760

750

740

760

760

770

760

750

750

790

800

780

790

790

790

790

780

780

780

780

780

780

810

800

800

SC-9

SR-42-37

SR-42-213

SR-42-212

SR-42-849

SR-42-74

SR-42-74

82°7' 82°6' 82°5' 82°4' 82°3' 82°2' 82°1' 82°0' 81°59' 81°58'

35°7'

35°6'

26

Figure 3. Bathymetry of Lake William C. Bowen and South Pacolet River Municipal Reservoir No. 1, Spartanburg County, South Carolina, February 2008.

Dam

Dam

Lake

William

C. Bowen

USGS gaging

station 02154950

Extent of data collection and survey

02154950

INDEX CONTOUR—Interval 10 feet. Datum NGVD 29

INTERMEDIATE CONTOUR—Interval 2 feet

EXPLANATION

Hydrography from 1:24,000-scale National Hydrography Dataset except

Lake Bowen and Municipal Reservoir shorelines which were digitized

from digital orthophotos captured on March 4, 2006

Universal Transverse Mercator projection, Zone 17

North American Datum of 1983

ROAD CROSSING LAKE AND ROAD NUMBER

USGS GAGING STATION AND NUMBER

0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 FEET

0 500 1,000 1,500 2,000 METERS

Abstract 

The increasing use and importance of lakes for water supply to communities 

enhance the need for an accurate methodology to determine lake bathymetry and 

storage capacity. A global positioning receiver and a fathometer were used to 

collect position data and water depth in February 2008 at Lake William C. Bowen 

and Municipal Reservoir #1, Spartanburg County, South Carolina. All collected 

data were imported into a geographic information system database. A bathymetric 

surface model, contour map, and stage-area and -volume relations were created 

from the geographic information database.

Introduction

Bathymetric surveys can be used to create maps of the lakebed and to compute water-level (stage) area and volume tables so that water-supply managers 

can regulate the use of these valuable resources more reliably. Knowledge of 

reservoir volume is particularly important for the management of water-supply 

reservoirs during periods of drought or high-water use in the area supplied by 

the lake. These data also can be used to document areas of sediment deposition 

and changes in storage volume, and when compared to historical surveys, to 

estimate sediment-deposition rates. As part of an investigation to assess waterquality conditions affecting taste and odor compounds in Lake William C. Bowen 

and Municipal Reservoir #1 (fig. 1), the U.S. Geological Survey (USGS), in

cooperation with the Spartanburg Water System (SWS), collected bathymetric

and shoreline data from these two reservoirs. 

Purpose and Scope

The purpose of this report is to provide the SWS personnel with bathymetric, stage-area, and stage-volume data that can be used to more effectively plan 

and manage the water resources available for Spartanburg County. The USGS 

conducted a bathymetric survey of Lake William C. Bowen and Municipal 

Reservoir #1 during February 2008. The survey was conducted using a global 

positioning system (GPS) receiver and data logger interfaced to a fathometer. 

The field data were differentially corrected and then transferred to groundwater 

modeling system (GMS) software and a geographic information system (GIS), 

which were used to map contour lines and determine stage-area and stage-volume 

curves. Since no previous bathymetric surveys exist for the study area, the results 

of this investigation will be a valuable tool by which to compare future surveys 

to predict sedimentation rates, sediment distribution, and the longevity of the 

two reservoirs.

Description of Study Area

Lake William C. Bowen is a manmade lake created in 1960 by the impoundment of the South Pacolet River (fig. 1). At full pool elevation of 815 feet (ft) 

relative to National Geodetic Vertical Datum of 1929 (NGVD 29), Lake 

William C. Bowen is an impoundment of 1,530 acres with 33.0 miles (mi) of 

shoreline (J. Cann, Spartanburg Water System, oral commun., June 2007). 

Water flows from Lake William C. Bowen downstream into a second 

impoundment, Municipal Reservoir #1, which was created in 1926 (fig. 1). At 

full pool elevation of 777 ft (NGVD 29), the lake surface of Municipal 

Reservoir #1 covers 272 acres with 13.1 mi of shoreline (J. Cann, Spartanburg Water System, oral commun., June 2007). Recreational activities are 

allowed on Lake William C. Bowen but are restricted on Municipal Reservoir #1.

Outflow from Municipal Reservoir #1 is about 2,600 ft upstream from the confluence of the South and North Pacolet Rivers.

The South Pacolet River watershed, which encompasses these lakes, drains 

91.4 square miles (mi2

) and is located in Spartanburg and eastern Greenville 

Counties, South Carolina (SC; fig. 1). The entire watershed for Lake William C. 

Bowen and Municipal Reservoir #1 lies within the Piedmont Physiographic 

Province. Flow in the South Pacolet River is measured at USGS gaging station 

02154790 (South Pacolet River near Campobello, SC). This gaging station is 

located 1.1 mi upstream from Lake William C. Bowen and monitors a drainage 

area of 55.4 mi . The average annual flow measured at station 02154790 2

was 96.6 cubic feet per second (ft3

/s) for the period 1989–2007 (U.S. Geological 

Survey, 2008).

Data-Collection Methodology

Bathymetric data were collected by interfacing a 12-channel GPS receiver 

and data logger (TrimbleTM Pro XL with TDC1 data logger running Asset SurveyorTM firmware) to a dual-frequency fathometer. The fathometer was set to the 

200-kilohertz (kHz) frequency because this signal produces greater detail and 

resolution relative to the lower frequency of 50 kHz, which produces a wider 

signal and generally is used to transverse depths greater than 400 ft. The horizontal coordinates and times in which the signals were received were recorded by the 

data logger. The depth soundings from the fathometer also were time-tagged and 

recorded to the data logger. These data were processed by using GPS mapping 

software (TrimbleTM Pathfinder Office 3.00). The horizontal coordinate information was differentially corrected from a dataset from another GPS receiver 

known as a base station. In this investigation, the closest base station used was a 

continuously operating reference station (CORS) operated and maintained by the 

National Geodetic Survey (NGS). Data processed this way, by using a GPS, can 

be expected to achieve accuracies in the horizontal of 1 meter (m) (multiply by 

3.281 to convert to feet) or less. Any horizontal coordinates that were found to 

be out of this tolerance were deleted from the dataset. The depth soundings were 

assigned a horizontal coordinate by interpolating the time reading from both sets 

of measurements.

The travel time of the sound pulse from a fathometer is measured either electronically in a depth digitizing device or mechanically (graphically) on an analog recording-type instrument. The accuracy of the absolute time measurement 

generally varies with depth because of signal attenuation, noise, and the ability 

of the measurement circuitry to correlate the outgoing and incoming pulses. In 

addition, the acoustic reflectivity characteristics of the target (size, shape, orientation, material, and so on) can significantly affect the returning pulse. Variations in return-signal strength and sharpness will affect the depth measurement 

accuracy. The irregularity of the reflected pulse causes uncertainty in the overall 

time-measurement process. There is no practical calibration process for minimizing this error. The accuracy of echo-sounding time measurement usually is 

rated by manufacturers at plus or minus (+/–) 0.1 ft plus 0.1 to 0.5 percent of 

the depth (U.S. Army Corps of Engineers, 2002). Depth readings were verified 

periodically by using a steel tape measured to tenths of a foot. 

Data were collected during February 2008. Transects were selected by plotting them on a 1:24,000-scale USGS topographic map and using visual recognition and line-of-sight landmarks (fig. 2). In this figure, while the transects are 

shown as lines they are actually comprised as data points. 

Shoreline data were digitized from March 4, 2006, aerial photography, and 

water-surface elevation data were monitored from USGS streamgaging station 

02154950 in Lake William C. Bowen and from a staff gage in Municipal Reservoir #1 that was manually read in the morning and in the afternoon. Table 1 

summarizes the data-collection dates, range of surface-water elevations, and 

number of data points collected in Lake William C. Bowen and Municipal 

Reservoir #1.

Data Analysis

The differentially corrected data were exported to a spreadsheet. The lake 

and reservoir levels that coincide with the date and time that the bathymetry data 

were collected also were exported into the spreadsheet. The depths were then 

subtracted from the recorded water level so that all depths for the data-collection 

period were based on a common datum. For the purposes of this report, all vertical data were referenced to NGVD 29.

A 2-ft contour interval map was produced for Lake William C. Bowen and 

Municipal Reservoir #1 using three-dimensional surface-mapping software 

(Environmental Modeling Systems, Inc.; fig. 3). The point data collected in 

the bathymetric surveys were interpolated using a geostatistical technique called 

natural neighbor interpolation (Sibson, 1981). Natural neighbor interpolation is 

based on the Thiessen polygon network of the scatter point set. Stage-volume 

and stage-area curves also were generated from this software (figs. 4–7; 

tables 2, 3). The upper-most water-surface elevations of 815.12 ft and 776.09 ft, 

for Lake Bowen and Municipal Reservoir #1, respectively, were the stages when 

the aerial photography was taken on March 6, 2006.

Two historical maps of the lake and reservoir area that were constructed 

prior to impoundment were obtained from the National Archives and Records 

Administration. However, both maps, dated 1907 and 1934, respectively, were 

at a scale of 1:125,000 and a contour interval of 100 ft and were not detailed 

enough to be useable. Therefore, no comparisons were made to document areas 

of sediment deposition or estimate rates of sediment deposition. 

Summary

A bathymetric survey was conducted on Lake William C. Bowen and Municipal Reservoir #1, Spartanburg County, South Carolina, in February 2008. The 

survey was performed by using a dual-frequency fathometer to collect water 

depths and a mapping-grade GPS receiver mounted above the fathometer to 

collect horizontal-position data. The accuracy of the vertical measurement 

obtained by echo sounding usually is rated by manufacturers at +/- 0.1 ft plus 

0.1 to 0.5 percent of the depth. The horizontal coordinates had an accuracy 

of 1 m (multiply by 3.281 to convert to feet) or less. The results of the survey 

included area and volume curves and a bathymetric-contour map.

References Cited

Environmental Modeling Systems, Inc., accessed on December 12, 2008, at

http://www.aquaveo.com/gms

National Records and Archives Association, Quadrangle RG 57: Scale 125,000, 

NC-Saluda (1907), and Quadrangle RG 57: Scale 125,000 NC-Saluda (1934).

Sibson, R., 1981, A brief description of natural neighbor interpolation, in Bar -

nett, V., ed., Interpreting multivariate data: New York, John Wiley & Sons, 

p. 21–36.

Trimble Pathfinder OfficeTM mapping software accessed December 19, 2008, at 

http://trl.trimble.com/docushare/dsweb/Get/Document145149/13269O_

GPS%20Pathfinder%20Office_DS_1208_LR.pdf

Trimble Pathfinder Pro-XLTM and TDC1 Data logger, accessed December 19, 

2008, at http://weather.nmsu.edu/Teaching_Material/SOIL698/dinus/gps/

sld001.htm

U.S. Army Corps of Engineers, 2002, Engineering and design, hydrographic 

surveying, Manual No. 1110-2-1003, chapter 9, 46 p.; accessed on December 22, 

2008, at http://www.usace.army.mil/publications/eng-manuals/em1110-2-

1003/c-9.pdf

U.S. Geological Survey, 2008, Water-resources data for the United States, 

water year 2007: U.S. Geological Survey Water-Data Report WDR-US-2007, 

accessed December 23, 2008, at http://wdr.water.usgs.gov/wy2007/search.jsp

Lake William

C.

Bowen

Inman

Campobello

Fingerville

Boiling Springs

82°8' 82°6' 82°4' 82°2' 82°0' 81°58'

35°8'

35°6'

35°4'

02154790 02155500

26

Dam

Dam

North

Pacolet

02154500 River

02154950

Pacolet

River

Municipal Reservoir # 1

 watershed boundary

USGS gaging station

02154790 location and number

EXPLANATION

9

11

0 1 2 MILES

0 1 2 KILOMETERS

Fingerville

82°6' 82°4' 82°2' 82°0'

35°8'

35°6'

35°4'

26

Dam Dam

Lake William C. Bowen

0 1 2 MILES

0 1 2 KILOMETERS

9

11

Bathymetric data-collection point

EXPLANATION

Figure 1. Lake William C. Bowen and Municipal Reservoir #1 in Spartanburg County, Spartanburg, South Carolina.

Figure 2. Bathymetric data-collection points used to generate contours for Lake William C. Bowen and Municipal Reservoir #1 in Spartanburg

County, Spartanburg, South Carolina.

Any use of trade, product, or firm names is for descriptive purposes only and does not imply 

endorsement by the U.S. Government.

Table 1. Measurement dates, water-surface elevations, and number of data points collected in Lake William C. Bowen 

and Municipal Reservoir #1, Spartanburg County, South Carolina.

[SC, South Carolina; ft, feet; elevations are relative to National Geodetic Vertical Datum of 1929; –, data not collected]

Date

Range of water-surface 

elevations for Lake 

Bowen, SC (ft)

Number of bathymetric 

points collected in Lake 

Bowen, SC

Range of water-surface 

elevations for Municipal 

Reservoir #1 (ft)

Number of bathymetric 

points collected in

Municipal Reservoir #1

02-06-2008 815.16 – 815.17 3,287 – –

02-07-2008 815.15 3,060 – –

02-08-2008 815.14 – 815.13 2,196 – –

02-13-2008 815.17 – 815.18 2,754 – –

02-14-2008 815.14 821 – –

02-14-2008 – – 777.88 2,282

02-15-2008 – – 777.94 1,698

02-28-2008 – – 777.56 782

Table 2. Stage-area and stage-volume relations for selected 

elevations of Lake William C. Bowen, Spartanburg County, South 

Carolina, February 2008.

Elevation (feet, 

NGVD 29) Surface area (acres) Volume (cubic 

feet x 106)

815.12 1,440 1,040

814 1,400 970

812 1,300 852

810 1,180 742

808 1,100 643

806 979 551

804 897 469

802 768 394

800 698 391

Table 3. Stage-area and stage-volume relations for selected 

elevations of Municipal Reservoir #1, Spartanburg County, South 

Carolina, February 2008.

Elevation (feet, 

NGVD 29) Surface area (acres) Volume (cubic 

feet x 106)

776.09 276 109

776 271 108

774 228 85.5

772 180 67.3

770 131 53.1

768 104 42.7

766 86 34.3

764 72 27.4

762 62 21.5

798

800

802

804

806

808

810

812

814

816

200 400 600 800 1,000 1,200

Elevation, in feet above NGVD 29

Volume, in million cubic feet

LAKE BOWEN VOLUME CURVE

Figure 4. Stage-volume curve for Lake William C. Bowen, Spartanburg 

County, South Carolina, February 2008.

Figure 5. Stage-area curve for Lake William C. Bowen, Spartanburg 

County, South Carolina, February 2008.

Figure 6. Stage-volume curve for Municipal Reservoir #1, Spartanburg

County, South Carolina, February 2008.

Figure 7. Stage-area curve for Municipal Reservoir #1, Spartanburg

County, South Carolina, February 2008.

798

800

802

804

806

808

810

812

814

816

600 700 800 900 1,000 1,100 1,200 1,300 1,400 1,500

Surface area, in acres

LAKE BOWEN STAGE-AREA CURVE

Elevation, in feet above NGVD 29

760

762

764

766

768

770

772

774

776

778

10 20 30 40 50 60 70 80 90 100 110 120

MUNICIPAL RESERVOIR #1 VOLUME CURVE

Volume, in million cubic feet

Elevation, in feet above NGVD 29

760

762

764

766

768

770

772

774

776

778

50 100 150 200 250 300

Surface Area in acres

MUNICIPAL RESERVOIR #1 STAGE-AREA CURVE

Elevation, in feet above NGVD 29

800

810

770

Prepared in cooperation with

SPARTANBURG WATER SYSTEM, SPARTANBURG, SOUTH CAROLINA

SCIENTIFIC INVESTIGATIONS MAP 2009-3076

Bathymetry of Lake William C. Bowen and Municipal Reservoir #1, Spartanburg, South Carolina, 2008

U.S. DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY

Nagle, D.D., Campbell, B.G., and Lowery, M.A., Bathymetry in Spartanburg County, 2008

Bathymetry of Lake William C. Bowen and Municipal Reservoir #1, Spartanburg County, South Carolina, 2008

By 

D.D. Nagle, B.G. Campbell, and M.A. Lowery

2009

Municipal

Reservoir #1

Municipal

Reservoir #1

Base from U.S. Geological Survey

1:24,000-scale digital line graphs

Universal Transverse Mercator projection

Zone 17

North American Datum of 1983

Base from U.S. Geological Survey

1:24,000-scale digital line graphs

Universal Transverse Mercator projection

Zone 17

North American Datum of 1983

770

Atlantic Ocean

GEORGIA

NORTH CAROLINA

Spartanburg

Coa s t a l Pl a in

Pi edm ont

Blue Ridge

SOUTH CAROLINA

GREENVILLE

COUNTY

SPARTANBURG

COUNTY

AREA

SHOWN