Belle Fourche Reservoir 

2006 Sedimentation Survey 

U.S. Department of the Interior 

Bureau of Reclamation 

Technical Service Center 

Denver, Colorado April 2007 
U.S. Department of the Interior 

Bureau of Reclamation 

Technical Service Center 

Water Resources Services Division 

Sedimentation and River Hydraulics Group 

Denver, Colorado April 2007 

Belle Fourche Reservoir 

2006 Sedimentation Survey 

prepared by 

Ronald L. Ferrari 
ACKNOWLEDGMENTS

The Bureau of Reclamation's (Reclamation) Sedimentation and River Hydraulics 

(Sedimentation) Group of the Technical Service Center (TSC) prepared and published 

this report. Ronald Ferrari of the Sedimentation Group along with Todd Potter, Curt 

Anderson, and John Strachan of the Great Plains Region conducted the hydrographic 

survey. Ron Ferrari completed the data processing needed to generate the new 

topographic map and area-capacity tables. Kent Collins of the TSC performed the 

technical peer review of this documentation. 

Mission Statements 

The mission of the Department of the Interior is to protect and 

provide access to our Nation’s natural and cultural heritage and 

honor our trust responsibilities to Indian Tribes and our 

commitments to island communities. 

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. 

Reclamation Report 

This report was produced by the Bureau of Reclamation’s Sedimentation and 

River Hydraulics Group (Mail Code 86-68540), PO Box 25007, Denver, 

Colorado 80225-0007, www.usbr.gov/pmts/sediment/.

Disclaimer 

No warranty is expressed or implied regarding the usefulness or completeness of 

the information contained in this report. References to commercial products do 

not imply endorsement by the Bureau of Reclamation and may not be used for 

advertising or promotional purposes.
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1. REPORT DATE (DD-MM-YYYY) 

April 2007 

2. REPORT TYPE 3. DATES COVERED (From – To) 

5a. CONTRACT NUMBER 

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4. TITLE AND SUBTITLE 

Belle Fourche Reservoir 

2006 Sedimentation Survey 

5c. PROGRAM ELEMENT NUMBER 

5d. PROJECT NUMBER 

5e. TASK NUMBER 

6. AUTHOR(S) 

Ronald L. Ferrari 

5f. WORK UNIT NUMBER 

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Bureau of Reclamation, Technical Service Center, Denver, CO 80225 

8. PERFORMING ORGANIZATION REPORT 

NUMBER 

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Bureau of Reclamation, Denver Federal Center, PO Box 25007 

Denver, CO 80225-0007 11. SPONSOR/MONITOR'S REPORT 

NUMBER(S) 

12. DISTRIBUTION/AVAILABILITY STATEMENT 

13. SUPPLEMENTARY NOTES 

14. ABSTRACT 

Reclamation surveyed Belle Fourche Reservoir in 2006 to develop updated reservoir topography and compute the present 

storage-elevation relationship (area-capacity tables). The underwater survey, conducted near water surface elevation 2,966 

(feet), used sonic depth recording equipment interfaced with real-time kinematic (RTK) global positioning system (GPS) that 

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

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

(USGS quad) maps of the reservoir area. RTK GPS above water data was collected along the reservoir shoreline while it was 

drawn down in fall of 2006. The RTK GPS data was used to develop contours where boat access was not possible and to adjust 

the digitized USGS quad map contours due to extensive shoreline erosion. This study assumed no change, since the 1949 

survey, from elevation 2,975.0 and above. Accurate mapping of the 2,975 contour and above would require aerial data 

collection. 

As of June 2006, at elevation 2,975.0, the surface area was 8,040 acres with a total capacity of 172,873 acre-feet. Since dam 

closure in April 1910, 36,364 acre-feet of change has occurred below elevation 2,975.0, resulting in 17.4 percent loss in 

reservoir volume. A large portion of this loss is due to extensive shoreline erosion that has occurred throughout the reservoir. 

15. SUBJECT TERMS 

reservoir area and capacity/ sedimentation/ reservoir surveys/ global positioning system/ multibeam 

sounders/ contour area/ 

16. SECURITY CLASSIFICATION OF: 19a. NAME OF RESPONSIBLE PERSON 

a. REPORT b. ABSTRACT a. THIS PAGE 

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OF ABSTRACT

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OF PAGES 

19b. TELEPHONE NUMBER (Include area code)

Standard Form 298 (Rev. 8/98) 

Prescribed by ANSI Std. Z39.18 
Table of Contents 

Page 

Introduction.........................................................................................................................1 

Summary and Conclusions .................................................................................................3 

Control Survey Data Information .......................................................................................4 

Reservoir Operations ..........................................................................................................5 

Hydrographic Survey Equipment and Method ...................................................................5 

Reservoir Area and Capacity ..............................................................................................7 

Topography Development............................................................................................7 

Shoreline Erosion .......................................................................................................11 

Development of the 2006 Belle Fourche Reservoir Surface Areas...........................12 

2006 Storage Capacity................................................................................................13 

2006 Reservoir Sediment Analyses..................................................................................14 

References.........................................................................................................................21 

Index of Figures 

Page 

 

Figure 1 - Reclamation reservoirs located in South Dakota. ..............................................1 

Figure 2 - South Canal intake during low reservoir exposing sediment deposition. ..........2 

Figure 3 - Survey vessel with mounted instrumentation on Jackson Lake in Wyoming....6 

Figure 4 - Belle Fourche Reservoir topographic map.........................................................9 

Figure 5 - Extensive eroded shoreline looking towards Belle Fourche Dam....................11 

Figure 6 - Eroded shoreline of Belle Fourche Reservoir, South Dakota. .........................12 

Figure 7 - Belle Fourche Reservoir area and capacity plots. ............................................19 

Index of Tables 

Page 

Table 1 - Reservoir sediment data summary (page 1 of 2). ..............................................15

Table 1 - Reservoir sediment data summary (page 2 of 2). ..............................................16

Table 2 - Summary of 2006 survey results. ......................................................................17

Belle Fourche Reservoir 

2006 Sedimentation Survey 

Introduction 

Belle Fourche Dam and Reservoir are principal features of the Belle Fourche Unit 

located in western South Dakota. Additional project features are Belle Fourche 

diversion dam, inlet canal, and system of canals and laterals that irrigate acres 

near Newell, Vale, and Nisland, South Dakota. The reservoir stores water from 

Owl Creek and diverted flows from the Belle Fourche River. The project was a 

single purpose development for irrigation, but provides flood control, fish and 

wildlife conservation, and recreation benefits. Belle Fourche Dam and Reservoir 

in Butte County near Owl Creek is an offstream reservoir, located on the northern 

edge of the Black Hills, nine miles east of Belle Fourche, South Dakota (figure 1). 

Figure 1 - Reclamation reservoirs located in South Dakota. 

Belle Fourche Dam is an earthfill structure that was completed in June of 1911, 

with first irrigation water delivery in 1908. The dam’s dimensions are as follows: 

 Hydraulic height1

 97 feet Structural height 122 feet 

 Crest length 6,262 feet Crest elevation 2,990.0 feet2

 

1

The definition of such terms as “hydraulic height,” “structural height,” etc. may be found in manuals such as 

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

and Reservoirs, or ASCE’s Nomenclature for Hydraulics.

2

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

Reclamation that is near the National Geodetic Vertical Datum of 1929 (NGVD29) and around 1.6 feet lower 

than the North American Vertical Datum of 1988 (NAVD88).

1
The spillway, reconstructed in 1979 to replace the original spillway on the left 

abutment, is located in a saddle on the reservoir rim around 1.5 miles south of the 

right abutment. The spillway, crest elevation 2,977.25, is a 70-foot-wide grasslined trapezoidal channel with an uncontrolled reinforced-concrete ogee cross 

section and three 66-inch-diameter culverts for passing spillway discharges 

beneath the South Canal. The discharge capacity is 4,500 cubic feet per second 

(cfs) at maximum reservoir elevation 2,984.4. 

The outlet works consists of two gated conduits for releasing water to two 

irrigation canals. The North Canal outlet works is located on the left abutment 

with a release capacity of 600 cfs and the South Canal outlet works is located on 

the right abutment with a release capacity of 410 cfs. A 1992 survey conducted 

during low reservoir elevations measured the North Canal inlet at elevation 

2,935.5 and the South Canal inlet at elevation 2,934.7, figure 2. 

Figure 2 - South Canal intake during low reservoir conditions, exposing sediment deposition. 

The drainage area above Belle Fourche Dam is approximately 170 square miles 

on Owl Creek and 4,310 square miles above the Belle Fourche Diversion Dam. 

The reservoir is considered two sections with the south section, Inlet Canal Arm, 

fed from diverted Belle Fourche River flows and the north section being the Owl 

Creek Arm. The total length of the reservoir is around 11 miles from the 

southwest inlet of the Belle Fourche River diversions to the upper end of Owl 

2
Creek in the northwest end of the reservoir at elevation 2,770 with an average 

reservoir width of 1.1 miles. 

Summary and Conclusions 

This Reclamation report presents the 2006 results of the survey of Belle Fourche 

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

$ develop reservoir topography 

$ compute area-capacity relationships 

$ estimate storage depletion, by sediment deposition, since dam closure 

The on-line positioning user service (OPUS) and real-time kinematic (RTK) 

global positioning system (GPS) control survey were used to establish a 

horizontal and vertical control network near the reservoir for the hydrographic 

survey. OPUS is operated by the National Geodetic Survey (NGS) and allows 

users to submit GPS data files where it is processed with known point data to 

determine positions of points relative to the national control network. Initially, 

the GPS base was set over the NGS brass cap “Lake” that is located near the left 

abutment of the dam. The NGS point “Lake” had a second order horizontal 

position with an estimated elevation. During the bathymetric survey a temporary 

point for the base station was established nearer the boat ramp area. This point 

was established by RTK GPS and verified by OPUS processing. The horizontal 

control for this study was in feet, South Dakota state plane coordinates, in the 

North American Datum of 1983 (NAD83). The vertical control was in feet, tied 

to the National American Vertical Datum of 1988 (NAVD88) and the 

Reclamation project vertical datum. All elevations in this report are referenced to 

Reclamation’s project or construction vertical datum that is near the National 

Geodetic Vertical Datum of 1929 (NGVD29) and around 1.6 feet lower than 

NAVD88. 

The June 2006 underwater survey was conducted near reservoir elevation 2,966.0, 

measured by the Reclamation gage at the dam. The bathymetric survey used 

sonic depth recording equipment interfaced with a RTK GPS for determining 

sounding locations within the reservoir. The system continuously recorded depth 

and horizontal coordinates of the survey boat as it navigated along grid lines 

covering Belle Fourche Reservoir. The positioning system also provided 

information to allow the boat operator to maintain a course along these grid lines. 

The water surface elevations recorded by Reclamation’s reservoir gage during the 

time of collection were used to convert the sonic depth measurements to reservoir 

bottom elevations. The initial above-water topography was determined by 

digitizing existing contour lines from the USGS quads of the reservoir area. 

During the bathymetric survey, the boat location at times plotted outside of these 

contours, indicating that extensive shoreline erosion has occurred throughout this 

3
reservoir. The previous survey in 1949 documented extensive shoreline erosion 

around the reservoir (Bureau of Reclamation, 1950). In the fall of 2006, the 

Dakotas Area Office conducted a RTK GPS land survey around the shoreline of 

the reservoir. The 1949 study estimated the shore line as being 44.45 miles at 

elevation 2,975.0. The purpose of the above water survey was to document the 

extensive shoreline erosion by collecting data along the toe and top bank of the 

reservoir. This data was used to adjust the digitized USGS quad contours to 

account for the measured changes. 

The Belle Fourche Reservoir topographic map is a combination of the adjusted 

digitized contours and the 2006 above and underwater survey data. A computer 

graphics program generated the 2006 reservoir surface areas at predetermined 

contour intervals from the collected reservoir area. The 2006 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 (Bureau of Reclamation, 1985). 

Tables 1 and 2 contain summaries of Belle Fourche Reservoir and watershed 

characteristics for the 2006 survey. The 2006 survey determined that the 

reservoir has a total storage capacity of 259,012 acre-feet and a surface area of 

9,871 acres at surcharge pool elevation 2,984.4. Since closure in May 1910, the 

reservoir has an estimated volume change of 36,364 acre-feet below top of 

conservation reservoir elevation 2,975.0. This volume represents a 17.4 percent 

loss in total original capacity at this elevation. 

Control Survey Data Information 

Prior to the bathymetric survey, a control network was set by the Dakota Area 

Office that was used throughout the survey. Initially, the RTK GPS base station 

was set over marker “Lake” that is located along the left abutment of dam. The 

coordinates for this point were determined by processing collected raw data 

through the NGS service OPUS. The bathymetric survey used the “Lake” base 

station the first few days of collection, then used it to establish a temporary point 

near the boat ramp used by the survey vessel. The temporary point was submitted 

to the OPUS web site for computation and verification of the RTK GPS 

measurements. The horizontal control was in South Dakota north zone state plane 

coordinates in NAD83 and the vertical control was tied to NAVD88 and the 

Reclamation project vertical datum. All elevations in this report are referenced to 

Reclamation’s project or construction vertical datum that is near NGVD29 and 

around 1.6 feet lower than NAVD88. The following “Lake” coordinates (in feet) 

were used for this survey: 

“LAKE”

4
North 355,815.466 

East 1,013,674.652 

Elevation 3,042.392 

Reservoir Operations 

Belle Fourche Reservoir is part of the Belle Fourche Project that provides storage 

for irrigation, flood control, fish and wildlife conservation, and recreation. The 

June 2006 capacity table lists 259,012 acre-feet of total storage below the 

maximum water surface elevation 2,984.4, table 1. The 2006 survey measured a 

minimum lake bottom elevation of 2,914.0. The following values are from the 

June 2006 capacity table: 

 $ 86,139 acre-feet of surcharge between elevation 2,975.0 and 2,984.4. 

 $ 169,790 acre-foot of conservation between elevation 2,927.0 and 2,975.0. 

 $ 3,083 acre-foot of dead storage below 2,927.0. 

Belle Fourche Reservoir computed annual inflow and reservoir stage records are 

listed by water year on table 1 for available period 1952 through 2006. The 

inflow values were computed by the Great Plains Regional Office and show 

annual fluctuation with a computed average inflow of 141,109 acre-feet per year. 

The maximum reservoir elevation was 2,975.6, recorded during water year 1996, 

and minimum recorded elevation was 2,927.0 during water year 1961. 

Hydrographic Survey Equipment and 

Method 

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

aluminum vessel equipped with twin in-board motors, figure 3. The hydrographic 

system included a GPS receiver with a built-in radio, a depth sounder, a 

helmsman display for navigation, a computer, and hydrographic system software 

for collecting the underwater data. An on-board generator supplied power to all 

the equipment. The shore equipment included a second GPS receiver with an 

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

over a known datum point and a 12-volt battery provided the power for the shore 

unit. 

5
Figure 3 - Survey vessel with mounted instrumentation on Jackson Lake in Wyoming. 

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

benefit being precise heights measured in real time to monitor water surface 

elevation changes. The basic output from a RTK receiver are precise 3-D 

coordinates in latitude, longitude, and height with accuracies on the order of 2 

centimeters horizontally and 3 centimeters vertically. The output is on the GPS 

datum of WGS-84 that the hydrographic collection software converted into South 

Dakota’s state plane coordinates, north zone in NAD83. The RTK GPS system 

employs two receivers that track the same satellites simultaneously just like with 

differential GPS. 

Belle Fourche Reservoir bathymetric survey was conducted in June of 2006 

between water surface elevation 2,966.0 and 2,966.3 (Reclamation project 

datum). The bathymetric survey was conducted using sonic depth recording 

equipment, interfaced with a RTK GPS, 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 transects (grid lines) 

were run somewhat perpendicular to the upstream-downstream inflow alignment 

of the reservoir at around 200-foot spacing. Data was collected along the shore 

by the survey vessel for the majority of the reservoir. The survey vessel's 

guidance system gave directions to the boat operator to assist in maintaining the 

course along these predetermined lines. During each run, the depth and position 

data were recorded on the notebook computer hard drive for subsequent 

processing. 

The 2006 underwater data was collected by a depth sounder calibrated by 

lowering an instrument that measured the sound velocity of the reservoir water 

column. The individual depth soundings were adjusted by the speed of sound of 

the measurements which can vary with density, salinity, temperature, turbidity, 

and other conditions. The soundings were further verified by lowering a weighted 

cable below the boat with beads marking known depths. The collected data were 

6
digitally transmitted to the computer collection system through a RS-232 port. 

The depth sounder also produced an analog hard-copy chart of the measured 

depths. These graphed analog charts were analyzed during post-processing, and 

when the analog charted depths indicated a difference from the computer recorded 

bottom depths, the computer data files were modified. The water surface 

elevations at the dam, recorded by a Reclamation gage, were used to convert the 

sonic depth measurements to true lake-bottom elevations. Additional information 

on collection and analysis procedures is listed in the reference, (Corps of 

Engineers, January 2002) and (Ferrari, R.L., 2006). 

In the fall of 2006, after the reservoir had dropped significantly in elevation, a 

RTK GPS land survey was conducted by Dakota Area Office personnel. This 

survey was conducted around the shoreline of the reservoir on foot and with the 

GPS units mounted on all terrain vehicles. The data was tied to the same control 

network as the bathymetric collection with the elevations tied to NAVD88. 

During post processing, the elevations were shifted to match the Reclamation 

vertical datum. 

Reservoir Area and Capacity 

Topography Development 

The topography of Belle Fourche Reservoir was developed from the 2006 above 

and below water survey data and the digitized contours from the USGS quad 

maps. The USGS quad contours at elevations 2,970 and 2,976 were developed 

from aerial photography dated 1940’s and 1960’s respectively. The 2006 survey 

data was used to make major adjustments to the digitized 2,970 contour due to the 

sediment delta that formed on upper reservoir on Owl Creek and the Inlet Canal, 

with the biggest adjustments along the reservoir shoreline due to the extensive 

bank erosion that has occurred throughout this reservoir. The best means to truly 

develop these contours and the rest of the above water reservoir area would be by 

a detailed aerial survey with the reservoir drawn down, but limited budget usually 

prevents such collection. 

The original digitized 2,970 contour was used during the underwater survey for 

setting up the collection gridlines guiding the survey vessel to assure complete 

reservoir coverage. During the 2006 underwater collection, there were times the 

vessel was outside this contour indicating it was on high ground when in actuality 

the bank had eroded extensively increasing the surface area of the reservoir in 

those areas. The 2006 RTK GPS land survey provided adequate detail to allow 

adjustment of the 2,970 contour, resulting in a surface area of 7,153.9 acres. 

7
The adjusted contour, elevation 2,970, was used to perform a hardclip around the 

2006 data of Belle Fourche Reservoir. The hardclip was used during the 

triangular irregular network (TIN) development to prevent interpolation outside 

the enclosed polygon. The 2,970 contour was selected for the hardclip boundary 

since it was the closest data available to represent the water surface during the 

2006 survey. Also, there was adequate RTK GPS ground collection data at 

elevation 2,970.0 to allow adjustments to be made to the USGS quad contour with 

confidence and accuracy. Using ARCEDIT, the 2006 above and below water data 

along with the digitized contours were plotted. The plot showed that the 

underwater data did not lie completely within these digitized USGS quad map 

contours due to reservoir bank erosion. The 2,970 contour was modified to 

include the entire underwater data set within the enclosed polygon and the RTK 

GPS ground elevation data was used to further determine the present location of 

the 2,970 contour. Using select and move commands within ARCEDIT, the 

vertices of the initial clip were shifted to develop the final clip that was assigned 

an elevation of 2,970.0. 

Contours for the reservoir below elevation 2,970.0 were computed from the 2006 

data sets using the triangular irregular network (TIN) surface-modeling package 

within ARC/INFO. A TIN is a set of adjacent non-overlapping triangles 

computed from irregularly spaced points with x,y coordinates and z values. TIN 

was designed to deal with continuous data such as elevations. The TIN software 

uses a method known as Delaunay's criteria for triangulation where triangles are 

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

circle drawn through the three nodes of a triangle will contain no other point, 

meaning that sample points are connected to their nearest neighbors to form 

triangles using all collected data. This method preserves all collected survey 

points. Elevation contours are then interpolated along the triangle elements. The 

TIN method is discussed in detail in the ARC/INFO V7.0.2 Users 

Documentation, (ESRI, 1992). 

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

used to interpolate contours from the Belle Fourche Reservoir TIN. The areas of 

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

survey data for elevations 2,914.0 through 2,970.0. Since no complete reservoir 

aerial data was collected, this study assumed no change in reservoir surface area, 

since the 1949 survey, for elevation 2,975.0 and above. The reservoir contour 

topography at 2-foot intervals is presented in figure 4. 

8
9

Shoreline Erosion 

The 2006 underwater survey witnessed and measured the extensive erosion along 

the shoreline of Belle Fourche Reservoir. During collection, the GPS boat 

positions were found at times to be outside the digitized USGS quad contour 

locations, indicating the boat was on solid ground. The USGS quad contours 

were developed from aerial photography flown in the 1940’s and 1960’s and at 

times, the position of the boat was tens-of-feet outside the 2,970 contour 

boundaries. Even with the extensive shore erosion that has occurred since dam 

closure in 1910, the survey vessel was able to maneuver close to some vertical 

banks where previous shore material had collapsed into the reservoir. It appears 

that over time the collapsed material washed further into the reservoir through 

wave action, similar to ocean waves smoothing the beaches. This is possible 

because the material dissipated in the water and consists of little to no gravel or 

large cobble. The extensive shoreline erosion was documented by the 1949 

survey of Belle Fourche Reservoir. At reservoir elevation 2,975.0, the 1949 study 

measured 44.45 miles of shoreline and estimated that of the 16,880 acre-feet of 

capacity loss due to sedimentation, 4,320 acre-feet was due to shoreline eroded 

material settling within the reservoir (Bureau of Reclamation, 1950). Following 

are pictures showing the shoreline erosion along Belle Fourche taken in March of 

2007, figures 5 and 6. 

Figure 5 – Extensive eroded shoreline looking towards Belle Fourche Dam. 

11
Figure 6 - Eroded shoreline of Belle Fourche Reservoir, South Dakota.

The above photographs show the extent of the shoreline erosion that has occurred 

throughout Belle Fourche Reservoir. If the erosion were just below the normal 

reservoir high water elevation of 2,975.0, the total volume of the reservoir would 

not be greatly affected from elevation 2,975.0 and below. In that case, the gain in 

surface area and resulting volume in the upper reservoir elevation zone would be 

offset by the loss of surface area and volume in the lower elevations of the 

reservoir due to the depositing material from the banks. For Belle Fourche 

Reservoir, it appears that a large amount of the bank erosion has occurred above 

the normal or conservation reservoir elevation 2,975.0. This indicates that a 

portion of the loss of the original total reservoir volume is due to material from 

the extensive reservoir shoreline erosion along with inflowing river sediments. 

The only means to accurately measure the extent of the shoreline erosion would 

be by an extensive above water survey. 

Development of the 2006 Belle Fourche Reservoir 

Surface Areas 

The 2006 surface areas for Belle Fourche Reservoir were computed at 1-foot 

increments, from elevation 2,914.0 through 2,970.0, directly from the TIN that 

covered the Belle Fourche Reservoir within the hard clip area only. This TIN was 

developed from the 2006 collected data within the hardclip polygon that was 

12
developed from the adjusted digitized contour 2,970 as described previously. 

These calculations were performed using the ARCGIS surface area and volume 

command that computes areas at user-specified elevations directly from the TIN 

and includes all regions of equal elevation. For the purpose of this study, the 

measured 2006 survey areas at 2- and 5-foot increments from elevation 2,914.0 

through 2,366.0 were used to compute the new area and capacity tables. For 

elevation 2,970.0, the surface area of the ARCGIS developed contour 2,970 

minus the reservoir islands was used. There were insufficient 2006 surveyed data 

points, for accurate computer development of surface areas for elevations above 

2,970.0. Straight line interpolation was used to compute the surface areas 

between elevations 2,966.0 and 2,970.0. This study assumed no change in surface 

area, since the 1949 survey, at elevation 2,975.0. During the 2006 study analysis 

a 1990 area and capacity table was located that extended the previous developed 

tables above elevation 2,975.0. The table appeared to have been developed as 

part of flood study, but no detail was provided on how the surface areas above 

elevation 2,975.0 were computed. The results appeared to be reasonable, and for 

the purpose of preserving this information it was included in 2006 area and 

capacity development. 

2006 Storage Capacity 

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

developed using the area-capacity computer program ACAP (Bureau of 

Reclamation, 1985). The ACAP program can compute the area and capacity at 

elevation increments from 0.01 to 1.0 foot by linear interpolation between the 

given contour surface areas. The program begins by testing the initial capacity 

equation over successive intervals to ensure that the equation fits within an 

allowable error limit. The error limit was set at 0.000001 for Belle Fourche 

Reservoir. The capacity equation is then used over the full range of intervals 

fitting within the 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. Differentiating the capacity equations, which are of second order 

polynomial form, final area equations are derived: 

y = a1 + a2x + a3x

2 

 where: y = capacity 

x = elevation above a reference base 

a1 = intercept 

a2 and a3 = coefficients 

Results of the Belle Fourche Reservoir area and capacity computations are listed 

in a separate set of 2006 area and capacity tables and have been published for the 

0.01, 0.1 and 1-foot elevation increments (Bureau of Reclamation, 2006). A 

13
description of the computations and coefficients output from the ACAP program 

is included with these tables. The original, 1949, and 2006 area-capacity 

relationships are listed on table 2 and the curves are plotted on figure 7. As of 

June 2006, at conservation use elevation 2,975.0, the surface area was 8,040 acres 

with a total capacity of 172,873 acre-feet. 

2006 Reservoir Sediment Analyses 

Results of the 2006 Belle Fourche Reservoir area and capacity computations are 

listed in table 1 and columns 8 and 9 of table 2. Columns 2 and 3 of table 2 list 

the original area and capacity values. The results from the 1949 survey are listed 

on column 4 and 5. Column 10 lists the capacity differences between the original 

and 2006 survey results due to sediment inflow and bank erosion. Figure 7 is a 

plot of the Belle Fourche Reservoir surface area and capacity values for all 

surveys and illustrates the differences. The comparisons show that the total 

reservoir capacity in 2006 is 36,364 acre-feet less than the original volume at 

conservation reservoir elevation 2,975.0. It must be noted that the 2006 area and 

capacity tables were generated assuming no surface area change, since the 1949 

survey at elevation 2,975.0. This is probably not the case, but it is assumed any 

loss due to sediment deposition above this elevation would not be significant and 

the shoreline erosion is not as great as was documented by the 1949 survey since 

the reservoir has not operated much above elevation 2,975.0 since that time. The 

only means to measure this would be by an extensive above water survey using 

aerial collection techniques. The 2006 RTK GPS land survey data was plotted 

with the 2,970 and 2,976 USGS quad contours. There were sufficient points to 

adjust the 2,970 contour with confidence, but not enough data to adjust the 2,976 

quad contours. It would require an extensive amount of topography data to 

accurately adjust the 2,976 USGS contour. Aerial collection would likely be the 

most efficient method to collect sufficient topography data above elevation 2,970. 

The estimated 100 years of sediment accumulation for Belle Fourche Reservoir 

was 22.5 percent or around 47,000 acre-feet at conservation pool elevation 

2,975.0. This computes to an annual loss of 470 acre-feet. Table 1 shows the 

1949 survey measured an average annual loss of 418.0 acre-feet. The 2006 

survey measured a slightly less average annual loss of 350.0 acre-feet for the 

operation period of 1949 through 2006. Since closure the average annual loss was 

computed to be 378.0 acre-feet by the 2006 study analysis. The reason for this 

slight drop in average annual loss could be reduction in the shoreline erosion rate 

since it is assumed that the majority of the shoreline eroded during the initial 

filling and high reservoir stages. Differences in survey methods between the 

original, 1949 and 2006 surveys also is a contributing factor. As seen in the 

figure 2 photo at the South Canal intake, sediment is an issue throughout the 

reservoir and not just along the shoreline or the upper deltas of Owl Creek and the 

Inlet Canal. 

14
1. 2. Owl Creek 1 3. STATE South Dakota

4. 5. Belle Fourche 6. COUNTY Butte

7. ° 44 ' 12 " ° 40 ' 27 " 8. 2 9. SPILLWAY CREST EL 3

10. 11. 12. GROSS STORAGE 15

CAPACITY, AC-FT

a. 4

b.

c.

d. 16

e.

f.

g.

17. LENGTH OF RESERVOIR 5

18. TOTAL DRAINAGE AREA 6 22. 7

19. NET SEDIMENT CONTRIBUTING AREA 6 23. MEAN ANNUAL RUNOFF 8

20. LENGTH MILES AVG. WIDTH MILES 24. MEAN ANNUAL INFLOW 8

21. 25. °F °F7

26. DATE OF 27. 28. 29. 30. 31. C/

9

10

11

26. DATE OF 35. 36

12

12

26. DATE OF 37. 38.

26. DATE OF 39.AVG. DRY WT. 40. SED. DEP. TONS/MI.2

-YR 41. STORAGE LOSS, PCT. 42 SEDIMENT 

(#/FT3

) b. TOTAL b. TOTAL TO INFLOW, PPM

TO DATE DATE a. PER. b. TOT.

43.

SURFACE

2-ft

5 - ft 8,010

45

AREA, AC. ACRE - FEET

11,394

197,843

BEGAN

4/1910

to 110

1.1

INCHES

INCHES

ACRE-FEET

209,237

2,927.0 11,394

BEGAN

DATE NORMAL

4/1910

OPERATIONS

DATA SHEET NO.

DATE

STORAGE

2990.0

14.

2977.25

ACRE-FEET

RESERVOIR SEDIMENT

DATA SUMMARY

Belle Fourche Reservoir NAME OF RESERVOIR 1

DATE

OF

SURVEY

6/06

SURVEY

26. 44.

DATE

OF

SURVEY

A

T

Y

SURVEY

26.

CAPACITY

WATER INFLOW TO DATE, AF

SURVEY

PERIOD CAPACITY LOSS, ACRE-FEET

TOTAL

SURVEY

V

I MAX. ELEVATION MIN. ELEVATION ANNUAL TEMP, MEAN 45 °F RANGE -38

N

S

a. TOTAL b.

R

AVG. ANN. c.

10/1949 39.6 39.6

D

U

ANNUAL

PRECIPITATION

114,109 6,350,305

TOTAL SEDIMENT DEPOSITS TO DATE, AF

6,350,305

a. AVG. ANNUAL

36,364

 /MI. a. 2

-YR.

1.83

172,873

RATIO AF/AF

32.

209,237

192,685

33.

87,050

1,077

MILES

296,287

2,975.0

a. MEAN ANN.

SQUARE MILES

8,010

Contour (D)

 

B

A

ORIGINAL 13. ORIGINAL 

S

E

POWER

S

R

V

O

I

R

MAX. ANN.

 

NO. OF

RANGES OR 

INTERVALS

M

TWP. 4 E

34.

b.

PERIOD PERIOD WATER INFLOW, ACRE-FEET

c.

NEAREST P.O.

44 TOP OF DAM ELEVATION

OWNER

SEC

LAT

18

D

A 9N RANGE

R

E

6/06 114,109 189,100

10/1949

MILES

15.5

114,109

11

AVG. WIDTH OF RESERVOIR

6/2006 19,812 350.0 13

13

 

1.69

1.51

378.0

418.0

10/1949

6/2006

 

PERCENT OF TOTAL SEDIMENT LOCATED WITHIN REACH DESIGNATION

10 20 30 40 60 70

50- 60-

DEPTH DESIGNATION RANGE BY RESERVOIR ELEVATION

2,970-

100-

2,950-

0.18

2,960-

17.4

30-

2,910-

17.6 25.0 19.2 10.5

2,950 2,960

2,940-

90-

2,920

3.9 10.0

2,910

REACH DESIGNATION PERCENT OF TOTAL ORIGINAL LENGTH OF RESERVOIR

13.8

2,930 2,970

111

0- 110-

90 115

70-

80

10- 20- 80-

2,975

0.0

2,920- 2,930-

2,940

103

Bureau of Reclamation

LONG

SURCHARGE 9,871

STORAGE

ALLOCATION

ELEVATION

SURFACE AREA, AC-FT

STREAM

INACTIVE

DEAD

TOP OF POOL

FLOOD CONTROL

JOINT USE

CONSERVATION

2,984.4

11

170

YRS YRS

6/2006

4/1910

SQUARE MILES MEAN ANNUAL PRECIPITATION

8,040 10

TYPE OF 

SURVEY

Contour (D) 8,040

Range (D)

170+

PER. PER.

PERCENT OF TOTAL SEDIMENT LOCATED WITHIN DEPTH DESIGNATION

120-

125

115-

105 120

2,897-

100

105-

E 56.6 96.2

A 

10/1949 16,552 13

7.9

TOTAL a. MEAN ANN. b. TOTAL

b. AVG. ANN. c. /MI.2

-YR.

13

PERIOD

13

0.20

418.0

a.

16,552 13

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

15
16

1

2

3

4

5

6

7

8

9

10

11

12

13

102,366 2,966.0 108,377

2,972.0 7,508

2,965.0 6,102

2,970.0

111,844

1982 2,974.8 2,951.2 155,500 1983 2,975.0 2,956.9 95,100

2,974.7 2,959.7 135,476

2002 2,972.8 2,951.0 99,709 2003 2,969.8 2,951.4

2000

149,500

2,975.0 2,967.2 105,881

2,974.8 2,964.2 104,622

104,500

2,963.1 2,948.3

1998 2,974.8 2,965.8 123,728

2,926.0 471

1976 2,969.9 2,935.3 129,330 1977 2,966.6 2,942.2

2,925.0 426 2,142

2,952.0 3,237

2,924.0 382 1,738

2,754 35,531

1,116

2,948.0 2,380 30,398 2,950.0

8,162 2,935.0 1,035 9,161 2,936.0

2,930.0 684 2,932.0 824

1966 2,971.2 2,952.3 55,480 1967 2,973.6 2,954.2 161,440

108,475

1964 2,975.0 2,960.9 104,422 1965 2,975.0 2,963.1 122,872

2,972.5 2,954.1 135,638

1962 2,972.5 2,932.2 183,318 1963 2,975.0 2,963.4

2,972.2 2,952.5 131,400 1971

1968 2,971.1 2,956.0 111,910 1969 2,972.5 2,951.7 119,050

1970

45. RANGE IN RESERVOIR OPERATION

4,647

127

255,075

2004

2,984.4 9,871 259,012

2,975.0

2,955.0 3,982 52,355

235,624

2,985.0 9,919 264,946

2,982.0 9,629

CAPACITY

2,980.0 9,435

2,960.0

ELEVATION AREA CAPACITY

85,442

2,976.0 8,319 181,053

2,962.0 5,388

149,551

1,054

2,956.0 4,216 56,455

6,374

10,236

41,522

2,590

2,920.0 213 540 2,922.0 302

172,873

216,561

8,040

5,045 75,010

7,154 134,888

5,920

4,866

2,914.0 0 0

2006 CAPACITY

ELEVATION AREA

2006 2,966.4 2,937.8 109,405

13 46. ELEVATION - AREA - CAPACITY - DATA FOR

2,965.9 2,943.0 85,704 2,963.4 2,937.2 76,917

1997

2005

1999

2,975.0 2,959.6 73,169 2001

1996 2,975.6 2,963.9 124,236

1994 2,975.1 2,958.0 84,372 1995 2,975.3 2,958.4 143,847

90,601

1992 2,959.4 2,934.7 63,646 1993 2,970.7 2,936.5 150,854

101,564 1991 2,964.7 2,941.0

1989 2,966.8 2,936.0 106,555

182,800

1988 2,973.9 2,942.0 75,773

1987 2,975.2 2,963.5 133,200

119,700

1984 2,975.5 2,956.9 152,500 1985 2,973.8 2,938.2

1980 2,943.8 93,300 1981

106,415 1975 2,973.3 2,951.8 145,355

1978 2,952.7 189,100 1979 2,974.9 2,952.4 115,100

1974 2,949.1

2,927.0 45,687

1972 2,960.9 151,282 1973 2,972.4 2,958.5 104,900

2,929.3 91,604 1961 2,950.3

1957 2,963.0 112,540

1958 2,934.3 100,140 1959 2,958.0 2,927.8 86,614

1956 91,250 2,932.8

2,965.4

1953 2,943.0 153,510

1954 2,970.2 2,946.3 84,720 1955 2,947.9 133,770

120,980 2,977.1

3,621

1952 2,941.3

2,929.3

1986 2,973.6 2,952.5

1990

2,965.7

2,969.5

48,496

65,318

164,922

198,249

121,107

96,548

 

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

48. Bureau of Reclamation

All elevations are in feet based on original project datum that is near NGVD29.

Spillway crest elevation 2,977.25. 70-foot-wide grass-lined trapezoidal channel with uncontrolled reinforced-concrete ogee crest section and 

Elevations from Reservoir Capacity Allocation table. Original surface areas and capacity values recomputed using ACAP program.

Bureau of Reclamation's Project Data Book, 1981.

 1949 table recomputed to elevation 2990 using surface area information from 1990 table and ACAP program.

Significant sediment computations with large portion due to diversions and extensive shoreline erosion. 

Mean annual runoff of 114,109 acre-feet from available records, water years 1952 through 2006. Computations Great Plains Region. 

12

2,918.0

2,954.0

2,958.0

2,974.0

2,984.0

YEAR MAX. ELEV.

49. Bureau of Reclamation March 2007

All 2006 capacities computed by Reclamation's ACAP computer program. 2-foot surface area data from elevation 2,975 below.

 Assumed no change since 1990 developed table from elevation 2980 and above.

AGENCY MAKING SURVEY

Mean annual runoff 114,109 acre-feet from available records, water years 1952-2006. Significant inflows from Belle Fourche River diversions. 

AGENCY SUPPLYING DATA DATE

47. REMARKS AND REFERENCES

Length at elevation 2,975. Consist of two length. One from south diversion inlet and one from Owl Creek to dam.

Total drainage area 170 mi2

 from Owl Creek. Diversions from Belle Fourche River with drainage 4,310 mi2. Values from SOP.

Reservoir is located on Owl Creek. Considered offstream structure. Significant inflows from Belle Fourche River diversions.

Surface area and capacity at elevation 2,975.0, conservation elevation. 1903-04 surveys, 5-foot contours developed. Original table recomputed

Surface area and capacity at elevation 2,975.0. 1949 range line method showed extensive reservoir bank erosion throughout the reservoir. 

 to elevation 2990 using surface area information from a 1990 table and ACAP program. Source for surface areas unknown. 

8,877

9,822

2,978.0

2,944.0

2,968.0 6,628

2,964.0 5,718

2,934.0

2,928.0

2,938.0

SURVEY

3,738

561

964

2,916.0 37 37

2,963.5

2,957.8

2,972.6

ELEVATION AREA CAPACITY

2,972.6

2,975.2

2,965.4 2,939.4

2,964.2

1960

1,288 12,641

2006

200

2,940.0 1,478 15,407 2,942.0 1,644 18,529

1,848 22,021 1,956 25,940

 three 66-inch-diameter culverts (450 cfs capacity) for passing spillway discharges beneath South Canal.

23,923 2,946.0

7,863

2,945.0 2,078

Table 1 - Reservoir sediment data summary (page 2 of 2).
1 2 3 4 5 6 7 8 9 10 11 1

Elevation 1903 1903 1949 1949 Sediment 1949 2006 2006 Sediment Percent Sed

 Surface Capacity Surface Capacity Volume Percent Surface Capacity Volume Computed Vo Area Area 1903-1949 Computed Area 1903-2006 Sediment 1949

Feet Acres Ac-Ft Acres Ac-Ft Ac-Ft Sediment Acres Ac-Ft Ac-Ft Sediment Ac

2,975 8,010 209,237 8,040 192,685 16,552 100.0 8,040.0 172,873 36,364 100.0 12,970 7,181 171,260 7,260 154,435 16,825 101.6 7,153.9 134,888 36,372 100.0 12,965 6,395 137,320 6,244 120,675 16,645 100.6 5,919.5 102,366 34,954 96.1 12,960 5,513 107,550 5,279 91,868 15,682 94.7 5,045.0 75,010 32,540 89.5 12,955 4,648 82,147 4,366 67,755 14,392 87.0 3,982.2 52,355 29,792 81.9 12,950 3,767 61,110 3,342 48,485 12,625 76.3 2,753.6 35,531 25,579 70.3 12,945 2,886 44,477 2,360 34,230 10,247 61.9 1,956.1 23,923 20,554 56.5 12,940 2,157 31,870 1,851 23,703 8,167 49.3 1,478.0 15,407 16,463 45.3 2,935 1,656 22,337 1,373 15,643 6,694 40.4 1,034.7 9,161 13,176 36.2 2,930 1,297 14,955 974 9,775 5,180 31.3 684.1 4,866 10,089 27.7 2,925 930 9,387 664 5,680 3,707 22.4 425.9 2,142 7,245 19.9 2,920 591 5,585 458 2,875 2,710 16.4 212.6 540 5,045 13.9 2,915 390 3,132 236 1,140 1,992 12.0 18.0 9 3,123 8.6 2,910 302 1,402 110 275 1,127 6.8 0.0 0 1,402 3.9 2,905 127 330 0 0 330 2.0 0.0 0 330 0.9 

2,900 3 5 0 0 5 0.0 0.0 0 5 0.0 2,897 0 0 0 0 0 0.0 0.0 0 0 0.0 

1 Elevation of reservoir water surface. All elevations tied to project datum.2 1903 or original reservoir surface areas, acres. Surface areas from table 9 of 1949 survey report.3 1903 or original reservoir capacity, acre-feet. Capacity recomputed using original surface areas and ACAP 4 1949 reservoir surface areas in acres. Surface areas from table 9 of 1949 survey report.5 1949 reservoir capacity, acre-feet. Capacity recomputed using 1949 surface areas and ACAP program.6 1949 computed sediment volume, column (3) - column (5).7 1949 measured sediment in percentage of total sediment, 16,552 acre-feet, by elevation.8 2006 measured reservoir surface area. Study assumed no change at elevation 2,975.9 2006 reservoir capacity computed using ACAP program.

10 2006 measured sediment volume = column (3) - column (9).11 2006 measured sediment in percentage of total sediment, 36,364 acre-feet, by elevation.12 Measured sediment volume from 1948 to 2006, column (5) - column (9).13 Measured sediment in percentage by elevation from 1948 to 2006. Total sediment volume of 19,812 acre-feet14 Depth of reservoir expressed in percentage of total depth (78.0), from maximum water surface.

Table 2 - Summary of 2006 survey results. 

17
18
19

Area-Capacity Curves for Bell Fourche Reservoir

2,8952,9052,9152,9252,9352,9452,9552,9652,975

0 21000 42000 63000 84000 105000 126000 147000 168000 1

Capacity (acre-feet)

Elevation (feet)

8,500 7,650 6,800 5,950 5,100 4,250 3,400 2,550 1,700 

Area (acres)

200619491903

Capacity

Area

Figure 7 - Belle Fourche Reservoir area and capacity plots. 
20
References 

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

Headquarters, New York. 

Bureau of Reclamation, 1950. Denver Office, Sedimentation Survey of Belle 

Fourche Reservoir South Dakota, Denver, CO. 

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

Bureau of Reclamation, 1985. Surface Water Branch, ACAP85 User's Manual, 

Technical Service Center, Denver CO. 

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

Procedures for Bureau of Reclamation Dams and Reservoirs, U.S. Government 

Printing Office, Denver, CO. 

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

Printing Office, Denver CO. 

Bureau of Reclamation May 2004. Standing Operating Procedures (SOP), Belle 

Fourche Dam and Belle Fourche Reservoir, Belle Fourche Unit, Pick-Sloan 

Missouri Basin Program, Great Plains Region, Billings, MT. 

Bureau of Reclamation, June 2006. Belle Fourche Reservoir Area and Capacity 

Tables, Belle Fourche Project, Great Plains Region, Billings, MT. 

Corps of Engineers, January 2002. Engineer and Design Hydrographic 

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

(www.usace.army.mil/inet/usace-docs/eng-manuals/em1110-2-1003/toc.htm). 

ESRI, 2006. Environmental Systems Research Institute, Inc. (www.esri.com) 

Ferrari, R.L., 2006. Reconnaissance Technique for Reservoir Surveys, U.S. 

Bureau of Reclamation, Denver, Colorado. 

http://www.usbr.gov/pmts/sediment/projects/index.html

21