SHADEHILL RESERVOIR

1993 SEDIMENTATION SURVEY

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U.S. Department of the Interior

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

September 1995 Final

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

Shadehill Reservoir

1993 Sedimentation Survey PR

6. AUTHOR(S)

Ronald L. Ferrari

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

Bureau of Reclamation REPORT NUMBER

Technical Service Center

Denver CO 80225

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

Bureau of Reclamation AGENCY REPORT NUMBER

Denver Federal Center DIBR P0 Box 25007

Denver CO 80225-0007

11. SUPPLEMENTARY NOTES

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Available from the National Technical Information Service,

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13. ABSTRACT (Maximum 200 words)

The Bureau of Reclamation surveyed the underwater area of Shadehill Reservoir in July 1993 to compile field

data for developing a reservoir topographic map and computing a present storage-elevation relationship. The

data were also used to calculate volume of reservoir capacity lost since dam closure in July 1950. The volume

lost is attributed to sediment accumulation and significant reservoir shoreline erosion. The 1993 bathymetric

survey used sonic depth recording equipment interfaced with an automated microwave positioning system that

gave continuous depth and sounding positions throughout the reservoir. The underwater topography was

developed by a computer graphics program using collected data. The above-water reservoir area was measured

from USGS (U.S. Geological Survey) topography maps developed from aerial photography obtained in 1978. The

new reservoir contour map and surface areas are a combination of 1993 underwater data and 1978 USGS aerial

topography.

As of July 1993, at reservoir spillway crest elevation 2272.0 (feet), the surface area was 5019.0 acres with a total

capacity of 120,172 acre-feet. Since initial filling in July 1950, an estimated 15,241 acre-feet of Shadehill

Reservoir capacity have been lost below elevation 2272.0, resulting in an 11.2-percent loss in reservoir volume.

Since 1950, the average annual rate of reservoir capacity lost below elevation 2272.0 is 354.4 acre-feet.

14. SUBJECT TERMS--reservoir area and capacity! sedimentation! reservoir surveys! 15. NUMBER OF PAGES

sonar! sediment distribution! contour area! reservoir area! sedimentation survey! 23

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

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

Prescribed by ANSI Std. 239-18

298-102
SHADEHILL RESERVOIR

1993 SEDIMENTATION SURVEY

by

Ronald L. Ferrari

Sedimentation and River Hydraulics Group

Water Resources Services

Technical Service Center

Denver, Colorado

September 1995
ACKNOWLEDGMENTS

The Bureau of Reclamation (Reclamation) prepared and

published this report under the supervision of the Sedimentation

and River Hydraulics Group. The reservoir survey is part of the

Shadehill Lake Protection Project, which is under the direction of

Bob Drown, SCS (Soils Conservation Service) Project Coordinator.

The reservoir survey was performed under the direction of J.

Craig Kjar, Chief, O&M Division of Reclamation's Newell Office

of the Great Plains Region. Ronald Ferrari of the TSC (Technical

Service Center) conducted the hydrographic survey. Personnel

from the Newell Office performed the required land survey and

assisted during the hydrographic data collection. Special thanks

to John Strachan, Douglas Bandy, and Robert Reedy, who

performed the land survey; and Walt Zell, Dave Lucas, and Curt

Anderson, who assisted during the hydrographic data collection.

Personnel from SCS participated during the hydrographic data

collection and surveyed several sediment range lines located in

the upper end of the reservoir area. Special thanks to Tom

VerHeist, Cindy Steele, Carol Reed, Michelle Lauritzen, and

Sharon Huber for their field assistance. Ronald Ferrari

completed the data processing and generated the new reservoir

topographic map and area-capacity tables. James Melena of the

TSC performed the peer review of the study.

U.S. Department of the Interior

Mission Statement

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

Interior has responsibility for most of our nationally-owned public lands

and natural resources. This includes fostering sound use of our land

and water resources; protecting our fish, wildlife, and biological

diversity; preserving the environmental and cultural values of our

national parks and historical places; and providing for the enjoyment of

life through outdoor recreation. The Department assesses our energy

and mineral resources and works to ensure that their development is in

the best interests of all our people by encouraging stewardship and

citizen participation in their care. The Department also has a major

responsibility for American Indian reservation communities and for

people who live in island territories under U.S. administration.

The information contained in this report regarding commercial

products or firms may not be used for advertising or promotional

purposes and is not to be construed as an endorsement of any

product or firm by the Bureau of Reclamation.

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

Description of watershed 4

Reservoir operations 4

Survey method and equipment 4

Reservoir area and capacity 6

Original area and capacity 6

Development of 1993 contour areas 7

1993 revised storage capacity 7

Sediment analyses 8

Sediment sampling 8

References 9

Table

TABLES

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

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

2 Summary of 1993 survey results 12

Figure

FIGURES

1 Shadehill Reservoir location map 13

2 Shadehill Dam, plan and section 14

3 Shadehill Dam, plan and profiles 15

4 Shadebill Reservoir topographic map (1 of 3) 17

5 Shadehill Reservoir topographic map (2 of 3) 19

6 Shadehill Reservoir topographic map (3 of 3) 21

7 1993 area and capacity curves-Shadehill Reservoir 23

in
INTRODUCTION

Shadehill Dam and Reservoir, major features of the Pick-Sloan Missouri Basin Program, are

located on the Grand River in northwestern South Dakota. The dam, located in Perkins

County, South Dakota, is 12 miles south of Lemmon, South Dakota, and immediately

downstream from the confluence of the North and South Fork of the Grand River (fig. 1).

The Shadehill Unit investigations began in 1931. The Corps of Engineers conducted a

topographic survey of a reservoir site immediately downstream from the confluence of the

North and South Forks of the Grand River. Reclamation followed with a reconnaissance

survey in 1938-39 to determine the quality of available water. The Shadehifl Unit was

authorized by the United States 78th Congress with the Flood Control Act of December 22,

1944. Detailed studies of the dam and reservoir were conducted from 1945 through 1948.

Construction of Shadehill Dam and Reservoir began April 19, 1949 and was completed August

15, 1951.

Closure of the dam and first reservoir storage began on July 1, 1950. At elevation 2772.0 (feet),

the reservoir extends around 10.2 miles up the South Fork and 8.0 miles up the North Fork

of the Grand River. The reservoir has an average width of 0.42 mile.

Shadehill Dam and two dikes that form the reservoir are modified, homogeneous, rolled

earthfill structures. The two dikes, located in saddles south of the right abutment, have

structural heights of 83 and 18 feet and respective crest lengths of 1,090 and 264 feet.

Shadehill Dam (figs. 2 and 3), at a crest elevation of 2318.0, has:

• a structural height* of 145 feet

• a hydraulic height of 102 feet

• a top crest width of 30 feet

• a crest length of 12,843 feet

Shadehill Dam has two spillways. The service spillway has a crest elevation of 2272.0 with a

maximum capacity of 5,700 cubic feet per second at reservoir water surface elevation 2312.0.

The service spillway is located near the left abutment of the dam and consists of:

• an uncontrolled morning-glory type inlet structure

• a 13.5-foot-diameter reinforced concrete conduit

• a chute

• a common stilling basin with the outlet works

• a downstream channel

The emergency spillway, located immediately upstream from the left abutment, consists of an

open-cut, unlined channel with a bottom width of 1,500 feet and an earthen crest at elevation

2302.0. The maximum discharge capacity is 127,000 cubic feet per second at reservoir

elevation 2312.0. The discharge flows downstream from the dam into Flat Creek, a tributary

of the Grand River.

* The definition of terms such as structural height, "hydraulic 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.
The river outlet works is located adjacent to the left side of the service spiflway and consists

of:

• three steel 10-foot-square intake trashracks

• 84-inch-diameter steel-lined upstream pressure conduit

• hoist house and access shaft

• a gate chamber housing a 6-foot-square emergency slide gate and a 6-foot-square top seal

radial gate to regulate flows

• a 7.25-foot horseshoe-shaped discharge conduit leading to a stilling basin

• a 6-foot-diameter steel pipe

• a common stilling basin with the service spillway

The rated discharge capacity of the outlet works is 600 cubic feet per second at reservoir

elevation 2272.0. No releases are made from the outlet works above elevation 2274.0 because

of restrictions on maximum flow when the reservoir is using the service spillway.

Shadehill Reservoir is a multi-purpose reservoir with primarily a flood control function. The

original calculated total capacity at reservoir elevation 2302.0 was 357,382 acre-feet, of which

217,708 acre-feet was exclusive flood control, 81,443 acre-feet was conservation space, and

58,231 acre-feet was dead storage. An additional 111,203 acre-feet of surcharge storage

capacity exists between the emergency spillway crest elevation 2302.0 and the design

maximum water surface of 2312.0. The original reservoir survey measured a total storage

capacity of 139,674 acre-feet and a surface area of 4,868 acres at reservoir spillway crest

elevation 2272.0.

The Bureau of Reclamation (Reclamation) operates Shadehill Dam and Reservoir. The Corps

of Engineers reservoir regulations for flood control have been canceled. Reclamation

administers the flood control component of the project. Because the reservoir is on a tributary

of the Missouri River, the Corps of Engineers is notified of flood control decisions at the

reservoir. Recreation areas and lands around the reservoir are administered by the South

Dakota Department of Game, Fish, and Parks under an agreement with Reclamation.

SUMMARY AND CONCLUSIONS

This report presents the 1993 results of the first extensive sedimentation survey of Shadehill

Reservoir since construction of Shadehill Dam. The primary objectives of the survey were to:

• establish accurate baseline data for future monitoring of storage depletion

• gather data needed for developing new reservoir topography

• compute area-capacity relationships

• estimate storage depletion since closure of the dam

The reservoir survey is part of the Shadehill Lake Protection Project, which is sponsored by the

Perkins County Conservation District. The project provides technical and financial assistance

from various Federal, State, and local agencies. The project is a 3-year effort consisting of

planning and implementing a voluntary program of Best Management Practices with users of

lands that drain into Shadehill Reservoir. The project's primary objectives, to be met by 1996,

are to:

2
• reduce 20,000 acres of cropland erosion to tolerable levels

• improve 60,000 acres of pastured rangeland that is currently in poor to fair condition and

upgrade to fair to good condition

• maintain water quality in the reservoir

• improve the beneficial use of the Grand River

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

for the hydrographic survey. A horizontal grid system was established using monumented

control points located in the reservoir area. The bathymetric survey was run using sonic depth

recording equipment interfaced with an automated survey system consisting of a line-of-sight

microwave positioning unit capable of determining sounding locations within the reservoir.

The system continuously recorded reservoir depth and horizontal coordinates as the survey

boat was navigated along close-spaced gridlines covering the reservoir area. The positioning

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

gridlines. Water surface elevations measured at the time of data collection were used to

convert the sonic depth measurements to true lake bottom elevations.

The 1993 underwater surface areas at predetermined 5-foot contour intervals were generated

by a computer graphics program using the collected data. The above-water reservoir areas

were measured from USGS 7.5-degree quadrangle maps with 5-meter contour intervals

developed from aerial photography obtained in 1978. The new reservoir contour map is a

combination of the 1993 generated underwater and the USGS above water topography (figs.

4, 5, and 6). The area and capacity tables were produced by a computer program that uses the

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

prescribed elevation increments.

iTabIe 1 contains a summary of reservoir watershed characteristics and sediment data for the

'1993 survey. The 1993 survey determined that the reservoir has a storage capacity of 120,172

acre-feet and a surface area of 5,019 acres at reservoir spillway crest elevation 2272.0. Since

closure in 1950, the reservoir has accumulated an estimated volume of 15,241 acre-feet of

sediment and reservoir shoreline erosion material below elevation 2272.0. This volume

represents an 11.2-percent loss in total capacity and an average annual loss of 354.4 acre-feet.

For the purpose of calculating reservoir depletion, the difference between the original and 1993

capacity was used, but questions exist regarding:

• accuracy of the original reservoir area-capacity values

• amount of shoreline erosion material versus accumulated sediment

• amount of shoreline erosion since development of the USGS topography maps.

The original 25-foot contour topography maps of the Shadehill Reservoir area were generated

by a plane table survey prior to dam construction. The 1993 sedimentation study found the

proposed axis of the dam's left bank levee on these original topography maps in a slight

northwest direction. The USGS maps had the final axis in a northeast direction. For

determining reservoir volume change, the original capacity was recomputed taking into

account the additional surface areas between the proposed and actual levee axis. An aerial

survey of the above water portion of the reservoir would resolve issues of present shoreline

topography and amount of shoreline erosion versus sediment inflow.

3
DESCRIPTION OF WATERSHED

Shadehill Reservoir watershed has a drainage area of 3,120 square miles; elevations range

from 2250.8 feet at the outlet works to around 4000 feet on top of the higher buttes. The

calculated net sediment contributing area is 2,841 square miles. This area represents the loss

of drainage area since closure of Bowman-Harley Reservoir in August 1966. The North Fork

of the Grand River drains about 900 square miles of the southwestern corner of North Dakota

before flowing southeastward into South Dakota. The North Fork joins the South Fork of the

Grand River about 2 miles upstream from Shadehill Dam. The South Fork of the Grand River

is formed by six large tributaries with several intermittent streams. The drainage basin has

a maximum width of 60 miles and a west to east length of 90 miles. The topography is

characterized by tablelands and buttes typical of the Great Plains Region. Pockets of typical

badland topography occur throughout the basin. The general geology is characterized by

resistant sandstone alternating with soft sands and shales forming broad terraces and flattopped buttes. The higher elevations of the tops of buttes are generally 500 to 600 feet higher

than the tableland elevation. The majority of the soils are well drained and are developed from

silty and clayey shales. A small portion of the drainage area of the North Fork of the Grand

River contains sandy loams. Rangeland used for livestock production is the major land use in

the watershed; less than 25 percent of the watershed is cultivated.

RESERVOIR OPERATIONS

The reservoir is a multi-use facility having (following values are from July 1993 area-capacity

tables):

• 119,560 acre-feet of surcharge flood storage between elevations 2302.0 and 2312.0

• 230,004 acre-feet of exclusive flood control storage between elevations 2272.0 and 2302.0

• 76,303 acre-feet of exclusive conservation storage between elevations 2250.8 and 2272.0

• 43,869 acre-feet of dead storage below elevation 2250.8

Records for Shadehill Reservoir show an average unregulated inflow of 63,607 acre-feet per

year. The estimated mean annual runoff from the basin is 0.38 inch. Since the initial filling,

Shadehill Reservoir operations have ranged from elevation 2258.6 in November 1981 to a

maximum elevation of 2297.9 in April 1952. The inflow and end-of-month stage records in

table 1 show the annual fluctuation of the reservoir. Except for water year 1952, the records

show that the normal reservoir operation does not include extreme reservoir water surface

fluctuations.

SURVEY METHOD AND EQUIPMENT

The original Shadehill Reservoir surface areas were measured from 25-foot contour topography

developed in the 1940s by a plane table survey. During the fall of 1949 through 1951, 51 range

lines were established, 42 within the reservoir area, for the purpose of monitoring sediment

accumulation. Reclamation's method of calculating sediment accumulation byresurveying the

range lines depends on the accuracy of the original surface areas. For the 1993 study, the

original reservoir topography of 25-foot contour intervals were determined to be insufficiently

accurate to use the range line method. To meet the objectives of the Shadehill Lake Protection

4
Project, a new 1993 topography map of the reservoir area was recommended and therefore

developed.

The 1993 Shadehill Reservoir hydrographic survey was completed using the contour method

as outlined by Blanton (1982). The procedure involves collecting adequate coordinate data for

developing a reliable contour map by photogrammetric and bathymetric survey methods.

Because of the cost of photogrammetric mapping, the above water data were obtained from the

USGS 5-meter contour topography of the area above the reservoir shoreline. Standard land

surveying methods were used by the Newell Office personnel to establish horizontal and

vertical control points for the 1993 bathymetric survey. A horizontal grid system was

established using monumented points, with state plane coordinates, located in the reservoir

area. The field survey involved establishing a triangulation network around the reservoir to

provide horizontal and vertical control for all required grid lines and shore stations for the

bathymetric survey. To a large extent, the previously established sediment range lines and

their monuments were used for this survey.

The hydrographic survey was run on July 6 through 13, 1993, with the reservoir water surface

between elevations 2272.97 and 2273.17. The bathymetric survey was run using sonic depth

recording equipment interfaced with an automated survey system consisting of a line-of-sight

microwave positioning unit capable of determining sounding locations within the reservoir.

This positioning system tl-ansmitted line-of-sight microwave signals to fixed shore stations and

converted the reply time to range distances, which were used by the system data logger to

compute the coordinate position of the sounding boat. The survey system continuously

recorded reservoir depth and horizontal coordinates as the survey boat moved across closespaced gridlines covering the reservoir area. To produce adequate data for developing contours

of Shadehill Reservoir, an average grid spacing of 300 feet was used. The system gave

directions to the boat operator to assist in maintaining course along these close-spaced

gridlines. During each run, the depth and position data were recorded on a hard drive disk at

1-second intervals for subsequent processing by Reclamation personnel. A graph plotter was

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

Water surface elevations measured at the time of collection were used to convert the sonic

depth measurements to true lake bottom elevations.

Personnel from the Belle Fourche and Bison SCS Offices collected data for several range lines

located in the upper reservoir area. Standard land survey methods were used to collect data

for range lines 9 through 13 and 25 through 28. SCS processed the data and provided hard

copy comparison plots of the 1950 versus 1993 data for the range lines surveyed. The

comparison plots found about 4 feet of sediment buildup at range line 9; the other surveyed

range lines measured little to minimal bottom change. Water in the reservoir was too deep to

collect channel bottom data for range line 25. Several of the ranges measured some bank

erosion. Results from these comparisons were used to finalize the upper contours of the

reservoir topography map. Copies of these plots can be obtained from the SCS Belle Fourche

and Bison Offices or Reclamation's Newell Office.

Meetings on the Shadehill Lake Protection Project revealed that the U.S. Forest Service had

a contract for the collection of aerial photography in the reservoir study area. The final product

was non-rectified, 60 percent overlapping photos at a scale of 1:24,000. The aerial photography

of the reservoir was obtained on September 23, 1993, at water surface elevation 2270.79. A few

known points were marked with panels by the Newell Office. It was hoped that the aerial

photos could be used by developing a contour of the reservoir water surface elevation at the

5
time of collection. Funding was not available for the aerial contractor to complete a map of the

above water portion of the reservoir area or to have the aerial photos rectified. The 1993

analysis determined that the use of the non-rectified photos would introduce an error that

could not be reliably corrected with the equipment and software presently available at

Reclamation's TSC (Technical Service Center).

The 1993 study concluded that the most accurate information of the upper reservoir contour

area was the USGS topography maps. The problem with the USGS topography was the

development from aerial photography obtained in 1978, which would not account for the

reservoir shoreline erosion that occurred from 1978 through July 1993. Digitizing programs

were used to measure the surface areas and develop state plane coordinates of the following

USGS topographic Shadehill Reservoir contours: elevation 2272.0 (692.5 meters), elevation

2280.2 (695.0 meters), elevation 2296.6 (700.0 meters), and elevation 2313.0 (705 meters).

RESERVOIR AREA AND CAPACITY

Original Area and Capacity

Detailed information on development of original surface areas of Shadehill Reservoir was not

located, but they appear to have been measured from four topography maps (dated December

4, 1946), Reclamation drawing numbers 276-626-214 through 276-626-217. Available copies

of original topography maps were of fair to poor quality, but they appear to have been

developed by a plane table survey method with contour elevations of 2225.0, 2250.0, 2275.0,

2300.0, and 2312.0. The 1993 study measured the surface area of contour elevation 2300.0 to

verify use of these maps for determining original surface area. Contour 2300.0 was chosen

because it was the easiest to distinguish on the maps. The measured value was within 1

percent of the surface area projected from a curve of Shadehill Reservoir surface areas.

The original 5-foot surface area values for reservoir elevation 2200.0 through 2310.0 were

projected from a July 30, 1948, Reclamation elevation versus area curve (drawing 276-D-28).

The area for reservoir elevation 2312.0 was projected from a June 26, 1963 revised Reclamation

area curve (drawing 276-602-465). The projected surface area values from the curves are listed

in column 2 of table 2.

A comparison of the projected original area curve values with the 1993 areas, listed in column

5 of table 2, found large differences at the higher contours (elevations 2275.0 through 2312.0).

Major shoreline erosion was expected, but the measured differences seemed too great to

attribute to shoreline erosion only. A major surface area difference was found when the

original topography maps were overlaid with the USGS topography maps. The original

topography map had the proposed axis of the dam's left bank levee in a slight northwest

direction; the USGS maps had the actual levee axis in a northeast direction. From the overlay

and the measurement of the 2300.0 contour, the difference in levee axis alignment was

assumed to have affected the original reservoir surface areas above contour elevation 2275.0.

To account for the difference, the surface areas between the two alignments for contour

elevations 2296.6 and 2313.0 were measured from the USGS topography. These measured

surface areas were used for calculating the adjusted original areas as listed on column 3 of

table 2. The adjusted original capacity, listed in column 4 of table 2, was recomputed using the

area-capacity computer program ACAP85 (Reclamation, 1985) with the adjusted original areas

in column 3.

6
Development of 1993 Contour Areas

The 1993 contour surface areas for Shadehill Reservoir were measured from the 1993 reservoir

topography and existing USGS topography maps. The 1993 contour map was generated from

the 1993 collected underwater coordinate data and state plane coordinate points of the USGS

above water reservoir contours. The state plane coordinate points were determined for contour

elevations 2272.0(692.5 meters), 2280.2(695.0 meters), 2296.6(700.0 meters), and 2313.0(705

meters). The USGS state plane coordinate points were used as boundary information for

developing the reservoir contours from the underwater data. The problem with using the

USGS topography was that it was developed from 1978 aerial photography that does not

account for the reservoir shoreline erosion that has occurred from 1978 through July 1993. An

overlay of the 1993 collected underwater data with the USGS maps illustrated large areas of

shoreline erosion. Because of the overlapping data, the coordinate points from the USGS

topography for contour elevation 2272.0 were not used for developing the final contour map.

Five-foot contour intervals of the underwater reservoir data, from elevation 2215.0 through

elevation 2265.0, were created by the computer graphics software program SURFACE II

(Kansas Geological Survey, 1978). The program developed closed 5-foot contours for reservoir

elevations 2215.0 through 2260.0 and calculated the closed contour surface areas of the

generated map. SURFACE II did not completely close the elevation 2265.0 contour. The final

2265.0 contour was developed by overlaying computer generated portions of the contour with

the USGS topography maps and a plot of the 1993 underwater data. With the available

information, the 2265.0 contour was finalized using engineering judgement to determine the

location. The 2272.0 contour on the final reservoir topography was projected from the USGS

maps. The USGS 2272.0 contour was adjusted to avoid crossing of the developed lower

elevation contours. The 1993 surface area for contour elevation 2272.0 was measured from the

USGS topography maps, not the modified 2272.0 contour on the 1993 reservoir maps. The

final reservoir maps shown on figures 4, 5, and 6 were prepared by the TSC Visual

Presentations Group. The map has a scale of 1 inch equals 1000 feet with a 5-foot contour

interval.

1993 Revised Storage Capacity

The storage-elevation relationships based on the aerial and underwater survey data were

developed using the area-capacity computer program ACAP85 (Reclamation, 1985). Surface

areas at 5-foot contour intervals, computed from the underwater survey data and the measured

reservoir surface areas from USGS topography, were used as the control parameters for

computing reservoir capacity. The program computes an area at elevation increments 0.01-

to 1.0-foot by linear interpolation between the given contour intervals. The program begins by

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

within an allowable error limit, which was set at 0.000001 for Shadehill Reservoir. This

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) tests the fit until it also

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 + a + a3x2

where:

y = capacity

x = elevation above a reference base

a = intercept

a2 and a3 = coefficients

Results of the 1993 Shadehill Reservoir area and capacity computations are listed in table 1

and columns 5 and 6 of table 2. Listed in columns 3 and 4 of table 2 are the original adjusted

surface areas and recomputed capacity values. A separate set of 1993 area and capacity tables

has been published for the 0.01-, 0.1-, and 1-foot elevation increments (Reclamation, 1993). A

description of the computations and coefficients output from the ACAP85 program is included

with these tables. Both the original and 1993 area-capacity curves are plotted on figure 7. As

of July 1993, at reservoir elevation 2272.0, the surface area was 5,019.0 acres with a total

capacity of 120,172 acre-feet.

SEDIMENT ANALYSES

Tables 1 and 2 contain the Shadehill Reservoir sediment accumulation and water storage data

based on the 1993 resurvey. The 1993 study based its sediment calculations on the difference

between the original and 1993 measured reservoir capacities. This method accounts for the

sediment accumulation during the 43.0 years of reservoir operation, but is only as accurate as

the original and 1993 reservoir areas. For sediment calculation purposes, the difference

between the original and 1993 capacity was used, but as previously noted, a question exists as

to the accuracy of the original area-capacity. Also, there is the problem of determining the

portions of measured reservoir lost to sediment inflow and shoreline erosion. Future

monitoring of the reservoir will continue to have this problem. During the 1993 high reservoir

period, additional bank erosion was observed, and it is assumed that this erosion will continue

throughout the life of the reservoir. To assist in measuring the difference between the inflow

sediments and bank erosion, an aerial reservoir area survey should be completed in the future.

Results could be compared with the original and 1978 USGS topography along with the 1993

aerial photography for measuring the changes in reservoir shoreline.

Prior to construction, the sediment inflow for Shadehill Reservoir was estimated to be 270 acrefeet per year for a 100-year total of 27,000 acre-feet. It was expected that 77 percent of the

total sediment would deposit in the dead storage pool. The 1993 reservoir survey computed

a total volume lost of 15,241 acre-feet for the first 43 years of reservoir operation, July 1950

through July 1993. The survey measured 73.3 percent of the total deposit in the dead storage

area, below elevation 2250.8. The average annual rate of deposition was 354.4 acre-feet per

year, or 0.12 acre-foot per square mile from the sediment contributing drainage area. The

storage loss in terms of percent of original storage capacity was 11.2 percent.

SEDIMENT SAMPLING

Underwater sediment samples were collected with a gravity core sampler for the purpose of

characterizing the type and distribution of the sediment in the reservoir. Eight sample point

locations were chosen to represent the sediment entering from the main tributaries (North and

South Forks of the Grand River) and the sediment deposited within the reservoir pool area

8
located downstream from the confluence of the Grand River North and South Forks. The

sampler was suspended over the bow of the survey vessel from a cable reeled off a poweroperated winch. The sampler was allowed to fall free into the sediment deposits to obtain

maximum possible penetration. The sampler was then retrieved, and the plastic liner

containing the sediment sample was withdrawn from the coring pipe. The samples were sealed

with plastic caps on each end of the liner and labeled. SCS personnel transported the samples

to a laboratory for analysis.

The four samples collected below the confluence of the Grand River North and South Forks

were composed of fine silty clay with some organic matter and about 2 percent fines. These

samples did not vary significantly in type and texture of sediment. The dry weight of the

samples ranged from 53 lb/ft3 (pounds per cubic feet) to 56 lb/ft3. Two samples collected from

the South Fork of the Grand River varied in the amount of fine sands that were present. The

sample collected 200 feet from the south bank was about 5 to 10 percent fines. These fines

were composed of fine sand, silt, and clay with a dry weight of 64 lb/ft3. The second sample,

located north of the first, had about 20 percent fines and a dry weight of 69 lb/ft3. The two

sediment samples collected from the North Fork of the Grand River had a wide variation in

type and texture. The sample nearer the southern bank had a dry weight of 79 lb/ft3 and was

comprised of about 60 percent fines with a mixture of silt and clay with coarse and fine sands.

The second sample closer to the northern bank was silty sand with about 30 to 35 percent fines

and a dry weight of 72 lb/ft3. As expected, the samples with a higher percentage of fines were

collected from the North Fork of the Grand River.

REFERENCES

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

York, 1962.

Blanton, J.O. III, Procedures for Monitoring Reservoir Sedimentation: Technical Guideline

for Bureau of Reclamation, Denver Office, Denver, CO, October 1982.

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

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, CO, 1987a.

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

1987b.

Bureau of Reclamation, Technical Service Center, Shadeh ill Reservoir Area and Capacity

Tables, Shadehill Unit, Great Plains Region, Denver, CO, July 1993.

Kansas Geological Survey, SURFACE II GRAPHICS SYSTEM, Lawrence, Kansas, 1978.

9
RESERVOIR SEDIMENT

DATA SUMMARY SHADEHILL RESERVOIR

NAME OF RESERVOIR 1

DATA SHEET NO.

D 1. OWNER Bureau of Reclamation 2. STREAM Grand River 3. STATE South Dakota

A 4. SEC. 25 TWP. 21N RANGE 15E 5. NEAREST P.O. Shadehill 6. COUNTY Perkins

M 7. LAT 45 45' 12' LONG 1076 12' 12' 8. TOP OF DAM ELEVATION 2318.0

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

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

a. SURCHARGE 2312.0 12,150 111,203 468,585 BEGAN

E

b. FLOOD CONTROL 2302.0 9,926 217,708 357,382 7/1150

v

c.POWER __________

O d.WATERSUPPLY 16. DATE

I e. IRRIGATION NORMAL

OPERATION R f. CONSERVATION 2272. 0 4, 868 81,443 139, 674

g. INACTWE 2250 . 8 2, 789 58, 231 58,231

17. LENGTH OF RESERTUIR 18.20 MILES AVG. WIDTH OF RES RVOIR 0.42 MILES

T 18. TOTAL DRAINAGE AREA 3,120 SQUARE MILES 22. MEAN ANNUAL PRECIPITATION 15.70 INCHES

A 19. NET SEDIMENT CONTRIBUTING AREA 2,841 SQUARE MILES 23. MEAN ANNUAL RUNOFF 0.38 INCHES

20 LENGTH MILES AV WIDTH MILES . . 24. MEAN ANNUAL RUNOFF 63,6076 ACRE-FEET

N 21. MAX. ELEVATION 4000 MIN. ELEVATION 2250.8 25. ANNUAL TEMP. MEAN 476F RANGE -45F to 115"F3

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. YRS. INTERVAL

V 7/1150 Contour(R) 25-ft 4,868 135,4130 2.13

F

7/93 43.0 43.0 Contour(D) 5-ft 5,019.0 120,172 1.89

D

A

_________________

26. DATE OF

_______________

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

T

SURVEY ANNUAL ___________________________________________________________________

A

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

7/93 15,7" 63,6076 388,2000 2,607,887 63,607 2,607,887

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

SURVEY

a. TOTAL b. AV. ANN. c. IMI.2-YR.

_____________

a. TOTAL

________________

b. AV. ANNUAL

_____________

c. /MI.2-YR.

7/93 15,241 354.4 0.12 15,241 354.4 .12

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

SURVEY (#f?76) INFLOW, PPM

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

DATE DATE PER. TOT.

7/93 0.26210 11,210

26 DATE 43. DEPTH DESIGNATION RANGE IN FEET BELOW, AND ABOVE, SPILLWAY CREST ELEVATION

s.mvEY J

72.0- J62.0- 52.0- 42.0- 32.0- 22.0- 12.0-

PERCENT OF TOTAL SEDIMENT LOCATED WITHIN DEPTH DESIGNATION

7/93 8.2 22.9 15.1 9.6 15.8 24.4 4.0

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

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

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

PERCENT OF TOTAL SEDIMENT LOCATED WITHIN REACH DESIGNATION

N/A

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

10
45. RANGE IN RESERVOIR OPERATION '

WATER YEAR MAX. ELEV. MIN. ELEV, INFLOW, AF WATER YEAR MAX, ELEV. MIN. ELEV. INFLOW, AF

1950 -

- 388,200 1951 -

- 400

1952 2297.9 2248.7 - 1953 2276.2 2270.9 -

1954 2272.9 2271.2 14,044 1955 2271.9 2270.6 5,426

1956 2272.6 2269.6 42,768 1957 2273.4 2270.7 22,295

1958 2272.6 2270.7 8,650 1959 2273.1 2269.8 16,337

1960 2273.3 2269.3 27,775 1961 2271.0 2261.5 -1,491

1962 2268.2 2258.9 36,185 1963 2270.3 2263.1 42,598

1964 2268.2 2259.3 35,663 1965 2274.2 2261.0 106,313

1966 2272.2 2262.0 63,077 1967 2274.3 2266.1 74,424

1968 2266,6 2261.7 15,064 1969 2274.1 2260.8 109,761

1970 2272.1 2264.7 41,594 1971 2275.0 2264.8 182,035

1972 2276.4 2264.6 170,636 1973 2272.8 2265.9 73,172

1974 2268.7 2262.8 20,020 1975 2273.4 2261.8 75,442

1976 2271.6 2266,9 27,793 1977 2269.7 2267.5 16,773

1978 2282.4 2266.8 227,841 1979 2273.1 2265.4 62,903

1980 2268.3 2260.9 326 1981 2260.9 2259.2 7,433

1982 2275.7 2258.6 166,483 1983 2271.9 2267.8 68,200

1984 2271,8 2266.5 35,083 1985 2271,6 2265.2 43,943

1986 2273.8 2267.8 103,588 1987 2273.9 2267.6 78,879

1988 2268.9 2264.4 11,987 1989 2267,9 2262.7 28,852

1990 2269.5 2266.1 19,856 1991 2267.3 2265.2 8,860

1992 2265.7 2264.0 11,216 1993 2275.3 2264.1 117,483

46. ELEVATION - AREA - CAPACITY JATA FOR 1993 TOiAL CAPACITY'2

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

2212.1 0 0 2215 33.5 49 2220 302.2 888

2225 655.3 3,282 2230 1,010,0 7,445 2235 1,413.4 13,503

2240 1,720.9 21,339 2245 2,061,6 30,795 2250 2,393.0 41,932

2255 2,748,4 54,785 2260 3,297.6 69,900 2265 4,076.9 88,337

2270 4,750 110,403 2272 5,019.0 120,172 2275 5,489 135,934

2280 6,272 165,335 2280.2 6,303.0 166,592 2285 7,221 199,050

2290 8,177 237,544 2295 9133 280,819 2296.6 9,439.0 295,677

2300 10,262 329,168 2305 11,472 383,503 2310 12,682 443,888

2312 13,166 469,736

______________

47. REMARKS AND REFERENCES

Two spillways. Service spillway, crest elevation 2272.0, is an uncontrolled concrete morning-glory inlet, with a concrete con duit through dam located left side of

original nver channel, with capacity of 5,700 ftls3 at reservoir elevation 2312.0, Emergency spiliway, crest elevation 2302.0, is unlined open cut structure located

at north end of dam with capacity of 127,000 ft/s' at elevation 2312,0,

Includes 10.2 miles from dam to upper end of the South Fork of the Grand River and 8.0 miles from the North and South Fo rk confluence to the u pper end of the

North Fork of the Grand River.

Bureau of Reclamation Project Data Book on Shadehill Unit, 1966 - 80.

Represents loss of contnbuting area since closure of Bowman-Harley Reservoir in August 1966.

Calculated using mean annual runoff value of 63,607 acre-feet (item 24).

Calculated unregulated monthly inflows for reservoir operation period July 1950 through July 1993. No calculated records for water years 195 2 and 1953. Inflow for 1950-51 from Reclamation Project Data Book.

Surface area at reservoir elevation 2272.0. Onginal areas projected from area curve drawing 276-D-28, for elevations 2275.0 and below only

Capacity at elevation 2272.0. Recomputed by Reclamation's ACAP program using original surface areas. Some question as to the accuracy of the original surface

areas because of projecting from area curve.

Total capacity loss calculated by companng recomputed capacity (see remarks No. 7 and 8) and 1993 capacity at reservoir el evation 2272.0. Reservoir experienced significant shoreline erosion.

Average annual and total sediment deposits of 354.4 and 15,241 acre-ft, respectively, divided by original capacity of 135,413 acre-ft. Original capacity at

El. 2272.0 computed by ACAP using projected original surface area data.

Maximum and minimum reservoir elevations for indicated water year.

'

1993 total capacity computed by ACAP using 1993 measured areas. Areas for elevation 2265.0 and below measured from July 1993 hydrographic survey data

Areas at elevation 2272.0 and above measured from USGS topography maps developed from aerial photography obtained in 1978.

48. AGENCY MAKING SURVEY Bureau of Reclamation

49. AGENCY SUPPLYING DATA Bureau of Reclamation DATE August 1994

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

11
(1)

Elevation

(feet)

(2)

Original

Area

(acres)

(3)

Adjusted

Original

Area

(acres)

(4)

Adjusted

Original

Capacity

(acre-feet)

(5)

1993

Area

(acres)

(6)

1993

Capacity

(acre-feet)

(7)

Measured

Sediment

Volume

(acre-feet)

(8)

Percent

Measured

Sediment

(9)

Percent

Reservoir

Depth

2312 12,150 12,773 474,056 (13,166) 469,736 4,320 - 100.0

2310 11,829 12,421 4-48,862 (12,682) 443,888 4,974 - 98.2

2305 10,600 11,116 390,020 (11,472) 383,503 6,517 - 93.8

2302 - (10,397) 357,751 (10,746) 350,176 7,575 - 91.1

2300 9,477 9,917 337,437 (10,262) 329,168 8,269 - 89.3

2296.6 - 9,133 305,052 9,439.0 295,677 9,375 - 86.2

2295 8,400 8,840 290,674 (9,133) 280,819 9,855 - 84.8

2290 7,490 7,925 248,761 (8,177) 237,544 11,217 - 80.4

2285 6,500 7,010 211,425 (7,221) 199,050 12,375 - 75.9

2280.2 - (6,131) 179,888 6,303.0 166,592 13,296 - 71.6

2280 5,790 6,094 178,666 (6,272) 165,335 13,331 - 71.4

2275 5,179 5,179 150,482 (5,489) 135,934 14,548 - 67.0

2272 - (4,868) 135,413 5,019.0 120,172 15,241 100.0 64.3

2270 4660 4,660 125,885 (4,750) 110,403 15,482 100.0 62.5

2265 4,120 4,120 103,935 4,076.9 88,337 15,598 100.0 58.0

2260 3,640 3,640 84,535 3,297.6 69,900 14,635 96.0 53.6

2255 3,160 3,160 67,535 2,748.4 54,785 12,750 83.6 49.1

2250.8 - (2,789) 55,043 (2,450) 43,869 11,174 73.3 45.4

2250 2,718 2,718 52,8-40 2,393.0 41,932 10,908 71.6 44.6

2245 2,290 2,290 40,320 2,061.6 30,795 9,525 62.5 40.2

2240 1,900 1,900 29,845 1,720.9 21,339 8,506 55.8 35.7

2235 1,540 1,540 21,245 1,413.4 13,503 7,742 50.8 31.2

2230 1,160 1,160 14,495 1,010.0 7,445 7,050 46.2 26.8

2225 874 874 9,410 655.3 3,282 6,128 40.2 22.3

2220 640 640 5,625 302.2 888 4,737 31.1 17.8

2215 430 430 2,950 33.5 49 2,901 19.0 13.4

2212.1 - (326) 1,854 0 0 1.854 12.2 10.8

2210 250 250 1,250 0 0 1,250 8,2 8.9

2200 0 0 0 0 0 0 0.0 0.0

(1) Elevation of reservoir water surface.

(2) Original reservoir surface area values projected from area curve drawing 276-D-28. Area for reservoir elevation 2312.0 is from area curve drawing 276-602-465.

(3) Original reservoir surface area values projected from area curve drawing 276-D-28. The original surface areas above elevation 2275.0 were adjusted for final dam axis

alignment projected from USGS topography maps. Areas in parentheses computed by ACAP85.

(4) Original reservoir capacity recomputed using ACAP85 from original surface areas from column two.

(5) Reservoir surface area from 1993 hydrographic surveys. Areas in parentheses computed by ACAP85. Areas above elevation 2265.0 were measured from USGS topography

maps. The maximum area measured at elevation 2313.0 (705 meters), was 13,408 acres.

(6) 1993 reservoir capacity computed by ACAP85 using areas from column 4.

(7) Measured sediment volume = column 4 - column 6.

(8) Measured sediment expressed in percentage of total sediment 15,241 acre-feet at spillway crest elevation 2272.0.

(9) Depth of reservoir in percentage of total depth of 112 feet, from maximum reservoir water surface elevation 2312.0 and original river channel elevation 2200.0.

Table 2. * Summary of 1993 survey results.

12
NORTH DAKO

Figure 1. - Shadehill Reservoir location map.

13
Space intentionally left blank due to security concerns 
Space intentionally left blank due to security concerns 


§

276-D-190

1410000 1411000 1412000 1413000 1414000 1415000 14160*0 1417000 1411

725000 I

724000

\ \

I

NORTH FORK GRAND RThR

o

I'

7

I

03000 ,-

-

--

/

\\ _/

l4

I

\

\

l

\

-

771000

4'

---.'

\

1/

720000

,_.

\ __-__\

-

715000

-S

C

7160*0

/

717000

\

716000

\\

\

715000

5'

-5

714-000

713000

B

712000

711000

710000

109000

700000

A

707000

706000 ---------------

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

4

200 1420000 1421000 1422000 1423000 1424000 1425000 1412600

SHADEHILL RESERVOIR

NORTH FORK

4

I I 3

1421000 1430000 1431000 1432000 1433000 1434000 1413200 1436000 1437000 1436000 1439000 1440000

I

I I

724000

723000

722000

731000

720000

719000

'V.

719000

717000

ii -

716000

1000 1000 2000 3000

SCMIOfFEET

715000

714000

713000

,,),

- 712000

NOTES

Roads:

:::: Trail:

711000

II III Grovel:

__________

See sheet /

I

Area features projected from USGS .

L topographic mops.

- - - - - -

Se,vice spil/woy crest elevation 2272.0 feet

+ ALWAYS THIII( SAFElY

LV15W 00073

4VflT ?I

kW roAIMtIV

PIc%-$LcMN MImI SZN W-$0U1H tMKOL4

SI-LADEHILL UNIT

RTH FWK

SHADEIIILL RESERIIOIR TOPOGRAPHY

- -

OI4

36I17W

C4LV 59511M flLi U'I AIW VJ IW

________________________

SIf3=M I Li

2 Figure 6.- ShadehiU Reservofr topographic map (3 of 3)
130 120

2310

2300

2290

2280

2270

U

Li

2260-

z

cD

2250-

>

Li

-j

Li 2240-

2230 -

2220 -

2210-

-nn

AREA 100 ACRES)

110 100 • 90 80 70 60 50 10 30 20 10 0

--

/'CAPACIT Y

//

t/I,

LEGEND

7/ 1993 SURVEY

___________ ______________ _______________ - __________ - _______________ ______________ ______________

--

- I I

tOO 150 200 250 300 350

CAPACITY (1000 ACRE-rEET)

Figure 7. - 1993 area and capacity curves-ShadehiH Reservoir.

400 450 500
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.