake.

A-1

CALCULATION OF DEPTH SOUNDER ACCURACY

This methodology was extracted from the Innerspace Technology, Inc. Operation Manual for the

Model 443 Velocity Profiler.

For the following examples, t = (D - d)/V

where: tD = travel time of the sound pulse, in seconds (at depth = D)D = depth, in feetd = draft = 1.2 feetV = speed of sound, in feet per second

To calculate the error of a measurement based on differences in the actual versus averagespeed of sound, the same equation is used, in this format:

D = [t(V)]+d

For the water column from 2 to 30 feet: V = 4832 fps

t30 = (30-1.2)/4832 = 0.00596 sec.

For the water column from 2 to 45 feet: V = 4808 fps

t45 =(45-1.2)/4808 =0.00911 sec.

For a measurement at 20 feet (within the 2 to 30 foot column with V = 4832 fps):

D20 = [((20-1.2)/4832)(4808)]+1.2 = 19.9' (-0.1')


D30 = [((30-1.2)/4832)(4808)]+1.2 = 29.9' (-0.1')


D50 = [((50-1.2)/4799)(4808)]+1.2 = 50.1' (+0.1')

A-2

For the water column from 2 to 60 feet: V = 4799 fps Assumed V80 = 4785 fps

t60 =(60-1.2)/4799 =0.01225 sec.


D10 = [((10-1.2)/4832)(4799)]+1.2 = 9.9' (-0.1')


D30 = [((30-1.2)/4832)(4799)]+1.2 = 29.8' (-0.2')


D45 = [((45-1.2)/4808)(4799)]+1.2 = 44.9' (-0.1')

For a measurement at 80 feet (outside the 2 to 60 foot column, assumed V = 4785 fps):

D80 = [((80-1.2)/4785)(4799)]+1.2 = 80.2' (+0.2')

IIItIIIItTITTItIItI

: -av. fEET

9529t39519t t9569579t09t9

961962963

965

964

970

97297'3

9n

9Ta

980981942981904985986987988989990991992tn3

995

998

MEOINA LAKE JULY 1995 SLJRVEY

VOLL]IiIE IN ACRE. FEET. 1 . ?

8 930 3365 69

1 1 1 1 1 7171 181251 259318 317135 145512 554662 674794 808939 954

1A97 11141269 12841159 14791666 1684189

1922?154 21412138 246a2751 2fA43089 3124l45l 31911843 l8a34254 43014703 1749r 184 52315708 l76a6270 63286861 69227181 75118128 81948401 84699498 9569

10220 1029310968 1104511741 1142112511 1?62613369 1145514222 145061 5 1 0 3 1 5 1 9 31 6 0 1 8 1 6 1 1 11696t 1746117940 1805918,11 1901319969 2007t21024 21131221A6 ?22162a216 23429

. 0

?7

1 0 6167243329

531

780924

10811252111916151A73?12724092719ta54341538031 ? 1 '

5131565462136801

806287329427

1 0 1 4 610892116661?4631324414135150111592516€69178l.1188401986t2091721997?3104

. l

l l

36T3

1 ? ?189264356155t6t687422

1 1 3 01306

1711

2209?4992417316035293921

52455818638669Al760842608938

103671 1 1 2 11190?127071313711396152&�16205171r41811819115?017821Ea22326?3442

l

1 3

781 2 8

276166

,71700836985

114713211 5 1 917331972?2162529285031963567396541881413t3365874

7672832790079712

1 1 1 9 81194212749136221446311371162991725418258192172024321346

I1 543a2

2032453n

589

713

8t01000

13431t39175619972?64256028443232560640061432/.891

53845929650371057V6439190n9783

1 0 5 1 6112761?4611287113707145711516516395171521A$71931920388214542251723664

TEXAS TATER DEVELOPMENT BOARD

RESERVOIR VOLUI.4E IABLE

TENTH FOOT

, a , 9

4 52? 24

t5 100151 160227 235311 320404 414509 5246?5 63fn3 767a91 t09

1018 14641216 12341400 14191602 16?I1825 18492474 ?1012550 23792651 264729a' 30203311 33743723 37634131 11734166 46115036 50855516 56006099 615666a1 6741729? rJ517931 79968596 86649286 9356

10000 10021A711 10816r 1509 r 15871?302 1?34?13119 1320?13961 1404914836 1492515710 1543216678 1671317e44 1n$18618 1A73919658 19-16220705 ?081121779 21884228a0 22992?1010 24124

ELEVATION INCRETIENT ]S ONE

1 7 1 916 5086 91

211 ?19293 3A?385 5954A7 498601 6 l l7?6 740865 gn

1016 10321 1 8 1 1 1 9 91162 l38t1560 15011779 180220?7 2044?293 23212591 26Zt2917 2941326a 33043645 3684

4939 49A75110 1493t98t 60426162 66217167 72297001 7&68461 45299146 9?169856 9928

10591 1066611353 1113112141 1?2211?9ra 1305613792 138n14659 1471715556 156,1816488 1658317449 1f5471A437 18t3819452 1955520193 205992,562 2167022658 ?276923782 ?3496

TABLE

ELEVATION INCREMENT IS OI IE TENTI ] 'OOT

. 5 . 6 , 7 . A _ 9

I,IED I NA LAKE JULY 1995 SIIRVEY

VOLUI.IE IN ACRE. FEEI

. t . 2: . E V . F E E T

"000" 0 0 1' ,442

r , 0 0 3' , !04

i , 0 0 61 , 0 0 71 , 0 0 41 , 0 0 91 , 0 1 01 , 0 1 11 , 0 1 21 , 0 1 3

1 , 0 1 5r , 0 1 61 , 0 1 71 , 0 1 81 , 0 1 91 , 0 2 01 ,4211 ,4221,4231,4241 ,4251,4261,0271 , 0 2 81 , 0 ? 91 , 0 3 01 , 0 3 11 , 0 t ?r ,0331 , 0 3 41 , 0 3 51,0361,0371 ,038r ,0391 ,0401 , 0 4 11,4421,043

1,0451,0161 , 0 1 71 ,04E

. 0

242392514126599279?529083303723169333045344413t851373113881440161119574359445241470t848402,46345251754458564605851460620627n64987

719507UAs76929795174216184866876219Uza932889624?99171

142?0510530110a1661117071 1 t 0 3 011&�36121931125519129211133024137007

?1351?552226724

29210J050231826l l t82345713599'371193896710r201?119

4145'

$943t042052749546555666354722644346299765211671786980172192

n1a5

4243185139878999071293577

1425121456141Aa7A7112035I153661147821?2Zt)412t8al129589133111137415

?1170?56102684224074?9334l06ll3196111320347123611437604191?0146761?ZS?459314r62717371

t 1 0 0 7t29015445456466589116104663216654356no77003772435

n41280042426998541?88178909969386696n199775

10281910t928109108112365115744119128122641126249129966133801137421

. 5

2154525759269632419929166107613?0953315731453362453775739274408t642115

157991f548

5119453093,r05257070

6126J6313665660679347427172679751t5776998030582968856a78t458912819115797447

10002103127106243109410112695116041119475122994126616130344131192138?55

?17012t878270862442429594308963224413596

364343790739424409951?608

459724772649529511815t24655252572755935161474636t6658866816a7 0 5 1 17292175106779578056983218859618AB791566

97344100t791034t6r065581497531134?611638?1198231233151269831307231345a5138616

2181821997272442445429f?33t028323653373135136365f6380t7395814 l 1 5 412772

16145

49712t1t69t348055452574805t561

634776 6 1 1 158400707197316975654742168o8tl83508a6237890189185291nA97680

100682103715106€751100771133t811672212417212371312n521 3 1 1 0 1134985139059

?19312611727331?457629Ar?3 1 1 6 032t0033472352743672234247397354131412936

1631918082$49,5175853674556525764659772

64098663386463270988Z�111759117&�758109841774865128929992134950t097974

1009451040551471911 1 0 4 0 t1136901170631205?212107?12n221114E513t386139472

2t0r126?3727454247422994131?93326363141235421366683035839894

41101

1649t142625007951947t3869t t85l57492t998362126613196656568464712?77-3661761657An141361u01986749895409?1219532294276

10128910136510750911072611102111710'12Aa7i124432128093131868135749139887

25168 2528626357 2617827577 2770128828 28955tot 11 3024131126 315593?772 3294934151 3429135564 35TAT37015 3715338510 3466210019 40?0641635 1179613?66 4344211943 4511346664 468431U41 1 21,0244 54449,?1r7 5?3?754065 5126156055 t62r758099 58t0650195 6040862343 625616154? 6476466n? 6702069097 693317146a 7170873904 74156

78995 7925681630 81896u321 4459347066 87343a9a62 9014t92712 9300095615 959089A575 98471

101594 1019001U6n 104988107424 108146111053 111379114359 111691117744 118092121??5 121578121n1 12115612U6' 128€1913?252 13?637136191 t36600140304 114721

IITtTtttI

RESERVOIR VOL1IIEIASLE

I{EDI'IA LAKE JULY 1995 SURVEY

VOLUI4E IH ACRE-FEET ELEVAT]ON INCRENEIII IS ONE IENTII FOOT

. 5 . 6 . 7 . A

, , 0 5 0

' ,45?' , 0 5 3' ,054

. , 0 t 5' ,056

' ,a57

: , 0 5 9j , 0 6 0

1 , 0 6 t1 , 0 6 ?r , 0 6 3

1 . 0 6 51 , 0 61,067r ,0681,0691 , 0 7 0' | ,o71

1,0721 , 0 7 31 , 0 7 11,075r ,0761 , A n1,0781,0791,0801 , 0 8 11 , 0 8 21 ,0831,084

. 0

1 4 1 1 1 914fi741497231511761582J01633841641t2172947177434182600107637192972198188?031.85208a57?1/.104219819225464?31166236961242837248794254823260926267104272359279693246102?925E629914630r7u31?186319174326/.52333508

115ra1458071t01611516?S1591921630591686111734t3178331183101184t1719349019471424401920959821485422039722602623171223751t2434?924939t25543026154026n252ZJ9492803t0286747293239299406306419313271320172327154

11197411623E1506041550801596551641111690891n919178€�24185E01188857194008199211204554209940215405220956226594232319238129

249994256038262155268348274620280969?87393293A92100466307155313957320816327457

. 3

1423991466741 5 1 0 4 8155534160119161801169570

179319184104lE9l6919152919976920509021018,/{2159152215172271624?A972347152146162505952566472627712.a9722n252281608288040294517301129307814a146153?1562328561

1424221471031514911559841605651652n170050171a95179411r84806189881195049200297?0r62521142721650722ZO7A22771123317523930124121125119725725626tt6E269597?75844242214282tB7295201!0t7913064913151553???54129265

1432451171371519361561131610441557511705tr1753e41805101E5t09'190394

1955702A1AZf206162211572217060222640228!01u4454239888245806251800?57865?6100,

27651728288828955529585730215430917:,316022322955329970

14364911797215?aa?156898r 6 1 5 1 4166226171013175A7314040614581f190908196092?01t57?067002121172176112232022204722!463424047624640225240325447626462127|uB2r|150283529289983296513303118109E5431671132t655330676

114A9511810815ZA?9152J551619811667011714951763611811041863181911?3196415z01EEa20723421262e1816E223765229444?31214241065216999253006259047265212?714742m812U\7' l29063!297170303785310555317101321351ll1l8!

. 9

111522 144949148846 149244153277 153726157813 15A271162149 152914167174 1676551719n 172163176854 177146181802 182101186824 187310191959 19?415197139 197661202420 2029r?zoTm 204317213209 213n621a721 219241221t30 224895210017 ?305922t5797 8!3n241655 242245217597 244195253512 254217259700 26431226546? 26644227?102 27273027A420 279056244815 285458?912U 291915297824 29UU301119 3051161 1 1 2 1 9 1 1 1 9 0 ?316093 318785325051 32rn2332091 442799

TEXAS I,JATER DEVELOPI'IENT SOARD

RESERVOIR AREA TABLE

, 8

l 1

263748

89

1 1 01 ? Z1t5

16117'193

262290318

369395120411489515564596

653674702727754741805El0858848922953980

10071055106110841 1 1 5

I,IEDIIIA LAKE JULY 1995 SIRVEY

:!Ev, FEET

9 5 1952953914955956957958959960

962963

965

960969

971972973

975976977974

980981942983944965986947988949990991992995

995

997998999

AREA IN ACRES. 1

30

55

a291

1421 1 41261 3 9t 5 1165181196219244270?99

3513n4034244615015165n

63466068570973576478681?838067497

98410151041106910961124

ELEVAIION IIICREI'IENT IS ONE TENIII F@I

tTIi

. 0

283953

81

1011 1 31?11371 5 0

1it9196? 1 6

296

t4at74400426159497542574602631658645707

7607468 1 0656861

924919986

1 0 1 21018106610951121

. 2

11 6

57728393

1031 1 51 2 7140152

142200??1246

50252835337910,431

505549t80608

663647712EA

7908 1 58418709019t5

10171043107210991127

51 933

8595

1 0 51171101121 5 5170t862032262512781085313583854 1 0418

, 1 4556585

642668692717713n1795820u7476908

970

1023101910n1 1 0 41132

. 5

6

2 134

62

86

t061 t 8131

157171187

2542813 1 0

36135741t

519

588617

67069t719745

79Eg?z

8198n9 1 1944972999

10251052108011A71135

. 6

a2l

6377a7

1071 1 91t2145158172189207231257zut 1 1ll8t&390415

481525,62590620

673697

718n6800825E5Z88291'9479n

10021028105510621 1 1 01 1 3 8

. 7

1 02436

657A8a9a

1091 2 01t4

160

191?092342592871 1 63403663921144tA485530565593623650675700725un98028?E85588t914950974

10041030105410651 1 1 31 1 4 1

1 227385 1688090

1001 1 11231461181611n

?14

- ?6429332131637?398123455

519571599624

680704730n7783807833861891

956985

10101036106310911 1 1 81147

. 3

31 73242587384

116t?8141r54164144?02224249

30trr1356382408

5095535826 1 1639&5690

740769793417u4873

9lE967

102014461071110e1129


IIEDINA LAKE JULY 1995 SI]RVEY

' , ! 0 0

' , 0 0 2' , 0 0 1

' ,005

' ,006

' , 4 4 7' , 0 0 8' , 0 0 9

: , 0 1 01 , 0 t 11 , 4 1 2r , 0 1 31 , 0 1 41 , 0 1 51 , 0 1 61 , 0 1 7t , 0 1 41 , 0 1 91 , 0 2 01 ,4211 ,4221 ,Aza1 ,4241 ,0251 ,4261 ,A271,4241 ,A291 , o t o1 , 0 3 1

1 ,0331,0341 , 0 3 51,0361,0371,0381 ,0391 , 0 4 01,0411,4421,443

1,A45

1 ,4171,01.81,019

. 0

1 1 5 01 1 8 0

124?12Zl130513371369140214391481152615711 6 1 81663l 7 t 01759180818571 9 1 019f220292081213221812?352?042319211921902558?6142674272927412844?&47291?3001t063312932013241

5450354036383E?38724076

. 3

1 1 5 8t1a9122412511283r 1 1 51316137814131151

15101t85163116771f?4

lSZZ1873192419912011?096?11821982251zl05237024412 5 1 02576263526?127152nf2450?9Al2960302010823 1 5 13??53306159031n35643671378639174109

1 1 6 111921223123112461 5 1 8135013821417

1r441t901616164217291774142718781931

24192 1 0 1215322032256?311237f244425172582?61126962750?80?28t t2904

3026t08a31t8

3414ll9a3445357436a2379439914121

1 1 9 51226125E128911211l5 l1345112Q1159150415191591

1686173117831612188319402002?0512106?1ra?2092261231623A52455252425ta2616274227552aa72A6A291129723032309531653211

3107319555EE3693381040041112

11671 1 9 812291251

1324135613881121

1508155315991645169117f9178418J71884

2008206021112163221122662322239224622531?59426522708?760?8122865291929n30383102317232193311311'350445971705342?4421

IS ONE

11701?0112321?64129513271359139?112811681 t 1 315t816041650r 696

179!1UZ149419532013206521172164?2192272?3292399

253826002654271427662E18?471292529al304431093180

33393423351336071717565410124155

. 9

1 1 7 7l20a1249127413021314116613991435

152115671 6 1 3161912054n418011852

J9051965202420762 1 2 7?1782?3022432312

2443255126122aa9272127762A292841293629953056312331943273335631113t31a627374058594065

AREA IN ACRES

1 1 5 1 1 1 5 51183 11861214 1?17124' 12181?76 12n1304 13121t40 13431472 13751406 1409

1445 149015J0 tSl t1176 15801622 16271664 167?1715 1719

1El l 181E1862 18641916 19221979 19852031 20392086 20912134 ?142188 21932240 22462294 2299?356 2tA32477 24!42197 ?5442561 25702624 262925gO ?6852751 271027 2791?6t9 264'2492 ?4972944 29543007 30143069 30753137 31443209 32173289 a29A33ZJ 33813159 31665550 15593619 36601763 37753886 19AZ4087 1099

ELEVATION INCRE ENT. 5 . 6

TEIITH FOOT. 8

1173120512361?6712991t l11462139514t114721517156216081654170017491na184718991959201820742 1 2 22173222122n213524052476

2646266!27192n1za23za762930294930503 1 1 631873265334834323522461737?Aaa464053116'

MEDINA LAKE JiILY 1995 SURVEY

RESERVOIR AREA TASLE

ELEVAI IOI I INCRENENT IS ONE TENTH F@T

. - :V . FEET .O

' ,c to 4186- c t1 4292' , .52 4399' ,a53 1508

' ,054 4617

' ,ot t 4706' ,056 17AA' ,a57 4454' ,058 4926

' , 0 1 9 5 0 0 0' ,060 toat' , 0 6 1 5 1 7 6:,ab7 5257r,06! 5536' , 0 5 4 5 4 1 0i ,065 '1U1,066 55421,A67 5651r,06a 57571,069 56141 ,070 ,9211,071 59941,A72 64661,AT3 61391,A74 62171,075 6295j ,076 6372

1,A7A 65221,079 65941,080 67421,081 &141,0a2 69311,083 70151,084 7098

, 1 , 2

1197 12Aa4303 4313

4120 45?84626 163!1715 172!

4861 406€49ll 49415007 50145099 511051t/ 5192

5313 53505118 54265192 55125590 55985669 56n,764 57725WZ '8l'95928 59356001 600860zJ 60816147 6154

6301 63106379 6347

6529 65376605 66136762 67n6f57 M6912 695070?3 7011

. 3

4Z1A432444424537

4801

19155A22t 1 1 9520052E15357,4335519,645568557n58585913601560886162621063186395

66216747687569587039

12?94331

4545

1fi448084883

t02951?A52095290,364514055275614569157475866595060226095616962186326&42

65526429

6884

7044

. 5

42394345

1r511657171548154490496250375136,2175Z9A5371,447553556215709579550745957602961036 1 n62566t546409

655966376805689269n7056

125013r5

456246654752$211897

,044514452245106,3795454

5629,717580?5885596460366 1 1 06146

6141

656766156a13690069817064

. 7

4260

1570

175948284905

5A5Z515?

5115538654615 5 5 1563757255 8 1 158915971

61176194627'l61496121

657566546422

69917an

. 8 . 9

1271 42414n 4J8a

4579 15874681 46494766 477348t5 1417

4985 199?5060 50675159 51675210 5248

,391 5401t468 54765561 15715645 5653tzJS 57155a18 5A265901 5909sg79 59A76051 605961?5 51326241 62096279 62476357 6361u32 64396506 651465A2 65906662 66716831 64406917 69?56999 70077081 7089

l

I)

700

1,400

2 ,100

^ 2.800

ag

1 3 , 5 0 0

JI

* 4,200l

4,900

5,600

6,300

7,000

300,000

270.000

240,000

210,000

90,000

60,000

30,000

180,000 HUJg.(.)

150,000 E(.)$o

120,000

0975 990 1,005 1,020 1,035

ELEVATION (FEET)

SURFACEAREA CAPACIry

- - - x - - -

MEDINA LAKEJuly 1995 SURVEY

PEpacd by: TWOB Apni 1996

' t ,050 1,065 1,080 1,095

\

\

\

\

x

\

\

I

\

K \

I

IIIIIIIIIIII!IIIIII

TEXAS I,JAIER DEVELoPl,tEllT BOARD

RESERVOIR VOLUiIE TABLE

OIVERSION LAKE JI]].Y 1995 SURVEY

oct 25 1995

l

l

2

91 21 72636

60

901091 1 0154100211?45282322364112165522583648719

878966

1059115712611369148516021f2718581995?136??u2114

VoLL E l{ ACnE- tEEt. 1 . 2.LEV. FEET

880881882883884885886887888889890891892891

895896497898899900901942903

9059069079089099 1 09 1 1912913

9 1 5

9179189 1 99209219?29239249?5926

. 3ELEVATIOII IIICRE'.!ENT IS ONE

'IEN'II IOOI

. 5 . 7 . 8. 0

112

l lt 8?al85062

9a1 1 11351 5 9t86

252249330373122

595661734412895941

10781 1 n12421392150616261753188520232166?3142472

1l

3

7i 0

1 92939

7g95

115137162149

256293

378427481539

668

820

99310841 1 8 8129314051 5 1 81639

14992a3f218025302449

l2

57

t 0

20lo

5 265

117140164192224259297338383433187,16608675

828912

100210971 1 9 81303

15301651

191220512195

?505

I

?357

1 01 5? 13 1

53

8 199

1 1 9'112

167195224261301342347/.38493

615685757

9211 0 1 111071208131414261512

179?192620652210?461212?

1z1t7

1 1t 5

32

5 '6a83

l 0 i

170198231267305317392

494t58621690

9501021111712191325113715511676180519392479222423762538

1l

?358

1 tt 6233l

566984

103124

172201

?70309351497

504561624697772851939

103011271?291336111�4156616491 8 1 819532093223923922r$

l

1235I

1 1

243445, 77186

t 0 5126

17.2042382743 1 3355lAZ4515 1 0570635

7aa861948

1040113712391317146015781702183219672104225421AA

112

68

1 21 72535

5a7288

1071281521742082112743 1 7360407

5 1 6,76

788870957

1117125013t8

159017151a4'r981?122??692124

l

2

l 31 82737486 l

, 7 5

911 1 1

- 133157183

218286326369

5245896557?6804847975

10681167127113801195

1744147220092151??992116

TEXAS I]ATER DEVELOPMENT BOARD


DIVERSION LAKE JULY 1995 SIJRVEY

ocr 25 1995

ELEVATION INCREI.iENI IS ONE TENIH IooT

ELEV. TEET

880881882885884885886887888889890891892891894695896497898899900901902?Aa9049059069079089099109 1 19129159149 1 59169179 1 8919920921922

924925926

AREA IN ACRES

. 1

11123

5

1 01 1

1 61 9

?526l0

3639

525660

70

81a79297

1011041 1 31 1 81241 1 01351 4 1

155

' ? . 1. 0

1l2235

1 01 t1 21 31 61 8

3033363942

5 15660

70

8186

97

147112117124129135

151163

. 5 . T . 8

112z3

59

1 0t 1

1 9

z4263 1

3739

18

61

65

71

a2a7929a

1031081 1 31 1 6125130136111

156165

I122l

5

t 01 1

1 7

22

3154

40

4855

61

71

a28a9398

1041091141 1 9126131116112144156166

1221

5

1 01 11 l

1 71 9222426l 1

3740

n8366

99

109

1191261 3 1137112148157167

1

l

z?3

59

1 0

1 11 72A

32

555862

7a8589

n1 0 51 1 0115120127132137143119158

l

?23

5

1 11 21 5

1 720

50

58

737Aa4E995

1 0 01051 1 01 1 5121127113118

119159

11z25

51 01 11 Z1 5

1 8202?

32

38

50545963

79849095

1011061 1 11 1 6121128113139

150160

112zl

t 01 1

1 820

25

r5384 1

50555963

80859096

1 0 11061 1 11 1 61ZZ1241341391451 5 0161

l

122l

t 01 11 2

1 E21

28

!9

155 1t t59

6875808591

1 0 2147112117

12911411.01151 5 1162

fr l

1,800 quJccg

-

1,200 Q

6uJto 8 0g

LUE

LIJ

ff 120ccla

3,000

2,400

600

ELEVATION (FEET)

IIIIIIIIIIIIIIIII

IIt

880 885 890 89s 9oo 905 910 915 920 925r 030200 9875

SURFACEABEA CAPACITY

DIVERSION LAKEJulY 1995 Survey

Prepared bY: TWDB August 1996

iE

s1

i.

1F

i E

i;

e.

E!

"=

!3

Ir

IT

iE

YI

rl

st

'E

.l

(J

O

8"

F P

RaI

E E

E F

E !

E E

EE

g

; E

i E

: B

NO

II1. 'E

I

il

I

ql

.s5 t

aF

EE

F:

:q !

x;

ez

tl

FE

Rt

rg

PR

E

il

E

vl

tl

gP

P

I

Te

ee

eE

SE

EE

Ea

sE

ce

sE

NO

LIVA

iTE

I

I

t\

l

YI

/\

l

t F

!c

tE

i

2 f

,i

FA

tz

tE

EN

:

5u

5E

E'

gt

t

tt

,t

oo

EI

'E

t8

!IIttE

--

i.-.-

-il*

Bc

:sd

3i

a<

I

i

E.

rF

Eg

Ft

di

;L

85

.9

€g

tv

.E

E?

dq

3€

:<

)E

nt

fi

vl

ll

l

"r

u9

4E

E

TIIIIIII t

EE

EE

Eg

t!

!E

tE

tt

t:

3IIO

IIVA

iTE

I

brrril

1 E

E>

Fa

Z.

EE

'-

si

E U

EE

1.

;E

.E

Nr

r

E 9

';

i

;l

r

-

c

gQ

€.

6

= -

SO

rl

l:

o:

=I

.9

,9

er

v:

:

sE

is

E

ov

8q

--

8'

.

E*-*E

E s E

E B

E t

t I

t 3

$ :

sN

OIIY

A'N

A

z-ll

Eg

:6

=z

Ei

o;

-5

;.

ss

:e

B I

'E

vI

tl

E!

gN

OlI'\l rE

t

:zz;\

?C

F:

-F

a

g|

;;

Ei?;52

Ic8I

z

eE

EE

EE

El

EE

se

ss

s:

e

t

qEc-)

III!lIN

OIIV

AS

:EI

FIGURE 1

MEDINA LAKElrcation MaD

DINA COUNTY

PREPARED BY: TWDB August, 1996

FIGURE 2

MEDINA I-AKELocatiotr of Survey Data

PRIFARED BY: TWDB August, 1996

FIGURE 4

MEDINA LAKESh4ded Relief

It

$1'-5500'

Uovatio! FrcDn3.2F\.

Elovatio!10EO R.


FIGURE 5

MEDINA LAKEryh RaDges

Ii

I1"-5500'

PREPARED Bt TWDB Augurt, 1

BANDERA AND MEDINACOUNTIES

MEDINA LAKEContour Map

EXPLANATION10 Ft. Contour Lines

5 Ft. Contour Lines

Top of Dam Elevation1080 Ft.

Conservation Pool Elevation1072 Ft.

Cross Section Line

Cross Section Line FromDam to Headwaters

Match Line

Match Line

Medina Dam

G

G

A

A

B B

C

CD D

E E

F F


volumetric survey of medina lake and ... survey of medina lake and diversion lake prepared for:...

Documents