CANYON FERRY LAKE

1997 SEDIMENTATION SURVEY

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FOR THE

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U.S. Department of the Interior

Bureau of Reclamation
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REPORT DOCUMENTATION PAGE I O=O88

P bhc reporting burden forth #ection of infonnation is estvnated to average 1 hour per response, induding the timefor reviewing instructions, S arching existing data sources, gain gand maintaining

the data needed, and completing and reviewing the cottect&On of arformation. Send Comments regarding this burden esheate or any other aspect of this collection of iniformation, includsig suggestions

for reducieg this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suit 1204, MingtOn VA22202-4,302, and to the Office

of Management and Budget, Paperwork Reduction Report (0704.01 88(, Washington DC 20503.

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

August 1998 Final

4. TITLE AND SUBTITLE

____________________________

5. FUNDING NUMBERS

Canyon Ferry Lake PR

1997 Sedimentation Survey

6. AUTHOR(S)

Ronald L. Ferrari ____________________________

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

REPORT NUMBER

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

9. SPONSORINGIMONITORING 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. DISTRIBU11ON/AVAILABIUTY 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 above-water area in October 1996 and the underwater area

of Canyon Ferry Lake in July and August of 1997 with the purpose to develop a topographic map and compute a

present storage-elevation relationship (area-capacity tables). The data were also used to calculate reservoir capacity

lost due to sediment accumulation since dam closure in March 1953. The bathymetric survey used sonic depth

recording equipment interfaced with a global positioning system (GPS) that gave continuous sounding positions

throughout the underwater portion of the reservoir. The above-water reservoir area was measured from aerial

photography obtained on October 7, 1996 near reservoir water surface elevation 3,787.7. Reservoir topography was

developed by a computer program using the collected data. Project features were determined by digitizing the U.S.

Geological Survey quadrangle (USGS quad) maps. The new topographic map of Canyon Ferry Lake is a

combination of the above information.

As of August 1997, at top of spillway gate elevation (feet) 3,800.0, the surface area was 34,048 acres with a total

capacity of 1,992,977 acre-feet. Since initial filling in March 1953, about 59,746 acre-feet of sediment have

accumulated in Canyon Ferry Lake below elevation 3,800.0, resulting in a 2.91 percent loss in reservoir volume.

Since 1953, the estimated average annual rate of reservoir capacity lost to sediment accumulation is

1,345.6 acre-feet.

14. SUBJECT TERMS 15. NUMBER OF PAGES

reservoir area and capacity! sedimentation/ reservoir surveys! sonar! sediment 33

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

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

OF REPORT OF THIS PAGE OF ABSTRACT

UL UL UL UL

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NSN 7540-01-280-5500 Sthfldard FOflil 298 (Rev. 2-89)

Prescribed by ANSI SId. 239-18

298-102
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CANYON FERRY LAKE

1997 SEDIMENTATION SURVEY

by

Ronald L. Ferrari

Sedimentation and River Hydraulics Group

Water Resources Services

Technical Service Center

Denver, Colorado

August 1998
ACKNOWLEDGMENTS

The Bureau of Reclamation's (Reclamation) Sedimentation and

River Hydraulics Group of the Technical Service Center (TSC)

prepared and published this report. Ron Ferrari of the TSC

conducted the hydrographic survey. Stephen Hughes and Kent

Collins of the TSC, who assisted during the hydrographic survey,

deserve special thanks. Facilities Manager James Lynes and

staff at Canyon Ferry Field Branch Office deserve very special

thanks for their assistance during the hydrographic survey.

Larry Edwards and staff at Aero-Metric also deserve special

thanks for providing the aerial data in the needed format.

Ronald Ferrari completed the data processing and generated the

new topographic map and area-capacity tables. Sharon Nuanes

of the TSC completed the USGS contour digitizing and was

consulted during the map development. Kent Collins of the TSC

performed the technical peer review of this documentation.

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U.S. Department of the Interior

Mission Statement

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 tribes.

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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.

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CONTENTS

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Introduction

Summary and conclusions

Reservoir operations

Hydrographic survey equipment and method

GPS technology and equipment

Survey method and equipment

Reservoir area and capacity

Topography development

Development of 1997 contour areas

1997 storage capacity

Sediment analyses

References

Table

TABLES

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1 Reservoir sediment data summary (page 1 of 2) 11

1 Reservoir sediment data summary (page 2 of 2) 12

2 Summary of 1997 survey results 13

Figure

FIGURES

1 Canyon Ferry Lake location map 15

2 Canyon Ferry Dam, plan and section 16

3 Canyon Ferry Dam, plan and section 17

4 Canyon Ferry Lake topographic map, No. 296-D-1158 19

5 Canyon Ferry Lake topographic map, No. 296-D-1159 21

6 Canyon Ferry Lake topographic map, No. 296-D-1160 23

7 Canyon Ferry Lake topographic map, No. 296-D-1161 25

8 Canyon Ferry Lake topographic map, No. 296-D-1162 27

9 Canyon Ferry Lake topographic map, No. 296-D-1163 29

10 Canyon Ferry Lake topographic map, No. 296-D-1164 31

11 1997 area and capacity curves 33

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INTRODUCTION

Canyon Ferry Dam, Lake, and Powerplant of the Canyon Ferry Unit are located on the

Missouri River in Broadwater and Lewis and Clark Counties approximately 17 miles

northeast of Helena, Montana (fig. 1). The dam was constructed in a narrow constriction of

the Missouri River Valley about 1.5 miles downstream from the old Canyon Ferry Dam that

formed Lake Sewell in 1898. The formation of Canyon Ferry Lake, located about 50 miles

downstream from where the Gallatin, Madison, and Jefferson Rivers join to form the Missouri

River, inundated the old Canyon Ferry Dam, powerplant buildings, and Lake Sewell.

The Canyon Ferry Unit is a multiple-purpose project that contributes power supply, flood

control, irrigation, and recreation in the upper Missouri Basin. The drainage area above the

dam is 15,904 square miles of which 11,248 square miles contributes sediment inflow. The

reservoir length at elevation 3,8001 is around 24 miles with an average width of about

2.2 miles.

Canyon Ferry Dam construction began May 24, 1949 and was completed June 23, 1954 with

first storage in March 1953. The dam is a concrete gravity structure, whose dimensions are

(figs. 2 and 3):

• Hydraulic height2 225 feet

• Structural height 172 feet

• Top width 20 feet

• Crest length 1,000 feet

• Crest elevations 3,808.5 feet

Canyon Ferry Dam's spiliway consists of an overflow section in the central portion of the dam

with a crest elevation of 3,766.0. The spillway is controlled by four 51- by 34.5-foot radial

gates with a top of gate elevation of 3,800.0. The spillway capacity is 150,000 cubic feet per

second (ft3Is) at reservoir elevation 3,800.0, (Bureau of Reclamation 1981).

Four river outlets are provided in the spillway section of the dam. Each is 84 inches in

diameter and controlled by 77-inch regulating gates. The discharge capacity, at reservoir

elevation 3,800.0, is 9,500 ft3Is. One 156-inch-diameter intake pipe is embedded in the

concrete of the dam near the left abutment for Helena Valley Pumping Plant. Three

162-inch-diameter penstock pipes for the power-generating units are embedded in the dam

near the right abutment. The powerplant is a reinforced concrete structure located at the

downstream toe of the dam on the right abutment adjacent to the spiliway apron.

'Elevation levels are shown in feet.

2The definitions 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.

3Parapet walls located on the upstream and downstream sides of the dam raised the maximum concrete

etevation to 3,810.7.
Wind-blown fine-grained material from exposed flats in the upper end of Canyon Ferry Lake

became a major contributor to air pollution upon initial filling and normal reservoir operation.

The Montana Department of Health reported the average deposition of material in the

Townsend area to be 301 tons per square mile per month compared to the acceptable limit of

15 to 20 tons per month. In 1968 a cooperative program between Reclamation and the

Montana Fish and Game Department planned and constructed a dike system in the upper end

of the lake for dust abatement that also included waterfowl-development features. The

construction of the dikes began in 1972 and finished in 1978 with the creation of four separate

enclosed ponds. The original reservoir area was affected by the dredging and diking between

elevation 3,780 and the top of dikes, elevation 3,800. These enclosed areas were essentially

removed from the original reservoir area, which is reflected in this report. The original

reservoir area-capacity, with these dike areas removed, was reported as 2,051,519 acre-feet

with a surface area of 33,535 acres at top of spiliway gate elevation 3,800.0.

SUMMARY AND CONCLUSIONS

This Reclamation report presents the 1997 results of the first extensive survey of Canyon

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

develop reservoir topography

compute area-capacity relationships

estimate storage depletion caused by sediment deposition since Canyon Ferry Dam

closure.

The 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 Canyon Ferry Lake. 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 reservoir bottom

elevations.

The above-water area of Canyon Ferry was measured from aerial photography obtained in

October of 1996 by Reclamation contract with Aero-Metric in Fort Collins, Colorado. Photo

interpretation produced 45 detailed drawings of the development around the reservoir with

5-foot contour topography of the above-water reservoir area that was around elevation 3,788.4

at time of flight. For the purpose of this study, the 737,402 aerial data points used to develop

these 5-foot contours were merged with the underwater data set to produce the 1997 reservoir

topography. The aerial data set completely saturated the reservoir area above elevation

3,788.4 and provided detailed information for the contour development.

The 1997 reservoir surface areas at predetermined contour intervals were generated by a

computer graphics program using the merged aerial and underwater collected data. The 1997

topographic map of Canyon Ferry Lake is a combination of the underwater and aerial

topography along with the digitized features of the U.S. Geological Survey 7.5 minute

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quadrangle (USGS quad) maps of Canyon Ferry Lake. Using the digitized underwater

contours from the USGS quad maps, a few data points were interpolated when needed. This

included the area near the dam and small coves not covered by the underwater survey. The

1997 reservoir surface areas at predetermined 5-foot contour intervals were generated by a

computer graphics program using all the collected data. The area and capacity tables were

produced by a computer program that used measured contour surface areas and a curve-fitting

technique to compute area and capacity at prescribed elevation increments.

Tables 1 and 2 contain a summary of Canyon Ferry Lake sedimentation and watershed

characteristics for the 1997 survey. The 1997 survey determined that the reservoir has a

storage capacity of 1,992,977 acre-feet and a surface area of 34,048 acres at reservoir elevation

3,800.0. Since closure in 1953, the reservoir has accumulated a sediment volume of

59,746 acre-feet below reservoir elevation 3,800.0. This-volume represents a 2.91 percent loss

in capacity and an average annual loss of 1,345.6 acre-feet.

RESERVOIR OPERATIONS

Canyon Ferry Lake is a multiple purpose project which operates for power production, flood

protection, irrigation, and recreation (the following values are from August 1997 area-capacity

tables):

• 101,089 acre-feet of flood control storage between elevations 3,797.0 and 3,800.0.

• 794,289 acre-feet of joint use between elevations 3,770.0 and 3,797.0.

• 701,568 acre-feet of active conservation storage between elevations 3,728.0 and 3,770.0.

• 394,971 acre-feet of inactive storage between elevations 3,650.0 and 3,728.0.

• 1,060 acre-feet of dead storage below elevation 3,650.0.

The Canyon Ferry Lake inflow and end-of-month stage records are listed by water year in

table 1 for the operation period of October 1953 through September 1997. The average annual

reservoir inflow for this operation period was 3,908,214 acre-feet. After initial filling to

spiliway gate elevation 3,800.0 in 1956, records show that Canyon Ferry Lake fills to near full

conditions the majority of the years. The minimum water surface, since filling, was elevation

3,764.7 that occurred in April of 1967.

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 global positioning system (GPS) receiver with a built-in radio and an

omnidirectional antenna, a depth sounder, a helmsman display for navigation, a plotter, a

computer, and hydrographic system software for collecting 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 attached

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

over a known datum point. The power for the shore unit was provided by a 12-volt battery.

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GPS Technology and Equipment

The positioning system used at Canyon Ferry Reservoir was Navigation Satellite Timing and

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

enables users to accurately determine three-dimensional position. The NAVSTAR system's

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 the Department of

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

and determines the receiver's position from 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.

The NAVSTAR system consists of three segments:

• The space segment is a network of 24 satellites maintained in precise orbit 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 which 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 of the altitude, Canyon

Ferry's water surface elevation parameter was known, which realistically meant only three

satellite observations were needed to track the survey vessel. During the Canyon Ferry Lake

survey, the best six available satellites were used for position calculations.

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

function of range measurement precision and the 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 of 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

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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 Canyon Ferry Lake 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 in 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.

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 differential GPS (DGPS). DGPS was used

during the Canyon Ferry Lake 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 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 that 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 Canyon Ferry Lake 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 6-channel Li coarse acquisition (C/A) code continuous paralleltracking 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 (RTCM) 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 postprocessing software. The GPS collection system has the

capability of collecting the data in 1927 or 1983 North American Datums (NAD) in the

surveyed area's state plane coordinate system's zone. For Canyon Ferry Lake, the data were

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collected in the Montana's 1927 NAD south state plane zone to match the data collected for

the 1996 aerial survey.

Survey Method and Equipment

The Canyon Ferry Lake hydrographic survey was conducted from July 11 through July 22, and

August 19, and August 20 of 1997 between reservoir water surface elevations 3,796.4 and

3,798.3. At the time the lower reservoir area was being mapped the dam was spilling due to

the higher than average inflow. In anticipation of the high runoff the reservoir was lowered

to elevation 3,769.2 in April of 1997. The bathymetric survey was 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 primarily in a east-west direction.

The spacing of the gridlines varied depending on the reservoir bottom conditions. The spacing

was set at 400 feet for the area downstream of Cemetery Hill island and the old Canyon Ferry

dam due to the varied bottom and vertical walls. Upstream of this location the spacing was

set at 500 feet due to the bottom being very flat with a gradual slope from bank to bank. hi

the very upper reservoir areas the spacing was set at 600 feet due to the very flat bottom

conditions. 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 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 139,785 data points. A graph plotter was used

in the field to track the boat and ensure adequate coverage during the collection process. 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.

For stationing the master GPS unit, known benchmarks (datums) that overlooked the

reservoir were established and or confirmed by the hydrographic survey crew prior to

underwater collection. This was accomplished using the hydrographic GPS units and

software. In establishing the control, previously established datums for a detailed aerial

survey of several of the reservoir campsites were used. The control for the 1996 aerial survey

was set as temporary control points marked with wooden stakes that in most cases could not

be located. Temporary control points for the hydrographic survey were established at Goon

Hill near the dam, an old USBR brass elevation datum overlooking White Earth campground,

and near Canyon Ferry airport at the Silos campground. At Goon Hill, a wood survey stake,

#7 10, that was established for the 1996 aerial survey, was located. As a check, the

hydrographic units and software measured the location within 1 foot of what was established

for the 1996 aerial survey. The shore-based master GPS unit, which transmits the correction

information to the mobile GPS unit on the survey vessel, was stationed at one of these three

datum sites throughout the survey. These locations were chosen because they were accessible

and overlooked the reservoir. The location allowed for good radio transmission of the

differential corrections to the mobile survey vessel throughout the reservoir survey.

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The underwater data were collected by a depth sounder which 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 density, salinity,

temperature, turbidity, and other conditions. The collected data were digitally transmitted

to the computer collection system via an RS-232 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

The topography of Canyon Ferry Lake was developed from the merged 1996 aerial and 1997

underwater data, points. All of the data were in the Montana's south zone state plane

coordinates in NAD 1927. ARC/INFO V7.0.2 geographic information system software was

used to digitize the USGS quad contours and other features such as roads and rivers along

with a boundary or polygon that enclosed all the collected data. The underwater contours of

the USGS quad maps were used as a guide to interpolate around 160 data points near the dam

and in a few coves not surveyed in 1997. The USGS quad maps were developed from aerial

photography dated 1970 and 1980. The digitized contours were transformed to Montana's

NAD 1927 south state plane coordinates using the ARC/INFO PROJECT command.

Contours from the collected data were computed using the triangular irregular network (TIN)

surface modeling package within ARCTNFO. 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

known as Delaunay's criteria for triangulation. Triangles are formed between all 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 all collected data. Using the hardclip option of the ARC/INFO CREATETIN

command, a clip or polygon boundary around the data was developed. The digitized polygon

enclosing the collected data was assigned an elevation of no data and was used to perform the

clip of the data set such that interpolation was not allowed to occur outside the boundary. The

elevation contours are then interpolated along the triangle elements. The TIN method is

discussed in detail in the ARC/INFO V7.0.2 ARC Command References (ESRI 1992).

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

interpolate contours from the Canyon Ferry Lake TIN. 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 Canyon Ferry Lake. The contour topography at 5-foot intervals is presented on

figures 4 through 10 (map Nos. 296-D-1158 though 296-D-1164).

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Development of 1997 Contour Areas

The interpolated contours from the Canyon Ferry Lake TIN confirmed that the tops of the dust

abatement dikes are around elevation 3,800. For the 1997 Canyon Ferry Lake contour surface

areas, 1-foot increments were computed from elevations 3,630.0 to 3,800.0 using a TIN that

removed the dike areas of the dust abatement ponds from the data set. The 1997 survey

measured the minimum reservoir bottom elevation at 3,625.3 feet. These calculations were

performed using the ARCIINFO VOLUME command. This command computes areas at userspecified elevations directly from the TIN and takes into consideration all regions of equal

elevation.

1997 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). Surface areas

at 5-foot contour intervals from minimum reservoir elevation 3,625.3 to elevation 3,800.0 were

used as the control parameters for computing the Canyon Ferry Lake capadity. The program

can compute an area and capacity at elevation increments of 0.01 to 1.0 foot by lineir

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 (set at 0.000001 for Canyon Ferry Lake). 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 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 = a1 + ax + a3x2

where:

y = capacity

x = elevation above a reference base

a1 = intercept

a2 and a3 = coefficients

Results of the 1997 Canyon Ferry Lake area and capacity computations are listed in table 1

and columns (4) and (5) of table 2. Listed in columns (2) and (3) of table 2 are the original

surface areas and recomputed capacity values. These original values listed were adjusted for

the reservoir areas and capacity removed due to the constructed dust abatement ponds. A

separate set of 1997 area and capacity tables has been published for the 0.01-, 0.1-, and 1-foot

elevation increments (Bureau of Reclamation 1997). A description of the computations and

coefficients output from the ACAP85 program is included with these tables. Both the original

and 1997 area-capacity curves are plotted on figure 5. As of August 1997, at elevation 3,800.0,

the surface area was 34,048 acres with a total capacity of 1,992,977 acre-feet.

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SEDIMENT ANALYSES

The 1997 study found that since storage of Canyon Ferry Lake began in March of 1953,

sediments have accumulated to a total volume of 59,746 acre-feet. This volume was calculated

at top of spillway gate elevation 3,800.0. Column 6 of table 2 gives the measured sediment

volume by elevation, and the area curve on figure 11 illustrates the resulting measured surface

areas and calculated capacities. This table and figure illustrate that the majority of the

sediment deposit is in the lower elevations of the reservoir. The average annual rate of

sediment deposition between closure and August 1997 (44.4 years) was 1,345.6 acre-feet or

0.12 acre-foot per square mile from the sediment-contributing drainage area of 11,248 square

miles. The storage loss in terms of percent of original storage capacity was 2.91 percent. This

compares to Reclamation's original 100-year sediment deposition estimate of 7.8 percent and

a sediment yield of 0.1 acre-foot per square mile from the contributing drainage area.

The 1997 sediment calculations were based on the differences between the original and 1997

measured reservoir capacities and are only as accurate as the two surveys. The measured

surface areas, columns 2 and 4 of table 2, the calculated sediment volume, column 6 of table

2, and the area curves of figure 11 show some interesting results. The table shows the 1997

surface areas are greater than the original areas from elevation 3,790 and above. These are

the reservoir areas mapped by the detailed aerial data. At elevation 3,790.0 the 1997 surface

area was measured around 1 percent larger than the original area. At elevations 3,795.0 and

greater the 1997 surface areas were measured around 1.5 percent larger than the original

areas. A portion of this difference can be attributed to the accuracy difference between the

original and the 1996 aerial survey. A comparison plot of the 3,797.0 contour developed from

the 1997 study and the digitized 3,797.0 contour from the USGS quad maps show a near

mirror image of each other. There are some small differences in some of the cove areas for

which the 1996 aerial data provided greater detail and the larger resulting areas.

A comparison plot of the 3,760.0 contour developed from the 1997 study and the digitized

3,760.0 contour from the USGS quad maps also show a near mirror image of each other. There

are some small differences in some of the cove areas, but in the upper portion of the reservoir

there is very little difference. This is reflected in the sediment calculations where only

2 percent of the computed sediment volume is above elevation 3,760. In anticipation of the

1997 high spring runoff the reservoir was lowered to elevation 3,769.2 in April of that year.

With these conditions it is possible that a portion of any delta that may have existed prior to

the 1997 spring runoff was flushed into the lower elevations of the reservoir.

REFERENCES

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

York, 1962.

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

Bureau of Reclamation, Surface Water Branch, ACAP85 User's Manual, Technical Service

Center, Denver, Colorado, 1985.

9
Bureau of Reclamation, Guide for Preparation of Standing Operating Procedures for Bureau

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

1987(a).

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

Colorado, 1987(b).

Bureau of Reclamation, Denver Office, Canyon Ferry Lake Area and Capacity Tables, Canyon

Ferry Unit, Great Plains Region, Denver, Colorado, August 1997.

Corps of Engineers, March 1991. Application of Differential Global Positioning System for

Hydrographic Survey and Dredge Positioning, ETL 1110-7-5 (FR), Department of the

Army, Washington DC.

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

10
I

I

RESERVOIR SEDIMENT

DATA SUMMARY Canyon Ferry Lake

NAME OF RESERVOIR 1

DATA SHEET NO.

D 1. OWNER Bureau of Reclamation 2. STREI4}f Missouri River 3. STATE Montana

A 4. SEC. 4 P. ION RANGE 1W 5. NEAREST P.O.Helena 6. COUNTY Lewis & Clark

M 7. LAT 46 38 57 LONG 111' 43' 39 8. TOP OF DAM FEVATION 3808.5 9. SPILWAY CREST EL. 3766.O

R 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 BEGAN E

R

______________________ ____________________

a. SURCHARGE

b. FLOOD CONTROL 3,800.0 33,535 99,460 2,O51,5l9

I

R

c. JOINT USE 3,797.0 32,866 795,135 1,952,059

d. CONSERVATION 3,770.0 24,126 411,462 1,156,924 16. DATE

e. IRRIGATION

________________ ________________ OP f. INACTIVE 3,728.0 11,479

________________

437,996

_________________

445,462

ERATION

BEGAN

g. DEAD 3,650.0 1,000 7,466 7,466 3/53

- 17. LENGTh OF RESERVOIR 24.0 MILES AVG. WIDTH OF RESERVOIR 2.2 MILES

8 18. TOTAL DRAINAGE AREA 15,904 SQUARE MILES 22. MEAN ANNUAL PRECIPITATION INCHES

19. NET SEDIMENT CONTRIBUTING AREA 11,248' SQUARE MILES 23. MEAN ANNUAL RUNOFF 4. 6' INCHES

I 20. LENGTH MILES AV. WIDTH MILES 24. MEAN ANNUAL RUNOFF 3,9ó8,214" ACRE-FEET N

21. MAX. ELEVATION WIN. ELEVATION 25. ANNUAL TEtP. MEAN FRANGE -F to F'

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 R YRS. YES. INTERVAL

V

E

_________________________________

y

7 7 3/53 Contour (D) 5-ft 33,535 2,052,723 .52

8/97 44.4 Contour (D) 5-ft 34,0488 1,992,9778 .51

T 26. DATE OF 34. PERIOD 35. PERIOD WATER INFLOW, ACRE FEET WATER INFLOW TO DATE AF A S'JRVEY ANNUAL

,

PRECIP.

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

8/97 3,908,2146 5,785,673 171,961,416 3,908,214 171,961,416

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

SURVEY

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

8/97 59,746 1,345.6 .12 59,746 1,345.6 .12

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

SURVEY MT. (#/F'r3)

_____________________________

INFLOW, PPM

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

______________

DATE ANNUAL DATE PER. TOT

8/97 .0656 2.91

26. 43. DEPTH DESIGNATION RANGE IN FEET BELOW ELEVATION

DATE

OF 3650- 3675- 3700- 3725- 3750- 3775- 3800-

SURVEY 3625.3 3650 3675 3700 3725 3750 3775

8/97

PERCENT OF TOTAL SEDIMENT LOCATED WITHIN DEPTH DESIGNATION

10.8 41.9 15.9 12.0 13.9 5.5 0.0

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

DATE 0-10 10- 20- 30- I 40- 1 50- 60- I 70- 80- 90- 100- 105- 1 110- 1 115- I 120-

20 30 40 50 I 60 70 I 80 90 100 105 110 I 115 120 I 125

_______ PERCENT OF TOTAL SEDIMENT LOCATED WITHIN REACH DESIGNATION

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

11
45. RANGE IN RESERVOIR OPERATION

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

1953 1954 3,780.3 3,754.0 3,011,836

1955 3,000.0 3,771.2 2,961,658 1956 3,800.0 3,782.4 3.821,747

1957 3,799.2 3,781.2 3,525,877 1958 3,798.9 3,784.0 3,460,498

1959 3,799.9 3,789.1 3,379,898 1960 3,799.9 3,788.5 3,906,155

1961 3,788.4 3,774.6 2,200,018 1962 3,80O.0 3,772.8 3,692,882

1963 3,799.7 3,793.4 3,791,881 1964 3,800.0 3,790.2 4,207,875

1965 3,799.9 3,785.6 4,991,376 1966 3,798.6 3,777.5 2,957,394

1967 3,798.3 3,764.7 4,210,664 1968 3,797.1 3,777.8 4,342,009

1969 3,791.1 3,797.6 4,830,498 1970 3,797.1 3,778.2 4,748,646

1971 3,797.5 3,777.0 5,031,866 1972 3,797.3 3,781.9 4.514.152

1973 3,796.6 3,780.6 3,364.578 1974 3,798.6 3,781.8 4.356,349

1975 3,799.9 3,774.8 5,184,447 1976 3,798.2 3,781.0 5,661,328

1977 3,797.1 3,789.8 -2,953,637 1978 3,797.9 3,780.7 4,288,383

1979 3,796.2 3,779.2 3,488,449 1980 3,799.2 3,781.8 3,904,306

1981 3,799.7 3,784.2 4,368,406 1982 3,798.8 3,779.7 4,975,431

1983 3,798.3 3,785.1 4,658,448 1984 3,799.1 3,785.0 5,769,112

1985 3,791.7 3,778.0 3,425,320 1986 3,797.2 3,781.4 3,889,138

1987 3,792.9 3,784.4 2,702,506 1988 3,791.9 3,779.8 2,399,306

1989 3,785.9 3,773.8 2,623,247 1990 3,794.4 3,777.8 2,749,861

1991 3,798.0 3,780.5 3,014,350 1992 3,786.8 3,780.1 2,423,802

1993 3797.9 3,778.8 4,186,638 1994 3,794.7 3,781.8 2,736,253

1995 3,798.8 3,781.4 4,536,841 1996 3,797.8 3,778.8 4,928,562

1997 3.'79R.S l.792 c7R6.61, _____________

46. ELEVATION - AREA - CAPACITY DATA FOR 1997 CAPACITY

____

__________

_________

__________ __________

_____________

_ __________

ELEVATION AREA CAPACITY ELEVATION AREA CAPACITY ELEVATION AREA CAPACITY

3625.3 0.0 0 3630 3.3 8 3635 13.7 51

3640 32.0 165 3645 91.1 473 3650 143.7 1.060

3655 226.6 1,986 3660 581.4 4,006 3665 1,443.4 9,068

3670 2,102.8 17,934 3675 2,628.1 29,761 3680 3,5723 45,262

3685 4,657.4 65,836 3690 5,382.6 90,936 3695 5,872.7 119,074

3700 6,705.2 150,519 3705 7,558.6 186,179 3710 8,353.9 225,960

3715 8,811.9 268,874 3720 9,498.5 314,650 3725 10,292.0 364,126

3730 11,435.1 418,444 3735 12,534.3 478,368 3740 13,643.4 543,812

3745 14,937.1 615,263 3750 16,442.0 693,711 3755 18,226.1 780,381

3760 20,227.8 876,516 3765 22,120.8 982,388 3770 23,963.7 1,097,599

3775 26,064.2 1,222,669 3780 28,457.4 1,358,973 3785 30,656.5 1,506,757

3790 31,942.6 1,663,620 3795 32,876.2 1,825,667 3797 33,345.0 1,891,888

3800 34,047.9 1,992,977 ____________

47. REMARKS AND REFERENCES

___________________________ _____________ ____________

Top of spillway gates, elevation 3800.0.

Original reservoir areas and volumes adjusted for area and volume removed du e to construction of dust abatement

dikes. 2 2 2

Represents loss of contributing areas behind dams at Lima (570 ml 2' Ruby ( 596 ml ), and Ennis (2,181 ml

reservoirs. Clark Canyon Reservoir closed June of 1964 (2, 321 ml ) . Contr ibuting area adjusted by time.

Calculated using mean annual runoff value of 3,908,214 AR, item 24.

6

Computed annual inflows from 10/53 through 9/97.

Adjusted original surface area and capacity at elevation 3,800.0. Original areas adjusted for reservoir area

removed due to construction of dikes. Capacity recomputed by Reclamation's ACAP program using adjusted original

surface areas.

Surface area and capacity at elevation 3800.0 computed by ACAP program using 1997 reservo ir surface areas.

Surface areas and capacity do not include areas of reservoir removed due to constructed dikes. The 1997 survey

computed a larger surface area then the original, at elevati on 3800.0, for both with and without dike areas

8

conditions.

Total capacity loss calculated by comparing original capacity and 1997 capac ity at reservoir elevation 3800.0.

Maximum and minimum elevations and inflow values in acre-feet by water year.

48. AGENCY MAKING SURVEY Bureau of Reclamation

49. AGENCY SUPPLYING DATA Bureau of Reclamation f DATE March 1998

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

12
1 2 3 4 5 6 7 8

Computed Percent of Percent of

Elevations Original Original 1997 1997 Sediment Computed Reservoir

Survey Capacity Survey Capacity Volume Sediment Depth

(acre-feet) (area) (acre-feet) (acre-feet)

3800 33535 2052723 34048 1992977 59746 100.0 100.0

3797 32866 1953121 33345 1891888 61233 102.5 98.3

3795 32420 1887835 32876 1825667 62168 104.1 97.1

3790 31634 1727700 31943 1663620 64080 107.3 94.3

3785 30730 1571790 30656 1506757 65033 108.8 91.4

3780 29125 1422153 28457 1358973 63180 105.7 88.6

3775 26279 1283643 26064 1222669 60974 102.1 85.7

3770 24126 1157630 23964 1097599 60031 100.5 82.9

3765 22241 1041713 22121 982388 59325 99.3 80.0

3760 20418 935065 20228 876516 58549 98.0 77.1

3755 18458 837875 18226 780381 57494 96.2 74.3

3750 16622 750175 16442 693711 56464 94.5 71 . 4

3745 15150 670745 14937 615263 55482 92.9 68.6

3740 13905 598108 13643 543812 54296 90.9 65.7

3735 12878 531150 12534 478368 52782 88.3 62.9

3730 11925 469142 11435 418444 50698 84.9 60.0

3725 10816 412290 10292 364126 48164 80.6 57.1

3720 9798 360755 9499 314650 46105 77.2 54.3

3715 9133 313428 8812 268874 44554 74.6 51.4

3710 8541 269243 8354 225960 43283 72.4 48.6

3705 7778 228445 7559 186179 42266 70.7 45.7

3700 6995 191513 6705 150519 40994 68.6 42.9

3695 6278 158330 5873 119074 39256 65.7 40.0

3690 5573 128703 5383 90936 37767 63.2 37.1

3685 4843 102663 4657 65836 36827 61.6 34.3

3680 4123 80248 3572 45262 34986 58.6 31.4

3675 3481 61238 2628 29761 31477 52.7 28.6

3670 2891 45308 2103 17934 27374 45.8 25.7

3665 2351 32203 1443 9068 23135 38.7 22.9

3660 1857 21683 581 4006 17677 29.6 20.0

3655 1408 13520 227 1986 11534 19.3 17.1

3650 1000 7500 144 1060 6440 10.8 14.3

3645 667 3333 91 473 2860 4.8 11.4

3640 333 833 32 165 668 1.1 8.6

3635 0 0 14 51 -51 -0.1 5.7

3630 0 0 3 8 -8 0.0 2.9

3625.3 0 0 0 0 0 0.0 0.0

1 Elevation of reservoir water surface in feet.

2 Original reservoir surface areas adjusted for constructed dikes.

3 Original reservoir capacity recomputed using ACAP from column 2 areas.

4 1997 reservoir surface areas.

5 1997 reservoir capacity computed using ACAP and column 4 areas.

6 Measured sediment volume = column 3 minus column 5.

7 Measured sediment expressed in percentage of total sed iment of 59, 746.

8 Depth of reservoir expressed in percentage of total depth (175 feet).

13
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23
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3790

3780

3770

3760

3750

3740

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3710

3700

3690

3680

3670

3660

3650

3640

3630

Capacity

_____ - _________ _______ ____

Area

________-

1997 Capacity

Oriainat Surve

0 210000 420000 630000 840000 1050000 1260000

Capacity (acre-feet)

.5l:iUU

3790

3780

3770

3760

3750

3740

3730

3720

3710

3700

3690

3680

3670

3660

3650

3640

3630

3620

1470000 1680000 1890000 2100000

Flqure 11. - 1997 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.