PRINEVILLE RESERVOIR

1998 SEDIMENTATION SURVEY

UOFR

U.S. Department of the tnterior

Bureau of Reclamation
REPORT DOCUMENTATION PAGE I

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

March_1999 Final

4. TITLE AND SUBTITLE

____________________________

5. FUNDING NUMBERS

Prineville Reservoir PR

1998 Sedimentation Survey

6. AUTHOR(S)

Ronald L. Ferrari

7. PERFORMING ORGANIZA11ON NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATiON

REPORT NUMBER

Bureau of Reclamation, Technical Service Center, Denver CO 80225-0007 ____________________________

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

AGENCY REPORT NUMBER

Bureau of Reclamation, Denver Federal Center, P0 Box 25007,

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

Available from the National Technical Information Service,

Operations Division, 5285 Port Royal Road, Springfield VA 22161 ___________________________

13. ABSTRACT (Maximum 200 words)

The Bureau of Reclamation (Reclamation) surveyed the underwater portion of Prineville Reservoir in May of 1998 to

develop a topographic map and compute a present storage-elevation relationship (area-capacity tables). The data

were used to calculate reservoir capacity lost due to sediment accumulation since dam closure in December 1960.

The underwater survey used sonic depth recording equipment interfaced with a global positioning system (GPS) that

gave continuous sounding positions throughout the reservoir. The above-water topography was measured from

aerial photography obtained in October 1987 near reservoir elevation 3220 feet. The new topography map of

Prineville Reservoir was developed by a computer graphics program using the combined 1987 and 1998 collected

data.

As of May 1998, at top of spillway crest elevation (feet) 3234.8, the reservoir surface area was 3,028 acres with a

total capacity of 150,216 acre-feet. Since initial filling in 1960, about 4,586 acre-feet of sediment have accumulated

in Prineville Reservoir below elevation 3234.8, resulting in 2.96 percent loss in reservoir volume. Since 1960, the

estimated average annual rate of reservoir capacity lost to sediment accumulation is 122.3 acre-feet.

14. SUBJECT TERMS 15. NUMBER OF PAGES

reservoir area and capacity! sedimentation! reservoir surveys/ sonar/ sediment 27

distribution! contour area! reservoir area! sedimentation survey! global positioning system 16. PRICE CODE

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

OF REPORT OF ThIS PAGE OF ABSTRACT

UL UL UL UL

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

Preacribed by ANSI Std. 239-18

298-102
PRINEVILLE RESERVOIR

1998 SEDIMENTATION SURVEY

by

Ronald L. Ferrari

Sedimentation and River Hydraulics Group

Water Resources Services

Technical Service Center

Denver, Colorado

March 1999
ACKNOWLEDGMENTS

The Bureau of Reclamation's (Reclamation) Sedimentation and

River Hydraulics Group of the Technical Service Center (TSC)

prepared and published this report. Ronald Ferrari and Kent

Collins of the TSC conducted the hydrographic survey. Special

thanks to Sam Trachsler of the Columbia Basin Project Office of

the Pacific Northwest Region for his assistance during the 1998

bathymetric survey by locating the necessary control points that

were established during the 1987 aerial survey. The aerial

photography interpretation was conducted by Delta Aerial

Survey, Inc. in Denver, Colorado in 1987. Dan Bingaman and

Randy Westphal of the Visual Presentations Group of the TSC

conducted the process of converting the 56 aerial maps into an

AutoCAD data file. Ronald Ferrari completed the underwater

data processing needed to generate the new map topology and

area-capacity tables. Sharon Nuanes of the TSC completed the

contour digitizing and edge matching of the U.S. Geological

Survey maps with the aerial maps, and generated the final maps

presented in this report. Kent Collins performed the peer review

of this documentation.

U.S. Department of the Interior

Mission Statement

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 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

Hydrographic survey equipment and method 3

GPS technology and equipment 3

Original survey 5

1987 aerial survey 6

1998 underwater survey 7

Reservoir area and capacity 7

Topography development 7

Development of 1998 contour areas 8

1998 storage capacity 9

Reservoir sediment analyses 10

References 10

TABLES

Table

1 Reservoir sediment data summary (page 1 of 2) 13

1 Reservoir sediment data summary (page 2 of 2) 14

2 Summary of 1998 survey results 15

3 Summary of 1998 survey and theoretical sediment distribution computations 16

Figure

FIGURES

1 Prineville Reservoir location map 17

2 Arthur R. Bowman Dam, plan and section 18

3 Prineville Reservoir topology map, No. 113-D-588 19

4 Prineville Reservoir topology map, No. 113-D-589 21

5 Prineville Reservoir topology map, No. 113-D-590 23

6 Prineville Reservoir topology map, No. 113-D-591 25

7 1998 area and capacity curves 27

111
INTRODUCTION

Prineville Reservoir, formed by Arthur R. Bowman Dam, is the largest of the two water

storage reservoirs of the Crooked River Project, the other storage feature being Ochoco

Reservoir. The dam, located on the Crooked River in Crook County, is about 20 miles south

of Prineville in central Oregon (fig. 1).

Arthur R. Bowman Dam closure and first reservoir storage occurred in December 1960. The

dam was formerly known as Prineville Dam until the name changed in the 1970's. The

multipurpose reservoir provides primarily irrigation storage with additional storage for flood

control and recreation. The original reservoir survey measured a surface area of about

3,034 acres and a capacity of 154,802 acre-feet at the reservoir's full pool and top of spillway

gate elevation 3234.8 (feet)'. At this elevation the reservoir is around 14 miles long and has

an average width of around 0.3 miles. The drainage basin area behind Arthur R. Bowman

Dam is about 2,700 square miles with an average elevation of 4,530 feet.

Arthur R. Bowman Dam is a zoned earth and rockfill structure (fig. 2) with:

• a structural height2 of 245 feet

• a hydraulic height of 182 feet

• a crest elevation of 3264 feet

• a top crest width of 35 feet

• a crest length of 800 feet

The spillway, located on the right abutment of the dam, has a design capacity 8,120 cubic feet

per second (ft3lsec) at water surface elevation 3257.9. It consists of:

• an excavated inlet channel

• 20-foot-wide uncontrolled concrete ogee crest at elevation 3234.8

• a 377.8-foot-long concrete chute

• a 54-foot-wide by 100-foot-long jump-type stilling basin shared with the outlet works

The river outlet works is located on the right abutment, has a design capacity of 3,300 ft3/sec

at elevation 3234.8, and consists of:

• a trashrack drop inlet-type intake structure

• 11-foot-inside-diameter concrete-lined circular tunnel

• gate chamber with two hydraulically operated emergency gates

• two hydraulically operated high-pressure regulating gates

• a concrete-lined modified-horseshoe-shaped downstream tunnel

'All elevations levels are shown in feet.

2The definitions of such terms as "structural height," and "hydraulic height" 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.
SUMMARY AND CONCLUSIONS

This Reclamation report presents the 1998 results of the first extensive survey of Prineville

Reservoir. The primary objectives of the survey were to gather data needed to:

• develop reservoir topography

• compute area-capacity relationships

• resolve conflicts about storage capacity

• estimate storage depletion caused by sediment deposition since dam closure

Standard land surveying methods were used to establish the horizontal and vertical control

points for the aerial survey that was flown in October of 1987 around reservoir water surface

elevation 3220. The aerial analysis was conducted by a private contractor who produced 5-foot

contours for the majority of the above water reservoir area. The final product was 56 reservoir

topographic maps at a scale of 1 inch equals 100 feet. The horizontal control grid established

in the 1987 aerial survey was used for the 1998 underwater survey.

The 1998 bathymetric survey was run using sonic depth recording equipment interfaced with

a differential global positioning system (DGPS) 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 Prineville Reservoir. The

positioning system provided information to allow the boat operator to maintain course along

these grid lines. Water surface elevations recorded by a Reclamation gauge during the time

of collection were used to convert the sonic depth measurements to true lake bottom

elevations.

The new Prineville Reservoir topographic map is a combination of the 1987 aerial and 1998

underwater survey data. The 1998 reservoir surface areas at predetermined 5-foot contour

intervals were generated by a computer graphics program using the collected data. The area

and capacity tables were produced 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).

Tables 1 and 2 contain a summary of the Prineville Reservoir sedimentation and watershed

characteristics for the 1998 survey. The 1998 survey determined that the reservoir has a total

storage capacity of 150,216 acre-feet and a surface area of 3,028 acres at spiliway crest

elevation 3234.8. The difference between the recomputed original and the 1998 capacities, at

reservoir elevation 3234.8, indicated a volume of 4,586 acre-feet of sediment has accumulated

since dam closure in December 1960. This volume represents a 2.96 percent loss in total

capacity and an average annual loss of 122.3 acre-feet per year.

2
RESERVOIR OPERATIONS

The reservoir is a multiuse facility having (the following elevation increments are from a

May 5, 1973 Reservoir Capacity Allocations table, and capacity values are from May 1998

area-capacity tables):

• 80,193 acre-feet of surcharge storage between elevations 3234.8 and 3257.9.

• 60,021 acre-feet ofjoint use storage between elevations 3211.17 and 3234.8.

• 88,612 acre-feet of conservation storage between elevation 3114.0 and 3211.17.

• 284 acre-feet of inactive storage between elevations 3112.0 and 3114.0.

• 1,299 acre-feet of dead storage below elevation 3112.0.

The Prineville Reservoir inflow and end-of-month stage records are presented in table 1. The

available records from December 1960 through May 1998 show that the average inflow into

the reservoir was 257,656 acre-feet per year. This inflow computes to a mean annual runoff

of 1.8 inches for the 2,700-square-mile basin. The end-of-month stage records show that

Prineville Reservoir initially filled to spillway crest elevation 3234.8 in water year 1962 and

since then the operation has ranged from elevation 3162.3 in 1993 to elevation 3241.3 in 1998.

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. The hydrographic system contained on the survey

vessel consisted of a GPS receiver with a built-in radio and an omnidirectional antenna, a

depth sounder, helmsman display for navigation, a plotter, a computer, and hydrographic

system software for collecting the underwater data. Power to the equipment was supplied by

an on-board generator.

The shore equipment included a second GPS receiver with a built-in radio and an

omnidirectional antenna. The GPS receiver and antenna were mounted on a survey tripod

over a known datum point. To obtain the maximum radio transmission range, known datum

points with clear line-of-sight to the survey boat were selected. The power for the shore units

was provided by a 12-volt battery.

GPS Technology and Equipment

The positioning system that was used at Prineville Reservoir was Navigation Satellite Timing

and Ranging (NAVSTAR) GPS, an all-weather, radio-based, sateffite navigation system that

enables users to accurately determine three-dimensional position. The NAVSTAR system1s

primary mission is to provide passive global positioning and navigation for land-, air-, and seabased strategic and tactical forces and is operated and maintained by Department of Defense

(DOD). The GPS receiver measures the distances between the satellites and itself and

determines the receiverts position from the intersections of the multiple-range vectors.

Distances are determined by accurately measuring the time a signal pulse takes to travel from

the satellite to the receiver.

3
The NAVSTAR system consists of three segments:

• The space segment is a network of 24 satellites maintained in precise orbits about

10,900 nautical miles above the earth, each completing an orbit every 12 hours.

• The ground control segment tracks the satellites, determining their precise orbits.

Periodically, the ground control segment transmits correction and other system data to all

the satellites, and the data are then retransmitted to the user segment.

• The user segment includes the GPS receivers that measure the broadcasts from the

satellites and calculate the position of the receivers.

The GPS receivers use the satellites as reference points for triangulating their position on

earth. The position is calculated from distance measurements to the satellites that are

determined by how long a radio signal takes to reach the receiver from the satellite. To

calculate the receiver's position on earth, the satellite distance and the satellite's position in

space are needed. The satellites transmit signals to the GPS receivers for distance

measurements along with the data messages about their exact orbital location and operational

status. The satellites transmit two "L" band frequencies (called Li and L2) for the distance

measurement signal. At least four satellite observations are required to mathematically solve

for the four unknown receiver parameters (latitude, longitude, altitude, and time). The time

unknown is caused by the clock error between the expensive satellite atomic clocks and the

imperfect clocks in the GPS receivers. For hydrographic surveying, the altitude or the

Prineville Reservoir water surface elevation parameter was known, which realistically meant

only three satellite observations were needed to track the survey vessel. During the Prineville

Reservoir survey, a minimum of five satellites were used for position calculations while the

majority of the time, the best six available satellites were used.

The GPS receiver's absolute position is not as accurate as it appears in theory because of the

function of range measurement precision and geometric position of the satellites. Precision

is affected by several factors-time, because of the clock differences, and atmospheric delays

caused by the effect on the radio signal by the ionosphere. Geometric dilution of precision

(GDOP) describes the geometrical uncertainty and is a function of the relative geometry of the

satellites and the user. Generally, the closer together in angle two satellites are from the

receiver, the greater the GDOP. GDOP is broken into components: position dilution of

precision (x,y,z) (PDOP), and horizontal dilution of precision (x,y) (HDOP). The components

are based only on the geometry of the satellites. The PDOP and HDOP were monitored during

the Prineville Reservoir Survey, and for the majority of the time, they were less than 3, which

is within the acceptable limits of horizontal accuracy for Class 1 and 2 level surveys (Corps of

Engineers, 1991).

An additional and larger error source of GPS collection is caused by false signal projection,

called selective availability (S/A). The DOD implements S/A to discourage the use of the

satellite system as a guidance tool by hostile forces. Positions determined by a single receiver

when S/A is active can have errors of up to 100 meters.

4
A method of collection to resolve or cancel the inherent errors of GPS (satellite position or S/A,

clock differences, atmospheric delay, etc.) is called DGPS. DGPS was used during the

Prineville Reservoir survey to determine positions of the moving survey vessel in real time.

DGPS determines the position of one receiver in reference to another and is a method of

increasing position accuracies by eliminating or minimizing the uncertainties. Differential

positioning is not concerned with the absolute position of each unit, but with the relative

difference between the positions of the two units, which are simultaneously observing the

same satellites. The inherent errors are mostly canceled because the satellite transmission

is essentially the same at both receivers.

At a known geographical benchmark, one GPS receiver is programmed with the known

coordinates and stationed over the geographical benchmark. This receiver, known as the

master or reference unit, remains over the known benchmark, monitors the movement of the

satellites, and calculates its apparent geographical position by direct reception from the

satellites. The inherent errors in the satellite position are determined relative to the master

receiver's programmed position, and the necessary corrections or differences are transmitted

to the mobile GPS receiver on the survey vessel. For the Prineville Reservoir Survey, position

corrections were determined by the master receiver and transmitted via an ultra-high

frequency (UHF) radio link every 3 seconds to the survey vessel mobile receiver. The survey

vessel's GPS receiver used the corrections along with the satellite information it received to

determine the vessel's differential location. Using DGPS resulted in positional accuracies of

1 to 2 meters for the moving vessel compared to positional accuracies of 100 meters with a

single receiver.

The Technical Service Center (TSC) mobile and reference GPS units are identical in

construction and consist of a six-channel Li coarse/acquisition (C/A) code continuous parallel

tracking receiver, an internal modem, and a UHF radio transceiver. The differential

corrections from the reference station to the mobile station are transmitted using the industry

standard Radio Technical Commission for Maritime Services message protocol via the UHF

radio link. The programming to the mobile or reference GPS unit is accomplished by entering

necessary information via a notebook computer. The TSC's GPS system has the capability of

establishing or confirming the land base control points by using notebook computers for

logging data and using postprocessing software. The GPS collection system has the capability

of collecting data in 1927 or 1983 North American Datums (NAD) in the surveyed area's state

plane coordinate system's zone. For the 1998 Prineville Reservoir survey, the state plane

coordinate system used was 1927 NAD in Oregon's South Zone. The reference GPS unit was

set over control points established for the 1987 aerial survey.

Original Survey

The original area and capacity tables for Prineville Reservoir appear to be generated from

reservoir topography developed prior to dam construction. Drawing 113-119-181, dated

September 1957, has a scale of 1 inch equals 1,000 feet with 10-foot contour intervals. The

upper enclosed contour for this drawing was elevation 3250. An original area-capacity table

for Prineville Reservoir, dated December 11, 1962, had area and capacity values from elevation

3077 to elevation 3260. It is assumed that the area value for elevation 3260 was projected

5
from the area curve since no other information on surface area and contour development was

located. For the purpose of computing sediment values for this study, the original surface area

values (listed in column 2 of table 2) were used to recompute the original capacity of Prineville

Reservoir (column 3 of table 2) using the area-capacity computer program ACAP (Bureau of

Reclamation, 1985).

1987 Aerial Survey

In October of 1987 an aerial survey of Prineville Reservoir was conducted. Standard land

surveying methods were used to establish the horizontal and vertical control points throughout

the reservoir area. The aerial analysis was conducted by a private contractor and resulted in

5-foot contours for the majority of the reservoir area. The reservoir water surface at the time

of collection was around elevation 3220. The uppermost complete contour was elevation 3285.

The final product was fifty six Prineville Reservoir topographic maps at a scale of 1 inch equals

100 feet. The horizontal control grid for this aerial survey was Oregon's NAD 1927 south state

plane coordinates. Several of these control points were located and used for the 1998

underwater survey.

During the planning of the 1998 underwater survey it was decided that the 1987 aerial data

would be used for the upper contour development of Prineville Reservoir. It was decided that

the expense of conducting a present aerial survey was not justified since the 1998 underwater

survey was projected to be conducted near spillway crest reservoir elevation 3234.8 and the

1987 aerial data was of such detail from elevation 3220 and above. Digital computer file data

were not available for the 1987 aerial topography, requiring the scanning of the 56 reservoir

maps. This process was accomplished fairly cleanly by the Visual Presentation Group of the

TSC since the maps were on mylar and did not have too much clutter. The original mylar

maps were scanned at 600 dots per inch using a large format scanner. Using computer

software, each map image was converted to vector elements, rubber sheeted to the proper

scale, cleaned of excess scanner noise, and converted to true size and true space. Each map

sheet was imported into a single base drawing where all map edges were matched within the

final map that was an AutoCAD DXF file.

During the scanning process it was found that the aerial flight line did not cover the entire

reservoir area. This affected the very upper area, where the Crooked River flows into the

reservoir, and a large part of the Bear Creek arm of the reservoir. The aerial flight line ended

in the upper reservoir area near state plane coordinate E196000 (start of map 113-D-591) and

the upper end of Bear Creek near state plane coordinate N884000 (map 113-D588). To

complete the upper reservoir contours required the digitizing of the available contours from

the U.S. Geological Survey (USGS) quad maps and matching them with the aerial scan map

contours. The available contours from the USGS quads included contour elevations 3235,

3240, and 3280. This had little effect on the underwater contour development and the

sediment calculations since elevation 3235 was used as the clip for the underwater contour

development. This is explained in the topography development section. Engineering

judgement for interpolating the contours for these affected areas was required to compute

surface areas for elevations 3245 through 3285. Contours were interpolated, for the affected

areas, for elevations 3245, 3250, 3255, 3260, 3270 and 3285. The maximum water surface of

6
Prineville Reservoir is elevation 3257.9, but since the majority of the reservoir contour areas

for elevations 3260 through elevation 3285 were available, these contours were also

interpolated for future reference. This information was used to compute an area-capacity

table for Prineville Reservoir up to elevation 3285.

1998 Underwater Survey

The Prineville Reservoir bathymetric survey was conducted May 14 through May 18, 1998

near reservoir water surface elevation 3235.5. The bathymetric surveys were run using sonic

depth recording equipment interfaced with a DGPS capable of determining sounding locations

within the reservoir. The survey system software continuously recorded reservoir depths and

horizontal coordinates as the survey boat moved along closely spaced grid lines covering the

reservoir area. Most of the transects (grid lines) were run perpendicularly to the original river

alignment at a spacing of 300 feet. Data were also collected along the shore as the boat

traversed to the next transect. The survey vessel's guidance system gave directions to the boat

operator to assist in maintaining course along these predetermined grid lines. During each

run, the depth and position data were recorded on the notebook computer hard drive for

subsequent processing by TSC personnel. The underwater data set includes 46,485 data

points. The water surface elevation recorded by a Reclamation gauge during the time of

collection was used to convert the sonic depth measurements to true lake bottom elevations.

The 1998 underwater data were collected by a depth sounder that was calibrated by lowering

a deflector plate below the boat by cables with known depths marked by beads. The depth

sounder was calibrated by adjusting the speed of sound, which can vary with water density,

salinity, temperature, turbidity, and other conditions. The accuracy of an instantaneous

reading from the depth finder is estimated to be ±0.5 feet, which takes into consideration

calibration error and data collection in a moving boat. The collected data were digitally

transmitted to the computer collection system via an RS232 port. The depth sounder also

produces an analog hard copy chart of the measured depths. These graphed analog charts

were printed for all survey lines as the data were collected and recorded by the computer. The

charts were analyzed during postprocessing, and when the analog charted depths indicated

a difference from the recorded computer bottom depths, the computer data files were modified.

RESERVOIR AREA AND CAPACITY

Topography Development

Using ARC/INFO, the topography of Prineville Reservoir was developed from the combined

1987 aerial and 1998 underwater collected data. ARC/INFO is a software package for

development and analysis of geographic information system (GIS) layers and development of

interactive GIS applications (ESRI 1992). GIS technology provides a means of organizing and

interpreting large data sets. As explained in the 1987 aerial survey section, the majority of

the upper contours of the reservoir were developed from scanned 1987 aerial contour data

supplemented by digitized USGS quad maps. ARC/INFO V7.0.2 GIS software was used to

digitize the USGS quad map contours and features such as the roads. The USGS quad maps

were developed from aerial photography dated 1984, with the last editing of the map dated

7
1990. The digitized information was transformed to Oregon's NAD 1927 south state plane

coordinates using the ARC/INFO PROJECT command.

Using ARCEDIT, the underwater data points and the scanned 1987 aerial contours layers

were plotted. Using the add and select commands, data points were added for the reservoir

areas not covered by the 1998 underwater survey. This included areas along the reservoir

shore line and the several islands within the reservoir area. This data set was used to

compute the present reservoir capacity.

The elevation 3235.0 contour from the 1987 aerial and digitized USGS quad maps was used

to perform a clip of the Prineville Reservoir triangular irregular network (TIN) such that

interpolation was not allowed to occur outside the 3235.0 contour. The enclosed 1987 area for

elevation 3235.0 was 3,036 acres which compares to the original area of 3,042 acres for the

same elevation. This complete contour was selected since it was the elevation that most nearly

enclosed the 1998 underwater data collected near reservoir elevation 3235.5.

A TIN is a set of adjacent, nonoverlapping 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 know as Delaunay's criteria for triangulation.

Triangles are formed between all collected data points including all boundary points. This

method preserves all collected survey points. The method requires that a circle drawn through

the three nodes of a triangle will contain no other point. This requirement means that sample

points are connected to their nearest neighbors to form triangles. Using the hardcip option

of the ARC/INFO CREATETIN command, the clip or polygon boundary (elevation 3235)

enclosed all the collected data, such that during TIN development, interpolation was not

allowed to occur outside the boundary. The elevation contours are interpolated along the

triangle elements. The TIN method is discussed in greater detail in the ARC/INFO V7.0.2

users documentation (ESRI, 1992).

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

interpolate contours from the Prineville Reservoir TIN for elevation 3235.0 and below. In

addition, the contours were generalized by eliminating select 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 little bearing on the

computation of surface areas and volumes for Prineville Reservoir because the surface areas

were calculated from the developed TIN. The contour topography at 10-foot intervals is

presented on figures 3 through 6 drawing numbers 113-D-588 through 113-D-591.

Development of 1998 Contour Areas

The 1998 contour surface areas for Prineville Reservoir were computed in 1-foot intervals from

elevations 3087.2 to 3235.0.0 using the Prinevifle Reservoir TIN discussed above. 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.

8
1998 Storage Capacity

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

the area-capacity computer program ACAP (Reclamation, 1985). The 1998 surface areas

(minimum reservoir elevation 3087.0) at 5-foot contour intervals from elevations 3090.0 to

3230.0 and the 1987 aerial surface areas at 5-foot contour intervals from elevations 3235.0 to

3260.0 along with the 1987 aerial surface areas for elevation 3270.0, 3280.0, and 3285.0 were

used as the control parameters for computing the Prineville Reservoir capacity. The program

can compute an area and capacity at elevation increments of 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 0.000001 for Prineville 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. Final area equations are derived by differentiating the capacity

equations, which are of second order polynomial form:

y = a + a2x + a3x2

where:

y = capacity,

x = elevation above a reference base,

a = intercept, and

a2 and a3 = coefficients

Results of the 1998 Prineville Reservoir area and capacity computations are listed in tables 1

and 2 and plotted on figure 7. A separate set of 1998 area and capacity tables was published

for the 0.01-, 0.1-, and 1-foot elevation increments (Bureau of Reclamation, 1998). These

tables include a description of the computations and coefficients output from the ACAP

program. Computation results are listed in columns 4 and 5 of table 2. Column 2 gives

original measured contour areas used in the original area and capacity computation, and

column 3 gives original capacity recomputed using ACAP. Both the original and 1998 area and

capacity curves are plotted on figure 7. As of May 1998, at spillway crest elevation 3234.8, the

surface area was 3,028 acres with a total capacity of 150,216 acre-feet. This study computed

1998 reservoir area and capacity up to elevation 3285.0. As explained previously the surface

areas in the upper reservoir elevations of the reservoir had to be interpolated using the USGS

quad map contours as a guide. These interpolated surface areas compared well with the

original surface areas for elevation 3250 and below. As shown on figure 7, the area curve

above elevation 3250 plotted reasonably well, but the accuracy of these values is questionable.

If a more accurate value is needed then the areas of the reservoir not covered by the 1987

aerial survey need to be remapped.

9
RESERVOIR SEDIMENT ANALYSES

Reservoir sediment survey data for Prineville Reservoir are shown in tables 1 and 2. The

computed volume difference between the original (1960 survey) and 1998 measured reservoir

capacities for Prineville Reservoir is 4,586 acre-feet below spiliway crest elevation 3234.8. The

average annual rate of lost capacity was 122.3 acre-feet per year, or 0.0453 acre-foot per

square mile from the sediment-contributing drainage area of 2,700 square miles. The storage

difference in terms of percent of original storage capacity was 2.96 percent.

The 1998 sediment calculations were based on the difference between the original and the

1998 measured reservoir capacities at elevation 3234.8. This method accounts for the

sediment accumulation during the 37.5 years of reservoir operation, but the calculations are

only as accurate as the two surveys. It is assumed that a portion of the 0.0453-acre-ftlmi2 yield

rate is attributable to the different survey collection methods, but all indications are the

differences due to the collection methods are minor.

For future reservoir planning, a theoretical distribution of sediment in the reservoir was

computed using the Empirical Area Reduction Method (Bureau of Reclamation, 198Th). A

sediment volume of 122.3 acre-feet per year was assumed in the distribution calculations using

the results from the May 1998 survey. An analysis of the original depth-capacity relationship

determined that Prineville Reservoir should be classified as type II, which was used for the

theoretical sediment distribution computations. The computed results are tabulated in

columns 8, 9, and 10 of table 2. For the year 1998, the theoretical computations indicated that

the sediment would reach an elevation of 3086.7 at the dam. This compares to the 1998 survey

that measured a sediment elevation of 3087.2 at the dam. For the year 2060, the computation

indicated that the sediment would reach an elevation of 3101.6 at the dam and would have a

dead pooi capacity of 219 acre-feet below elevation 3112.0. For the year 2098, the computation

indicated that the sediment would reach an elevation of 3109.3 at the dam and would have a

dead pooi capacity of 18 acre-feet below elevation 3112.0.

REFERENCES

American Society of Civil Engineers, Nomenclature for Hydraulics, ASCE Headquarters, New

York, 1962.

Bureau of Reclamation, Surface Water Branch, ACAP85 User's Manual, Denver Office,

Denver, Colorado, 1985.

Bureau of Reclamation, Guide for Preparation of Standing Operating Procedures for Bureau

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

1987a.

Bureau of Reclamation, Design of Small Dams, U.S. Government Printing Office, Denver,

Colorado, 1987b.

10
Bureau of Reclamation, Denver Office, Prineville ReservoirArea and Capacity Tables, Crooked

River Project, Pacific Northwest Region, Denver, Colorado, May 1998.

Corps of Engineers, Application of Differential Global Positioning System for Hydrographic

Survey and Dredge Positioning, ETL 11 1O-7-5(FR), Department of Army, Washington DC,

March 1991.

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

11

RESERVOIR SEDIMENT

DATA SUMMARY Prineville Reservoir

NAME OF RESERVOIR

DATA SHEET HO.

O 1. OWNER Bureau of Reclamation 2. STREAM Crooked River 3. STATE Oregon

A 4. SEC. 11 TWP. 17 S RANGE 16 E 5. NEAREST P.O. Prineville 6. COUNTY Crook

N 7. LAT 440 06' 50" LONG 120° 46' 50" 8. TOP OF DAM ELEVATION 3264.0 9. SPILLWAY CREST EL 3234.8'

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

S ALLOCATION TOP OF POOL SURFACE AREA, AC CAPACITY, AR ACRE- FEET STORAGE

S BEGAN

R

a. SURCHARGE 3257.9 3997 80300 234990

v b. FLOOD CONTROL ________________ _________________

___________________ _____________________

O C. POWER

________________ _________________ 12/60

I d. JOINT USE 3234.8 3034 60000 154690 16. DATE

R e. CONSERVATION 3211.17 2098 92800 94690

f. INACTIVE 3114.0 138 260 1890

OPERATION

BEGAN

g. DEAD 3112.0 124 1630 1630 12/60

17. LENGTH OF RESERVOIR 14 MILES AVG. WIDTH OF RESERVOIR 0.3 MILES

B 18. TOTAL DRAINAGE AREA 2,700 SQUARE MILES 22. MEAN ANNUAL PRECIPITATION 9.9 INCHES

A 19. NET SEDIMENT CONTRIBUTING AREA 2,700 SQUARE MILES 23. MEAN ANNUAL RUNOFF 1. 8 INCHES

20. LENGTH MILES AV. WIDTH MILES 24. MEAN ANNUAL RUNOFF 257,656' ACRE-FEET

__

21. MAX. ELEVATION MIN. ELEVATION 25. ANNUAL TEMP. MEAN 47°F RANGE -34°F to 1050F1

S 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

S _____ J_____ _______________

V 12/60 Contour (D) 10-ft 3034

______

154,802

____

.60

E

Y

D

5/98 37.5 37.5 Contour (D) 5-ft 3028'

__________________________________________________

150,216'

__

.58

A

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

___________________________________

WATER INFLOW TO DATE, AR

T

ANNUAL

A

PRECIP. a. MEAN ANN. f

b. MAX. ANN. C. TOTAL a. MEAN ANN. b. TOTAL

5/98 992 257,656' 636,560 9,662,110 257,656 9,662,110

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

SURVEY

a. TOTAL b. AV. ANN. c. /MI.-YR. a. TOTAL b. AV. ANNUAL C. /Mi.3-YR.

5/98 4,586k 122.3 .0453 4,586 122.3 .0453

26. DATE OP 39. AV. DRY 40. SED. DEP. TONS/MI.-YR. 41. STORAGE LOSS, PCT. 42. SEDIMENT

SURVEY WT. (#/FT3)

_________________________________

a. PERIOD b. TOTAL TO a. AV. b. TOTAL TO a. b.

5/98 .O79 2.96

26.

DATE

43. DEPTH DESIGNATION RANGE BY RESERVOIR ELEVATION

OF

SURVEY

3075-

3100

3100-

3140

3140-

3160

3160-

3180

3180-

3200

3200-

3234.8

PERCENT OF TOTAL SEDIMENT LOCATED WITHIN DEPTH DESIGNATION

5/98 7.4 9.6 26.2 20.5 23.8 12.5

26.

DATE

44. REACH DESIGNATION PERCENT OF TOTAL ORIGINAL LENGTH OF RESERVOIR

0-10 10-

20

20-

30

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 OP TOTAL SEDIMENT LOCATED WITHIN REACH DESIGNATION

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

13
45. RANGE IN RESERVOIR OPERATION7

YEAR MAX. ELEV. MIN. ELEV. INFLOW, AR YEAR MAX. ELEV. MIN. ELEV. INFLOW, AR

1960 1961 3,219.9 3,211.4 122,330

1962 3,235.8 3,200.2 216,420 1963 3,235.1 3,210.0 233,170

1964 3,229.9 3,211.6 110,490 1965 3,239.0 3,208.1 434,450

1966 3,232.9 3,210.2 133,170 1967 3,236.1 3,209.6 227,540

1968 3,224.5 3,199.8 58,490 1969 3,236.1 3,199.8 248,420

1970 3,237.5 3,210.9 273,490 1971 3,236.0 3,204.5 314,130

1972 3,235.4 3,210.1 323,360 1973 3,234.5 3,210.6 99,620

1974 3,236.8 3,208.7 400,020 1975 3,235.0 3,211.3 237,820

1976 3,237.8 3,211.0 219,040 1977 3,217.0 3,178.0 49,160

1978 3,237.8 3,177.4 343,570 1979 3,238.7 3,210.9 374,620

1980 3,237.4 3,211.3 253,100 1981 3,237.4 3,211.3 179,980

1982 3,235.6 3,210.8 459,510 1983 3,236.4 3,210.6 546,400

1984 3,242,7 3,209.9 636,560 1985 3,236.3 3,201.6 367,700

1986 3,237.0 3,210.2 357,030 1987 3,236.9 3,208.6 212,140

1988 3,233.0 3,201.0 111,700 1989 3,237.2 3,202.4 336,790

1990 3,225.8 3,199.8 82,830 1991 3,206.0 3,173.7 67,750

1992 3,204.6 3,163.4 65,150 1993 3,242.4 3,162.3 454,110

1994 3,224.7 3,161.8 72,060 1995 3,237.6 3,188.8 204,420

1996 3,237.3 3,210.1 263,590 1997 3,236.7 3,207.5 314,290

1998 3.241.3 3.206,9 257.690

46. ELEVATION - AREA - CAPACITY DATA FOR 198 CAPACITY'0

ELEVATION AREA CAPACITY ELEVATION AREA CAPACITY ELEVATION AREA CAPACITY

3087.2 0 0 3090 2.1 3 3095 19.6 57

3100 45.9 221 3105 79.9 536 3110 122.4 1,041

3115 155.1 1,735 3120 189.3 2,596 3125 234,9 3,657

3130 289.7 4,968 3135 338.8 6,539 3140 405.1 8,399

3145 487.7 10,631 3150 574.2 13,286 3155 671,0 16,399

3160 754.7 19,963 3165 844.9 23,962 3170 967.5 28,493

3175 1,123.4 33,720 3180 1,247.4 39,647 3185 1,356.3 46,157

3190 1,468.4 53,218 3195 1,589.2 60,862 3200 1,723.8 69,145

3205 1,867.5 78,123 3210 2,010.6 87,818 3211.2 2,054 90,257

3215 2,190.9 98,322 3220 2,411.4 109,828 3225 2,643.2 122,465

3230 2,831.7 136,152 3234.8 3,028 149,611 3235 3,036.3 150,822

3240 3,194 166,398 3245 3,402 182,888 3250 3,606 200,408

3255 3,843 219,030 3257.9 4,004 230,409 ____________ _____________ ____________

47. REMARKS AND REFERENCES

' Uncontrolled ogee crest at elevation 3,234.8.

2 Bureau of Reclamation Project Data Book, 1981. Reported value for all of Crooked River Project.

Calculated using mean annual runoff value of 257,656 AR, item 24, 12/60-5/98.

Computed annual inflows from 12/60 through 5/98.

Original surface area and capacity at el. 3,234.8. For sediment computation purposes the original capacity was

recomputed by the Reclamation ACAP program using the original surface areas.

' Surface area & capacity at el. 3,234.8 computed by ACM' program using 1988 aerial and 1998 underwater survey data.

1988 aerial data was 1 i n. - 100 ft. With 5-ft contour interval. Flight line did not cover all of reservoir area

and was completed using USGS 71/2 quad map contours. Mainly affected areas above el. 3235.

Inflow values in acre-feet and maximum and minimum elevations in feet by water year from 12/60 through 5/98.

Inflow for 1995, 1996, 1 997, and 1998 have missing monthly records. Elevation data fo r 1960 through 1976 from

USGS water records.

Computed sediment volume at elevation 3234.8.

Storage losses at elevat ion 3234.8.

10 Capacities computed by Reclamation's ACM' computer program.

48. AGENCY MAKING SURVEY Bureau of Reclamation

49. AGENCY SUPPLYING DATA Bureau of Reclamation DATE September 1998

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

14
1 2 3 4 5 6 7 8 9 10

Measured Computed Computed Computed

Elevations Original Original 1998 1998 SedIment Percent of 1998 2060 2098

Area Capacity Area Capacity Volume Computed Capacity Capacity Capacity

(feet) (acres) (acre-feet) (acres) (acre-feet) (acre-feet) Sediment (acre-It) (acre-It) (acre-ft)

3234.8 3034 154802 3028 150216 4586 100.0 150216.0 142572.0 137925.0

3230 2830 140730 2832 136152 4578 99.8 136185.0 128611.0 124010.0

3225 2613 127123 2643 122485 4858 101.6 122675.0 115273.0 110783.0

3220 2400 114590 2411 109828 4762 103.8 110262.0 103070.0 98716.0

3215 2218 103045 2191 98322 4723 103.0 98853.0 91899.0 87697.0

3211.2 2098 94845 2054 90257 4588 100.0 90764.0 84005.0 79930.0

3210 2060 92350 2011 87818 4532 98.8 88306.0 81610.0 77576.0

3205 1918 82405 1867 78123 4282 93.4 78518.0 72098.0 68241.0

3200 1780 73160 1724 69145 4015 87.5 69438.0 63306.0 59636.0

3195 1643 64603 1589 60862 3741 81.6 61052.0 55220.0 51743.0

3190 1520 56695 1468 53218 3477 75.8 53319.0 47795.0 44517.0

3185 1415 49358 1356 46157 3201 69.8 46162.0 40952.0 37878.0

3180 1300 42570 1247 39647 2923 63.7 39556.0 34666.0 31797.0

3175 1142 36465 1123 33720 2745 59.9 33635.0 29068.0 26408.0

3170 1020 31060 968 28493 2567 56.0 28416.0 24173.0 21722,0

3165 908 26240 845 23962 2278 49.7 23781.0 19863.0 17623.0

3160 810 21945 755 19963 1982 43.2 19671.0 16078.0 14047.0

3155 734 18085 671 16399 1686 36.8 15995.0 12724.0 10901.0

3150 640 14650 574 13286 1364 29.7 12743.0 9791.0 8174.0

3145 544 11690 488 10631 1059 23.1 9962.0 7325.0 5912.0

3140 460 9180 405 8399 781 17.0 7629.0 5301.0 4087.0

3135 382 7075 339 6539 536 11.7 5697.0 3671.0 2653.0

3130 310 5345 290 4968 377 8.2 4135.0 2403.0 1575.0

3125 244 3960 235 3657 303 6.6 2912,0 1466.0 822.0

3121.5 201 3172 203 2890 282 6.1 2235.0 982.0 462.0

3120 190 2875 189 2596 279 6.1 1984.0 812.0 345.0

3114 138 1896 149 1583 313 6.8 1183.0 324.0 59.0

3112 124 1634 135 1299 335 7.3 1183.0 219.0 18.0

3110 110 1400 122 1041 359 7.8 800.0 138.0 1.0

3109.3 0.0

3105 83 918 80 536 382 8.3 451.0 22.0

3101.6 0.0

3100 60 560 46 221 339 7.4 215.0

3095 40 310 20 57 253 5.5 76.0

3090 25 148 2 3 145 3.2 12.0

3087.2 18 87 0 0 87 1.9

3086.7 0.0

3085 13 53 0 0 53 1.2

3080 4 10 0 0 10 0.2

3075 0 0 0 0 0 0.0

Table 2. - Summary of 1998 survey results.
Computed

Elevations Original Original 1998 1998 Sediment Percent of Percent of

Area Capacity Area Capacity Volume Computed Reservoir

(feet) (acres) (acre-feet) (acres) (acre-feet) (acre-feet) Sediment Depth

3285 4939 352898

3280 4834 328465

3270 4475 281920

3260 4100 4121 238940

3257.9 3997 235053 4004 230409 100.0

3255 3855 223668 3843 219030 98.4

3250 3610 205005 3606 200408 95.7

3245 3393 187498 3402 182888 92.9

3240 3200 171015 3194 166398 90.2

3235 3042 155410 3036 150822 87.5

3234.8 3034 154802 3028 150216 4586 100.0 87.4

3230 2830 140730 2832 136152 4578 99.8 84.7

3225 2613 127123 2643 122465 4658 101.6 82.0

3220 2400 114590 2411 109828 4762 103.8 79.3

3215 2218 103045 2191 98322 4723 103.0 76.5

3211.2 2098 94845 2054 90257 4588 100.0 74.5

3210 2060 92350 2011 87818 4532 98.8 73.8

3205 1918 82405 1867 78123 4282 93.4 71.1

3200 1780 73160 . 1724 69145 4015 87.5 68.3

3195 1643 64603 1589 60862 3741 81.6 65.6

3190 1520 56695 1468 53218 3477 75.8 62.9

3185 1415 49358 1356 46157 3201 69.8 60.1

3180 1300 42570 1247 39647 2923 63.7 57.4

3175 1142 36465 1123 33720 2745 59.9 54.7

3170 1020 31060 968 28493 2567 56.0 51.9

3165 908 26240 845 23962 2278 49.7 49.2

3160 810 21945 755 19963 1982 43.2 46.5

3155 734 18085 671 16399 1686 36.8 43.7

3150 640 14650 574 13286 1364 29.7 41.0

3145 544 11690 488 10631 1059 23.1 38.3

3140 460 9180 405 8399 781 17.0 35.5

3135 382 7075 339 6539 536 11.7 32.8

3130 310 5345 290 4968 377 8.2 30.1

3125 244 3960 235 3657 303 6.6 27.3

3120 190 2875 189 2596 279 6.1 24.6

3115 145 2038 155 1735 303 6.6 21.9

3114 138 1896 149 1583 313 6.8 21.3

3112 124 1634 135 1299 335 7.3 20.2

3110 110 1400 122 1041 359 7.8 19.1

3105 83 918 80 536 382 8.3 16.4

3100 60 560 46 221 339 7.4 13.7

3095 40 310 20 57 253 5.5 10.9

3090 25 148 2 3 145 3.2 8.2

3087.2 18 87 0 0 87 1.9 6.7

3085 13 53 0 0 53 1.2 5.5

3080 4 10 0 0 10 0.2 2.7

3075 0 0 0 0 0 0.0 0.0

Elevation of reservoir water surface.

Original reservoir surface area.

Original calculated reservoir capacity computed using ACAP.

Reservoir surface from 1998 for elevations 3235 and below. Areas for elevation

3240 and greater from 1988 aerial survey.

1998 calculated reservoir capacity computed using ACAP from 1998 surface areas.

Measured sediment volume = column (3) - column (5).

Measured sediment expressed in percentage of total sediment 4586 acre-feet at

elevation 3234.8.

Depth of reservoir expressed in percentage of total depth (182.9 feet).

Table 3. - Summary of 1998 survey and theoretical sediment distribution computations.

16
OES

(f(

0c:lv.r'

S 0 P

COUNTY

MiIl.n

0

IRRIGATED AREA

• PUMPING PLANT

5 0 5 10

Figure 1. - Prineville Reservoir location map.

C 0 U P4 T V

PRINEVILLE

RESERVOIR

-'

L..__

Brothers

0

17
Space intentionally left blank due to security concerns 
Horizontal based an Oregon State Plane

Coordinate System, South Zone (NA027)
N

901000+

900000+

, §

900000+

w

90,000+

S

Antelope

Creek

I V .U'

$*I,: I:AW

809000k 800000+

4

001000+

Deer

Creek

095000+

,' To Prinville

Crooked

River

800000+

881000+

800000+ 80000

J I

- 0

000000+

Alkali

Creek

Horizontal based on Oregon State Plane

Coordinate System, South Zone (NAD27)

Ficuir 4. - PrineviIk Rcsrvnir trinnIrnv msn NA I 1-fl-PO
p,.,,;II---.---- .'
Eagle

Creek

915000* 9*5000+ 5000+ 9,5000+ 915000-4- 915000+ 915000*

Crooked River

N

9±0000+ 910000* 910000+ 910000* 9.0600+ 9,0000+

TP E

Sand

Creek _______________________

I -

2Ws, f:fAW

905000+ 905000+ 905000+

Horizontal based on Oregon State Plane

Coordinate System. South Zone (NAD27)

960000+ 900600± °*

P81MEV/LIE 8ESERVOIN

eawar______ ______

Iv _________

,,1,, 4/Iff? Pf u1 I

IfJI
Area-Capacity Curves for PrineviHe Reservoir

Area (acres)

5000 4500 4000 3500 3000 2500 2000 1500 1000 500 0

-- -

-1

/ CaP

_ _ Ii ili_im iii

_!

_ ___

_

_

______ _______

I 19i

Li - ...OriginaJ

______

J_

3270

3250

3230

3210

3190

3170

3150

3130

3110

3090

____ ____ ____ ____ - 3070

0 36000 72000 108000 144000 180000 216000 252000 288000 324000 360000

CapacIty (acre-feet)

QLV

3270

3250

3230

3210

3190

>

0

Ui

3170

3150

3130

3110

3090

n7n

Figure 7. - 1998 area and capacity curves.
MISSION

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.