LAKE TEXANA

1991 Sedimentation Survey

Operated by

Lavaca-Navidad River Authority

Edna, Texas

United States Department of the Interior

Bureau of Reclamation
7-2090 (4-81>

Furp.tj of RectamRtion TECHNICAL REPORT STANDARD TITLE PAGE

1. REPORT ro. AC ESCtD, 3. RECIPIENTS CATALOG .

4. TITLE AJ\O SLUTITLE 5. REPORT DATE

December 1991

Lake Texana - 1991 Sedimentation Survey

6. PERFORMIIJ3 ORGANIZATlT'J COGE

7. AUTF3R(S) 8. PERFORMIF'83 OPOANI2ATICIJ

REPORT M).

James 0. Blanton III and Ronald L. Ferrari

9. PERFORMINI3 ORGANIZATIctl NAME AND ACORESS 10. WOI< U'IIT O.

Bureau of Reclamation

Denver Office

______________________________

11. CCXJTRACT OR GRANT M).

Denver, Colorado ______________________________

13. TYPE OF REPORT At'U PERICID COVERED

12. SPCI'JSORIN3 AGENCY NAME Ar'C ALORESS

Same

14. SPIISORIN3 AGENCY CGOE

15. SUPPLEMENTARY N.KJTES

Microfiche and/or hard copy available at the Denver Office, Denver, Colorado, Ed:RNW

16. ABSTRACT

Lake Texana was surveyed in 1991 to compile field data needed to compute the reservoir

capacity. The data were also used to compute the volume of sediments that had accumulated in

the reservoir since storage began in May 1980. Sonic depth recording equipment and electronic

distance measuring equipment were used to run the bathymetric survey. Reservoir capacity was

computed based on surface areas determined by a width adjustment method.

The capacity of the reservoir at elevation 44.0 is now 163,506 and the surface area is 10,134 acres.

Since 1980, sediments accumulated to a volume of 3,787 acre-feet, which represents 2.3-percent

loss of reservoir capacity.

17. KEY WOPOS At'1D (YJCUMENT ANALYSIS

a. DE$CR / PTORS-- /*reservoir silting/sedimentation/*reservoir surveys/reservoir capacity

/*area capacity curves /*sediment distribution/sonar/sediment yield /

b. / DENT/Fl ERS-- /reservoir area/range lines/sedimentation surveys/Lake Texana, Texas

c. COSAT/ Fiald/Gi-oup OSH COWRR: 0808 SRIM:

¶8. DISTPIBUTIc STATEMENt 19. SECURITY CLASS 21. MD. OF PAGES

ITHIS REPORT)

Qailab/e from th Natio,,a/ Tec/,n,cal loformation gervic, Operf ions UNCLQSSIFIED

Division, 5285 Port Royal Road, Springfield, Virginia 22151. 20. SECURITY CLASS 22. PRICE

(Microfiche and/or hard copy available from NTIS) ED
LAKE TEXANA

1991 SEDIMENTATION SURVEY

by

James 0. Blanton III

and

Ronald L. Ferrari

United States Department of the Interior

Bureau of Reclamation

Denver Office

Division of Earth Sciences

Surface Water Branch

Sedimentation Section

Denver, Colorado

December 1992
ACKNOWLEDGEMENTS

The Bureau of Reclamation prepared and published this report. The hydrographic survey

was supervised by Ronald Ferrari, Hydraulic Engineer of the Denver Office, assisted by

Delbert Smith in the Denver Office. Personnel from the Lavaca-Navidad River Authority,

Edna, Texas, completed the preliminary field work and assisted in the hydrographic survey.

Robert I. Strand, Head, Sedimentation Section and James 0. Blanton III, Hydraulic Engineer

in the Sedimentation Section consulted in the sediment computations and preparation of the

report.

MISSION STATEMENTS

As the Nation's principal conservation agency, the Department of the Interior has

responsibility for most of our nationally-owned public lands and natural and cultural

resources. This includes fostering wise use of our land and water resources, protecting

our fish and wildlife, preserving the environmental and cultural values of our national

parks and historical places, and providing for the enjoyment of life through outdoor

recreation. The Department assesses our energy and mineral resources and works to

assure that their development is in the best interests of all our people. The Department

also promotes the goals of the Take Pride in America campaign by encouraging

stewardship and citizen responsibility for the public lands and promoting citizen

participation in their care. The Department also has a major responsibility for

American Indian Reservation Communities and for people who live in Island

Territories under U.S. Administration.

The mission of the Bureau of Reclamation is to manage, develop, and protect water and

related resources in an environmentally and economically sound manner in the interest

of the American public.

The information contained in this report regarding commercial products or firms may not be used for

advertising or promotional purposes and is not to be construed as an endorsement of any product or

firm by the Bureau of Reclamation.
CONTENTS

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Page

Introduction i

Summary and Conclusions 2

Description of Basin 2

Surveys 3

Survey History 3

Survey Methods and Equipment 3

Reservoir Sediment Distribution 4

Longitudinal Distribution 4

Lateral Distribution 4

Depth Distribution 5

Sediment Analyses 5

Sediment Accumulation 5

Reservoir Sedimentation Summary 6

Reservoir Area and Capacity 6

Bibliography 8

Tables

Table

I Reservoir sediment summary 9

2 Lake Texana sediment distribution 11

3 Summary of 1991 survey results and sediment

distribution computations 12

Figures

Figure

I Vicinity map 13

2 General plan and sections of dam and spifiway 14

3 Drainage area map 15

4 Lake Texana inflows 16

5 Sediment range location map 17

111
CONTENTS - Continued

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Figures -Continued

6 Longitudinal proffles - Navidad River 18

7 Longitudinal profiles - Mustang Creek 19

8 Longitudinal proffles - Sandy Creek 20

9 Sediment Range I - Navidad River 21

10 Sediment Range 2 - Navidad River 21

11 Sediment Range 3 - Navidad River 22

12 Sediment Range 4 - Navidad River 22

13 Sediment Range 5 - Navidad River 23

14 Sediment Range 6 - Navidad River 23

15 Sediment Range 7 - Navidad River 24

16 Sediment Range 8 - Navidad River 24

17 Sediment Range 9 - Navidad River 25

18 Sediment Range 10 - Navidad River 25

19 Sediment Range 11 - Navidad River 26

20 Sediment Range 12 - Navidad River 26

21 Sediment Range 13 - Navidad River 27

22 Sediment Range 14 - Navidad River 27

23 Sediment Range 21 - Mustang Creek 28

24 Sediment Range 22 - Mustang Creek 28

25 Sediment Range 23 - Mustang Creek 29

26 Sediment Range 24 - Mustang Creek 29

27 Sediment Range 25 - Mustang Creek 30

28 Sediment Range 26 - Mustang Creek 30

29 Sediment Range 27 - Mustang Creek 31

30 Sediment Range 28 - Mustang Creek 31

31 Sediment Range 31 - Mustang Creek 32

32 Sediment Range 32 - Mustang Creek 32

33 Sediment Range 41 - Mustang Creek 33

34 Sediment Range 42 - Mustang Creek 33

35 Sediment Range 43 - Mustang Creek 34

36 Sediment Range 51 - Sandy Creek 34

37 Sediment Range 52 - Sandy Creek 35

38 Sediment Range 53 - Sandy Creek 35

39 Sediment Range 54 - Sandy Creek 36

40 Sediment Range 55 - Sandy Creek 36

41 Sediment Range 56 - Sandy Creek 37

42 Sediment Range 61 - Sandy Creek 37

43 Reservoir depth-capacity relationship 38

44 Percent depth versus percent sediment deposited 38

45 Area and capacity curves - Lake Texana 39

iv
INTRODUCTION

Palmetto Bend Dam was the first major feature constructed by the Bureau of Reclamation

(Reclamation) as part of the Palmetto Bend Project. Construction of the dam began in

1976 and was essentially completed in 1980. Water storage operations were begun in

May 1980. The Lavaca-Navidad River Authority (LNRA) of Edna, Texas manages and

operates the dam, reservoir, and all recreational facilities on the project. Located on the

Navidad River in Jackson County about 7 miles southeast of Edna and 90 miles

southwest of Houston (figure 1), the dam is the first stage of the multipurpose project

developed to supply water for municipal and industrial use, for conserving fish and

wildlife resources, and for recreational use.

The dam extends across the Navidad River along an axis about 4 miles upstream of the

confluence of the Lavaca and Navidad Rivers. The dam is a zoned embankment

structure with a structural height of 93 feet. The dam crest rises to a maximum height

55 feet above sea level and 69 feet above original streambed which is 14 feet below sea

level. The dam has a crest length of 7.9 miles, a maximum base width of 820 feet, a

maximum crest width of 42 feet in the typical flood plain sections, and contains a total

volume of 5,991,000 cubic yards of soil and rock materials. The spiliway is a concrete

overflow weir controlled by twelve 22.6 x 35 foot radial gates with a discharge capacity of

190,000 cubic feet per second at elevation 47.0. The general plan and sections of the

dam, spillway, and outlet works are shown on figure 2.[111

Since the dam is in the tidewater area of the Gulf of Mexico it is subject to high tidal

surges caused by hurricanes. Special treatment on the face of the dam slopes and extra

steel anchors in the concrete spillway provide additional protection during hurricane

conditions.

In 1980 at the beginning of operations the reservoir at elevation 44.0 had a surface area of

10,141 acres and a total capacity of 167,293 acre-feet. The reservoir space allocations

include 20,700 acre-feet allowance for 100 years of sediment deposition between the

streambed and elevation 44.0, of which 15,200 acre-feet is in active storage above

elevation 15.0.

Lake Texana has a length of 41.9 miles and an average width of 0.46 miles. The length is

the sum of the lengths of all significant arms of the reservoir. The average width is

determined by dividing the surface area by the reservoir length. The reservoir includes

an 18 mile reach within the Navidad River Valley and the lower portions of the Mustang

Creek and Sandy Creek valleys.

The total Navidad River drainage area above the dam is 1,404 square miles, all of which

contribute sediment inflow. The drainage basin is about 71 miles in length with an

average width of 19.8 miles.

'Numbers in the brackets refer to the bibliography.
SUMMARY AND CONCLUSIONS

This report presents the results of an investigation to monitor changes in Lake Texana

after 11.1 years of reservoir sediment accumulations. It also briefly describes the field

surveying procedures and equipment used in the investigation.

The primary purpose of running the 1991 survey was to gather data needed to compute

the capacity of Lake Texana for operation of the reservoir. New capacity information was

needed to satisfy the state water rights permit issued to LNRA and the Texas Water

Development Board requiring that sediment survey data and corrected area and capacity

tables for Lake Texana be submitted to the Texas Water Commission in 1992.

Standard land surveying methods were used to augment previously established

horizontal control for the survey. The hydrographic survey was completed using sonic

depth recording equipment together with both land based electronic distance measuring

(EDM) equipment and an automated survey system with a line-of-sight electronic

positioning unit. The system continuously recorded reservoir depths and horizontal

distances from a fixed point as the boat was steered across the range line. Reservoir

water surface elevations read on the gage at the dam were used as control in converting

sonic depth measurements to true bottom elevations and to delineate the cross-sectional

profiles.

The capacity of the reservoir from the 1991 survey was determined to be 163,506 acre-feet,

with a surface area of 10,134 acres at the top of conservation elevation 44.0. The

reservoir area and capacity tables were produced by a computer program which uses

measured contour surface areas and a curve-fitting technique to compute both area and

capacity at prescribed elevation increments.

A comprehensive summary of the reservoir sediment data for the 1991 survey is

contained in table 1. The volume of sediments that have accumulated in the reservoir

since the initial filling amounted to a total volume of 3,790 acre-feet below maximum

water surface elevation 47.0 or 3,787 acre-feet below top of conservation elevation 44.0,

indicating a loss in capacity of about 2.3 percent. An average annual sediment

accumulation rate of 341 acre-feet was determined for the period from May 1980 to

June 1991. The sediment yield rate from the drainage area was 0.243 acre-feet per square

mile per year for the same period.

DESCRIPTION OF BASIN

Topography of the Navidad River drainage basin is varied. Figure 3 shows the limits of

the drainage basin including Lake Texana. The basin extends upstream from sea level at

the base of the dam to a maximum elevation of about 400 feet near La Grange, Texas.

There are no major reservoirs in the river basin above Palmetto Bend Dam, although

there are some small diversions from the river for irrigation purposes. The northern

portion of the drainage basin can be characterized as rolling topography resulting in

relatively high runoff peaks from the area, whereas the southern portion of the basin has

very flat coastal plain topography with a considerable area devoted to rice growing which

2
tends to dampen the runoff peaks due to water retention. Soils in the western portion of

the basin are largely clay loam with relatively low retention rates. Soils in the eastern

portion are quite sandy with higher retention rates. Dense tree growth in portions of the

flood plain adjoining the stream channels also slow runoff during flood events. The

mean annual precipitation over the basin is about 38 inches resulting in a mean annual

runoff of about 411,000 acre-feet at Palmetto Bend Dam.[1] The bar graph on figure 4

shows how the annual inflow to the reservoir has varied since storage began.

SURVEYS

Survey History

The original sediment ranges were surveyed by Reclamation from 1977 to 1980. The

original contour surface areas were obtained from U.S. Geological Survey 7.5 minute

quadrangle maps developed from photographic data obtained in 1962. Field work for the

1991 survey began in June, 1990 and was essentially completed by June 30, 1991. A

layout of the reservoir sediment range system is shown on figure 5.

Survey Methods and Equipment

The preliminary field work for the 1991 survey consisted of locating and flagging the

existing sediment range end markers and relocating those which had been lost or

destroyed. To prepare for the range line resurvey, a line clearing program was conducted

in the reservoir area along most of the range lines to improve line of sight conditions

from the range monuments to water's edge. Standard land surveying procedures and

equipment were used to profile 5 range lines in the upper reach of the Navidad River

arid tributaries.

The hydrographic survey was completed in June, 1991 using sonic depth recording

equipment to sound the underwater portion of 25 range lines. Procedures described by

Blanton [2] were followed as closely as possible. For seven of the longer range lines,

located in the most downstream portion of the reservoir, the surveyed range distances

were obtained by the automated survey system using a single Mini-Ranger III

receiver/transmitter set up at one range end. As the boat proceeded along the line range

distances at selected intervals were read and recorded as marks on the sonar chart. For

18 of the shorter range lines, located in the upstream portion of the reservoir, a small boat

system was used. The range distances were determined by an electronic distance

measuring (EDM) instrument set up on a control point on one bank aimed at a reflector

target mounted on the survey boat. Range distances were communicated by radio from

shore to the boat at preselected intervals and marked on the sonar charts as the boat

proceeded on line across the reservoir. For both procedures the boats were kept on line

by radio communication between the shore station operator and the boat crew. Auxiliary

field equipment included hand-held radios for communication between shore and boat

crews and another small boat to move personnel and equipment around the reservoir.

3
RESERVOIR SEDIMENT DISTRIBUTION

Longitudinal distribution

The distribution of sediment throughout the length of the reservoir is illustrated in part

by plots of the thalweg profiles representing the original and 1991 resurveyed profiles

shown on figures 6, 7, and 8. Thaiweg elevations representing original reservoir

conditions are taken from the original range survey notes. Except for the possibility of

some missed low point soundings during the original survey the plotted profiles should

closely resemble actual channel bottom conditions during the original range survey

completed in 1977 and 1978. Thalweg elevations for the 1991 profiles were derived from

the sonar charts and from field notes of the ground survey. Except for some minor

inaccuracies in sounding, the bottom of these profiles should closely represent channel

bottom conditions along the thaiweg at the time of the 1991 resurvey.

The profiles of the Navidad River (figure 6) show some lower thalweg elevations in 1991

than those measured in the original survey at Ranges 9, 10, and 14, whereas the

elevations would be expected to be higher due to sediment deposits. Several plausible

explanations can be given for these differences, one being that some minor river scour

may have occurred in these upstream locations during high inflow events, or another

being that some error in sounding or probing may have occurred in either the original or

1991 resurvey. An examination of the original and 1991 data tend to support the

measured profiles indicating the possibility that some scour has occurred.

The profiles for Mustang Creek (figure 7) show the 1991 thaiweg proffle roughly

paralleling the original profile except at Range 26 where the 1991 thalweg is below the

original. This could be due to stream bed scour or an error in either the original or 1991

soundings. Future resurveys may help to explain this difference.

The proffles for Sandy Creek (figure 8) from Range 53 upstream appear normal for a

reservoir with small sediment inflow operated at near full conditions most of the time.

At Ranges 51 and 52, however, the 1991 thalweg elevations are lower than the original

thalweg elevations. An examination of the bottom portion of the original profile data

revealed range width intervals of 43 feet and 38 feet for Ranges 51 and 52 respectively

where no bottom soundings occurred. This would suggest the possibility that the

maximum depths of these range lines were not sounded during the original survey.

These problems with the original and 1991 thalweg profiles are confined to the very

narrow river channel areas and had no significant effect on the sediment volume

computations. In those locations where scour may have occurred it would be confined to

the narrow stream channel and may not extend very far upstream or downstream of the

sediment range where it may have occurred, unlike what appears to be the case on the

thaiweg proffle plots.

Lateral distribution

Ground proffles for the 34 original sediment ranges are shown on figures 9 through 42.

The 1991 range profile data is superimposed on these plots to indicate the changes which

4
have occurred and to represent in general the lateral distribution of sediment within the

reservoir. No resurveys were accomplished on Ranges 27, 28, and 43 on Mustang Creek

or Range 56 on Sandy Creek. These omissions have no significant impact on storage

capacity computations since these ranges are all in the extreme upstream part of the

reservoir where very little sediment deposition has occurred.

The comparative plots of Range 8 on figure 16 show significant differences in elevations

near the right bank, the south side of the range line. The bathymetric survey of this

range line in 1991 was run in two parts with the distance meter set at Station 22+33 for

both parts. The main channel portion in the direction of the left bank was surveyed with

little difficulty. The overbank portion toward the right bank required much maneuvering

of the survey boat to avoid vegetation growth, which may have led to some data being

collected considerably off-line. Assuming that the original survey through this portion

was made with dry land conditions along a cleared ailnement, this is the most likely

explanation. These measured differences along the right bank portion were not used in

the reservoir capacity computations.

Depth DistributiOn

Of special interest for future reservoir planning, a theoretical distribution of sediment in

the reservoir was computed (table 2) using the Alternate Area-increment Method [3]. The

method was used in lieu of the preferred Empirical Area-increment Method since the

reservoir condition with the small quantity of sediment deposition did not lend itself to

an application of the preferred method. The total 1991 sediment volume of 3,790 acre-feet

was assumed in the distribution. The depth-capacity relationship plotted on figure 43,

indicating the reservoir to be a Type II [3], did not apply since the Alternate Areaincrement Method of distribution was used. Sediment distribution results are tabulated

on columns (8), (9), and (10) of table 3. These computations indicate the sediment would

reach an elevation of 2.2 feet by 1991, whereas the measured elevation of sediment at the

dam was -3.6 feet mean sea level. The sediment distribution curves on figure 44 show

how the measured distribution compares with the theoretical distribution by the Alternate

Area-increment Method. The curves show percentage of depth plotted against percentage

of sediment deposited.

SEDIMENT ANALYSES

Sediment Accumulation

Sediments have accumulated in Lake Texana to a total volume of 3,790 acre-feet at

elevation 47.0, maximum water surface, and 3,787 acre-feet at elevation 44.0, top of

conservation, since storage began in May 1980. An average annual accumulation rate of

341 acre-feet was computed for the 11.1 year period of operation. The net sediment

accumulation rate from the contributing basin was 0.243 acre-feet per square mile per

year for the same period.

The results of the sediment volume computation are shown in table 3. Column 2 in the

table gives the original measured contour areas used in the original area and capacity

5
computation with the exception of the interpolated values at Elevation 44 and 47. In

order to make a valid comparison with the 1991 computed values, these original capacity

values were recomputed by current methods using the same original surface areas. Thus

the capacity values in column 3 differ somewhat from those found in the original (1982)

area and capacity tables [41. The difference is due to differences between the cubic spline

curve fitting technique used for producing the 1982 tables and the least squares curve

fitting technique used for producing the recomputed tables. While the cubic spline

technique has been used occasionally in the past, Reclamation no longer recommends use

of the method since it distorts the area curve, which is the basis for the capacity

computation.

The annual sediment yield from the basin during the 11.1 year period of 341 acre-feet,

based on the recomputed results, is greater than the yield estimated during the project

planning stage. This higher annual yield should not be used for making long term

projections of storage loss. The increase is probably due to the fact that the annual inflow

for five of those 11.1 years was about 1.9 times the long term mean annual inflow, and

the average annual inflow for the period was 1.3 times the long term mean annual inflow

(see No. 24 and No. 45 of table 1).

Reservoir sedimentation summary

A summary of the reservoir sediment data for the 1991 survey is contained in table 1.

The data include a tabulation of incremental sediment inflow volume and sediment

accumulation computed for the period between initial 1980 conditions and the 1991

resurvey. Also included are information on the drainage basin, records of inflow,

reservoir operations and reservoir storage. These data are considered of value for

practical and research studies.

RESERVOIR AREA AND CAPACITY

The 1991 reservoir surface areas were computed by the Width Adjustment Method

described by Blanton [2]. Briefly the method entails computing the revised contour areas

between any two ranges by applying an adjustment factor to each of the original

segmental contour areas between adjacent ranges. The adjustment factor is determined as

the ratio of the new average width to the original average width for both the upstream

and downstream ranges at a specified contour. Computations were facilitated by

subdividing the reservoir into segments using the sedimentation range lines to delineate

the limit of each segmental boundary. Segmental contour areas for each elevation were

determined by digitizing the segmental contours on the original topography. For any

given contour elevation, the original segmental area was multiplied by the adjustment

factor to obtain the 1991 surface area for that elevation. The total surface area at a given

contour elevation was computed as the summation of all segmental areas at that

elevation. These computations were obtained by means of the Reclamation program

RESSED.

6
The 1991 surface areas were used as control parameters for computing the reservoir

capacities by means of Reclamation's program ACAP85 [51. The resulting surface area

and storage capacity versus elevation relationships are shown graphically on figure 44.

The computer program was written to include computation of 0.01 to 1.0-foot area

increments by linear interpolation between measured contour areas. The respective

capacities and capacity equations are then obtained by integration of the area equations.

The initial capacity equation is tested over successive intervals to check whether it fits

within an allowable error term. This one equation is used over the whole range that fits

within this error term. At the next interval beyond, a new capacity equation (integrated

from the basic area equation over that interval) begins testing the fit until it too exceeds

the error term. The capacity curve thus becomes a series of curves, each fitting a certain

region of data. The final area equations are obtained by differentiation of the capacity

equations. Capacity equations are of the form:

y = a1 + a2x + a3x2

where: y = capacity

x = elevation above an elevation base

a1 = intercept

a2 and a3 coefficients

Results of the 1991 area and capacity computations are listed in columns (4) and

(5) of table 3. Listed in columns (2) and (3) of this table are the original area and

capacity values. Capacity values have been revised by using the same curve fitting

technique as was used for the 1991 area and capacity computation. A special set of

area and capacity tables has been published separately for the 0.01-, 0.10-, and 1-foot

elevation increments[6]. Both the original and 1991 area and capacity curves are plotted

on figure 44. At the top of active conservation elevation 44.0 the 1991 capacity if

163,506 acre-feet and the surface area is 10,134 acres.

7
BIBLIOGRAPHY

[1] "Project Data," Water and Power Resources Service, Denver, Colorado,

pp. 751-754, 1981.

[2] Blanton, James 0. III, "Procedures for Monitoring Reservoir Sedimentation:

Technical Guideline," Bureau of Reclamation, Denver, Colorado, 1982.

[3] "Design of Small Dams," 3rd ed., Bureau of Reclamation, Denver Office,

Denver, Colorado, 1985.

[4] "Lake Texana - Area and Capacity Tables," Bureau of Reclamation, Southwest

Region, Amarillo, Texas, 1982.

[5] "ACAP85 User's Manual," Bureau of Redamation, Denver Office, Denver,

Colorado, 1985.

[61 "Lake Texana - Palmetto Bend Dam - Area and Capacity Tables," Bureau of

Redamation, Great Plains Region, Billings, Montana, 1992.
RESERVOIR SEDIMENT

DATA SUMMARY Lake Texana

NAME OF RESERVOIR

DATA SHEET NO.

1. ONNER USD1 - USSR 2. STREAM Navidad River 3. STATE Texas

A 4. SEC. TWP. RANGE 5. NEAREST P.O. E&a, Texas 6. COUNTY Jackson

N 7. LAT 28'53'30" LONG 9634'OO" 8. TOP OF DAM ELEVATION 55.0 9. SPILLWAY CREST 44.0'

i 10. STORAGE 11. ELEVATION 12. ORIGINAL 13. ORIGINAL 14. GROSS STORAGE 15. DATE

E ALLOCATION TOP OF POOL SURFACE AREA. Ac CAPACITY. AF ACRE-FEET STORAGE

S a. FLOOD CONTROL 47.O 12,364 33,11O 199,028 BEGAN

E b. MULTIPLE USE _________________ _________________ ________________ __________________

NAY, 1980

R c. POIER _________________ _________________ ________________ __________________

16. DATE

d. WATER SUPPLY _________________ _________________ ________________ __________________

NORMAL

e. IRRIGATION ________________ ________________ _______________

OPERATION

R f. CONSERVATION 44.0 9,934 157,884 165,918 BEGAN,

'

g. INACTIVE 15.0 1,639 8,034' 8,034

1

17. LENGTH OF RESER VOIR 4 1.9 MILES AVG. WIDTH OF RES ERVOIR O.4o MILES

B 18. TOTAL DRAINAGE AREA 1,404 SQUARE MILES 22. MEAN ANNUAL PRECIPITATION 38.4 INCHES

A 19. NET SEDIMENT CONTRIBUTING AREA 1,404 SQUARE MILES 23. MEAN ANNUAL RUNOFF 5.5' INCHES

S 20. LENGTH 71 MILES AV. WIDTH 19.8 MILES 24. MEAN ANNUAL RUNOFF 411,000' ACRE-FEET

21. MAX. ELEVATION 400 NI H. ELEVATION 0 25. ANNUAL. TEMP. MEAN 70F RANGE 4OF to 97F

26. DATE OF 27. 28. 29. TYPE OF 30. NO. OF 31. SURFACE 32. CAPACITY 33. C/I

U SURVEY PER. ACCL. SURVEY RANGES OR AREA, AC. ACRE-FEET RATIO AF/AF

R

V

____________________________________________

5/30/1980 Contour(D) 5-ft 10,141' 167,293'

E

y 6/30/1991 11.1 11.1 Range(D) 31 10,134 163,506 .398

D

A

T

A

26. DATE OF 34. PERIOD 35. PERIOD WATER INFLOW, ACRE FEET WATER INFLOW TO DATE, AF

SURVEY ANNUAL ________________________________________________________________________

PRECIP. a. MEAN ANN. b. MAX. ANN. c. TOTAL a. MEAN ANN. b. TOTAL

6/30/1991 *20.56 525,475' 791,571' 5,648,860' 525,475' 5,648,860'

26. DATE OF 37. PERIOD CAPACITY LOSS, ACRE-FEET 38. TOTAL SEDIMENT DEPOSITS TO DATE, AF

SURVEY

a. TOTAL f

b. AV. ANN. c. /NI.'-YR. a. TOTAL b. AV. ANNUAL (

c. /MI.2-YR.

6/30/1991 3,787 341 0.243 3,787 341 0.243

(3,790) (341) (0.243) (3,790) (341) (0.243)

26. DATE OF 39. AV. DRY 40. SEt). DEP. TONS/MI.2-YR. 41. STORAGE LOSS, PCI. 42. SEDIMENT

SURVEY WT. (1/Fl') L INFLOW PPM

a. PERIOD b. TOTAL TO

DATE

a. AV.

ANNUAL

b. TOTAL TO

DATE

a.

PER.

b.

TOT.

6/30/1991 no data no data 0.20 2.26 no data

(0.20) (2.26)

* Estimated

Table I .-Reservoir sediment summary
26. DATE 43. DEPTH DESIGNATION RANGE IN FEET BELOW AI ABOVE CREST ELEVATION

" 3934 34-29 29-24 24-19 J

19-14 14-9 4-0 0-(-6.O)

PERCENT OF TOTAL SEDIMENT LOCATED WITHIN DEPTH DESIGNATION

6/30/91 0.1 J 5.6 8.4 13.2 20.2 20.8 18.2 11.3 2.1 0.1

26. DATE 44. REACH DESIGNATION PERCENT OF TOTAL ORIGINAL LENGTH OF RESERVOIR

OF

E'

0-

10

10-

20

20-

3u

30-

40

40-

50

50-

60

60-

70

70-

80

80-

90

90-

100

100-

105

105-

110

110-

115

115-

120

120-

125

PERCENT OF TOTAL SEDIMENT LOCATED WITHIN REACH DESIGNATION

6/30/91 N/A

45. RANGE IN RESERVOIR OPERATION ____________ ____________

WATER YEAR MAX. ELEV.' NIH. ELEV.' INFLOW, AFb WATER YEAR

____________

MAX. ELEV. NIN. ELEV. INFLOW, AF

1980 33.93 tsavai tabLe travel tabLe 1981 41.75 31.85 778,740

1982 43.32 41.36 735,728 1983 44.00 42.16 791,571

1984 43.32 42.47 371,969 1985 43.44 42.40 716,281

1986 43.33 42.67 450,086 1987 44.21 42.59 779,903

1988 43.13 41.56 188,928 1989 43.13 41.90 241,688

1989 43.13 41.90 241,688 1990 43.13 42.04 164,600

1991 43.02 41.36 429,366 ___________ ___________ ____________ ___________

46. ELEVATION - AREA - CAPACITY DATA FOR ORIGINAL CAPACITY

ELEV. AREA CAP. ELEV. AREA CAP. ELEV. AREA CAP.

O 0 0 20 3,004 19,613 40 8,348 129,719

5 178 354 25 4,151 37,565 45 10,589 176,167

10 702 2,396 30 5,396 61,343 50 15,722 241,040

15 1,639 8,034 35 6,819 91,818

46. ELEVATION AREA - CAPACITY DATA FOR 1991 TOTAL CAPACITY __________ __________

ELEV. AREA CAP. ELEV. AREA CAP. ELEV. AREA CAP.

O 0 0 20 2,872 19,070 40 8,314 126,610

5 165 413 25 3,976 36,190 45 10,589 173,868

10 642 2,430 30 5,256 59,270 50 15,722 239,645

15 1,571 7,963 35 6,683 89,118

47. REMARKS AND REFERENCES

1 Top of active conservation

2 Top of surcharge - maxir water surface

3 OriginaL storage .L Locations

4 Date reservoir pooL reached eLevation 44.0

5 Arwiuat normaL precipitation for Hattettvitte, Texas - CLimetography of the U.S. No. 81

6 Estimat.d fLow with future içstr.ma conservation measures - Project Data, USD01, WPRS, 1981

7 OriginaL area and capacity vaLues reccaçuted by current methods for coeperision with 199 1 vaLues to cospute

sediment deposition

8 mt Low from 1980 coivuted by form4a: InfLow Outf Low - Storage

9 From GP RegionaL records representing end of month storage

48. AGENCY MAXING SURVEY Bureau of Rectma.tion

49. AGENCY SUPPLYING DATA Bureau of Rectanetion DATE JuLy 1992

Table 1.-Reservoir sediment summary - continued

10
ALTERNATE AREA - INCREMENT METHOD

ELEV

(FT)

50.0

47.0

45.0

44.0

40.0

35.0

30.0

25.0

20.0

15.0

10.0

5.0

2.2

.0

1991 LAKE TEXANA SEDIMENT DISTRIBUTION

SEDIMENT INFLOW 3790.00

ORIGINAL

AREA CAPACITY

(AC) (AF)

15722.0 243435.

12642.0 200889.

10589.0 177657.

10141.0 167293.

8348.0 130315.

6819.0 92397.

5396.0 61860.

4151.0 37992.

3004.0 20105.

1639.0 8497.

702.0 2645.

178.0 445.

77.5 84.

.0 0.

SEDI MENT

AREA VOLUME

(AC) (AF)

77.5 3790.

77.5 3558.

77.5 3403.

77.5 3325.

77.5 3015.

77.5 2628.

77.5 2240.

77.5 1853.

77.5 1465.

77.5 1078.

77.5 691.

77.5 303.

77.5 84.

.0 0.

RE V I SED

AREA CAPACITY

(AC) (AF)

15644.5 239645.

12564.5 197331.

10511.5 174254.

10063.5 163968.

8270.5 127300.

6741.5 89769.

5318.5 59620.

4073.5 36139.

2926.5 18640.

1561.5 7419.

624.5 1954.

100.5 142.

.0 0.

.0 0.

SUPP L EMENT

VS AD ( H - HO )+

3790.0 = 77.5 ( 50.00 - 2.18 ) +

VO

84.

Table 2.-Lake Texana sediment distribution
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

Elevation 1980 1980 1991 1991 Measured Percent of 1991 Computed Percent of

(it) Original area Original Revised Revised sediment measured Computed sediment computed

(acres) capacity area capacity volume sediment capacity volume sediment

(acre-feet) (acres) (acre-feet) (acre-feet) (acre-feet) (acre-feet)

50 15.722 243.435 15.722 239,645 3.790 100 239,645 3.790 100

47 12.642 200.889 12.642 197,099 3,790 100 197.331 3.558 93.9

45 10,589 177,657 10,589 173,868 3,789 100 174,254 3,403 89.8

44 10.141 167,293 10,134 163,506 3,787 99.9 163,968 3,325 87.7

40 8.348 130.315 8,314 126,610 3.705 97.8 127,300 3,015 79.6

35 6,819 92,397 6.683 89.118 3,279 86.5 89,769 2,628 69.3

30 5.396 61,860 5.256 59.270 2,590 68.3 59,620 2,240 59.1

25 4,151 37,992 3.976 36.190 1,802 47.5 36.139 1,853 48.9

20 3,004 20,105 2,872 19.070 1.035 27.3 18,640 1,465 38.6

15 1,639 8,497 1,571 7,963 534 14.1 7,419 1.078 28.4

10 702 2.645 642 2.430 215 53 1,964 691 18.2

05 178 445 165 413 32 0.1 142 303 8.0

2.2 0 84 2.2

0 1) 0 0 0 0 0 0 0 0

Explanation of columns:

(1) ElevatIon of reservoir water surface

(2) OrIginal reservoir water surface area surveyed In 1980, recomputed by current methods for comparison with 1991 results

(3) OrigInal reservoir capacity from 1980 survey recomputed by current mehtods for compa rison with 1991 results

(4) ReservoIr surface area Surveyed In 1991

(5) Reservoir capacity from the 1991 survey

(6) Measured sediment volume - column (3) minus column (5)

(7) Measured sediment expressed In percentage of total sediment (3.790 acre-feet)

(8) Computed 1991 reservoIr capacity using area-Increment method

(9) Computed sediment volume for period from 1980-1991 - column (3) - column (8)

(10) Computer sediment expressed In percentage of total sediment (3,790 acre-feet)

Table 3.-.-Summary of 1991 survey results and sediment distribution computations
• 4 ANADOr

\y

#--

x

i-

-__ -

AREA r

,I / ;- c) '

)

(

.)

k.. t

I

pj

___ \___•___

(

'

/

Si?

.

.

/ .:-:•

5??

A'

v .

/ -

'- .'c•-., :1.:

i•: ' .•'

2 PALMETTO BEND / DAM

rn .

.

(

.

: ___ -I

___ _____ ____

¶1

I' /

t,

) I ft ________

5

is.. .*tsoso

LOLITA

1

., J

VANDERBILT

0 I 2 5

SCALL 0 MILES

Figure 1.-Vicinity map.

13
Space intentionally left blank due to security concerns 
5 0 5 JO 15 20

I- -

SCALE OF MILES

Figure 3.-Drainage area map.

DAM

15
800

700

Iii 600

w

th

500

100

0

Figure 4.-Lake Texana inflows.

1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991

WATER YEAR

N

0

III:

0

-RANGE 14

-RANGE 13

-RANGE 12

-RANGE II

-RANGE tO

-RANGE 9

-RANGE 8

RANGE 7

RANGE 6

-RANGE 5

RANGE 4

RANGE 3

RANGE 2

N

0

0

0 N) (J

0 0 0 0

ELEVATION, ft. M.S.L.

-RANGE

a-DAM AXIS
RANGE 28

0

- m

o o

(D -l

rJ)

c.)

s11 cj

q

(•) 0

(tI

0

- RANGE 27

RANGE 26

-RANGE 25

-RANGE 24

-RANGE 23

-RANGE 22

-RANGE 2

0 6 0 0

ELEVATION, ft. M.S.L.

CONFLUENCE WITH NAVIDAD RIVER
a:

o Ui cj- C\J - Lu I- U, If) tO If) If)

z -

o Lu Lu Lu Lu w cr

o 0 0 0 0

z z z z z 0

U, a: a: a: a: a: o

0

50

40

-J

(I)

30

z

0

I.-

20

Lu

-J

Lu

I0

0-

60

>

z

-J

(I)

30

.4-

z

0

I.- 20 <

>

Lu

-J

Lu

I0

0

0

Figure 8.-Longitudinal profiles - Sandy Creek.

40 20

THALWEG CHANNEL DISTANCE, ft. io
Ui

ORIGINAL SURVEY - 1991 RESURVEY

Li t)

Li

FCE

>

Li

-J

Li c

500 1000 1500 20(X) 2500 3000 3500 4000 4500 5000 5500 6000 6500 7000 7500

DISTANCE - FEET

Figure 9.-Sediment Range I - Navidad River.

U)

FLi

Li

z

FCE

>

Li

-J

Li 0

0

ORIGINAL SURVEY 1991 RESURVEY

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

DISTANCE - FEET

Figure 1O.-Sediment Range 2 - Navidad River.

21
C

C

tj

U

Li

C

z

D

> C

Li

-J

Li

C

U,

C

ORIGINAL SURVEY 1991 RESURVEY

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500

DISTANCE - FEET

Figure 11.-Sediment Range 3 - Navidad River.

C

LI)

C

Li '

Li

I-

>

Li

-J

Li C

C

ORIGINAL SURVEY 1991 RESURVEY

0 500 lOGO 1500 2000 2500 3000 3500

DISTANCE - FEET

Figurel2.-Sediment Range 4- Navidad River.

22

1000 4500
tr

-

Ui

ILi

Li

U)

z

CE

> U,

Li '

-J

Li

U)

U)

ORIGINAL SURVEY - 1991 RESURVEY

I

0 500 1000 1500 2000 2500 3000 3500 1000 4500 5000 5500 6000

DISTANCE - FEET

Figure 13.-Sediment Range 5 - Navidad River.

U)

U)

U)

U)

ILi

Li

L.

I U) r.)

0

CE

>

Li

-J

Li U)

0

U)

0

ORIGINAL SURVEY 1991 PESURVEY

0 500 1000 1500 2000 2500 3000 3500 4000 4500

DISTANCE - FEET

Figure 14.-Sediment Range 6 - Navidad River.

23
____ ORIGINAL SURVEY 1991 RESURVEY

-

Li

Li

z

F-

>

Lit

-J

Li

I 500 1000 150(3 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

DISTANCE - FEET

Figure 15.-Sediment Range 7- Navidad River.

ORIGINAL SURVEY 1991 RESURVEY

U-,

U,

0

U-,

U,

FLi

1-i

z

Fa: > I.,

Li

-J

Li

U,

-

0 250 500 750 100(3 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 3750 4000

DISTANCE - FEET

Figure 16.-Sediment Range 8 - Navidad River.

24
____ ORIGINAL SURVEY - 1991 RESURVEY

U)

U)

- - - - - - -

C

U)

U)

Li

Li

L.

z

>

Li

-J

Li

C

U)

C

250 5u0 750 1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 3750

DISTANCE - FEET

Figure 17.-Sediment Range 9 - Navidad River.

U)

U)

C

U)

U)

U

Li

z

a:

Li

-J

Li

r)

ORIGINAL SURVEY 1991 RESURVEY

U)

C. ____

0 50 100 150 200 250 300 350 400 450 500 550 600 650

DISTANCE - FEET

Figure 18.-Sediment Range 10 - Navidad River.

25
ORIGINAL SURVEY - 1991 RESURVEY

Ui

Q

U)

Li

Li

f-.

>

Li

-J

Li

U-,

1)

0 ______ ______ ______ ______ ______ ______ ______ ______ ______ ______ ______

0 25 50 75 100 125 150 175 200 225 250 275

DISTANCE - FEET

Figure 19.-Sediment Range 11 - Navidad River.

L.

L

4

C

Ia

L

L

ORIGINAL SURVEY 1991 RESURVEY

0 SO IOU ISO 200 250

DISTANCE - FEET

Figure 20.-Sediment Range 12 - Navidad River.

26

0
U)

U)

ORIGINAL SURVEY - 1991 RESURVEY

U)

U) U)

ILi

Li

IU)

C

>

Li

-J

Li .------- 'I

U)

U)

U)

U)

Li

Li

U)

U)

z

C

F-

>

Li

-J

Li

U)

0 10 20 30 40 50 60 70 80 90 lOU 110 120 130 140 150 160

DISTANCE - FEET

Figure 22.-Sediment Range 14 - Navidad River.

27

20 40 60 80 100 120 110 160 ISO 200 220

DISTANCE - FEET

Figure 21.-Sediment Range 13 - Navidad River.

ORIGINAL SURVEY 1991 RESURVEY
U,

UC

U,

U,

C

F-.

LI

LI

L. ,,

1

z

F-

> U.'

LI r'J

-J

LI

C

U-,

C

U)

ORIGINAL SURVEY - 1991 RESURVEY

0 250 SuO 750 1000 1250 1500 1750 2000 2250 2500

DISTANCE - FEET

Figure 23.-Sediment Range 21 - Mustang Creek

C

U,

U,

C

1- U

LI '

Li

F-

>

LI

-J

LU Q

U,

0

4)

ORIGINAL SURVEY 1991 RESURVEY

0 200 luO 600 800 1000 1200 1100 1600 1800 2000

DISTANCE - FEET

Figure 24.-Sediment Range 22- Mustang Creek.

28
_____ ORIGINAL SURVEY - 1991 RESURVEY

_

U,

C

U,

---

- --- - ,

LU.-

_______7____

>

LU

-J

LJn

(J

--

CD --

UD - - - - - - - - -

0 250 500 750 1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500

DISTANCE - FEET

Figure 25.-Sediment Range 23- Mustang Creek

hi

U')

CD

U')

U•)

ILi

LU

z

CD

hi')

CD

ORIGINAL SURVEY 1991 RESURVEY

0 100 2(10 300 100 500 600 700 800 900 1000 1100 1200 1300

DISTANCE - FEET

Figure 26.-Sediment Range 24 - Mustang Creek.

29
LI)

U)

U,

LI)

Li

Li

0

ci:

>

U

-J

Li

r)

ORIGINAL SURVEY - 1991 RESURVEY

LI)

___ ___ -

0 100 200 3u0 400 500 600 700 BuO 900 1000 1100 1200 1300

DISTANCE - FEET

Figure 27.-Sediment Range 25 - Mustang Creek

_____ ORIGINAL SURVEY 1991 RESURVEY

ILi

Li

L

z

0

F-.

>

Li

-J

Li

-

D _______ _______ _______ _______ _______ _______ _______ _______ _______ _______

I)

0 100 200 30(1 400 500 600 700 600 900 lOGO 1100

DISTANCE - FEET

Figure 28.-Sediment Range 26 - Mustang Creek

30
____ ORIGINAL SURVEY 1991 RESURVEY

U)

U-)

U•)

(N

Li

Li

C)

0

a: r)

Li

-J

Li

U)

U)

(Nr)

C) r)

0 20 40 60 80 100 120 140 160

DISTANCE - F'EET

Figure 29.-Sediment Range 27 - Mustang Creek.

ORIGINAL SURVEY 1991 RESURVEY

U)

U)

(N

U)

C)

U)

U)

N.

Li

Li

U)

0 CU

a:

> C)

Li

-J

N.

I.)

U)

r)

U)

NJ

C)

180

DISTANCE - FEET

Figure 30.-Sediment Range 28 - Mustang Creek

31
U)

U)

C)

U)

U)

f-.

Li

Li

0

Li

-i

Li

C)

U•)

C)

ORIGINAL SURVEY 1991 RESURVEY

0 100 200 300 400 500 600 700 800 900 1000

DISTANCE - FEET

Figure 31.-Sediment Range 31 - Mustang Creek

ORIGINAL SURVEY 1991 RESURVEY

Li

Li

L.

z

0

F-.

a:

>

Li

-J

Li

U-) ______ ______ ______ ______ ______ ______

U) -

C) ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___

25 SO 75 lOU 125 - ISO 175 200 225 250 275

DISTANCE - FEET

Figure 32.-Sediment Range 32 - Mustang Creek

32
____ ORIGINAL SURVEY 1991 RESURVEY

U,

N

UN

FLi

U

1

D

ci N.Ni

Li

Li

to

U-)

04

Ni

D

N,

iiIiiII IiIii

0 t O 20 30 40 50 60 70 80 90 100 It O 120 130 140 150 16(

DISTANCE - FEET

Figure 33.-Sediment Range 41 - Mustang Creek

U,

ILi

Li

1

z

D

F--

'I

>

Li

-i

Li

ORiGINAL SURVEY 1991 FESURVEY

04

'I,

U,- ____ ___ ___ ____ ____ ___ ____ ____ ___ ____ ___

0 20 40 60 60 100 120 140 160 ISO 200 220

DISTANCE - FEET

Figure 34.-Sediment Range 42 - Mustang Creek

33
U)

U)

U)

U)

ILi U)

Li

L U)

> U)

LJ

Li

U,

U)

ORIGINAL SURVEY - 1991 RESURVEY

0

DISTANCE - FEET

Figure 35.-Sedithent Range 43 - Mustang Creek.

U,

U,

0

I')

U•)

I- o

Li '

Li

U)

D

0

CE

>

Li

-J

Li U'

0

U)

0

ORIGINAL SURVEY 1991 RESURVEY

0 200 400 600 800 1000 1200 1400 1600 1800 2000

DISTANCE - FEET

Figure 36.-Sediment Range 51 - Sandy Creek.

34
_____ ORIGINAL SURVEY 1991 RESURVEY

C)

U-,

U-,

ILi U

Li

L.

I LI)

z

ci

C)

Ct

>

Li

-J

Li

cI

IN

C)

(N

0 IOU 200 300 100 500 600 70& 60C) 900 1000

DISTANCE - FEET

Figure 37.-Sediment Range 52 - Sandy Creek.

C)

U-,

LI)

C)

Li U

Li

Ct

>

LI

-J

Li C)

ORIGINAL SURVEY 1991 RESURVEY

U-,

I--,

- --------- - - - - -

0 100 200 300 400 500 600 700 800 900 1000 HOG 1200 1300 1400 1500

DISTANCE - FEET

Figure 38.-Sediment Range 53 - Sandy Creek.

j.

35
_____ ORIGINAL SURVEY 1991 RESURVEY

- - - - - - - - - -

U) U)

- c

Li J

Li

I-

>

Li

-i

Li

U) r)

D

25 50 75 IuO 125 150 IfS 200 225 250 275 300 35 350 375

DISTANCE -

Figure 39.-Sediment Range 54 - Sandy Creek.

_____ ORIGINAL SURVEY 1991 RESURVEY

U)

I)

I). -

I)

I)

ILI

Li

C

I-.

>

Li

-J

Li

-I)

-

-

I)

I,

0 25 50 75 100 125 ISO 175 200 225 250 275 300 325

DISTANCE - FEET

Figure 40.-Sediment Range 55 - Sandy Creek.

36
_____ ORIGINAL SURVEY 1991 RESURVEY

U,

Li

Li

z

I-.

>

Li

-J

Li

Q -

(0

U-,

U)

U) -

U)

U)

-U)

-

U)

Li)

N -

_n. -

1)

-

25 50 75 100 125 150 175 200 225 250 275 300 325

DISTANCE - FEET

Figure 41.-Sediment Range 56 - Sandy Creek

ORIGINAL SURVEY 1991 RESURVEY

IL

L

C

FL

LI) r)

1

0 200 400 600 800 1000 1200 1400

DISTANCE - FEET

Figure 42.-Sediment Range 61 - Sandy Creek

37

1600 1800
100

--

M = 2.77, TYPE H

10

Ii; wLi.

aw

a

10 100 1000 10000 100000

CAPACITY - ACRE-FEET

Figure 43.-Reservoir depth-capacity relationship.

1000000

100

80

60

w

Ui

a- 40

20

I I I I

ALThRNATh AREA-INCA

T-1 _______

-

-' -91 MEASURED AM

0 20 40 60 80 100

PERCENT SEDIMENT DEPOSITED -

Figure 44.-Percent depth versus percent sediment deposited.

38

0

/
16 14 12

50 -.--.._i

40

j

C,;

30

z

0

4

> 20

LU

-J

w

l0

0

SURFACE AREA, ACRES x io

10 8 6 4 2

v El. 47.0 Maximum Wo' /440 Top of surface conservation-

/99/ Capacity- -/99/ Area

/980 (Or -

El 23.0 Spit/way

/

// /980 (Original) Capacily

N

0

50

40

-J

30 C')

z

0

I20

LU

-J

w

I0

0

0 40 80 120 160 200 240 28

STORAGE CAPACITY, ACRE-FEET x

Figure 45.-Area arid capacity curves - Lake Texana.