Willow Creek Reservoir

2002 Survey

(

I*&\

U.S. Department of the Interior

Bureau of Reclamation

Technical Service Center

Denver, Colorado August 2005
REPORT DOCUMENTATION PAGE Form Approved

0MB No. 0704-0188

1. AGENCY USE ONLY (Leave Blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED

August 2005 Final ________________________________

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

Willow Creek Reservoir PR

2002 Survey

6. AUTHOR(S)

Ronald L. Feffari __________________________

7. PERFORM[NG ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION

Bureau of Reclamation, Technical Service Center, Denver CO 8022 5-0007 REPORT NUMBER

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING

Bureau of Reclamation, Denver Federal Center, P0 Box 25007, AGENCY REPORT NUMBER

Denver CO 80225-0007 DIBR

11. SUPPLEMENTARY NOTES

Hard copy available at Bureau of Reclamation Technical Service Center, Denver, Colorado

12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words)

The Bureau of Reclamation surveyed Willow Creek Reservoir in June 2002 to develop new reservoir

topography and compute a present storage-elevation relationship (area-capacity tables). The underwater

survey, conducted near reservoir elevation 4,141 (project datum), used sonic depth recording equipment

interfaced with a real-time kinematic (RTK) global positioning system (GPS) that gave continuous

sounding positions throughout the underwater portion of the reservoir covered by the survey vessel. The

above-water topography was obtained by digitizing the developed reservoir contour lines from the U.S.

Geological Survey quadrangle (USGS quad) map. This study assumed no change, since the original

survey, from elevation 4,135 (feet) and above.

As of June 2002, at maximum water surface elevation 4,149.0, the surface area was 1,644 acres with a total

capacity of 42,691 acre-feet. Since initial survey in 1905, about 431 acre-feet of change have been

measured below elevation 4,144.0, resulting in a 1.2 percent loss in reservoir volume. This calculated

change is due to accuracy difference between the two surveys, shoreline erosion of the islands, and

sediment inflow.

14. SUBJECT TERMS 15, NUMBER OF PAGES

reservoir area and capacity! sedimentation! reservoir surveys! sonar/ sediment distribution!

contour area! reservoir area! sedimentation survey/ global positioning system! lake

______________________

16. PRICE CODE

17. SECURITY 18. SECURITY 19. SECURITY CLASSIFICATION 20. LIMITATION OF

CLASSIFICATION CLASSIFICATION ABSTRACT

OF REPORT OF ABSTRACT

OF THIS PAGE

CL UL UL

UL

NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89)

Prescribed by ANSI Six!. 239-18

298-102
Willow Creek Reservoir

2002 Survey

Prepared by

Ronald L. Ferrari

-

U.S. Department of the Interior

Bureau of Reclamation

Technical Service Center

Water Resources Services

Sedimentation and River Hydraulics Group

Denver, Colorado August 2005
ACKNOWLEDGMENTS

Reclamation's Sedimentation and River Hydraulics Group of the

Technical Service Center (TSC) prepared and published this report.

Ronald Ferrari and Tom Pruitt of the TSC conducted the hydrographic

survey. Ron Ferrari of the TSC completed the data processing needed to

generate the new topographic map and area-capacity tables. Sharon

Nuanes of the TSC developed the final topographic map. Kent Collins

of the TSC performed the technical peer review of this documentation.

UNITED STATES DEPARTMENT OF THE

INTERIOR

The mission of the Department of the Interior is to protect

and provide access to our Nation's natural and cultural

heritage and honor our trust responsibilities to Indian tribes

and our commitments to island communities.

BUREAU OF RECLAMATION

The mission of the Bureau of Reclamation is to manage,

develop, and protect water and related resources in an

environmentally and economically sound maimer 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

Reclamation.

The information contained in this report was developed for the Bureau of

Reclamation; no warranty as to the accuracy, usefulness, or completeness

is expressed or implied.

11
CONTENTS

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Page

Introduction 1

Summary and Conclusions 2

Reservoir Operations 3

Hydrographic Survey Equipment and Method 3

Willow Creek Datum 4

Reservoir Area and Capacity 5

Topography Development 5

Development of 2002 Contour Areas 6

2002 Storage Capacity 6

Reservoir Sediment Analyses 7

References 8

TABLES

Table

I Reservoir sediment data summary (page 1 of 2) 9

1 Reservoir sediment data summary (page 2 of 2) 10

2 Summary of 2002 survey results 11

FIGURES

Figure

I Willow Creek Reservoir location map 1

2 Survey vessel with mounted hydrographic equipment on Jackson Lake in Wyoming 4

3 Willow Creek 2002 underwater data 13

4 Willow Creek Reservoir topographic map 15

5 2002 area and capacity curves 17

111
Figure 1 - Willow Creek Reservoir location map. 

Willow Creek Dam was initially constructed fiom 1907 to 19 1 1 and raised 2 feet in 191 7. In 

1941, the dam (dike 1) was raised an additional 12 feet and three small dikes (named dike 2, dike 

4 and dike 5) were constructed about % mile northeast of the dam to form the present Willow 

Creek Reservoir. The dam is a homogeneous earthfill structure whose dimensions are: 

Hydraulic height' 76 feet 

Top width 30 feet 

Crest elevation 4,154.0 feet2 

Structural height 93 feet 

Crest length 650 feet 

1 The definition of such terms as "hydraulic height," "structural height," etc, may be found in manuals such as 

Reclamation's Design of Small Dams and Guide for Preparation of Standing Operating Procedures for Dams and 

Reservoirs, or ASCE's Nomenclature for Hydraulics. 

2 Elevations in feet. All elevations in report based on the original project datum established by U.S. Bureau of 

Reclamation. The 2002 survey found Reclamation's datum to be around 3.4 feet less than the National Geodetic Vertical 

Datum of 1929 (NGVD29) and 6.7 feet less than North American Vertical Datum of 1988 NAVD88. 
Dike 5 consists of two wing embankments where an uncontrolled grass lined overflow spiliway

is located. The spillway crest elevation is 4,144.0 and provides a maximum discharge of

280,800 cubic feet per second (cfs) at reservoir elevation 4J49.0. A river outlet works is located

near the right abutment of the dam with a crest elevation of 4,085.28. The outlet capacity is 500

cfs at reservoir water surface elevation 4,142.0.

The drainage area above Willow Creek Dam is 118 square miles and all is considered sediment

contributing. In addition to storing water from Willow Creek, the reservoir obtains diverted

flows from the Sun River through the Willow Creek Feeder Canal. The lake is around 2.5 miles

in length and around 1.1 miles in width.

SUMMARY AND CONCLUSIONS

This Reclamation report presents the 2002 results of the survey of Willow Creek Reservoir. The

primary objectives of the survey were to gather data needed to:

• develop reservoir topography

• compute area-capacity relationships

A Real-time Kinematic (RTK) GPS control survey was conducted to establish a temporary

horizontal and vertical control point near the boat ramp with the base set on the National

Geodetic Survey (NGS) datum point "Choteau" that is located near the lake. The horizontal

control was established in the Montana state plane coordinate zone in the North American Datum

of 1983 (NAD83) and the vertical control tied to NAVD88 and the Reclamation project datum.

All elevations in report are referenced to the Reclamation project or construction datum that for

this study was found to be around 6.7 feet less than NAVD88 and 3.4 feet less than NGVD29.

The underwater survey was conducted in June of 2002 near reservoir water surface elevation

4,141.0. The bathymetric survey used sonic depth recording equipment interfaced with the RTK

GPS making it capable of determining sounding locations within the reservoir. The system

continuously recorded depth and horizontal coordinates of the survey boat as it was navigated

along grid lines covering Willow Greek Reservoir. The positioning system provided information

to allow the boat operator to maintain a course along these grid lines. Water surface elevations

recorded by the reservoir gauge (tied to the Reclamation vertical datum) during the time of

collection were used to convert the sonic depth measurements to true reservoir bottom

elevations. The above-water topography was determined by digitizing the developed contour

lines from the U.S. Geological Survey quadrangle (USGS quad) maps of the reservoir area.

The 2002 Willow Creek Reservoir topographic map is a combination of the USGS quad contour

and the underwater survey data. A computer graphics program generated the 2002 reservoir

surface areas at predetermined contour intervals from the collected data. The 2002 area and

capacity tables were computed by a computer program that uses measured contour surface areas

and a curve-fitting technique to compute area and capacity at prescribed elevation increments

(Bureau of Reclamation, 1985).

2
Tables 1 and 2 contain summaries of the Willow Creek Reservoir and watershed characteristics

for the 2002 survey. The 2002 survey detennined that the reservoir has a total storage capacity

of 34,819 acre-feet and a surface area of 1,509 acres at active conservation elevation 4,144.0.

Since closure in 1911, the reservoir had an estimated volume change of 431 acre-feet below

reservoir elevation 4,144.0. This volume represents a 1.2 percent change in total capacity at this

elevation.

RESERVOIR OPERATIONS

Willow Creek Reservoir is part of the Sun River Project that includes Gibson and Pishkun

Reservoirs that supply water for irrigating 91,000 acres of land along the Sun River. The June

2002 capacity table shows 42,691 acre-feet of total storage below the maximum water surface

elevation 4,149.0. The 2002 survey measured a minimum lake bottom elevation of 4,084.2. The

following values are from the June 2002 capacity table:

7,872 acre-feet of surcharge elevation 4,144.0 and 4,149.0.

34,818 acre-feet of conservation use between elevation 4,085.3 and 4,144.0.

acre-foot of dead storage below 4,085.3.

Willow Creek Reservoir available iuflow and end-of-month stage records listed on table 1,

operation period 1952 through 2002, show the calculated inflow and annual fluctuation for these

years of operation. The computed average inflow into the reservoir for these years was 14,600

acre-feet per year. The maximum-recorded elevation was 4,144.0 on June 22, 1975 and the

minimum recorded was no storage on July 31 and August 31 of 1940 (USGS, 2000).

HYDROGRAPHIC SURVEY EQUIPMENT AND METHOD

The hydrographic survey equipment was mounted in the cabin of a 24-foot trihull aluminum

vessel equipped with twin in-board motors (figure 2). The hydrographic system included a GPS

receiver with a built-in radio, a depth sounder, a helmsman display for navigation, a computer,

and hydrographic system software for collecting the underwater data. An on-board generator

supplied power to all the equipment. The shore equipment included a second GPS receiver with

an external radio powered by a 12-volt battery. The GPS antenna and receiver were mounted on

a survey tripod over a known datum point.

The Sedimentation and River Hydraulics Group uses RTK GPS with the major benefit being

precise heights measured in real time to monitor water surface elevation changes. The basic

outputs from an RTK receiver are precise 3D coordinates in latitude, longitude, and height with

accuracies on the order of two centimeters horizontally and three centimeters vertically. The

output is on the GPS datum of WGS-84 that the hydrographic collection software converted into

Montana's NAD83 state plane coordinate system. The RTK GPS system employs two receivers

that track the same satellites simultaneously just like with differential GPS.

3

applied during post processing. The water surface measurement found the NGS vertical of

NAVD88 to be around 6.7 feet higher then the Reclamation gauge readings. All vertical

information for this study is referenced to the Reclamation reservoir water surface gauge

measurements. The 2002 RTK GPS survey determined the Reclamation vertical datum to be

around 3.4 feet lower than NGVD29. Note that all elevations in this report are tied to the

Reclamation vertical elevations that were measured by the Reclamation gauge during the time of

collection. The reported vertical shifts were from this one time RTK GPS survey and should be

confirmed by a control survey.

RESERVOIR AREA AND CAPACITY

Topography Development

The topography of Willow Creek Reservoir was developed from the 2002 collected underwater

and a digitized contour from the USGS quad map. The digitized USGS contour line was the

Willow Creek water surface that was not labeled with an elevation. The USGS quad maps were

developed from aerial photography dated 1982. This study found the enclosed digitized contour

area with the island surfaces removed to correspond the original surface area at elevation 4,136.

ARC/INFO V7.0.2 geographic information system software was used to digitize the USGS quad

contour. The digitized contours were transformed to Montana's NAD 1983 state plane

coordinates using the ARC/INFO PROJECT command.

The digitized contour line was used to perform a clip of the Willow Creek Reservoir triangular

irregular network (TIN) such that interpolation was not allowed to occur outside the enclosed

polygon. This contour was selected since it was the only available data to represent the reservoir

water surface at the time the survey was conducted (near reservoir elevation 4,141). This clip

was performed using the hardclip option of the ARC/iNFO CREATETIN command. Using

ARCEDIT, the underwater collected data and digitized contour from the quad maps were

plotted. The plot showed that the underwater data did not lie completely within this clip, which

required modifications to include the entire underwater data set. Modified areas included the

shoreline around the islands and some of the shoreline of the reservoir. It is assumed these

changes were due erosion of the islands and the fact that the 2002 survey was conducted on a

nearly full reservoir. Using select and move commands within ARCEDIT, the vertices of the

clip were shifted to fit all the collected underwater data. The clip was assigned an elevation of

4,136.0 to reflect the original area of the developed polygons.

Contours for the reservoir below elevation 4,136.0 were computed from the underwater data set

using the triangular irregular network (TIN) surface-modeling package within ARC/INFO. A

TiN is a set of adjacent non-overlapping triangles computed from irregularly spaced points with

x,y coordinates and z values. TIN was designed to deal with continuous data such as elevations.

The TIN software uses a method known as Delaunay's criteria for triangulation where triangles

are formed among all data points within the polygon clip. The method requires that a circle

drawn through the three nodes of a triangle will contain no other point, meaning that sample

points are connected to their nearest neighbors to form triangles using all collected data. This

method preserves all collected survey points. Elevation contours are then interpolated along the

5
triangle elements. The TIN method is discussed in greater detail in the ARC/INFO V7.O.2 Users

Documentation, (ESRI, 1992).

The linear interpolation option of the ARC/INFO TINCONTOUR command was used to

interpolate contours from the Willow Creek Reservoir TIN. In addition, the contours were

generalized by filtering out vertices along the contours. This generalization process improved

the presentability of the resulting contours by removing very small variations in the contour

lines. This generalization had no bearing on the computation of surface areas and volumes for

Willow Creek since the areas were calculated from the developed TIN. The areas of the

enclosed contour polygons at one-foot increments were developed from the survey data for

elevations 4,085.0 through 4,136.0. The 2002 study assumed no change in area since the original

survey for elevation 4,135.0 and above. The contour topography at 2-foot intervals is presented

on figure 4.

Development of 2002 Contour Areas

The 2002 TIN surface areas for Willow Creek Reservoir were computed at 1-foot increments

from elevation 4,085.0 to 4,136.0. The 2002 underwater survey measured a minimum reservoir

bottom elevation of 4,084.2. These calculations were performed using the ARC/INFO

VOLUME command. This command computes areas at user-specified elevations directly from

the TIN and takes into consideration all regions of equal elevation. As indicated above, the 2002

underwater survey data was collected near reservoir elevation 4,141. For the purpose of this

study, the measured 2002 survey areas at 2-foot increments from elevation 4,086.0 through

4,130.0 were used to compute the new area and capacity tables. Due to the limited amount of

2002 shallow water data, this study assumed no change in original area from elevation 4,135.0

and above. The area and capacity program computed the areas between elevation 4,130.0 and

4,135.0 by assuming a straight-line interpolation.

2002 Storage Capacity

The storage-elevation relationships based on the measured surface areas were developed using

the area-capacity computer program ACAP85 (Bureau of Reclamation, 1985). The 2002

surveyed surface areas at 2-foot contour intervals from reservoir elevation 4,086.0 to elevation

4,130.0 were used as the control parameters for computing the 2002 Willow Creek Reservoir

capacity. Since this study did not collect above water data, the original 5-foot surface areas from

elevation 4,135.0 to 4,150.0 were used to complete the area and capacity table.

The ACAP85 program can compute an area and capacity at elevation increments 0.01- to 1.0-

foot by linear interpolation between the given contour surface areas. The program begins by

testing the initial capacity equation over successive intervals to ensure that the equation fits

within an allowable error limit. The error limit was set at 0.00000 1 for Willow Creek Reservoir.

The capacity equation is then used over the full range of intervals fitting within this allowable

error limit. For the first interval at which the initial allowable error limit is exceeded, a new

capacity equation (integrated from a basic area curve over that interval) is utilized until it

exceeds the error limit. Thus, the capacity curve is defined by a series of curves, each fitting a

certain region of data. By differentiating the capacity equations, which are of second order

polynomial form, the final area equations are derived:

6
y a1 ± a2x + a3x2

where: y = capacity

x = elevation above a reference base

a1 = intercept

a2 and a3 coefficients

Results of the Willow Creek Reservoir area and capacity computations are listed in table 1 and

columns 4 and 5 of table 2. On table 2, columns 2 and 3 list the original surface areas and

recomputed original capacities. A separate set of 2002 area and capacity tables has been

published for the 0.01, 0.1 and 1 -foot elevation increments (Bureau of Reclamation 2002). A

description of the computations and coefficients output from the ACAP8S program is included

with these tables. Both the original and 2002 area-capacity curves are plotted on figure 5. As of

June 2002, at elevation 4,149.0, the surface area was 1,644 acres with a total capacity of 42,691

acre-feet.

RESERVOIR SEDIMENT ANALYSES

Figure 5 is a plot of Willow Creek Reservoir original surface area and capacity versus the 2002

measured surface area and capacity that illustrates the differences between the two surveys.

Since Willow Creek Dam closure in 1911, the measured total volume change at reservoir

elevation 4,144.0 was estimated to be 431 acre-feet. The estimated average annual rate of

capacity lost for this period (91 years) was 4.7 acre-feet per year. The storage loss in terms of

percent of original storage capacity was 1.2 percent at elevation 4,144.0. It must be noted that

the 2002 area and capacity tables were generated assuming no change in original area and

capacity from elevation 4,135.0 and above that in all probability is not the case.

Figure 5 plot and table 2 show the maximum volume change to be 671 acre-feet at elevation

4,115.0. It is assumed that a portion of this material is from island shoreline erosion that

redistributed material from the upper reservoir elevations to the lower elevation areas.

A resurvey of Willow Creek Reservoir should be considered in the future if major sediment

inflow events are observed. An above water survey should be conducted if better information is

needed for elevation 4,135.0 and above. The 2002 survey has shown little change over the 91

years of reservoir operation.
REFERENCES

American Society of Civil Engineers, 1962. Nomenclature for Hydraulics, ASCE Headquarters,

New York.

Bureau of Reclamation, 1981. Project Data, Denver Office, Denver CO.

Bureau of Reclamation, 1985. Surface Water Branch, AAP85 User's Manual, Technical

Service Center, Denver CO.

Bureau of Reclamation, 1987(a). Guide for Preparation of Standing Operating Procedures for

Bureau of Reclamation Dams and Reservoirs, U.S. Government Printing Office, Denver, CO.

Bureau of Reclamation, 1987(b). Design of Small Dams, U.S. Government Printing Office,

Denver CO.

Bureau of Reclamation, June 2002. Denver Office, Willow Creek Reservoir Area and Capacity

Tables, Sun River Project, Great Plains Region, Billings, MT.

Corps of Engineers, January 2002. Engineer and Design - Hydrograpliic Surveying,

EM 1110-2-1003, Department of the Army, Washington DC,

(www.usace.army.mullinet/usace-docs/eng-maflUalS/em 1110-2-1 003/toc.htm).

Environmental Systems Research Institute, Inc. (ESRI), 1992. ARC Command References.

USGS, 2000. Water Resources Data Montana Water Year 2000, U.S. Geological Survey, U.S.

Department of the Interior.

8
RESERVOIR SEDIMENT

DATA SUMMARY Willow creek Reservoir

BANE OF RESERVOIR

1

DATA SHEET NO.

C 1. OWNER Bureau of Reclamation 2. STREAM Willow Creek 3. STATE Montana

A 4. SEC. 30 TWF. 21 N RANGE 6 W 5. NEAREST P.O. Auqusta 6. COUNTY Lewis & Clark

M 7. hAT 47 32' 48" LONG 112' 25' 45" 8. TOP OF DAY ELEVATION 4,154.0- 9. SpILLWAy CREST EL 4l44.o

F

P

3

1C. STORAGE

ALLOCATION

11. ELEVATION

TOP OF POOL

12. ORIGINAL

SURFACE AREA, AC

13. ORIGINAL

CAPACITY, AF

14. GROSS

STORAGE ACREFEET

15. DATE

STORAGE

BEGAN

S

a. SURCHARGE 4,149.O 1644 7872 43,122

F

v

, FLOOD CONTROL _________________ -

c

POWER

__________________ ________________ 191i

: d. JOINT USE _______________ 16. DATE

R e. CONSERVATION 4,144.0 1,509 32,187 38,250 NORMEL

f. INACTIVE OPERATION

g. DEAL 4,085.3 12 53 63

- 17, LENGTH OF RESERVOIR 25 AVG. WIDTH OF RESERVOIR 1.1 MILES

B 18. TOTAL DRAINAGE AREA 55 SQUARE 22. MEAN ANNUAL PRECIPITATION l9 INCHES

A 19. NET SEDIMENT CONTRIBUTING AREA PS SQUARE 23. MEAN ANNUAL RUNOFF 2.9 INCHES

20. LENGTH MILES AV. WIDTH 24. MEAN ANNUAL RUNOFF 14,600h ACRE-FEET

___ 21. MEN. ELEVATON NIH. ELEVATION 25. ANNnAT, TEMP. MEAN 48SF RANCH -49"F to l06"F4

S

U

R

26. DATE OF

SURVEY

__________________

27.

PER.

________

26.

ACCL

________

29. TYPE OF

SURVEY

_________________

30. NC. OF

RANGES OR

__________________

31. SURFACE

AREA, AC -

_________________

22. CAPACITY

ACRE - FEET

33. C/I

RATIO

V

E

Y

___________________________________

1911 COntour (D) S-ft l,509 35,250 2.41

6/02 91 91 Contour (D 2-ft 1,5091 34,8l9 2.38

D

A

26. DATE OF

SURVEY

34. PERIOD

ANNUAL

35. PERIOD WATER INFLOW, ACRE FEET

____________________________________________

WATER INFLOW TO DATE, AF

A

P168311k'. a. MEAN ANN. U. MAX. ANN. c. TOTAL

________________

a. MEAN ANN.

______________

b. TOTAL

6/02 14,600" 35,900 744,500 14,600 744,600

26. DATE CF

SURVEY

37. PERIOD CAPACITY LOSS, ACRE-FEET

____________________________________________________

38. TOTAL SEDIMENT DEPOSITS TO DATE, AF

a. TOTAL h. AV. ANN. C. /MI.2-YR. a. TOTAL b. AV. ANNUAL J

c. /MI.-YR.

6/02 43l 4.8 .05 431 4.8 .05

26. DATE OF

SURVEY

39. AV. DRY

MT. (#/FTt

40. SED. DEP. TONS/MI.-YR.

____________________________

41. STORAGE LOSS, PCT. 42.

a. PERIOD b. TOTAL TO

______________

a. AV.

________________

b. TOTAL TO

______

a. (

______

b.

6/02 .01

26.

DATE

43. DEPTH DESIGNATION RANGE BY RESERVOIR ELEVATION

SURVE

PERCENT OF TOTAL SEDIMENT LOCATED WITHIN DEPTH DESIGNATLON

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

SURVE

0-10 10-

20

20-

30

30-

40

40-

50

50-

60

50-

70

70-

80

50-

90

90-

100

100-

105

105-

:10

110-

115

115-

120

123-

115

V PERCENT OF TOTAL SEDIMENT LOCATED 8ETHIN REACH DESIGNATION

Table 1. ReservoIr sediment data summary )page I of 2).

9
45. RANGE IN RESERVOIR OPERATION6 ____________ ____________ ____________

YEAR MAX. ELEV. WIN. ELEV. INFLOW, AF YEAR MAX. ELEV. WIN. ELEV. INFLOW, AF

1952 4,139.0 4,131.0 13,800 1953 4,139.3 4,131.7 33,629

1914 4,139.8 4,135.5 10,700 1955 4,140.0 4,136.0 4,700

1956 4,039.7 4,135.3 2,400 1957 4,139.5 4,131.3 0,900

1958 4,141.7 4,131.4 30,200 1959 4,140.9 4,085.3 9,700

1960 4,139.5 4,121.2 35,900 1951 4,142.2 4,122.5 20,500

1862 4,141.1 4,122.7 23,700 1963 4,141.9 4,133.4 3,200

1954 4,136.8 4,130.0 28,300 1965 4,138.9 4,127.5 21,300

1956 4,142.0 4,129.5 9,900 1967 4,141.2 4,128.9 27,100

1958 4,141.0 4,126.2 15,400 1969 4,140.4 4,129.5 6,500

1970 4,141.2 4,130.5 12,400 1971 4,141.5 4,132.4 6,800

1972 4,141.2 4,132.5 11,300 1973 4,141.6 4,117.3 9,200

1974 4,41.2 4,128.7 17,800 1975 4,141.7 4,136.2 29,600

1976 4,141.0 4,137.1 13,500 1977 4,138.4 4,125.0 2,800

1978 4,137.8 4,125.9 13,500 1979 4140.7 4,.32.6 5700

1980 4,140.9 4,131.1 14,300 1981 4,140.6 4,121.1 13,200

1982 4,140.9 4,134.5 9,800 1983 4,140.2 4,135.2 9,100

1980 0,141.2 4,122.2 7,900 1985 4,14 ,4 4,199.8 23,900

1986 4,141.6 4,126.5 18,100 1987 4,142.8 4,130.5 11,600

1986 4,141.0 4,118.2 3,100 1989 4,141.5 4,118.2 25,102

1990 4141.9 4,139.2 1,900 1991

-

4,142.0

-

4,138.7 18,400

1992 4,141.0 4,132.0 500 1993 4,141.6 4,132.1 14,000

1994 4,141.6 4,124.8 8,400 1995 4,141.7 4,127.6 24,700

1996 4,140.7 4,114.0 21,200 1997 4,142.1 4,114.0 29,100

1998 4,141.4 4,133.4 12,300 1999 4,139.5 411.3.6 21,700

2000 4,134.7 4,113.8 19,200 2001 4,136.3 4,127.0 7,200

7777 47 7 5 178 7 16477 _____________ _____________

45. ELEVATION - AREA CAPACITY DATA FOR 2002 CAPACITY°

ELEVATION AREA CAPACITY ELEVATION AREA CAPACITY ELEVATION AREA CAPACITY

4,084.2 0 0 4,086 2 2 4,085 4 7

4,090 7 17 4,092 27 51 4,094 50 128

4,095 60 183 4,096 70 245 4,098 96 414

4,100 125 835 4,102 183 915 4,104 186 1,254

4,105 209 1,451 4,106 232 1,572 4,108 273 2,176

4,110 317 2,765 4,112 374 3,456 4,114 439 4,259

4,115 477 4,727 4,118 515 5,224 4,115 599 6,338

4,120 680 7,617 4,122 754 9,051 4,125 866 11,478

4,126 905 12,353 4,128 979 14,247 4,130 1,051 16,277

4,132 1,153 18,480 4,134 1,254 20,887 4,135 1,305 22,187

4,136 1,327 23,483 4,138 1,372 25,182 4,140 1,415 25,969

4,142 1,462 31,848 4,144 1,509 34,819 4,145 1,532 36,339

4,146 1,560 37,585 4,148 1,615 41,061 4,149 1,544 42,691

47. REMARKS AND REFERENCES

0 All elevations are in feet and based on the original pro ject datum established by Reclamation that were

found by the 2002 study to be around 6.7 feet less then the NAVOSS.

Uncontrolled overflow spillway.

0 Capacity computed from surface areas measured in 1908 from a detailed topographic survey developed on a

scale of one inch equ alS 1000 feet and 5-foot contour in tervals.

Bureau of Reclamation Project Data Book, 1981. Values for Sun River Project.

Calculat ed using mean annual mnnoff value of 14,600 AF, item 24, 1982 through 2002 . (See remark 6(

Annual computed inflows by water year, from 1952 through 2002. Inflows from Willow Creek drainage and

diverted flows from the Sun River through the Willow Cre ek Feeder Canal.

Surface area & capaci ty at elevation 4,144.0 computed by ACAP program.

Iuioual computed inflows by watan year, from 1902 through 2002. Inflows from Willow Crock drainage and

diverted flows from the Sun River through the Willow Cre ek Feeder Canal. Maximum and mnirrrum elevations

from available Reclamatcon records by end of the month w ater year recc'rda.

Volume change at alevaton 4,144.0. Value affected by accuracy difference between two surveys. 2002 survey

assume no change from elevation 4,135 and above. Maxim um capacity change at elevation 4,115.0. Assume

portion of change in lower elevations due to island shoreltne erosion .

Capacitcea computed by Reclamation's ACAP computer program.

48. AGENCY MAKING SURVEY Bureau of Reclamation

49. AGENCY SUPPLYING DATA Bureau cf Reclamation J

DATE April 2003

Tabie 1. - Reservoir sediment data summary (page 2 of 2)

10
2 3 4 5 6 7 8

Elevations Original Original 2002 2002 2002 202 Percent of

_______

Durvey Capacity Curvcy Survey Vluxne Percent of svrir

feet) (acres) (acre -feet) (acres> (acre -feet) Chance C1anoe Depth

4,154.0 1,782 51,689 1782 51,258 100.0

4,150.0 1,672 44,780: 1,672 44,349 94.9

4,149.0 1,644: 43,122 1,644 42,691 431 100.0 93.7

4,145.0 1,532,

4,144.0 1,509

36,770

35,250

1,532

1,509

36,339

34,819

431

431

100.0 88.6

100.0 87.3

4,142.0 1,462: 32,278] 1,4621 31,848 430 99.8 84.8

4,140.0 1,416 29,400 1,416 28,969 431 100.0 82.3

4,135.0 1,305[ 22,598 1,305: 22,167 431 100.0 75.9

4,130.0 1,054: 16700] 1,05l 16,2771 423 98.1 69.6

4,125.0 857 _____

_ 11,923] 866 11,478 445 103.2 63.3

4,120.0 651 8,153] 680 7,617 536 124.4 57.0

4,115.0 451 ______5,398] 477 4,727 671 155.7 50.6

4,l10.0 ______341 3,4181 317 2,765 653 151.5 44.3

4,105.0 223

4,100.0 146

2,09L2.9

1,085 126

1,451

636

557

449:

129.2

104.2

38.0

31.6

4,095.0 _____87 503, 60 183 25.3

4,090.0 4 0 17 168 39 . 0 19.0

4,085.0 10 601 1 0 60] 13.9 12.7

4,084.2 10: 52 0 0 52 12.1 11.6

4,080.0 7 18 o: 0 18 4.2 6.3

oH o

o 0 0 ____

0.0

-

___

0.0

1 Elevation of reservoir water surface.

2 Original reservoir surface area from 1905 survey. _____

3 Original reservoir capacity computed from 1905 surface areas.

_____

4 Reservoir surface area from 2002 survey.

5 Reservoir capacity computed from 2002 surface areas using ACAP.

_______ ___________

6 Measured volume difference = column (3) - column (5) .

7 Measured difference_expressed in percentage of total

_________

431 at elevation 4,144 .0.

S Depth of reservoir expressed in percentage of total depthof79 j

Table 2. - Summary of 2002 results.

11
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13

Figure 3. - Willow Creek 2002 underwater data.
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di

Vertical datum based on original

Proect Datum established bA US

Bureau of declamation which is

67 feet lower thai-i the North

Amer-iSon Vertical Datum of 198B (IIAVDBS)

15

Figure 4. - Willow Creek Reservoir topograprnc map.

V.

5.
1,800

4,155

4,145

4,135

4,125

0

9-

C

0

4..

>

4,115

Ui

4,105

4,095

4,085

4,075

0

Area-Capacity Curves for Willow Creek Reservoir

Area (acre)

1,620 1,440 1,260 1,080 900 720 540 360 180 0

A1L

-- -r i:i-J

2002 Survey

Original Survey

-

I

- 4,145

4,135

4,125

4,115

Area

4,105

4,095

- 4,085

- ------ - 4,075

16500 22000 ?7500 33000 38500 44000 49500 55000

Capcty (acre-feet)

Figure 5. - 2002 area and capacity curves.

5500 11000