U.S. Department of the Interior	 Prepared in cooperation with the SCIENTIFIC INVESTIGATIONS MAP 3213 

Bathymetric Contours of Breckenridge Reservoir, Quantico, Virginia U.S. Geological Survey	 U.S. Marine Corps, Quantico, Virginia Wicklein, S.M., Lotspeich, R.R., and Banks, R.B., III, 2012 

Abstract 

Breckenridge Reservoir, built in 1938, is fed by Chopawamsic Creek 

and South Branch Chopawamsic Creek. The Reservoir is a main source 

of drinking water for the U.S. Marine Corps (USMC) Base in Quantico, 

Virginia. The U.S. Geological Survey (USGS), in cooperation with the 

USMC, conducted a bathymetric survey of Breckenridge Reservoir in 

March 2009. The survey was conducted to provide the USMC Natural 

Resources and Environmental Affairs (NREA) with information regarding reservoir storage capacity and general bathymetric properties. The 

bathymetric survey can provide a baseline for future work on sediment 

loads and deposition rates for the reservoir. 

Bathymetric data were collected using a boat-mounted Wide Area Augmentation System (WAAS) differential global positioning system 

(DGPS), echo depth-sounding equipment, and computer software. Data 

were exported into a geographic information system (GIS) for mapping 

and calculating area and volume. Reservoir storage volume at the time 

of the survey was about 22,500,000 cubic feet (517 acre-feet) with a 

surface area of about 1,820,000 square feet (41.9 acres).
 

Introduction
 

Bathymetric mapping can provide useful information for water-quality 

and water-supply managers to address a variety of issues regarding lakes 

and reservoirs. Since 1983, the USGS Virginia Water Science Center 

has collected streamflow, water-quality, and suspended sediment information for a number of streams on the USMC Base Quantico as well as 

another manmade reservoir, Lunga Reservoir. This bathymetric survey 

in this report was conducted along with a water-quality assessment to 

provide the NREA with information regarding the general condition of 

Breckenridge Reservoir (Lotspeich, 2012). 

The bathymetric contours also can provide a baseline for future work on 

sediment loads and deposition rates for the reservoir. Understanding 

sedimentation rates in reservoirs provides insight into the role(s) of 

reservoirs on watershed sediment-transport processes, so that systems of 

watershed structures can be designed efficiently to provide floodwater 

retention and other uses of the stored water (USGS, 2009). 

Breckenridge Reservoir was constructed in 1938 and is located in 

northeast Virginia, 5.4 miles northwest of Quantico in Prince William 

County, Virginia. The reservoir straddles the border between Prince 

William and Stafford Counties. Breckenridge Reservoir is primarily 

used for drinking-water supply on the USMC Base Quantico, but recreational activities, mainly fishing, do occur at times. The reservoir is fed 

by two streams, Chopawamsic Creek and South Branch Chopawamsic 

Creek, that drain areas located on the base located west of the reservoir. 

Breckenridge Reservoir discharges over a fixed spillway at the dam at 

the southern end of the reservoir into Chopawamsic Creek, which is a 

tributary of the Potomac River (fig. 1). 

Methods 

Bathymetric data were collected on March 30–31, 2009, using a boatmounted DGPS and echo depth-sounding equipment. The DGPS allowed 

for accuracies of less than 10 feet (ft; about 3 meters) in the horizontal 

direction (Garmin Ltd., 2005). The echo sounder emits pulses of sound 

that are reflected off the lake bottom and received by a transducer. 

Depths are computed by measuring the time it takes for a sound pulse to 

travel down and reflect back, which is a function of the speed of sound in 

water and bed-sediment type (Garmin Ltd., 2005). The accuracy of the 

depth sounder was quantified by the repeatability of depth measurements, 

as described in the Quality Assurance section. Shallow areas of the reservoir (less than 2.0 ft) were manually measured using a graduated survey 

pole marked in 0.5-ft increments due to depth limitations of the sounding 

equipment. Data were collected along lateral transects throughout the 

reservoir and longitudinally along the reservoir perimeter as well as 

through the middle of the reservoir. Individual data points were collected 

at 5-second intervals while traversing the reservoir (fig. 2). The depth 

data were later converted to elevation during postprocessing by subtracting the depths at each location from the reference-surface elevation of the 

reservoir. 

The reference-surface elevation was determined by calculating the 

elevation difference between the water-surface elevation and a reference 

point on shore that was surveyed using DGPS equipment. A submersible 

pressure transducer was deployed at the reference point. Water levels 

were recorded hourly throughout the survey, downloaded, and corrected 

for changes in atmospheric pressure, then converted to elevations above 

North American Vertical Datum of 1988 (NAVD 88). 

The corrected water-level elevations were averaged to compute a mean 

water-surface elevation of 135.5 ft (NAVD 88) for the period of time when 

the survey was conducted. Bathymetric data were filtered to eliminate any 

erroneous data points and then exported to GIS software where a threedimensional surface model of the reservoir-bottom elevations was generated. The three-dimensional surface was contoured using the Inverse Distance Weighted method, and the resulting 2-ft contours were adjusted 

manually where needed to correct for interpretive errors (fig. 3). Reservoir 

storage volumes (fig. 4A) and surface areas (fig. 4B) were then computed 

for a range of reservoir water-surface elevations. 

Quality Assurance 

A depth check on the echo sounder was performed once at the beginning of

the survey to ensure that the echo sounder was calibrated correctly. The

check was performed by lowering a 0.01-ft graduated steel tape with a

sounding weight on the end to the bottom of the reservoir directly below

the echo sounder, then comparing the measured depth to the echo sounder 

reading. The offset of the transducer, or the draft of the transducer below 

the water surface, was adjusted to generate the same depth as the measured

depth within about 0.1 ft. The precision (repeatability) of the sounding data 

collected with the echo sounder was evaluated to estimate the accuracy of 

the contours (Wilson and Richards, 2006). The primary dataset, which 

consisted of over 4,000 data points collected on March 30–31, 2009 (fig. 

2), was compared to a smaller dataset of 233 data points that were collected 

on February 24, 2009. Points from each survey that were collected within 

1.5 ft of each other were considered coincidental and were paired for comparison. This process produced 32 coincidental pairs of points. The standard deviation of the depth measurement for the data point pairs was 1.2 ft. 

The horizontal precision was evaluated by comparing surveyed data points 

to a georeferenced reservoir boundary. Less than 0.5 percent of surveyed 

data points plotted beyond the georeferenced reservoir boundary. 

Bathymetric Contours 

The average water-surface elevation of Breckenridge Reservoir on March 

30–31, 2009, was 135.5 ft (NAVD 88). The depth of water in the reservoir 

increases toward the dam (fig. 3). The deepest part of the reservoir is just 

above the dam with an elevation of 96.8 ft (NAVD 88), or 38.7 ft deep. The 

average elevation of the reservoir bottom is 121.1 ft (NAVD 88), or 14.4 ft 

deep. The slope of the reservoir bottom is greatest between the mouth of 

South Branch Chopawamsic Creek and the dam, and the slope of the banks 

increases where the reservoir narrows along this reach. The total surface 

area of Breckenridge Reservoir was computed to be approximately

1,820,000 square feet (41.9 acres) and the total water volume was about

22,500,000 cubic feet (517 acre-feet) at the time of the survey. 

References 

Garmin Ltd., 2005 GPSMAP 198C Sounder manual: Olathe, Kans.,

Garmin International, Inc., 118 p. 

Gray, J.R., Bernard, J.M., Stewart, D.W., McFaul, E.J., Laurent, K.W.,

Schwarz, G.E., Stinson, J.T., Jonas, M.R., Randle, Timothy, and Webb,

J.W., 2010, Development of a national, dynamic reservoir sedimentation

database, in Federal Interagency Sedimentation Conference, 9th, Las 

Vegas, Nev., June 27–July 1, 2010, Proceedings, 12 p.	 

Lotspeich, R.R., 2012, Quality of water and bottom material in Breckenridge Reservoir, Virginia, September 2008 through August 2009: U.S. 

Geological Survey Open-File Report 2011–1305, 29 p., plus appendixes, 

available at http://pubs.usgs.gov/of/2011/1305/. 

United States Geological Survey, 2009, The Reservoir Sedimentation 

Database (RESSED) - Background, Website accessed April 16, 2012 at 

http://ida.water.usgs.gov/ressed/background/index.cfm 

Wilson, G.L., and Richards, J.M., 2006, Procedural documentation and 

accuracy assessment of bathymetric maps and area/capacity tables for small 

reservoirs: U.S. Geological Survey Scientific Investigations Report 2006-

5208, 24 p., CD-ROM. 

Any use of trade, product, or firm names is for descriptive purposes only

and does not imply endorsement by the U.S. Government.	 

POTOMAC RIVER 

UNITED STATES MARINE CORPS BASE, QUANTICO BOUNDARY 

BRECKENRIDGE RESERVOIR 

WATERSHED 

Prince William County 

Breckenridge

Reservoir 

Quantico 

Lunga Reservoir 

Stafford County 

Figure 1. Map showing location of Breckenridge Reservoir, Virginia. 

Chopawamsic 

Chopawamsic

South Branch 

Chopawam

Creek 

Creek 

77°23'45" 

38°32'45" 

38°32'30" 

77°23'30" 

EXPLANATION
 

Data-collection point–On transect lines 

and around perimeter 

Base from U.S. Geological Survey digital data, 1 : 24,000, 1972,

 Universal Transverse Mercator projection, Zone 15,

 North American Datum of 1983 

0	 500 1,000 FEET 

0	 150 300 METERS 

38°32'15" 

Approximate location 

of spillway 

Figure 2. Data-collection points used to construct bathymetric 

contours of Breckenridge Reservoir, Virginia, 2009. 

eek

Chopawam

Creek 

120

130

130

77°23'45"
 

38°32'45" 

EXPLANATION
 

Lake boundary—Edge of water at lake-surface elevation,

 135.5 feet above North American Vertical Datum of 1988. 

120 Bathymetric contour—Line of equal lake-bottom elevation,


 in feet above North American Vertical Datum of 1988.


 Interval is 2 feet.
 

38°32'30" 

Base from U.S. Geological Survey digital data, 1 : 24,000, 1972,


 Universal Transverse Mercator projection, Zone 15,


 North American Datum of 1983
 

Figure 3. Bathymetric contours of Breckenridge Reservoir, 

Virginia, March 2009 (not for navigational use). 77°23'30" 

Chopawamsic Creek 

100

120

110 130

130

110

38°32'15"

Approximate location of spillwa

0	 500 1,000 FEET

0 100 200 300 METERS 

y

Chopawamsic Cr

South Branch 

sic 

Creek 

sic 

140

Reservoir elevation, in feet above NAVD 1988 Reservoir elevation, in feet above NAVD 1988

(A)

130 

120 

110 

100
 

90
 

80 

 0 5 10 15 20 25

Storage volume, in million cubic feet 

140 

(B)

130
 

120 

110 

100 

90
 

80 

0 5 10 15 20 25 30 35 40 45 

Surface area, in acres 

Figure 4. Storage volume (A) and surface area (B) curves for 

Breckenridge Reservoir, Virginia. 

Bathymetric Contours of Breckenridge Reservoir, Quantico, Virginia
 

By 

S.M. Wicklein, R.R. Lotspeich, and R.B. Banks III 

2012