Box Butte Reservoir 

2003 Survey 

U.S. Department of the Interior 

Bureau of Reclamation 

Technical Service Center 

Denver, Colorado April 2007 

i

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1. REPORT DATE 

April 2007 

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

5a. CONTRACT NUMBER 

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4. TITLE AND SUBTITLE 

Box Butte Reservoir 

2003 Survey 

5c. PROGRAM ELEMENT NUMBER 

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5e. TASK NUMBER 

6. AUTHOR(S) 

Ronald L. Ferrari 

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

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

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

14. ABSTRACT 

The Bureau of Reclamation (Reclamation) surveyed Box Butte Reservoir in June of 2003 to develop a topographic map and 

compute a present storage-elevation relationship (area-capacity tables). The underwater collection was conducted on June 9, 10, 

27 and 28, 2003 at surveyed lake elevation 3994.8 feet (project datum). The underwater survey used sonic depth recording 

equipment interfaced with a global positioning system (GPS) that gave continuous sounding positions throughout the underwater 

portions of the reservoir covered by the survey vessels. The above-water topography was determined from digitized contour 

lines from the U.S. Geological Survey (USGS) quadrangle (quad) maps and the original reservoir topography map. The new 

topographic map of Box Butte Reservoir was developed from the combined above and below water data sets. 

The surveys measured a minimum elevation 3,962.0 (feet) and lake contours were developed from elevation 3,992.0 and below. 

All elevations shown in this report are based on the project datum in feet that is tied to the National Geodetic Vertical Datum of 

1929 (NGVD29) and 2.0 feet lower than the North American Vertical Datum of 1988 (NAVD88). The upper contour 

development was limited due to extensive vegetation growth around the reservoir. As of June 2003, at water surface elevation 

4,007.0, the surface area was 1,605 acres with a total capacity of 29,161 acre-feet. Since initial closure, October 3, 1945, about 

1,896 acre-feet of volume loss due to sediment was measured by the 2003 survey.

15. SUBJECT TERMS 

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

area/ sedimentation survey/ global positioning system/ lake/ multibeam/ bathymetry

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a. REPORT b. ABSTRACT a. THIS PAGE 

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OF ABSTRACT

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Standard Form 298 (Rev. 8/98) 

Prescribed by ANSI Std. Z39.18 
U.S. Department of the Interior 

Bureau of Reclamation 

Technical Service Center 

Sedimentation and River Hydraulics Group 

Denver, Colorado April 2007 

Box Butte Reservoir 

2003 Survey 

prepared by 

Ronald L. Ferrari 
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. 

Acknowledgments 

Reclamation's Sedimentation and River Hydraulics Group of the Technical Service 

Center (TSC) prepared and published this report. Ronald Ferrari and Sharon Nuanes of 

the TSC conducted the underwater data collection using the TSC’s large survey vessel. 

Ron Ferrari with assistance from Alexander Ferrari conducted the shoreline and shallow 

water collection using a smaller survey vessel. Ron Ferrari completed the data 

processing needed to generate the new topographic map, area-capacity tables, and report. 

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

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. 
Table of Contents 

Page 

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

Summary and Conclusions .................................................................................................2 

Control Survey Data Information .......................................................................................3 

Reservoir Operations ..........................................................................................................7 

Hydrographic Survey Equipment and Method ...................................................................7 

Reservoir Area and Capacity ............................................................................................10 

Topography Development..........................................................................................10 

Development of the 2003 Box Butte Reservoir Surface Areas..................................15 

2003 Storage Capacity................................................................................................15 

2003 Reservoir Sediment Analyses..................................................................................16 

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

Index of Figures 

Page 

Figure 1 - Box Butte Reservoir location map. ....................................................................1 

Figure 2 - BOR cap, left abutment, d/s 15-feet, elevation 4028.00. ...................................5 

Figure 3 - BOR cap, left abutment, u/s 15-feet, elevation 4027.92. ...................................5 

Figure 4 - Temporary hydrographic survey control point near boat ramp..........................6 

Figure 5 - Survey vessel with mounted instrumentation on Jackson Lake in Wyoming....8 

Figure 6 - Vegetation along shoreline of box Butte Reservoir. ..........................................9 

Figure 7 - Thick vegetation islands in upper reservoir that blocked survey vessels.........10 

Figure 8 - Box Butte Reservoir topographic map.............................................................13 

Figure 9 - Box Butte Reservoir area and capacity plots. ..................................................20 

Index of Tables 

Page 

Table 1 - Reservoir sediment data summary (page 1 of 2). ..............................................17 

Table 2 - Summary of 2003 survey results. ......................................................................19

iv
Box Butte Reservoir 2003 Survey 

Introduction 

Box Butte Dam and Reservoir, located on the Niobrara River, are principal 

features of the Mirage Flats Project. The reservoir is located in Dawes County 

about nine miles north of Hemingford in northwest Nebraska (figure 1). The 

reservoir’s primary function is water releases for irrigation, but the reservoir also 

provides flood control, fish and wildlife, and recreation benefits. 

Figure 1 - Box Butte Reservoir location map. 

The Box Butte Dam was completed in 1946 and the reservoir began filling with 

the closure of the outlet gates on October 3, 1945. The dam is a zoned earthfill 

embankment structure with the following dimensions: 

 Hydraulic height1 52 feet Structural height 87 feet 

 Top width 24 feet Crest length 5,508 feet 

 Crest elevation 4,024.0 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 ASCE’s Nomenclature for Hydraulics.

2

Elevations in feet. Unless otherwise noted, all elevations shown in this report are based on the project water 

surface gage datum that is reported to be tied to the National Geodetic Vertical Datum of 1929 (NGVD29) and 2.0 

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

1
The Box Butte Dam structure contains a controlled outlet works for irrigation 

releases, a modified side channel service spillway, and a fuse plug emergency 

spillway. The gated outlet works passes through the base of the dam and has a 

capacity of 420 cubic feet per second (cfs) at reservoir water surface elevation 

4,007.0. The service spillway is a reinforced concrete side channel located in the 

left abutment with a capacity of 2,700 cfs at elevation 4,007.0. The emergency 

spillway located around the left end of the dam is 450 feet wide, consisting of 

nine sections varying in elevation from 4,014.00 to 4,015.75. The emergency 

spillway fuse plugs are designed to erode in a controlled manner when overtopped 

and have a maximum capacity of 22,800 cfs. The drainage area above the dam is 

around 1,460 square miles. 

Summary and Conclusions 

This Reclamation report presents the 2003 results of the survey of Box Butte 

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

 $ develop lake topography 

 $ compute area-capacity relationships 

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

A Real-time Kinematic (RTK) global positioning system (GPS) control survey 

was conducted by the bathymetric survey crew to establish a temporary horizontal 

and vertical control point near the boat ramp for the underwater collection and 

measurements of the water surface elevation during the survey. The RTK GPS 

control survey was conducted with the base set on the National Geodetic Survey 

(NGS) datum point “Hemingford.” The horizontal control was established in 

Nebraska state plane coordinates in North American Datum of 1983 (NAD83) 

and the vertical control in NAVD88. All elevations in this report are referenced 

to the Reclamation project datum that is tied to NGVD29. Initially, the 

processing of the bathymetric data was delayed due to conflicts with the 

bathymetric survey crew control and a previous control survey conducted around 

the reservoir. Further details on the survey control are in the section “Control 

Survey Data Information.” 

The June 2003 underwater survey was conducted over four days near reservoir 

elevation 3,994.8. The water surface was measured by the hydrographic survey 

crew during the days of collection and was adjusted to Reclamation’s project 

datum in NGVD29. The bathymetric survey used sonic depth recording 

equipment interfaced with 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 Box Butte Reservoir. 

The positioning system provided information to allow the boat operator to 

2
maintain a course along these grid lines. The equipment was later mounted in a 

small pontoon raft that allowed collection along the shallow shoreline around the 

reservoir. Due to extensive vegetation growth there were some areas of the 

reservoir where boat access was not possible. The vegetation also affected the 

digital sounding records, requiring additional time for processing to ensure 

accuracy. The initial above-water topography was determined by digitizing 

existing contour lines from the USGS quads and an original topographic drawing 

of the reservoir area. During the bathymetric survey, the boat location at times 

plotted outside of these contours indicating some shoreline erosion. 

The Box Butte Reservoir topographic map is a combination of the digitized 

contours and the 2003 underwater survey data. A computer graphics program 

generated the 2003 reservoir surface areas at predetermined contour intervals 

from the collected and digitized reservoir area. The 2003 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 Box Butte Reservoir and watershed 

characteristics for the 2003 survey. The 2003 survey determined that the 

reservoir has a total storage capacity of 29,161 acre-feet and a surface area of 

1,605 acres at conservation pool elevation 4,007.0. Since closure in October 

1945, the reservoir has an estimated volume change of 1,896 acre-feet below top 

of conservation reservoir elevation 4,007.0. The 2003 underwater survey was 

conducted near reservoir elevation 3,995.0 and assumed no change since the 

original survey from elevation 4,000.0 and above. This volume represents a 6.1 

percent loss in total original capacity at conservation elevation 4,007.0. 

Control Survey Data Information 

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

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

station was set over NGS marker “Hemingford” that is located along State 

Highway 2 near the reservoir and allowed RTK GPS survey control shots. The 

RTK GPS survey established a temporary control point near the boat ramp that 

was used by the survey vessel during collection and for shots of existing reservoir 

brass caps and the water surface during the underwater collection. The horizontal 

control was in Nebraska state plane coordinates in NAD83 and the vertical control 

was tied to NAVD88 and the Reclamation project vertical datum in NGVD29. 

All elevations in this report are referenced to Reclamation’s project or 

construction vertical datum that is in NGVD29 and around 2.0 feet lower than 

NAVD88. The following coordinate information was used for this analysis. 

3
NGS control point “Hemingford”

 

NAD83/NAVD88 (degree/feet) 

 42/17/48.27424 (latitude) North 911,852.97 

 103/02/45.87229 (longitude) West 816,665.05 

 4,180.30 feet (ellipsoid elevation) (NAVD88) 4,240.25 

 

Note: The NGS published sheet on Hemingford indicates around a two 

foot difference between NAVD29 and NGVD88. 

Following are the state plane coordinates of the indicated points. The coordinates 

were surveyed by the hydrographic crew prior to underwater collection with some 

photographs taken of the brass caps. Many appeared to have been recently reset 

in concrete or repaired. As noted, the RTK GPS elevations in NAVD88 appeared 

to be around two feet higher than the stamped elevation on the brass caps, 

indicating elevations tied to NGVD29. The notes also show the provided 2001 

survey control elevations. The 2001 survey data differed from the hydrographic 

survey control causing delay in processing of the underwater data until this was 

resolved with the 2006 control survey. A 2006 control survey conducted for a 

reservoir boundary survey confirmed the project control elevations for Box Butte 

Reservoir are in NGVD29. 

Left Abutment, BOR cap, c/l stamped “4027.8”

 North 971,678.94 

 East 811,798.22 

 Elevation 4,029.88 (NAVD88, difference of 2.08 feet) 

The 2001 survey measured elevation 4,027.43, difference of 2.46 feet.

Left Abutment, BOR cap, d/s 15-ft stamped “4028.00”

 North 971,669.62 

 East 811,810.00 

 Elevation 4,030.05 (NAVD88, difference of 2.05 feet) 

4
Figure 2 – BOR cap, left abutment, d/s 15-feet, elevation 4028.00. 

Left Abutment, BOR cap, u/s 15-feet stamped “4027.92”

 North 971,688.15 

 East 811,786.48 

 Elevation 4,029.90 (NAVD88, difference of 1.98 feet) 

Figure 3 - BOR cap, left abutment, u/s 15-feet, elevation 4027.92. 

5
Water surface, June 9, 2003, 10:05am (gage projected at 3,993.4)

 North 972,477.99 

 East 810,228.07 

 Elevation 3,996.8 (NAVD88) 

During the time of collection, the reservoir gage was not working properly 

requiring readings to be estimated. A difference of 3.4 feet was found between 

NAVD88 and the estimated reservoir gage elevations. Since the hydrographic 

and 2006 control surveys determined that the project elevations are tied to 

NGVD29, all RTK GPS water surface shots were reduced 2.0 feet to match the 

project elevation used during data processing. On June 9, 2003, the project water 

surface elevation was 3,994.8. 

Temporary hydrographic sediment survey control point near boat ramp.

North 972,509.94 

 East 810,618.70 

 Elevation 4,016.96 (NAVD88) 

Figure 4 - Temporary hydrographic survey control point near boat ramp. 

6
Reservoir Operations 

Box Butte Reservoir is part of the Mirage Flats Project that provides storage for 

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

2003 capacity table lists 45,901 acre-feet of total storage below the maximum 

water surface elevation 4,016.0, table 1. The 2003 survey measured a minimum 

lake bottom elevation of 3,962. The following values are from the June 2003 

capacity table: 

 $ 16,740 acre-feet of surcharge between elevation 4,007.0 and 4,016.0. 

 $ 28,973 acre-foot of conservation between elevation 3,969.0 and 4,007.0. 

 $ 188 acre-foot of dead storage below 3,969.0. 

Box Butte Reservoir computed annual inflow and reservoir stage records are 

listed by water year on table 1 for available period 1967 through 2003. The 

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

annual fluctuation with a computed average inflow of 19,000 acre-feet per year. 

The maximum reservoir elevation was 4,002.1, recorded during water year 2000, 

and minimum recorded elevation was 3,968.2 during water year 1985. 

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 5. 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. A 12-volt battery provided the power for the shore 

unit. The collection gear was later mounted on a pontoon raft for mapping the 

shallow water areas of the reservoir around the shoreline and in the upper reaches. 

All equipment was run off 12-volt batteries. 

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 

Nebraska’s state plane coordinates in NAD83. The RTK GPS system employs 

7
two receivers that track the same satellites simultaneously just like with 

differential GPS. 

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

The Box Butte Reservoir bathymetric survey was conducted on June 9, 10, 27, 

and 28, 2003 at RTK GPS measured lake elevation 3,994.8, project datum in 

NGVD29. 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 perpendicular to the upstream-downstream inflow alignment of the 

reservoir. Data was collected along the shore by the survey vessels. The survey 

vessels’ guidance system gave directions to the boat operator to assist in 

maintaining the course along the predetermined lines. During each run, the depth 

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

subsequent processing. 

The 2003 underwater data was collected by a depth sounder that was 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 

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. Due to thick reservoir 

bottom vegetation, these charts were relied upon to obtain true reservoir bottom 

depths. The water surface elevations of the reservoir were measured by the 

8
hydrographic survey crew and were used to convert the sonic depth measurements 

to true lake-bottom elevations. Additional information on collection and analysis 

procedures is listed in the following references: Corps of Engineers, January 

2002; Ferrari, R. and Collins, K., 2006. 

Thick vegetation was a significant factor during the Box Butte Reservoir 

hydrographic survey, affecting the depth sounding signal in the most densely 

vegetated portions of the reservoir. Dense vegetation also hindered the survey 

vessels, damaging one outdrive of the larger vessel. In the upper portion of the 

reservoir the survey crew collected depth measurements using a range pole to 

confirm true reservoir depths. In late June 2003, the crew returned with a smaller 

boat that allowed the mapping along the banks and increased maneuverability in 

the shallow reservoir areas along the shore and upper end where there were 

openings in the vegetation. Following are two photographs of the reservoir 

vegetation, figures 6 and 7. 

Figure 6 - Vegetation along shoreline of Box Butte Reservoir. 

9
Figure 7 - Thick vegetation islands in upper reservoir that blocked survey vessels. 

Reservoir Area and Capacity 

Topography Development 

The topography of Box Butte Reservoir was developed from the 2003 below 

water data and the digitized water surface contour from the USGS quad and the 

original project contour map of the reservoir. The developed USGS quad 

contours were developed from aerial photography dated in the 1940’s and only 

included the maximum water surface elevation 4,007.0. Since the survey was 

conducted near elevation 3,995.0, the available USGS contour was too high for 

mapping purposes. As part of the analysis, the original contours (Reclamation 

drawing number 278-D-11) were digitally projected within the USGS quad 

contour. Using the quad contour and the 2003 underwater data as a guide, the 

digitized original project contour 3,995.0 was adjusted to surround the 2003 

underwater data that was collected near elevation 3,995.0. 

The USGS quad contour 4,007.0 was used during the underwater survey for 

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

10
reservoir coverage. During the 2003 underwater collection, the vessel 

occasionally plotted outside the contours indicating bank erosion, but it did not 

appear that bank erosion was extensive on Box Butte Reservoir. During the field 

survey, the collection vessels were forced to stop well short of the upper reaches 

of the 4,007.0 contour due to thick vegetation and assumed sediment delta. 

However, a plot of the adjusted 3,995.0 contour versus original topography 

showed that the upper end of the 2003 survey was near the upper portion of the 

original elevation 3,995.0 contour, indicating a lack of substantial delta formation 

in this area since dam closure in 1946. 

The adjusted contour, elevation 3,995.0, was used to perform a hardclip around 

the 2003 data of Box Butte Reservoir. The hardclip was used during the 

triangular irregular network (TIN) development so interpolation did not occur 

outside the enclosed polygon. This contour was selected since it was the closest 

data available to represent the water surface during the 2003 survey. Using 

ARCEDIT, the 2003 below water data along with the contours were plotted. The 

plot showed that the underwater data did not lie completely within these contours 

which were then modified to include the entire underwater data set within the 

enclosed polygon. Using select and move commands within ARCEDIT, the 

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

elevation of 3,995.0. 

Contours for the reservoir below elevation 3,995.0 were computed from the 2003 

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 Box Butte Reservoir TIN. The areas of the 

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

survey data for elevations 3,961.0 through 3,995.0. Since no complete reservoir 

aerial data was collected for this study, no change was assumed in original 

reservoir surface area for elevation 4,000.0 and above. The reservoir contour 

topography at 2- and 5-foot intervals is presented on figure 8. 

11
12
13
14
Development of the 2003 Box Butte Reservoir Surface 

Areas 

The 2003 surface areas for Box Butte Reservoir were computed at 1-foot 

increments, from elevation 3,992.0 through 3,995.0, directly from the TIN that 

covered the Box Butte Reservoir within the hard clip area only. This TIN was 

developed from the 2003 collected data within the hardclip polygon that was 

developed from the adjusted digitized 3,995.0 contour 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 2003 survey areas at 2- and 5-foot increments from elevation 3,962.0 

through 3,992.0 were used to compute the new area and capacity tables. For 

elevation 4,000.0 and above, the surface areas of the original developed 

topography were used assuming no change. There were insufficient 2003 

surveyed data points for accurate computer development of surface areas at 

elevations above 3,992.0. Straight line interpolation was used to compute the 

surface areas between elevations 3,992.0 and 4,000.0. 

2003 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 Box Butte 

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 a 

basic area curve over that interval) is utilized until it exceeds the error limit. 

Thus, the capacity curve is defined by a series of curves, each fitting a certain 

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

order polynomial form, 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 

15
Results of the Box Butte Reservoir area and capacity computations are listed in a 

separate set of 2003 area and capacity tables that have been published for the 

0.01, 0.1 and 1-foot elevation increments (Bureau of Reclamation, 2003). A 

description of the computations and coefficients output from the ACAP program 

is included with these tables. The original and 2003 area-capacity relationships 

are listed on table 2 and the curves are plotted on figure 9. As of June 2003, at 

conservation use elevation 4,007.0, the surface area was 1,605 acres with a total 

capacity of 29,161 acre-feet. 

2003 Reservoir Sediment Analyses 

Results of the 2003 Box Butte Reservoir area and capacity computations are listed 

in table 1 and columns 4 and 5 of table 2. Columns 2 and 3 of table 2 list the 

original area and recomputed capacity values. Column 7 lists the capacity 

differences between the original and 2003 survey results due to sediment inflow. 

Figure 9 is a plot of the Box Butte Reservoir surface area and capacity values for 

the original and 2003 surveys and illustrates the differences. The comparisons 

show that the total reservoir capacity in 2003 was 1,896 acre-feet less than the 

original volume at conservation reservoir elevation 4,007.0. It must be noted that 

the 2003 area and capacity tables were generated assuming no surface area change 

since the original survey at elevation 4,000.0. This is not likely the case, but with 

no new above water data available, it is assumed any loss due to sediment 

deposition above this elevation would not be significant since the original survey. 

The only means to verify this would be by an extensive above water survey, but 

the thick above water vegetation would greatly hinder any such collection. 

The estimated 100 years of sediment accumulation for Box Butte Reservoir was 

25.8 percent or around 8,000 acre-feet at conservation pool elevation 4,007.0. 

This computes to an annual loss of 80 acre-feet. Table 1 shows that the 2003 

survey measured an average annual loss of 32.9 acre-feet since dam closure. The 

information used to project the 100 year sediment accumulation is unknown. It 

must be noted that the 2003 study estimated no change in capacity from elevation 

4,000.0 and above. Due to lack of new topography data in that range, surface 

areas and volumes between the 2003 measured surface area at elevation 3,992.0 

and the original surface area at elevation 4,000 were linearly interpolated. An 

aerial survey would be needed to more accurately map the reservoir from 

elevation 3,992.0 and above, but the thick vegetation there may prevent aerial 

data collection in certain areas.

16
1. 2. 3. STATE Nebraska

4. 5. Heminford 6. COUNTY Dawes

7. ° 27 ' 30 " ° 04 ' 03 " 8. 1 9. SPILLWAY CREST EL 2

10. 11. 12. GROSS STORAGE 15

CAPACITY, AC-FT

a. 3

b.

c.

d. 16

e.

f.

g.

17. LENGTH OF RESERVOIR 4

18. TOTAL DRAINAGE AREA 5 22. 6

19. NET SEDIMENT CONTRIBUTING AREA 5 23. MEAN ANNUAL RUNOFF 7

20. LENGTH MILES AVG. WIDTH MILES 24. MEAN ANNUAL INFLOW 7

21. 25. °F °F6

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

26. DATE OF 35. 36

7

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.

5 - ft 1,605 8

AREA, AC. ACRE - FEET

655

30,402

BEGAN

10/1945

to 104

0.6

INCHES

INCHES

ACRE-FEET

MILES

15.1

19,000

3,969.0 655

DATA SHEET NO.

DATE

STORAGE

4,024.0

14.

4,007.0

ACRE-FEET

Neobrara River

RESERVOIR SEDIMENT

DATA SUMMARY

Box Butte Reservoir NAME OF RESERVOIR 1

DATE

OF

SURVEY

6/03

SURVEY

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

10.6

3,980 4,000

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 47 °F RANGE -32

N

S

a. TOTAL b.

R

AVG. ANN. c.

 

D

2 - ft

U

ANNUAL

PRECIPITATION

 /MI.2-YR.

19,000 664,000

TOTAL SEDIMENT DEPOSITS TO DATE, AF

664,900

a. AVG. ANNUAL

1,896

a.

1.63

33.

8

29,161

RATIO AF/AF

32.

47,797

31,057

BEGAN

DATE NORMAL

10/1945

31,057 OPERATIONS

132

MAX. ANN.

 

1,605

1,605

E

POWER

R ORIGINAL 13. ORIGINAL 

S

E

17,395

S

R

V

O

I

R

B

A

M

TWP. 49 W

27,500

34.

b.

PERIOD PERIOD WATER INFLOW, ACRE-FEET

c.

NEAREST P.O.

42 TOP OF DAM ELEVATION

OWNER

SEC

LAT

28

D

A 29N RANGE

 

 

6/03

AVG. WIDTH OF RESERVOIR

NO. OF

RANGES OR 

INTERVALS

SQUARE MILES

Contour (D)

SURFACE

SQUARE MILES

MILES

0.24

6/03 32.9

1460

1,896 10

 

9 1.53

32.9

6/2003

 

PERCENT OF TOTAL SEDIMENT LOCATED WITHIN REACH DESIGNATION

10 20 30 40 60 70

100-

3,990- 3,995-

3,975

50- 60-

DEPTH DESIGNATION RANGE BY RESERVOIR ELEVATION

4000-

0.11 6.1

30-

3,969-

13.4 20.9 13.1 3.9

3,990 3,995

3,985-

90-

4,007

111

0- 110-

90 115

70-

80

10- 20- 80-

0.0

3,975- 3,980-

3,985

24.6 13.5

3,969

103

Bureau of Reclamation

LONG

SURCHARGE 2,116

STORAGE

ALLOCATION

ELEVATION

SURFACE AREA, AC-FT

STREAM

INACTIVE

DEAD

TOP OF POOL

FLOOD CONTROL

JOINT USE

CONSERVATION

4,016.0

4,007.0

4.5

1460

15.1

YRS YRS

6/03

10/45

MEAN ANNUAL PRECIPITATION

TYPE OF 

SURVEY

Contour (D)

19,000

9

PER. PER.

a. MEAN ANN.

PERCENT OF TOTAL SEDIMENT LOCATED WITHIN DEPTH DESIGNATION

120-

125

115-

105 120

bottom100

105-

E 57.7 57.7

A 

 

0.02

TOTAL a. MEAN ANN. b. TOTAL

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

-YR.

0.02

a. PERIOD

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

17
1

2

3

4

5

6

7

8

9

10

5,920 3,988.0 683 7,224 3,990.0 790 8,696

3,710 3,984.0 550 4,748 3,985.0 587 5,316

1984 4,000.0 3,978.9

3,997.0

ELEVATION - AREA - CAPACITY - DATA FOR

6

SURVEY

1972 3,977.0

2003

1980 3,998.8

3,975.2

37 37

3,996.5

AREA CAPACITY

3,998.4

3,993.3

3,992.4 3,978.3

1,492

152

281

488

621

3,976.0

3,972.0

3,982.0

2,058

3,986.0

 Maximum and minimum from Reclamation available records. Some inflow years not available, 1967, 1996, 1997. 

47. REMARKS AND REFERENCES

Total drainage area from USGS water records.

All elevations are in feet based on the original project datum that is reported as NGVD29 and two feet lower than NAVD88.

49. Bureau of Reclamation March 2007

All 2003 capacities computed by Reclamation's ACAP computer program. 2- and 5-foot surface data from elevation 3,992 and below.

 Assumed no change since original developed table from elevation 4,000 and above.

AGENCY MAKING SURVEY

 Portion of computed loss, by comparing differences, is due to differences in detail between original and 2003 surveys.

AGENCY SUPPLYING DATA DATE

7

3,964.0

4,005.0

4,015.0

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

48. Bureau of Reclamation

Spillway crest elevation 4,007.0, located at left abutment of dam.

Values from Reservoir Capacity Allocation table dated 9/1963. Capacity values recomputed using ACAP.

Length at elevation 4,007.

Bureau of Reclamation's Project Data Book, 1981.

Mean annual runoff of 19,000 acre-feet from available records, water years 1968 through 2003. Computations by Great Plains Region. 

Surface area and capacity at elevation 4,007.0, spillway crest elevation.

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

 

2002

 

3,981.2

26,064

542

1986 3,997.6 3,977.9

1990

1994 4,000.0 3,971.5

1974

18,700 1973 3,997.5

3,981.4

24,200

18,000

1978 3,976.2 18,800 1979 3,995.8 3,980.5 18,300

20,000 1975 3,970.4

18,200

20,000

19,800 1981

3,996.5

20,400 1985 3,995.3 3,968.2

14,000

22,300

1988 3,995.7 3,973.0 17,400

1987 3,998.4 3,975.1 20,400

1991 3,998.4 3,981.5

1989 3,992.1 3,973.0

22,600

1992 3,997.5 3,985.8 14,900 1993 3,998.5 3,998.0 23,500

14,800

16,600

1996 3,999.5 3,986.2 1997

22,200 1995 4,000.7 3,986.2

4,002.1 3,988.4 18,600 2001

3,979.6 12,700

ELEVATION AREA

3,980.6 16,700

9 46.

ELEVATION

2003

3,961.0 0 0

2003 CAPACITY

3,994.5

3,962.0

3,965.0 17 17 3,966.0 27 38

4,010.0 1,775 34,232

1,136

2,792

19,117

282

CAPACITY ELEVATION AREA CAPACITY

4,016.0 2,116 45,901

4,007.0 1,605 29,161

1970

45. RANGE IN RESERVOIR OPERATION

6

43,814

1968 1969 27,500 3,999.2 3,975.3 17,700

3,999.4 3,972.9 18,500 1971 3,999.4 3,972.9 21,700

 1967 18,800

3,974.0 213 907 3,975.0 246

1,399 3,978.0 346 2,026 3,980.0 425

3,992.0 897 10,382 3,995.0 1,043 13,292 4,000.0 1,287

3,968.0 55 120 3,969.0 81 188 3,970.0 108

1976 3,994.3 3,969.8 17,200 1977 3,994.7 3,976.2

1998 4,000.1 3,973.6 16,000 1999

17,400

3,995.7 3,977.8

3,986.2 16,700

4,001.4 3,973.6 17,800

4,000.0 3,988.1

2000

1982 3,995.8 3,980.5 18,800 1983 4,001.1 3,986.5 23,700

4,000.3

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

18
1 2 34 5 6 7 8 9

2003 2003 Percent Percent of

Elevation Original Original 2003 2003 Area Sediment Computed Reservoir

Survey Capacity Survey Survey Difference Volume Sediment Depth

(feet) (acres) (acre-feet) (acres) (acre-feet) (acres) (acre-feet) Orig. - 2003

4,016.0 2,116 47,797 2,116 45,901 0 100.0

4,015.0 2,058 45,710 2,058 43,814 0 98.4

4,010.0 1,775 36,128 1,775 34,232 0 90.2

4,007.0 1,605 31,057 1,605 29,161 0 1,896 100.0 85.2

4,005.0 1,492 27,960 1,492 26,064 0 1,896 100.0 82.0

4,000.0 1,287 21,013 1,287 19,117 0 1,896 100.0 73.8

3,995.0 1,072 15,115 1,043 13,292 29 1,823 96.1 65.6

3,992.0 948 12,084 896.6 10,382 51 1,702 89.8 60.7

3,990.0 866 10,270 789.8 8,696 76 1,574 83.0 57.4

3,988.0 778 8,626 682.5 7,224 96 1,402 73.9 54.1

3,986.0 689 7,160 621.0 5,920 68 1,240 65.4 50.8

3,985.0 645 6,493 586.6 5,316 58 1,177 62.1 49.2

3,984.0 609 5,865 550.2 4,748 59 1,117 58.9 47.5

3,982.0 538 4,719 487.6 3,710 50 1,009 53.2 44.3

3,980.0 466 3,715 425.2 2,792 41 923 48.7 41.0

3,978.0 390 2,859 345.9 2,026 44 833 43.9 37.7

3,976.0 315 2,153 280.8 1,399 34 754 39.8 34.4

3,975.0 277 1,858 246.0 1,136 31 722 38.1 32.8

3,974.0 251 1,593 212.5 907 39 686 36.2 31.1

3,972.0 200 1,143 152.1 542 48 601 31.7 27.9

3,970.0 148 795 107.8 282 40 513 27.1 24.6

3,969.0 132 655 81 188 51 467 24.6 23.0

3,968.0 116 531 54.7 120 61 411 21.7 21.3

3,966.0 85 329 26.8 38 58 291 15.3 18.0

3,965.0 69 253 16.5 17 53 236 12.4 16.4

3,964.0 58 189 5.6 6 52 183 9.7 14.8

3,962.0 37 93 0.0 0 37 93 4.9 11.5

3,961.0 27 61 0.0 0 27 61 3.2 9.8

3,960.0 16 40 0.0 0 16 40 2.1 8.2

3,955.0 0 0 0.0 0 0 0 0.0 0.0

1 Elevation of reservoir water surface.

2 Original reservoir surface area.

3 Original reservoir capacity recomputed using ACAP.

4 Reservoir surface area from 2003 survey from elevation 3,992 and below. Original

 surface area from elevation 4,000 and above assuming no change. 

 Elevation 3,995 surface area projected between 3,992 and 4,000 surface area values.

5 Reservoir capacity computed using ACAP.

6 Area difference between original and 2003 survey = column (3) - column (5).

7 Sediment Volume from original (1945) and 2003 surveys = column (4) - column (5).

8 Percent of sediment volume, total 1,896 acre-feet.

9 Depth of reservoir expressed in percentage of total depth of 61.0 feet.

Table 2 - Summary of 2003 survey results.

19
20

Area-Capacity Curves for Box Butte Reservoir

3,955.03,960.03,965.03,970.03,975.03,980.03,985.03,990.03,995.04,000.04,005.04,010.04,015.04,020.0

0 4800 9600 14400 19200 24000 28800 33600 38400 43

Capacity (acre-feet)

Elevation (feet)

2,200 1,980 1,760 1,540 1,320 1,100 880 660 440 2

2003 SurveyOriginal Survey

Capacity Area

Area (acre)

Figure 9 – Box Butte Reservoir area and capacity plots. 
21

References 

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

Headquarters, New York. 

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

Bureau of Reclamation, 1985. Surface Water Branch, 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), Box 

Butte Dam and Reservoir, Mirage Flats Project, Nebraska, McCook Field 

Office, McCook, Nebraska. Great Plains Region, Billings, MT. 

Bureau of Reclamation, June 2003. Box Butte Reservoir Area and Capacity 

Tables, Mirage Flats 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. and Collins, K., 2006. Reservoir Survey and Data Analysis, Erosion 

and Sedimentation Manual, Chapter 9, U.S. Bureau of Reclamation, Denver, 

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