Prepared in cooperation with the South Carolina Department of Health and 

Environmental Control

Low-Flow Frequency and Flow Duration of Selected 

South Carolina Streams in the Saluda, Congaree, and 

Edisto River Basins through March 2009

Open-File Report 2012–1253

U.S. Department of the Interior

U.S. Geological Survey
Cover photograph. South Rabon Creek near Gray Court, South Carolina.
Low-Flow Frequency and Flow Duration 

of Selected South Carolina Streams in the 

Saluda, Congaree, and Edisto River Basins 

through March 2009

By Toby D. Feaster and Wladmir B. Guimaraes

Prepared in cooperation with the South Carolina Department of Health 

and Environmental Control

Open-File Report 2012–1253

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2012

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Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Feaster, T.D., and Guimaraes, W.B., 2012, Low-flow frequency and flow duration of selected South Carolina 

streams in the Saluda, Congaree, and Edisto River basins through March 2009: U.S. Geological Survey 

Open-File Report 2012–1253, 53 p.
iii

Contents

Abstract...........................................................................................................................................................1

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

Purpose and Scope ..............................................................................................................................2

Previous Studies ...................................................................................................................................2

Description of the Study Area ............................................................................................................2

Low-Flow Statistics .......................................................................................................................................4

Analytical Approach.............................................................................................................................4

Quality Assurance and Quality Control .............................................................................................6

Results of Quality Assurance and Quality Control Analyses................................................6

Diversions.............................................................................................................................................10

Frequency Analysis ............................................................................................................................10

Record-Extension Technique............................................................................................................12

Partial-Record Type Analysis............................................................................................................13

Flow-Duration Analysis......................................................................................................................14

Analytical Considerations...........................................................................................................................15

Stations 02163000, Saluda River near Pelzer, South Carolina, and 02163001, 

Saluda River near Williamston, South Carolina ......................................................16

Station 02167000, Saluda River at Chappells, South Carolina ............................................16

Station 02169000, Saluda River near Columbia, South Carolina ........................................16

Station 02168504, Saluda River below Lake Murray Dam near Columbia, 

South Carolina ..............................................................................................................16

Station 02164110, Reedy River above Fork Shoals, South Carolina...................................16

Stations 02165000, Reedy River near Ware Shoals, South Carolina, and 

021650905, Reedy River near Waterloo, South Carolina........................................19

Station 02169500, Congaree River at Columbia, South Carolina ........................................19

Considerations for Accuracy of Low-Flow Statistics ............................................................................19

Additional Considerations .................................................................................................................20

Comparison with Previously Published Low-Flow Statistics ...............................................................23

Summary........................................................................................................................................................26

Selected References...................................................................................................................................27

Figures

1. Map showing the eight major river basins in South Carolina as defined 

by the South Carolina Department.of Health and Environmental Control...........................3

2. Map showing streamgaging stations in the Saluda, Congaree, and Edisto 

River basins of South Carolina, as well as the physiographic provinces, 

and 8-digit hydrologic-unit code boundaries...........................................................................5

3. Annual minimum 7-day average streamflow at U.S. Geological Survey 

streamgaging stations in South Carolina: 02164000, Reedy River near 

Greenville; 02165200, South Rabon Creek near Gray Court; 02167582, 

Bush River near Prosperity; 02169570, Gills Creek at Columbia; 02173051, 

South Fork Edisto River near Bamberg; 02174250, Cow Castle Creek near 

Bowman; and 02175000, Edisto River near Givhans..............................................................11
iv

4. Low-flow frequency curve for the annual minimum 7-day average streamflow 

for the U.S. Geological Survey streamgaging station 02173000, South Fork Edisto 

River near Denmark, South Carolina. ......................................................................................13

5. Correlation of annual minimum 7-day average streamflow at U.S. Geological 

Survey South Carolina streamgaging stations 02172500, South Fork Edisto 

River near Montmorenci; and 02173000, South Fork Edisto River near Denmark 

for the concurrent period of record 1940–1965. ....................................................................14

6. Daily mean flow for stations 02163000, Saluda River near Ware Shoals, 

 South Carolina, and 02163001, Saluda River near Williamston, South Carolina. .............17

7. Annual minimum 7-day average streamflow and the ratio of the median 

weekday to median weekly streamflow and the median weekend to median 

weekly streamflows at U.S. Geological Survey streamgaging station 02167000, 

Saluda River at Chappells, South Carolina.............................................................................18

8. Annual minimum 7-day average streamflow and ratio of the median 

weekday to median weekly streamflow and the median weekend to median 

weekly streamflows at U.S. Geological Survey streamgaging station 02169000, 

Saluda River near Columbia, South Carolina. ........................................................................18

9. (A) Comparison of flow-duration curves for U.S. Geological Survey 

South Carolina streamgaging stations 02164000, Reedy River near Greenville; 

02164110, Reedy River above Fork Shoals; and 02165000, Reedy River near 

Ware Shoals, and (B) flow duration curves normalized by drainage area for 

the same three stations. ............................................................................................................20

10. Daily mean flow for U.S. Geological Survey South Carolina streamgaging 

stations 02165000, Reedy River near Ware Shoals, and 

021650905, Reedy River near Waterloo...................................................................................21

11. (A) Annual minimum 7-day average streamflow and (B) ratio of the median 

weekday to median weekly streamflow and the median weekend to median 

weekly streamflow for the combined records of U.S. Geological Survey 

South Carolina streamgaging stations 02165000, Reedy River near Ware 

Shoals, and 021650905, Reedy River near Waterloo.............................................................22

12. (A) Annual minimum 7-day average streamflow and (B) ratio of the 

median weekday to median weekly streamflow and the median weekend 

to median weekly streamflow for U.S. Geological Survey streamgaging 

station 02169500, Congaree River at Columbia, South Carolina..........................................22

13. Annual minimum 7-day average streamflow and 7Q10 estimates at 

U.S. Geological Survey streamgaging station 02175000, Edisto River near 

Givhans, South Carolina. ...........................................................................................................24

14. Annual minimum 7-day average streamflow and 7Q10 estimates from a 

synthesized dataset where the annual minimum 7-day average streamflows

from U.S. Geological Survey streamgaging station 02175000, Edisto River 

near Givhans, South Carolina, were reversed for the period of record. ...........................24
v

Tables

1. South Carolina Department of Health and Environmental Control (SCDHEC) 

schedule for basin data analysis and statistics availability ..................................................3

2. Low-flow statistics for continuous-record streamgaging stations in the 

Saluda, Congaree, and Edisto River basins of South Carolina............................................29

3. Eight-digit hydrologic unit code subbasins, subbasin name, drainage 

area in South Carolina, and number of U.S. Geological Survey continuousrecord streamgaging stations analyzed per subbasin for the Saluda, 

Congaree, and Edisto River basins of South Carolina............................................................6

4. Streamgaging stations in the Saluda, Congaree, and Edisto River 

basins of South Carolina that were considered for computations 

of low-flow statistics....................................................................................................................7

5. Streamgaging stations for which record was augmented, index 

streamgaging stations, additional climatic years of record, and 

correlation coefficients for gaging stations where record was 

augmented using MOVE.1 for the Edisto River basin of South Carolina ...........................15

6. Streamflow regulation in the Saluda River basin, South Carolina .....................................17

7. Unit annual minimum 7-day average streamflow with a 2- and 10-year 

recurrence interval for U.S. Geological Survey streamgaging stations 

on the Saluda and Reedy Rivers, South Carolina..................................................................24

8. Differences between the annual minimum 7-day average streamflow 

with a 10-year recurrence interval in this report and previously 

published values for continuous-record streamgaging stations in 

the Saluda, Congaree, and Edisto River basins of South Carolina.....................................25
vi

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2

) 2.590 square kilometer (km2)

Volume

cubic foot (ft3

) 0.02832 cubic meter (m3)

Flow rate

cubic foot per second (ft3

/s) 0.02832 cubic meter per second (m3/s)

million gallons per day (Mgal/d) 0.04381 cubic meter per second (m3

/s)

Horizontal coordinate information is referenced to the North American Datum of 1927 (NAD 27) 

or 1983 (NAD 83). Vertical coordinate information is referenced to the National Geodetic Vertical 

Datum of 1929 (NGVD 29).

Acronyms and abbreviations

CR continuous record

CY climatic year

loratio ratio of the 10 percentile to the 50 percentile of the average 7-day flows

MOVE.1 Maintenance of Variance Extension, Type 1

PR partial record

QAQC quality assurance and quality control

SCDNR South Carolina Department of Natural Resources

SCDHEC South Carolina Department of Health and Environmental Control

TMDL total maximum daily load

USGS U.S. Geological Survey

WWQMS Watershed Water Quality Management Strategy

7Q2 annual minimum 7-day average streamflow with a 2-year recurrence interval

7Q10 annual minimum 7-day average streamflow with a 10-year recurrence interval
Low-Flow Frequency and Flow Duration of Selected 

South Carolina Streams in the Saluda, Congaree and 

Edisto River Basins through March 2009 

By Toby D. Feaster and Wladmir B. Guimaraes

Abstract

Part of the mission of the South Carolina Department 

of Health and Environmental Control and the South Carolina 

Department of Natural Resources is to protect and preserve 

South Carolina’s water resources. Doing so requires an ongoing understanding of streamflow characteristics of the rivers 

and streams in South Carolina. A particular need is information concerning the low-flow characteristics of streams, which 

is especially important for effectively managing the State’s 

water resources during critical flow periods, such as during 

periods of severe drought like South Carolina has experienced 

in the last decade or so.

The U.S. Geological Survey, in cooperation with the 

South Carolina Department of Health and Environmental 

Control, initiated a study in 2008 to update low-flow statistics 

at continuous-record streamgaging stations operated by the 

U.S. Geological Survey in South Carolina. This report presents 

the low-flow statistics for 25 selected streamgaging stations 

in the Saluda, Congaree, and Edisto River basins in South 

Carolina, and includes flow durations for the 5-, 10-, 25-, 50-, 

75-, 90-, and 95-percent exceedances and the annual minimum 

1-, 3-, 7-, 14-, 30-, 60-, and 90-day average flows with recurrence intervals of 2, 5, 10, 20, 30, and 50 years, depending 

on the length of record available at the streamgaging station. 

The low-flow statistics were computed from records available 

through March 31, 2009. 

Of the 25 streamgaging stations for which recurrence 

interval computations were made, 20 were compared to lowflow statistics that were published in previous U.S. Geological Survey reports. A comparison of the low-flow statistics 

for the annual minimum 7-day average streamflow with a 

10-year recurrence interval (7Q10) from this study with the 

most recently published values indicates that 18 of the 20 

streamgaging stations have values lower than the previous 

published values. The low-flow statistics are influenced by 

length of record, hydrologic regime under which the record 

was collected, analytical techniques used, and other changes, 

such as urbanization, diversions, droughts, and so on, that may 

have occurred in the basin.

Introduction

Low-flow stream statistics are used by State agencies in 

South Carolina (SC), such as the South Carolina Department 

of Health and Environmental Control (SCDHEC) and the 

South Carolina Department of Natural Resources (SCDNR), 

for many applications, including determining waste-load allocations for point sources, development of total maximum daily 

loads (TMDLs) for streams, determining the quantity of water 

that can be withdrawn safely from a particular stream, and 

preparing the State Water Plan. In addition, low-flow statistics 

are useful for improving the general level of understanding 

of natural and regulated stream systems. The droughts of the 

past decade in South Carolina (South Carolina Department of 

Natural Resources, 2012) have heightened awareness of the 

importance of having up-to-date statistics for making critical 

water-resources decisions. 

Because of the importance of these applications, it is 

critical to effectively measure and document stream baseflow data for use in updating low-flow statistics on a regular 

basis, preferably about every 10 years. Low-flow statistics, as 

defined in this report, are annual minimum daily mean streamflow averaged over designated time periods (Riggs, 1972). The 

use of “average” with respect to the low-flow statistics in this 

report refers to the arithmetic mean. Low-flow statistics for 

streams in South Carolina have not been updated in a systematic way since 1987. In 2008, the U.S. Geological Survey 

(USGS), in cooperation with the SCDHEC, initiated a study to 

update low-flow statistics at continuous-record streamgaging 

stations (hereafter referred to as stations in this report) operated by the USGS in South Carolina. The investigation was 

originally planned (2008) for a period of 5 years to coincide 

with the SCDHEC Watershed Water Quality Management 

Strategy (WWQMS) for monitoring and assessment of eight 

major river basins in South Carolina (fig. 1), which is completed every 5 years (South Carolina Department of Health 

and Environmental Control, 2009, table 1). However, the 

schedule for updating the low-flow statistics was modified 

(2010) at the request of the SCDHEC. The remaining basins 

will now be assessed by the USGS on a 2-year schedule, and 
2 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

the results will be published during the second year (table 1). 

The SCDHEC incudes the Congaree River basin as part of the 

Saluda River basin and, although the Congaree River basin is 

not listed in table 1, it was included in the analysis. 

Purpose and Scope

The purpose of this report is to present updated low-flow 

statistics at continuous-record (CR) stations in the Saluda, 

Congaree, and Edisto River basins of South Carolina. Depending on the length of record available at the CR stations, the 

report presents estimates of annual minimum 1-, 3-, 7-, 14-, 

30-, 60-, and 90-day average streamflows with recurrence 

intervals of 2, 5, l0, 20, 30, and 50 years. Low-flow statistics 

are presented for 25 CR stations. In addition, daily flow durations for the 5-, 10-, 25-, 50-, 75-, 90-, and 95-percent exceedances are presented for these stations (table 2, located at the 

end of the report). 

The scope of this report includes unregulated and 

regulated streams in the Saluda, Congaree, and Edisto River 

basins of South Carolina. In order for the low-flow statistics 

to be updated for CR stations included in the previous study 

(Zalants, 1991a, b), at least 3 years of additional streamflow 

data had to be collected after 1987. Of the new CR stations 

that began collecting data after 1987, only the stations that had 

at least 5 years of data were included. 

Daily mean streamflow data for this study were collected 

through March 31, 2009, which is the end of the 2008 climatic 

year. The climatic year (CY) is a continuous 12-month period 

during which a complete annual cycle occurs and is arbitrarily 

selected for the presentation or analysis of data relative to 

hydrologic or meteorological phenomena (Langbein and Iseri, 

1960). The CY is usually designated by the calendar year during which most of the 12 months occur. For this investigation, 

the CY is the 12-month period from April 1 through March 31 

and is designated by the year in which it begins. For example, the 2008 CY is the period from April 1, 2008, through 

March 31, 2009. In South Carolina, minimum streamflows 

typically occur in the fall months (September, October, and 

November) and, therefore, use of the CY, as defined, prevents 

the annual low-flow cycle from being artificially placed in 

separate years. 

Previous Studies

Previous reports by Stallings (1967), Johnson and 

others (1968), Bloxham and others (1970), Bloxham (1976, 

1979, 1981), Barker (1986), Zalants (1991a,b), Feaster 

and Guimaraes (2009), and Guimaraes and Feaster (2010), 

described the low-flow frequency and flow-duration streamflows for selected CR stations and partial-record (PR) stations in South Carolina. Stallings (1967) presented low-flow 

statistics for 61 CR stations and 83 other sites where flow 

was measured during the 1954 drought. Johnson and others 

(1968) focused on the low-flow statistics of streams in Pickens 

County. Low-flow streamflow measurements from 1945 

through 1967 were presented for 32 PR stations. The PR stations were correlated with 4 index stations to estimate annual 

minimum 7-day average streamflow with 2- and 10-year recurrence intervals (7Q2 and 7Q10, respectively). Bloxham and 

others (1970) presented magnitude and frequency of low-flow 

streamflows for 9 CR stations in Spartanburg County, and 

streamflow measurements were presented for 63 sites. At 35 of 

the 63 sites, correlation methods were used with index stations 

to estimate the 7Q2 and 7Q10. Bloxham (1976) used 6 index 

stations from the upper Coastal Plain to estimate the 7Q2 and 

7Q10 at 54 PR stations and miscellaneous-measurement sites. 

Bloxham (1979) used data through the 1976 CY to compute 

low-flow frequency and flow-duration estimates at 71 CR 

stations in South Carolina. Bloxham (1981) estimated the 

7Q2 and 7Q10 at 113 PR stations in the Piedmont and lower 

Coastal Plain of South Carolina. Barker (1986) detailed the 

establishment of 361 PR stations with measurements made 

from August 1980 through July 1986. Zalants (1991a) provided estimates of the 7Q2 and 7Q10 at 564 PR stations and 

27 CR stations on streams in the Blue Ridge, Piedmont, and 

upper Coastal Plain Physiographic Provinces in South Carolina and parts of North Carolina and Georgia. Zalants (1991b) 

provided estimates of annual minimum 1-, 3-, 7-, 14-, 30-, 60-, 

and 90-day average streamflows with recurrence intervals of 

2 to 50 years, depending on the length of record, for 55 CR 

stations in South Carolina for which at least 5 years of unregulated daily mean streamflow data were available through the 

1986 CY. Feaster and Guimaraes (2009), and Guimaraes and 

Feaster (2010), presented low-flow statistics for 17 and 23 

CR stations in the Pee Dee and Broad River basins in South 

Carolina, respectively. Estimates are presented for the Pee 

Dee River basin through the 2006 CY and for the Broad River 

basin through the 2007 CY. In addition, daily flow durations of 

the 5- to 95-percent exceedances were presented for most of 

these stations. Much of the general information for this report 

was taken directly from Feaster and Guimaraes (2009) and 

Guimaraes and Feaster (2010).

Description of the Study Area

The Saluda River basin of South Carolina includes parts 

of the Blue Ridge, Piedmont, and upper Coastal Plain Physiographic Provinces (fig. 2). The headwaters of the Saluda River 

basin begin in the Blue Ridge Physiographic Province and 

flow toward the City of Greenville. The Saluda River eventually converges with the Reedy River near the City of Greenwood in the headwaters of Lake Greenwood. The Saluda River 

then flows toward Columbia where it flows into Lake Murray. 

The Saluda River basin ends in Columbia at its convergence 

with the Broad River where it forms the Congaree River. The 

Congaree River then flows south and east where it converges 

with Wateree River in the headwaters of Lake Marion to form 

the Santee River. 
Introduction 3

ofr20121253_fig 01

EXPLANATION

Major river basin

Pee Dee

Broad

Saluda

Santee

Edisto

Salkehatchie

Savannah

0 20 40 60 80 MILES

0 20 40 60 80 KILOMETERS

Catawba-Wateree

CONGAREE SUBBASIN

Base from 1:500,000-scale hydrography dataset

and 1:250,000-scale watershed boundary dataset.

Albers Equal Area projection; central meridian –96°00’;

rotation angle –8.5°; datum NAD 27.

N

Area shown

NORTH

CAROLINA

SOUTH

CAROLINA

GEORGIA

Atlantic Ocean

Figure 1. Map showing the eight major river basins in South Carolina as defined by the South Carolina Department of 

Health and Environmental Control.

Table 1. South Carolina Department of Health and Environmental Control 

(SCDHEC) schedule for basin data analysis and statistics availability.

SCDHEC basin name 

(fig. 1)

Data analysis, 

year1

Low-flow information 

available, year1

Pee Dee 2008 2009

Broad 2009 2010

Saluda and Edisto 2010 and 2011 2012

Catawba-Wateree and Santee 2012 and 2013 2014

Savannah and Salkehatchie 2013 and 2014 2015

1

The year is the Federal fiscal year, which begins in October and ends in September, 

and is designated by the calendar year in which it ends. For example, year 2009 is the 

12-month period from October 1, 2008, through September 30, 2009.
4 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

The Edisto River basin includes parts of the upper and 

lower Coastal Plain Physiographic Provinces of South Carolina. The North and South Fork Edisto Rivers begin in the 

upper Coastal Plain Physiographic Province and converge near 

the town of Branchville, South Carolina, to form the Edisto 

River (fig. 2). The Edisto River then flows south and east 

through the lower Coastal Plain Physiographic Province and 

eventually flows to the Atlantic Ocean at Edisto Island, south 

of Charleston, SC. 

Within South Carolina, the Saluda, Congaree, and Edisto 

River basin encompasse approximately 6,630 square miles 

(mi2) and includes all or part of six 8-digit (subbasin) hydrologic units (Eidson and others, 2005; fig. 2; table 3). There are 

many man-made reservoirs in the study area. For example, 

there are more than 150 State and Federally-regulated dams 

and more than 2,500 non-regulated dams (mostly owned by 

private citizens), in the Saluda River basin upstream from 

Lake Greenwood. There are two reservoirs in the Saluda River 

basin that have surface areas that exceed 10,000 acres: Lake 

Greenwood (11,400 acres) and Lake Murray (51,000 acres) 

(South Carolina Department of Natural Resources, 2009). 

The reservoirs within the study area have varying degrees of 

storage capacity and some are used for hydroelectric power 

generation (see remarks, table 2).

Low-Flow Statistics

Hydrologic information on the availability of streamflow 

under low-flow conditions is essential for the effective management of water resources. Low-flow statistics that define the 

magnitude and frequency of low-flow events typically are provided as a minimum average streamflow over some designated 

time period at a streamgaging location. For example, one of 

the most common low-flow statistics is the annual minimum 

7-day average streamflow with a 10-year recurrence interval 

(7Q10). In terms of probability of occurrence, there is a onetenth or 10-percent probability that the annual minimum 7-day 

average streamflow in any single year will be equal to or less 

than the estimated 7Q10 value for a specific location (Riggs, 

1985).

Analytical Approach

The analyses of CR stations included in this study were 

based on four categories of stations: (1) long-term record stations; (2) short-term record stations that have at least 10 years 

of record; (3) stations that have between 5 and 10 years of 

record, which were analyzed for a limited set of low-flow 

statistics by using techniques typically used in analyzing PR 

stations; and (4) regulated stations. 

Typically, low-flow statistics are computed at CR stations 

if at least 10 years of record are available; however, computing 

low-flow statistics from long-term records is preferred because 

the long-term records are considered to be more representative 

of a broader range of hydrologic conditions. Thus, long-term 

streamgaging data are better suited for trend assessments 

and statistical estimates. The USGS uses a value of 30 years 

of streamflow record to designate long-term streamgages 

(U.S. Geological Survey, 2009). 

 For stations with short-term records (those which have 

at least 10 years of record but less than about 30 years), the 

low-flow statistics can be improved by using record extension 

or augmentation methods (Hirsch, 1982) based on correlations 

with long-term stations. This approach is particularly beneficial if the streamflow data at the short-term record station were 

collected during an unusually dry, wet, or otherwise unrepresentative period. As a result, the record-extension techniques 

allow a more representative range of low-flow conditions at 

the site. For the short-term records included in this study for 

which no suitable index station was available, the low-flow 

statistics were computed using the measured data. In situations 

where long-term record stations (more than 30 years of record) 

are not candidates for record augmentation, if two long-term 

record stations are located on the same stream, and one of the 

stations has many more years of record that includes different 

hydrologic conditions, it also may be beneficial to extend the 

long-term record station that has the least years of record. This 

report presents selected low-flow statistics for three CR stations where record-extension techniques were applied. 

A standard PR station is a site where limited streamflow 

data are collected on a systematic basis over a period of years 

for use in hydrologic analyses. For low-flow analyses, typically 10 to 20 base-flow measurements are made over a period 

of about 2 years. Then, mathematical or graphical techniques 

are used to correlate the base-flow measurements with concurrent daily mean flows at a CR station (index station) (Riggs, 

1972; Zalants, 1991a). As noted by Riggs (1972), such a relation can be used to define a limited set of low-flow statistics 

at the PR station, but should not be used to define an entire 

frequency curve, because to do so would imply a greater accuracy than is warranted. Consequently, only the annual minimum 7-day average low-flow statistics with 2- and 10-year 

recurrence intervals (7Q2 and 7Q10, respectively) usually are 

estimated at PR stations (U.S. Geological Survey, 1979). 

This report and study include only CR stations. However, 

as with standard PR stations, similar techniques can be used 

to correlate daily mean flows at CR stations that have more 

than 5 years but less than 10 years of CR streamgaging data. 

In Feaster and Guimaraes (2009) and Guimaraes and Feasater 

(2010), such CR stations were referred to as PR stations and 

represented a third category of stations that were analyzed. 

Similar to the analyses at standard PR stations, only the 7Q2 

and 7Q10 low-flow statistics were estimated at such CR stations. However, no PR stations were analyzed in the Saluda, 

Congaree, and Edisto River basins because no suitable index 

stations were found. Index station criteria will be discussed 

later in the report.

A fourth category of stations included in this study are 

CR stations on regulated streams. If an assessment of the daily 

mean flow at a regulated station indicates that the pattern of 
Low-Flow Statistics 5

ofr20121253_fig02.ai

021650905

02168504

77

85

20

26

95

02162350

02162500

02163000

02163500

02164000

02164110

02165000

02165200

02166970

02167000

02167450

02167582

02169000

02169500

02169570

02169630

02172500

02172640

02173000

02173051

02173500

02174000

02174250

02175000

02162290

02162525

02167200

02167557

02167563

02172300

02163001

021677037

Wateree River

Columbia

03050110

03050204

03050109

03050203

03050205

03050206

03050110

03050204

03050109

03050203

03050205

03050206

Reedy

River

Saluda River

Edisto River Wateree River

Reedy

River

Saluda River

Edisto River

Charleston

Greenville

Greenwood

Edisto

Island

Branchville

82° 81° 80°

35°

34°

33°

NORTH

CAROLINA

SOUTH

CAROLINA

GEORGIA

Area shown

PIEDMONT

UPPER COASTAL PLAIN

LOWER COASTAL PLAIN

Piedmont

Blue Ridge

Lake Greenwood Lake Murray

NORTH CAROLIINA

SOUTH CAROLIINA

GEORGIA Lake Marion

Santee River

Boyd Mill Pond

Conestee Lake

Congaree River

Atlantic Ocean

Lake Greenwood Lake Murray

Lake Marion

Santee River

Boyd Mill Pond

Conestee Lake

Congaree River

Atlantic Ocean

EXPLANATION

03050206

02172500

02163000

Base from ESRI® Data & Maps, 2010

National Hydrography Dataset and digital line graphs, 1:100,000

Watershed Boundary Dataset, 1:24,000

Universal Transverse Mercator projection, zone 17

Subbasin and associated hydrologic unit code

Physiographic province boundary

USGS streamgaging station and number

Low-flow statistics were computed

Noted in text but low-flow statistics were

not computed

0 10 20 30 40 MILES

0 10 20 30 40 KILOMETERS

Figure 2. Streamgaging stations in the Saluda, Congaree, and Edisto River basins of South Carolina, as well as the physiographic 

provinces, and 8-digit hydrologic-unit code boundaries
6 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

Table 3. Eight-digit hydrologic unit code subbasins, subbasin 

name, drainage area in South Carolina, and number of U.S. 

Geological Survey continuous-record streamgaging stations 

analyzed per subbasin for the Saluda, Congaree, and Edisto 

River basins of South Carolina. 

[HUC, hydrologic unit code; mi2, square mile; USGS, U.S. Geological Survey; Subbasins in bold text are wholly contained within South Carolina]

Eight-digit 

(subbasin) 

HUC number 

(fig. 2)

Subbasin 

name

Drainage area in 

South Carolina, 

in mi2

USGS continuousrecord streamgaging 

stations analyzed

03050109 Saluda 2,520 14

03050110 Congaree 689 3

03050203 North 

Fork 

Edisto

759 1

03050204 South 

Fork 

Edisto

1,070 4

03050205 Four Hole 

Swamp

654 2

0305206 Edisto 940 1

Total 6,630 25

regulation has been relatively consistent, and if the logarithms 

of the N-day flows (where N is the number of days used to 

compute the annual minimum average flow) are consistent 

with a Pearson Type III distribution, low-flow statistics can 

be computed for that period using similar techniques for the 

unregulated stations (Riggs, 1972). The techniques used for 

estimating low-flow statistics at PR sites usually are applicable 

only to unregulated streams and, therefore, should not be 

applied to streams that are highly regulated, such as for power 

generation. In addition, the low-flow statistics for regulated 

streams are relevant to similar future regulation patterns and 

would not be applicable if the future regulation patterns were 

altered significantly. Information regarding regulation at applicable CR stations is provided in the “Remarks” sections for 

stations listed in table 2. All stations considered for computations for low-flow statistics are listed in table 4, along with the 

period of record and drainage area.

Quality Assurance and Quality Control

For this study, a quality assurance and quality control 

(QAQC) analysis was done using the daily mean flow data and 

the annual minimum 7-day average streamflow data for CR 

stations that had a minimum of 10 years of record. The data at 

each station were reviewed for homogeneity, which suggests 

relatively stable basin conditions during the period of record. 

The Kendall’s tau test was used to assess the homogeneity of 

the record at each station (Helsel and Hirsch, 1992). If a trend 

was indicated (using a significance level of 0.05), additional 

assessments were used to determine if the trend may have 

been caused by a short-term condition. For example, if the 

station record happened to begin or end under extreme conditions (excessively wet or dry), the test may indicate a trend, 

but additional analysis that excludes the extreme events may 

indicate no trend. Trends at unregulated stations may result 

from changes in climatic cycles, land use, groundwater pumpage, or other practices that may affect groundwater levels. For 

stations downstream from a major source of regulation, such 

as a dam, the data were assessed for gross trends, which may 

indicate a long-term change in the pattern of regulation (William Kirby, U.S. Geological Survey, written commun., June 6, 

2005). Additionally, some investigations have shown that substantial urbanization can lead to a reduction in low flows (U.S. 

Environmental Protection Agency, 2009). Final decisions to 

include or exclude data from a specific station were made by 

using hydrologic judgment based on the results of the QAQC 

analyses and other available information, such as comparisons 

with other long-term stations. 

The QAQC analyses included the use of several computer 

programs that were developed by using commercial statistical 

software (SAS Institute, Inc., 1989). The components of the 

QAQC reviews that were conducted for the CR stations are as 

follows.

Plot of the ratios of median daily mean flows during the 

weekend (Saturday and Sunday) and entire week (Sunday 

through Saturday), and work week (Monday through Friday) 

and entire week against CY. These plots are useful for regulated streams and can show if the discharge patterns differ 

from week days to weekends.

The Kendall’s tau test to check for trends in the annual 

minimum 7-day average streamflow data over time.

Plot of the annual minimum 7-day average streamflow 

against CY, which is used along with the Kendall’s tau results 

to assess potential trends.

Plot of the relation of the ratio of the 10th percentile to the 

50th percentile of the average 7-day flows (loratio) against CY, 

which is useful for graphically assessing potential trends.

Plot of the relation of the 50th percentile of the average 

7-day flow against CY. This plot is useful for assessing potential changes in the median average 7-day flow over time.

Plot of the relation of the cumulative loratio against CY. 

A significant change in the slope of this relation indicates a 

change in flow patterns.

Plot of the relation of the cumulative 50th percentile of 

the average 7-day flow against CY. A significant change in the 

slope of this relation indicates changes in the median average 

7-day flow patterns.

Results of Quality Assurance and Quality Control 

Analyses

A trend analysis, as described previously, was made for 

all stations in the investigation and the analyses indicated a 

trend in the annual minimum 7-day average streamflow for the 
Low-Flow Statistics 7

Table 4. Streamgaging stations in the Saluda, Congaree, and Edisto River basins of South Carolina that were considered 

for computations of low-flow statistics.—Continued

[mi2, square miles; MOVE.1, Maintenance of Variance Extension, Type 1]

Streamgaging 

station number 

(fig. 2)

Station name Period of record

Number of 

climatic years 

of record

Drainage area 

(mi2) Remarks

Stations for which low-flow statistics were computed

02162350 Middle Saluda River 

near Cleveland

Oct. 1980 – Sept. 2003 22 21.0

02162500 Saluda River near 

Greenville

Jan. 1942 – Sept.1978, 

and Mar. 1990 – Mar. 

2009

54 295

a

02163001 Saluda River near 

Williamston

May 1995 to Mar. 2009 13 414 The record was combined with USGS 

streamgaging station 

02163000 to complete the record from 

Oct. 1929 to Sept. 

1971 and May 1995 

to Mar. 2009. 

02163500 Saluda River near 

Ware Shoals

Mar. 1939 – Mar. 2009 70 580

02164000 Reedy River near 

Greenville

Nov. 1941 – Sept. 1971, 

and Jun. 1987 – Mar. 

2009

50 48.6

02164110 Reedy River above 

Fork Shoals

Sept. 1993 – Mar. 2009 15 110

b

021650905 Reedy River near 

Waterloo

Nov. 2004 – Mar. 2009 4 251 The record was combined with USGS 

streamgaging station 

02165000 to complete the record from 

Apr. 1939 to Sep. 

2004 and Nov. 2004 

to Mar. 2009. Lowflow statistics were 

computed from Apr. 

1988 to Mar. 2009.

02165200 South Rabon Creek 

near Gray Court

Jan. 1967 – Sept. 1981, 

and May 1990 – Mar. 

2009

29 29.5

02166970 Ninety Six Creek 

near Ninety Six

Oct. 1980 – Sept. 2001 19 17.4 Zero flows

02167000 Saluda River at 

Chappells

Oct. 1926 – Mar. 2009 81 1,360 Low-flow statistics were 

computed from Apr. 

1983 to Mar. 2009.

02167450 Little River near 

Silverstreet

Mar. 1990 – Mar. 2009 18 230
8 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

Table 4. Streamgaging stations in the Saluda, Congaree, and Edisto River basins of South Carolina that were considered 

for computations of low-flow statistics.—Continued

[mi2, square miles; MOVE.1, Maintenance of Variance Extension, Type 1]

Streamgaging 

station number 

(fig. 2)

Station name Period of record

Number of 

climatic years 

of record

Drainage area 

(mi2

) Remarks

Stations for which low-flow statistics were computed—Continued

02167582

02168504

02169000

02169500

02169570

02169630

02172500

02172640

02173000

02173051

02173500

02174000

02174250

02175000

Bush River near 

Prosperity

Saluda River below 

Lake Murray Dam 

near Columbia

Saluda River near 

Columbia

Congaree River at 

Columbia

Gills Creek at Columbia

Big Beaver Creek 

near St. Mathews

South Fork Edisto 

River near Montmorenci

Dean Swamp near 

Salley

South Fork Edisto 

River near Denmark

South Fork Edisto 

River near Bamberg

North Fork Edisto 

River at Orangeburg

Edisto River near 

Branchville

Cow Castle Creek 

near Bowman

Edisto River near 

Givhans

Feb. 1990 – Mar. 2009

Oct. 1988 – Mar. 2009

Aug. 1925 – Mar. 2009

Oct. 1939 – Mar. 2009

Oct. 1966 – Mar. 2009

July 1966 – Sept. 1993

Apr. 1940 – Sept. 1966

Oct. 1980 – Mar. 1987, 

and Feb. 1988 – Oct. 

2000

Aug. 1931 – Sept. 1971, 

and Oct. 1980 – Oct. 

2009

Apr. 1991 – Mar. 2009

Oct. 1945 – Sept. 1996

Oct. 1945 – Sept. 1996

Oct. 1970 – Sept. 1981, 

and Oct. 1995 – Mar. 

2009

Jan. 1939 – Mar. 2009

18

19

82

68

41

25

24

16

65

17

69

49

21

68

115

2,420

2,520

7,850

59.6

10.0

198

31.2

720

807

683

1,720

23.4

2,730

Low-flow statistics were 

computed from Apr. 

1989 to Mar. 2009.

Low-flow statistics were 

computed from Apr. 

1980 to Mar. 2009.

Record extended using 

MOVE.1

Record extended using 

MOVE.1

Record extended using 

MOVE.1

Zero flows

Stations noted in text but for which low-flow statistics were not computed

02162290

02162525

South Saluda River 

near Cross Hill

Hamilton Creek near 

Easely

Feb. 2000 – Sept. 2005

Jan. 1981 – Sept. 1986

5

5

18

1.6

Not analyzed because 

no suitable index 

station was found.

Not analyzed because 

no suitable index 

station was found.
Considerations for Accuracy of Low-Flow Statistics 9

Table 4. Streamgaging stations in the Saluda, Congaree, and Edisto River basins of South Carolina that were considered 

for computations of low-flow statistics.—Continued

[mi2, square miles; MOVE.1, Maintenance of Variance Extension, Type 1]

Streamgaging 

station number 

(fig. 2)

Station name Period of record

Number of 

climatic years 

of record

Drainage area 

(mi2

) Remarks

Stations noted in text but for which low-flow statistics were not computed—Continued

02163000

02165000

02167200

02167557

02167563

021677037

02172300

Saluda River near 

Pelzer

Reedy River near 

Ware Shoals

Watkins Creek near 

Cross Hill

Bush River near 

Joanna

Bush River near 

Newberry

Little Saluda River at 

Saluda

Mc Tier Creek near 

Monetta

Oct. 1929 – Sept. 1986

Apr. 1939 – Sept. 2004

Feb. 1967 – Feb 1975

June 1995 – Sept. 2005

Mar. 1999 – Sept. 2006

May 1992 – Mar. 2009

Oct. 1995 – Mar. 2009

55

63

8

9

9

16

12

405

236

0.62

11.1

62.2

90.0

15.6

Not analyzed because 

of its proximity to 

station 02163001. 

The average daily 

mean flows were 

combined with station 

02163001, to become 

a record from Oct. 

1939 to Sept. 1971, 

and Oct. 1995 to Mar. 

2009.

Not analyzed because 

of its proximity to 

station 02165905. 

The average daily 

mean flows were 

combined with 

station 021650905, to 

become a record from 

Apr. 1939 to Sept. 

2004, and Nov. 2004 

to Mar. 2009. 

Not analyzed because 

no suitable index 

station was found.

Not analyzed because 

zero flows were 

observed at 

station and therefore, MOVE.1 can 

not be used to augment record.

Not analyzed because 

zero flows were 

observed at 

station and therefore, MOVE.1 can 

not be used to 

augment record.

Not analyzed because 

station was in 

backwater from Lake 

Murray

Not analyzed because 

no suitable index 

station was found.

a

 Daily flows from USGS streamgaging station 02163001, Saluda River near Williamston (1995 – 2009) have been combined with daily flows 

from USGS streamgaging station 02163000, Saluda River near Pelzer (1939 – 1971) to produce a daily flow record that results in a data set from 

1939 – 1971 and 1995 – 2009. The proximity of the two streamgaging stations to each other made this possible. 

b

 Daily flows from USGS streamgaging station 021650905, Reedy River near Waterloo (2004 – 2009) have been combined with daily flows 

from USGS streamgaging station 02165000, Reedy River near Ware Shoals (1939 – 2004) to produce a daily flow record that results in a data set 

from 1939 – 2009, but only the period from 1988 – 2009 was used in the analyses because of changes in regulation patterns.The proximity of the 

two streamgaging stations to each other made this possible. 
10 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

period of record at the following stations in South Carolina: 

02164000, Reedy River near Greenville; 02165200, South 

Rabon Creek near Gray Court; 02167582, Bush River near 

Prosperity; 02169570, Gills Creek at Columbia; 02173051, 

South Fork Edisto River near Bamberg; 02174250, Cow 

Castle Creek near Bowman; and, 02175000, Edisto River near 

Givhans. The annual minimum 7-day average streamflow for 

the period of record at these stations is plotted in figure 3. The 

longer period at stations 02164000, 02165200, 02169570, 

and 02175000 reflect the historic dry years that have occurred 

in approximately the last decade. Thus, the trends at these 

stations are likely a result of the hydrologic conditions under 

which these particular records were collected and are not 

related to actual changes in the watershed. As noted by Lins 

and others (2010), sometimes hydrologic records for a timeframe of a few years to a few decades may indicate a trend in 

the data, but when viewed in the context of longer timeframes 

spanning decades to centuries, the short–term trends may be 

recognized as part of a much longer term oscillation. Therefore, low-flow statistics were computed for stations 02164000, 

02165200, 02167582, 02169570, 02173051, 02174250, and 

02175000 using the complete period of record for each station, respectively. Similar patterns also have been noted in the 

low-flow assessments for the Pee Dee River and Broad River 

basins (Feaster and Guimaraes, 2009; Guimaraes and Feaster, 

2010).

One other station that was not analyzed, and therefore, not included in this report was station 021677037, 

Little Saluda River at Saluda, SC. This station (021677037) 

had a period of record from October 1, 1996, through 

March 3, 2007, but because the station was influenced by 

backwater from Lake Murray, the flow values do not fully 

represent natural flow conditions and, therefore, this station 

was excluded. 

Diversions

Diversions from natural streamflows occur for a variety 

of reasons. Some diversions are the result of water-supply 

withdrawals, manufacturing, point-source discharges, and 

agricultural needs, such as irrigation. Diversions by manufacturers are sometimes confined to short distances along rivers. 

Water may be taken from the river channel, passed through the 

manufacturing plant for use in processing, cooling, dilution 

of wastes, and then returned to the river. Therefore, in many 

cases, consumptive losses from diversions by manufacturers 

may be negligible (Ries, 1994). Thus, the effects of diversions 

to the streamflow regime of a river are variable and depend 

not only on where the diversions occur but also on the final 

outcome of the diverted water. 

Ries (1994) noted that water diverted from a stream or 

adjacent aquifer for municipal supplies, which is then returned 

to the basin as effluent from individual septic systems or from 

wastewater- treatment plants within the basin, generally causes 

little loss of water to the basin; however, such diversions may 

affect the temporal pattern of streamflows. Diversions from 

one basin to another reduce streamflow in the donor basin and 

increase streamflow in the receiving basin. Diversions between 

subbasins of a larger basin can substantially affect streamflows 

in the subbasins, but if consumptive losses are negligible, 

streamflows in the larger basin may be nearly unaffected. 

The various diversion scenarios described above, indicates that a proper accounting of all diversions in a basin is 

typically difficult; therefore, most USGS low-flow analyses 

are made on the flow data as measured at the station without adjustments for diversions. For this study, diversion 

data, when available, were obtained from the SCDHEC and 

assessed to determine significance. Diversions upstream from 

a station were considered significant if the average annual 

diversion equaled or exceeded 10 percent of the mean annual 

minimum 1-day streamflow for the period of record. The 

assumptions for this comparison were that the diversion and 

streamflow data are of similar quality and were measured with 

the same frequency and based on concurrent periods of record. 

If these conditions did not exist, assessments still were made 

and comments were noted regarding the diversions in table 2, 

but no adjustments were made to the low-flow estimates. 

Frequency Analysis

Low-flow frequency statistics at CR stations are computed by fitting a series of annual minimum N-day average 

streamflows to some known statistical distribution, where N

can equal any number from 1 to 365. Low-flow frequency 

statistics for this study were computed by fitting logarithms 

(base 10) of the annual minimum 1-, 3-, 7-, 14-, 30-, 60-, and 

90-day average streamflows to a Pearson Type III distribution, 

which also is referred to as a log-Pearson Type III distribution. 

Fitting the distribution requires calculating the mean, standard 

deviation, and skew coefficient of the logarithms of the N-day 

streamflows. Estimates of the N-day nonexceedance flows for 

a specified recurrence interval T are computed by using the 

following equation:

, (1)

where 

QT is the N-day low flow, in cubic feet per second, and 

 T is the recurrence interval, in years; 

 is the mean of the logarithms of the annual minmum 

 N-day average streamflows; 

K is a frequency factor that is a function of the 

 recurrence interval and the coefficient of skew; and 

S is the standard deviation of the logarithms of the 

 annual minimum N-day average streamflows.

Low-flow statistics typically are presented as a set of 

nonexceedance probabilities or, alternatively, recurrence 

intervals along with the associated low-flow values. The nonexceedance probability is defined as the probability that a flow 

at a given station will be equal to or less than the associated 

low-flow value once in a 1-year period, and is expressed as a 

decimal fraction less than 1.0 or as a percentage less than 100. 

logQ X KS T = +

X
Low-Flow Statistics 11

0

10

20

30

40

50

02164000

0

5

10

15

20

25

30

0

5

10

15

20

25

30

35

0

5

10

15

20

02165200

02167582 02169570

02173051

02175000

02174250 

0

100

200

300

400

500

600

700

800

0

1

2

3

4

5

6

1930 1950 1970 1990 2010

0

500

1,000

1,500

2,000

1930 1950 1970 1990 2010

Annual minimum7-day average flow, in cubic feetper second

Climate year

Climate year

Figure 3. Annual minimum 7-day average streamflow at U.S. Geological Survey streamgaging stations in

South Carolina: 02164000, Reedy River near Greenville; 02165200, South Rabon Creek near Gray Court; 02167582,

Bush River near Prosperity; 02169570, Gills Creek at Columbia; 02173051, South Fork Edisto River near Bamberg;

02174250, Cow Castle Creek near Bowman; and 02175000, Edisto River near Givhans 

Annual minimum 7-day average streamflow at U.S. Geological Survey streamgaging stations in 

South Carolina: 02164000, Reedy River near Greenville; 02165200, South Rabon Creek near Gray Court; 02167582, 

Bush River near Prosperity; 02169570, Gills Creek at Columbia; 02173051, South Fork Edisto River near Bamberg; 

02174250, Cow Castle Creek near Bowman; and 02175000, Edisto River near Givhans.
12 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

Recurrence interval is defined as the average interval of years 

(usually referred to as the return period) during which flows 

at a given station will be equal to or less than the associated 

low-flow value once. For example, a low-flow value at a given 

station with a nonexceedance probability of 0.10 indicates that 

flows at that station have a 10-percent chance of being equal 

to or less than the low-flow value once in any given year. 

Recurrence interval and nonexceedance probability are the 

mathematical inverses of one another; therefore, a flow with 

a nonexceedance probability of 0.10 has a recurrence interval 

of 1 divided by 0.10, or 10 years. It should be emphasized that 

recurrence intervals, regardless of length, always refer to an 

average period of time (or years) where flows at a given station will be equal to or less than the associated low-flow value 

once. A 10-year recurrence interval does not mean that the 

low-flow value will have a nonexceedance every 10 years; it 

does indicate, however, that the average time between recurrences is equal to 10 years. Consequently, an observed interval 

between a nonexceedance of the 7Q10 may be as short as 

1 year or may be considerably longer than 10 years.

The low-flow frequency curve is generated by application of equation 1 to a set of annual minimum N-day average 

flows for a range of specified return periods. To estimate 

low-flow statistics for recurrence intervals greater than the 

period of record, these frequency curves must be extended. 

For this study, the following criteria were used to limit the 

extension of the curves based on the period of record at the 

station: The following criteria were established for extending 

frequency curves: 

1. Curves for stations with 10 or more years of annual 

low-flow streamflow record, but less than 20 years 

of record, were extended to a recurrence interval of 

20 years; 

2. Curves for stations with 20 or more years of record, 

but less than 30 years of record, were extended to a 

recurrence interval of 30 years; and 

3. Curves for stations with 30 or more years of record 

were extended to a recurrence interval of 50 years. 

No data were compiled for recurrence intervals 

greater than 50 years. 

An example of the frequency curve using the log-Pearson 

Type III curve-fitting procedure is illustrated in figure 4.

Record-Extension Technique

Streamflow statistics are needed to estimate probabilities of occurrences for periods much longer than the actual 

measured period of record. Consequently, short records that 

may have been collected during an unusually dry, wet, or 

otherwise unrepresentative period may not represent the more 

desirable fuller range of potential hydrologic regimes. Under 

certain conditions, it is possible to extend or augment a short 

record by using a correlated station having a longer record. 

The extended record at the short-term record station will 

better reflect low-flow conditions over a longer period and 

provide better estimates of low-flow statistics at that station. 

The record extension can be accomplished in the following 

manner. 

If a linear relation between the logarithms of the N-day 

flows at a short-term record station is determined to be significantly correlated to a concurrent set of the N-day flows at 

a long-term record station, or index station, a mathematical 

record-extension method known as the Maintenance of Variance Extension, Type 1 (MOVE.1) method (Hirsch, 1982) can 

be used to extend the record at the short-term record station. 

The MOVE.1 relation maintains the mean and the variance of 

the data at the short-term record and, therefore, allows for the 

generation of a longer-term set of data that will possess the 

statistical characteristics of the actual measured data from the 

short-term record. 

The MOVE.1 equation is 

, (2)

where

Yi is the logarithm of the estimated N-day flow for the 

 short-term record station;

is the mean of the logarithms of N-day flows for the 

 concurrent period at the short-term record station;

Sy is the standard deviation of the logarithms of N-day 

 flows for the concurrent period at the short-term 

 record station;

Sx is the standard deviation of the logarithms of N-day 

 flows for the concurrent period at the long-term 

 record station or index station;

Xi is the logarithm of the flow statistic or observed 

 N-day flow at the index station; and

is the mean of the logarithms of the N-day flows for 

 the concurrent period at the index station.

For an index station to be considered for this study, it had 

to have (1) a minimum of 10 years of concurrent record relative to the short-term record station, (2) similar basin geology 

as the short-term record station, and (3) a basin less than 10 

times larger than the size of the smaller basin (Telis, 1991). 

A minimum correlation coefficient between concurrent flows 

has not been developed for the MOVE.1 technique; however, 

similar correlation studies have used values ranging from 0.70 

to 0.80 (Hydrology Subcommittee of the Interagency Advisory 

Committee on Water Data, 1982; Stedinger and Thomas, 1985; 

Ries, 1994; Nielsen, 1999). In addition, if the record at the 

short-term record station or available index station included 

zero flows, record extensions were not applied, because 

including such values in record-extension techniques has not 

been adequately tested (Julie Kiang, U.S. Geological Survey 

Office of Surface Water, written commun., January 26, 2010). 

For gaging stations that have relatively long records, such 

as 30 years or more, record extension may still be beneficial if an index station is available that has additional record 

XX )( S

S

YY i

x

y

i −+=

XX )( S

S

YY i

x

y

i −+=

X
Low-Flow Statistics 13

10

100

1,000

Nonexceedance probability

.9999 .998 .99 .98 .95 .9 .8 .7 .6 .5 .4 .3 .2 .1 .05 .02 .01 .002 .0001

Annual minimum 7-day flow, in cubic feet per second

Figure 4. Low-flow frequency curve for the annual minimum 7-day average streamflow for the

U.S. Geological Survey streamgaging station 02173000, South Fork Edisto River near Denmark,

South Carolina.

Figure 4. Low-flow frequency curve for the annual minimum 7-day average streamflow for the 

U.S. Geological Survey streamgaging station 02173000, South Fork Edisto River near Denmark, 

South Carolina.

collected under hydrologic conditions that are not included 

in the record being analyzed. Currently, no standard criteria 

are available for assessing when use of MOVE.1 is warranted 

with respect to improvement in the low-flow statistics at such 

stations. Therefore, for this investigation, an arbitrary criterion 

was set. If the average difference in the 7-day low-flow statistics (computed from the data at index station for the concurrent period of record as compared to those computed using 

the complete period of record at the index station) was greater 

than 10 percent, MOVE.1 was used to augment the record at 

the station of interest. Otherwise, no augmentation was done. 

Three CR stations in the Edisto River basin met the 

criteria listed above and the records were augmented using 

the MOVE.1 record-extension technique (table 5). Two of 

these stations were 02172500, South Fork Edisto River near 

Montmorenci and 02173051, South Fork Edisto River near 

Bamberg, which used station 02173000, South Fork Edisto 

River near Denmark as the index station. A plot of the relation for the annual minimum 7-day average streamflow 

between stations 02172500, South Fork Edisto River near 

Montmorenci and 02173000, South Fork Edisto River near 

Denmark is shown in figure 5. Additionally, the record at 

station 02174000, Edisto River near Branchville, was augmented using station 02175000, Edisto River near Givhans 

as the index station. The MOVE.1 technique allowed for the 

inclusion of an additional 41 and 50 years of record for stations 02172500 and 02173051, respectively, and an additional 

20 years of record at station 02174000.

Partial-Record Type Analysis

As previously discussed, when limited streamflow data 

are collected on a systematic basis over a period of years for 

use in hydrologic analyses, the data-collection site is called a 

partial-record (PR) station (Zalants, 1991a). With respect to 

low-flow statistics, once a sufficient number of base-flow measurements have been made over a reasonable period of time, 

techniques can be used to transfer low-flow statistics from an 

index station to the PR station (Riggs, 1972). If the relation 

between the flows at the PR station and the index station is 

linear, mathematical correlation methods, such as MOVE.1, 

can be used (Hirsch, 1982). If the relation is nonlinear, then a 

graphical correlation described by Riggs (1972) can be used. 

The MOVE.1 technique can be used to establish a relation between the concurrent daily mean flows. To use daily 

mean flows that are representative of low-flow conditions, 

only concurrent flows that are less than or equal to the 

90-percent flow duration at the index station were used in 

the MOVE.1 analysis. That relation is then used to transfer 

a limited set of low-flow statistics from an appropriate index 

station to the PR station. Criteria similar to those that were 

described for extending the record at a short-term record station can be used with the exception of the concurrent-record 

length. USGS Office of Surface Water Technical Memorandum No. 86.02 (U.S. Geological Survey, 1985), recommended 

that only the 7Q2 and 7Q10 statistics be estimated for the PR 

stations. Because of the limited records available at the PR 

stations, providing a broader set of statistics would suggest an 

accuracy that is not warranted. 
14 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

10

100

1,000

10 100 1,000 10,000

Annual minimum 7-day average flow at station 02172500, South Fork Edisto

River near Montmorenci, South Carolina, in cubic feet per second 

Annual minimum 7-day average flow at station 02173000, South Fork Edisto River

near Denmark, South Carolina, in cubic feet per second 

Figure 5. Correlation of annual minimum 7-day average streamflow at

U.S. Geological Survey South Carolina streamgaging stations 02172500,

South Fork Edisto River near Montmorenci; and 02173000, South Fork

Edisto River near Denmark for the concurrent period of record 1940–1965.

Figure 5. Correlation of annual minimum 7-day average streamflow 

at U.S. Geological Survey South Carolina streamgaging stations 

02172500, South Fork Edisto River near Montmorenci; and 02173000, 

South Fork Edisto River near Denmark for the concurrent period of 

record 1940–1965.

The same MOVE.1 equation (eq. 2) as described previously is used to transfer the low-flow characteristic from the 

index station to the PR station. The difference is that now Xi

is the low-flow characteristic computed from the index or 

long-term record station, and Yi is the low-flow characteristic 

estimated at the PR station. Four CR stations in the Saluda 

or Edisto River basins had greater than 5 years and less than 

10 years of record, but no suitable index stations were found 

for any of the stations. The four CR stations were 02162290, 

South Saluda River near Cleveland; 02162525, Hamilton 

Creek near Easley; 02167200, Watkins Creek near Cross Hill; 

and 02172300, McTier Creek near Monetta. Two additional 

CR stations on the Bush River (02167557, Bush River near 

Joanna and 02167563, Bush River near Newberry) had greater 

than 5 years and less than 10 years of record, and had a suitable index station, but because both stations had minimum 

daily flows of 0.0 cubic feet per second (ft3/s), no computations were done. 

Flow-Duration Analysis

Flow durations represent the percentage of time that a 

specified streamflow is equaled or exceeded during a given 

period (Searcy, 1959). Flow durations are computed by 

sorting the daily mean flows for the period of record from 

the largest value to the smallest value and assigning each 

streamflow value a rank, starting from 1 to the largest value. 

The frequencies of exceedance are then computed using the 

Weibull formula for computing plotting position (Helsel and 

Hirsch, 1992):

P = 100 * [M / (n+1)] , (3)

where

P is the probability that a given flow will be equaled or 

 exceeded (percentage of time),

M is the ranked position (dimensionless), and

n is the number of events for the period of record 

 (dimensionless). 

Flow durations are a summary of the past hydrologic 

events. Yet, if the streamflow during the period for which the 

duration curve is based is a sufficiently long period of record, 

the statistics can be used as an indicator of probable future 

conditions (Searcy, 1959). To compare flow durations at different stations or in different basins, flow-duration estimates 

can be normalized by drainage area to represent a streamflow 

per unit area. Again, it should be noted that the most useful 

comparisons will be those based on similar lengths of record 

from similar hydrologic periods.

Flow durations for this report are presented in tabular 

form for the 5-, 10-, 25-, 50-, 75-, 90-, and 95-percent exceedances (table 2). To be consistent with the low-flow statistics, 

flow durations were computed based on the CY using daily 

mean flows through March 2009. For stations where recordextension techniques were used to extend a short-term record 

based on a relation to a long-term record (table 5), daily mean 
Analytical Considerations 15

flows were extended by using MOVE.1. Limited sensitivity 

tests indicated that this extension technique was appropriate for flows between the 5- and 95-percent duration values 

(Julie Kiang, U.S. Geological Survey Office of Surface Water,

written commun., January 26, 2010). The flow durations were 

computed by combining the measured data with the synthesized data generated from the record extension. 

Analytical Considerations

Streamflow statistics computed at CR stations are based 

on historical streamflow records but can be useful for making decisions about the future if it can be reasonably assumed 

that the future streamflow patterns are likely to be relatively 

similar to historical streamflow patterns. Thus, streamflow 

statistics computed from records that capture a wide range of 

hydrologic conditions are more desirable. When a stream is 

influenced by regulation, techniques for estimating low-flow 

statistics that are similar to those used for analysis of natural 

streams can be applied; however, consistency in the regulation patterns also must be considered. If assessments of the 

historical streamflow records indicate that the regulation 

patterns have been relatively consistent and if the logarithm 

of the annual minimum flows for a given averaging period 

are consistent with a Pearson Type III distribution, low-flow 

statistics can be computed for the regulated station with the 

understanding that using those statistics for future planning 

assumes relatively similar regulation patterns will occur in the 

future (Riggs, 1972). 

In the upper part of the basin, the Saluda River is regulated by a number of dams, many of which are run-of-the-river 

dams that tend to have little to no water storage capacity, and 

are sometimes associated with small hydroelectric operations 

that can have an influence on flow patterns, particularly for the 

lowest averaging periods, such as annual minimum 1-day and 

3-day average flows (table 6; U.S. Army Corp of Engineers, 

2007). The influence that the run-of-the-river dam will have 

on the low-flow statistics tends to decrease the farther downstream a station is located from the dam. On the Reedy River, 

regulation of low to medium flows occurs at Lake Conestee 

and Boyds Mill Pond Dam (fig. 2) which include small hydroelectric plants. 

Table 5. Streamgaging stations for which record was augmented, index streamgaging stations, additional climatic years of 

record, and correlation coefficients for gaging stations where record was augmented using MOVE.1 for the Edisto River basin 

of South Carolina.

[USGS, U.S. Geological Survey; mi2, square miles]

Streamgaging stations 

where record was 

augmented

Index streamgaging station Number of 

additional 

climatic 

years of 

record 

computed

Correlation coefficient

USGS 

streamgaging 

station number and name 

and drainage 

area

Period of 

record

USGS 

streamgaging 

station number and name 

and drainage 

area

Period of 

record 1-day 3-day 7-day 14-day 30-day 60-day 90-day

02172500, Apr. 1940– 02173000, Aug. 1931 – 41 0.93 0.94 0.96 0.96 0.96 0.94 0.95

South Fork Sept. 1966 South Fork Sept.1971, 

Edisto Edisto and 

River near River near Oct. 1980 – 

Montmo- Denmark, Mar. 2009

renci, SC SC 

(198 mi2

) (720 mi2)

02173051, Aug. 1991– 02173000, Aug. 1931 – 50 0.96 0.96 0.97 0.97 0.98 0.98 0.99

South Fork Mar. 2009 South Fork Sept. 1971, 

Edisto Edisto and 

River near River near Oct. 1980 – 

Bamberg, Denmark, Mar. 2009

SC (807 SC 

mi2

) (720 mi2)

02174000, Jan. 1945– 02175000, Jan. 1939 – 20 0.96 0.96 0.97 0.97 0.98 0.96 0.96

Edisto Sept. 1996 Edisto Mar. 2009

River near River near 

Branch- Givhans, 

ville, SC SC 

(1,720 mi2

) (2,730 mi2) 
16 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

In the lower part of the basin, the Saluda River includes 

two large dams associated with major reservoirs, Lake Greenwood and Lake Murray, both having substantial storage and 

used for power generation (table 6; Wachob and others, 2009). 

Flows downstream from the large reservoirs will tend to 

experience the greatest fluctuation. Therefore, for the stations 

that are affected by considerable regulation, an additional part 

of the low-flow analysis involves determining the most recent 

period of record that can be considered to have relatively 

stable regulation patterns. Any special considerations for the 

low-flow analyses included in this report, whether related to 

regulation or not, are discussed in the following sections. 

Stations 02163000, Saluda River near Pelzer, 

South Carolina, and 02163001, Saluda River near 

Williamston, South Carolina

Station 02163000 was operated from 1929 to 1971 and 

has a drainage area of 405 mi2. Station 02163001 was established in 1995 and is currently (2012) still active and has a 

drainage area of 414 mi2. Given that the difference in drainage area between the two stations is only about 2 percent, in 

addition to comparisons of the daily mean flows for the two 

stations (fig. 6), the data from the two stations were combined 

for the low-flow analysis, which provides a longer period of 

record that encompasses a broader range of hydrologic conditions. Before combining the daily mean flows from the two 

stations, the flows from station 02163000 were adjusted using 

the drainage-area ratio method (Ries and Friesz, 2000) to 

account for the potential increase in flow due to the increase in 

drainage area at 02163001.

Station 02167000, Saluda River at Chappells, 

South Carolina

Station 02167000 is located 6.7 miles (mi) downstream 

from Buzzards Roost Dam, Lake Greenwood, and has daily 

mean flow records from October 1926 to the current year 

(2012). The dam was constructed in 1940 for the production of 

hydroelectric power (Wachob and others, 2009). As part of the 

1995 Federal Energy Regulatory Commission (FERC) dam 

relicensing agreement, minimum flow requirements were set 

with minimum flow varying by season, inflow, weekday, and 

weekend (Federal Energy Regulatory Commission, 1995). 

An assessment of the annual minimum 7-day average 

streamflows for the regulated period from CY 1941– 2008 

indicated a trend in the data. A plot of the data shows that flow 

patterns appear to have changed in the early 1980s (fig. 7A). 

An assessment of median weekday and weekend flows also 

indicates a change in flow patterns in the early 1980s (fig. 7B). 

The plots show that prior to the early 1980s, regulation patterns at 02167000 were such that the ratio of median weekend 

flows to 7-day weekly flows tended to be lower than the ratio 

of median weekday flows to 7-day weekly flows, indicating 

less power generation during the weekend. From the early 

1980s forward, the ratios of weekday and weekend flows are 

more similar, indicating a more consistent pattern of flow 

releases throughout the week. It was concluded that although 

a minimum release agreement was put into place in 1995, the 

regulation patterns appear to be relatively similar back to at 

least about 1983. Consequently, the low-flow statistics for station 02167000 were computed using the period of record from 

April 1983 to March 2009 (CY 1983-2008).

Station 02169000, Saluda River near Columbia, 

South Carolina

The daily mean flow record for station 02169000 began 

in 1925 prior to construction of the Saluda Dam. The Saluda 

Dam was completed in 1930, and assessment of the flow patterns indicates that regulation patterns have varied throughout 

the period of record (fig. 8A, B). On April 22, 1988, a minimum flow release agreement was established between the 

SCDHEC and the South Carolina Electric and Gas Company 

(Wade Cantrell, South Carolina Department of Health and 

Environmental Control, written commun., May 18, 2011). 

Assessments of the flow data indicate relatively consistent 

flow patterns since then. Because flow data from most of April 

1988 was under old flow conditions, the 1988 CY could not be 

assessed; therefore, the period of record used to compute lowflow statistics for station 02169000 was April 1989 to March 

2009 (CY 1989 – 2008).

Station 02168504, Saluda River below Lake 

Murray Dam near Columbia, South Carolina

The daily mean flow record for station 02168504 began 

in October 1988. As noted previously, a minimum flow release 

was established for the Saluda Dam in April 1988. Consequently, regulation patterns have been relatively consistent 

during the period of record at station 02168504 and, therefore, 

the daily mean flow data for CY 1989 – 2008 were included in 

the low-flow analysis.

Station 02164110, Reedy River above Fork Shoals, 

South Carolina

Station 02164110 has a drainage area of 104 mi2 and 

has daily mean flow record from September 1993 through 

October 2011. The station is located downstream from Lake 

Conestee, which has a drainage area of about 66 mi2 and was 

created when the current dam was completed in about 1892 

(Lake Conestee Nature Park, 2012). Since that time, sediment 

infilling has substantially reduced the size of the lake. As a 

result, it is reasonable to assume that the lake has had little, 

if any, impact on flows at station 02164110 during the period 

of record. On the other hand, analysis of the flow records 

from 02164110 in addition to the flow records from station 

02164000, Reedy River near Greenville, and 02165000, 
Analytical Considerations 17

Table 6. Streamflow regulation in the Saluda River basin, South Carolina.

[mi2, square miles]

Dam or reservoir name Drainage area, in 

mi2 Year completed Stream

Table Rock Reservoir 14.4 1925 (modified in 1980) South Saluda River

North Saluda Reservoir 26.2 1956 (modified in 1980) North Saluda River

Saluda Dam 290 1905 Saluda River

Hollidays Bridge 300 1906 Saluda River

Piedmont 375 1874 Saluda River

Upper Pelzer 410 1881 Saluda River

Lower Pelzer 411 1893 Saluda River

Ware Shoals 564 1905 Saluda River

Buzzards Roost (Lake 

Greenwood) 1,170 1940 Saluda River

Saluda Dam (Lake Murray) 2,420 1930 Saluda River

Lake Conestee 65.5 1812 Reedy River

Boyds Mill Pond 131 1909 Reedy River

10

100

1,000

10,000

100,000

192919311933193519371939194119431945194719491951195319551957195919611963196519671969197119731975197719791981198319851987198919911993199519971999200120032005200720092011

Daily mean flow, in cubic feet per second

Climate year

Station 02163000, Saluda River near

Pelzer, South Carolina

Station 02163001, Saluda River near

Williamston, South Carolina

Figure 6. Daily mean flow for stations 02163000, Saluda River near Ware Shoals,

South Carolina, and 02163001, Saluda River near Williamston, South Carolina.

Figure 6. Daily mean flow for stations 02163000, Saluda River near Ware Shoals, 

South Carolina, and 02163001, Saluda River near Williamston, South Carolina.
18 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

0

200

400

600

800

1,000

1,200

Annual minimum 7-day average flow,

in cubic feet per 

0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1940 1950 1960 1970 1980 1990 2000 2010

Ratio

Climate Year

A

B

Figure 7. (A) Annual minimum 7-day average streamflow

and (B) the ratio of the median weekday to median weekly

streamflow and the median weekend to median weekly

streamflows at U.S. Geological Survey streamgaging

station 02167000, Saluda River at Chappells, South Carolina.

Median weekday flow / median

7-day weekly flow

Median weekend flow / median 

7-day weekly flow

EXPLANATION

Figure 7. Annual minimum 7-day average 

streamflow and the ratio of the median weekday 

to median weekly streamflow and the median 

weekend to median weekly streamflows at U.S. 

Geological Survey streamgaging station 02167000, 

Saluda River at Chappells, South Carolina.

Reedy River near Ware Shoals, indicates that the low flows at 

02164110 are being influenced by discharge from the Mauldin 

Road Wastewater Treatment Plant (WWTP). 

The Mauldin Road WWTP is located just south of 

Interstate 85 in Greenville, SC, and station 02164000 (fig. 2). 

A comparison of flow duration curves for the concurrent 

period of record (October 1, 1996 to September 30, 2004) at 

the three Reedy River streamflow stations shows the influence of the discharges from the WWTP, particularly on low 

flows (fig. 9A, B). As can been seen, the duration curves for 

02164000 and 02165000 tend to be parallel with similar 

shapes, whereas the duration curve for 02164110 intersects the 

curve for 02164000 at the lower flows (fig. 9A). When plotted 

on a per square mile basis, the duration curve at 02164110 

shows that, except for the highest flows, the rate of flow per 

square mile is increasingly larger as the percentage exceedence 

0

400

200

600

1,00

800

1,400

1,200

1,800

1,600

2,000

Annual minimum 7-day average flow,

in cubic feet per second 

0

0.4

0.2

0.6

0.8

1.2

1.0

1.4

1.6

1.8

1920 1930 1940 1950 1960 1970 1980 20001990 2010

Ratio

Climate year

Median weekday flow / median

7-day weekly flow

Median weekend flow / median 

7-day weekly flow

A

B

Figure 8. (A) Annual minimum 7-day average streamflow

and (B) the ratio of the median weekday to median weekly

streamflow and the median weekend to median weekly

streamflows at U.S. Geological Survey streamgaging

station 02169000, Saluda River near Columbia, South Carolina.

EXPLANATION

Figure 8. Annual minimum 7-day average 

streamflow and ratio of the median weekday to 

median weekly streamflow and the median weekend 

to median weekly streamflows at U.S. Geological 

Survey streamgaging station 02169000, Saluda River 

near Columbia, South Carolina.

values increase (flows decrease) indicating that the percentage 

of flow from the Mauldin Road WWTP becomes increasingly 

larger as the streamflow decreases (fig. 9B). The influence of 

the Mauldin Road WWTP discharge suggests that it is unwise 

to augment the streamflow record at 02164110 based on correlation with either 02164000 or 02165000. Also, the influence 

from the WWTP discharge would need to be considered when 

comparing low-flow statistics from the three stations. For 

example, the 7Q10 estimates for the three stations are 11, 55, 

and 50 ft3

/s for stations 02164000, 02164110, and 02165000, 

respectively (table 2). As discussed in the next section, the 

7Q10 for 02165000 was computed using data combined from 

stations 02165000 and 021650905, Reedy River near Waterloo. Given that the drainage area at 02165000 (021650905) is 

more than twice the size of the drainage area at 02164110 and 

that the period of record at 02164110 is much shorter and was 

collected in a relatively dry period, under natural conditions, 
Considerations for Accuracy of Low-Flow Statistics 19

the 7Q10 at 02165000 (021650905) should be higher than that 

of 02164110. Thus, if a 7Q10 estimate were needed between 

stations 02164110 and 02165000 (021650905) or between 

stations 02164110 and 02164000, hydrologic judgment would 

need to be applied with respect to appropriateness of shifting 

the 7Q10 estimate if based solely on drainage area as is sometimes done (Zalants, 1991a).

Stations 02165000, Reedy River near Ware 

Shoals, South Carolina, and 021650905, Reedy 

River near Waterloo, South Carolina

From 1939 to 2004, daily mean flow was collected at 

station 02165000, located 6.0 mi. downstream from Boyd 

Mill Pond. In 2004, the gage was moved to a location 1.8 mi 

downstream and became station 021650905, Reedy River 

near Waterloo. The drainage area at 02165000 was 236 mi2

and the drainage area at 021650905 is 251 mi2

, an increase 

of about 6 percent. Based on a comparison of the daily mean 

flows (fig. 10) and the similarity in the drainage areas, the 

records for the two stations were combined for the low-flow 

analysis. Before combining the daily mean flows from the 

two stations, the flows from station 02165000 were adjusted 

by the drainage-area ratio method (Ries and Friesz, 2000) to 

account for the potential increase in flow due to the increase 

in drainage area at 021650905. As can be seen in figure 10, 

the lowest daily mean flows appear to have increased from 

those previously recorded sometime around the late 1980s. A 

comparison of the median weekday and weekend flows shows 

several changes, suggesting variations in the patterns that are 

likely due to changes in the regulation patterns at Boyd Mill 

Pond Dam (fig. 11B). The weekday and weekend flow patterns 

as well as the annual minimum 7-day flows appear to have 

been relatively consistent since the late 1980s (figs. 11A, B). 

Consequently, the low-flow statistics were run using data from 

CY 1988 – 2008.

Station 02169500, Congaree River at Columbia, 

South Carolina

Daily mean flow data are available at 02169500 from 

1939 to the current year (2012). Approximately two-thirds 

of the drainage basin for 02169500 is from the Broad River. 

However, because regulation on the Saluda River is much 

more substantial than that on the Broad River, the ratio of 

flow from the Saluda River during low-flow periods is likely 

increased with respect to the total flow in the Congaree River.

Annual median weekday and weekend flows were 

compared to assess regulation patterns. Similar to patterns for 

station 02169000, Saluda River near Columbia (fig. 8B), several variations can be seen (fig. 12B). In addition to the annual 

minimum 7-day average streamflows, flow patterns appear to 

have been relatively stable since about 1980 (figs. 12A, B). As 

noted earlier, a minimum flow release agreement was established for the Saluda Dam in 1988. However, due to the flows 

from the Broad River, the influence on the low flows at station 

02169500 is not as apparent as it was for station 02169000 

(fig. 8). Consequently, based on the assessment of flows at 

station 02169500, and in order to use the longest period of 

record that indicates relatively stable regulation patterns, the 

low-flows statistics for station 02169500 were computed using 

data from CY 1980 to 2008.

Considerations for Accuracy of LowFlow Statistics

With respect to streamflow statistics, the period of collected record can be thought of as a sample, or small portion 

of the population, which represents all possible measurements. 

Statistics allow for making inferences about the characteristics 

of the population based on samples from the population. For 

example, statistical measures, such as mean, standard deviation, or skew coefficient, can be described in terms of the 

sample and then used to make inferences about the population 

from which the sample was obtained. Statistical measures 

computed from the sample record are estimates of what the 

measure would be if the entire population were known and 

used to compute the given measure. Consequently, the accuracy of low-flow statistics at streamgaging stations is related to 

the length of record (sample from the population) upon which 

the statistics are based. The longer the period of record at a 

streamgaging station that covers a broad range of hydrologic 

conditions, the more accurate or reflective of long-term conditions the low-flow statistics will be.

The streamflow statistics for short-term records are much 

more sensitive to extreme hydrologic events than those for 

long-term records. As a result, streamflow statistics, whether 

high or low, from one 10-year period may differ significantly 

from another 10-year period. Thus, a long-term record is 

always more desirable when computing streamflow statistics. 

To test the effect of record length and hydrologic conditions 

on low-flow statistics, the 7Q10 for station 02175000, Edisto 

River near Givhans, was computed beginning with the first 10 
20 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

1

10

100

1,000

10,000

A. Reedy River (Oct. 1, 1996–Sep. 30, 2004)

B. Reedy River (Oct. 1, 1996–Sep. 30, 2004)

0.01

0.10

1

10

100

0 10 20 30 40 50 60 70 80 90 100

Daily mean flow, in cubic feet per

second per square mile

Daily mean flow, in cubic feet per second

Percent of time indicated streamflow was equaled or exceeded

Station 02164000, Reedy River near Greenville, South Carolina

Station 02164110, Reedy River above Fork Shoals, South Carolina

Station 02165000, Reedy River near Ware Shoals, South Carolina

Figure 9. (A) Comparison of flow-duration curves for

U.S. Geological Survey South Carolina streamgaging

stations 02164000, Reedy River near Greenville; 02164110,

Reedy River above Fork Shoals; and 02165000, Reedy River

near Ware Shoals, and (B) flow duration curves normalized

by drainage area for the same three stations.

EXPLANATION

Figure 9. (A) Comparison of flow-duration curves for 

U.S. Geological Survey South Carolina streamgaging 

stations 02164000, Reedy River near Greenville; 

02164110, Reedy River above Fork Shoals; and 02165000, 

Reedy River near Ware Shoals, and (B) flow duration 

curves normalized by drainage area for the same three 

stations.

years of record (April 1939–March 1949) and then updated on 

a 5-year basis through CY 2008. Figure 13 shows the annual 

minimum 7-day average streamflow by CY for the period of 

record along with the computed 7Q10 estimates. The figure 

shows that the 7Q10 for the first 10 years of record was 516 

ft3

/s. By CY 1958, the 7Q10 had decreased to 393 ft3/s due 

to the addition of records collected during a historic drought 

period in the 1950s. The 1960s and 1970s tended to be a 

relatively wet period, and the 7Q10 generally increased during that time. In CY 2002, the lowest annual minimum 7-day 

average flow of record occurred during the historic drought 

of 1998-2002. The last few years of the record resulted in two 

additional dry years (CY 2007 and 2008) and, therefore, the 

7Q10 value decreased to 347 ft3/s in CY 2008. In this analysis, 

the percent difference between the highest (516 ft3/s in CY 

1948) and lowest (347 ft3/s in CY 2008) 7Q10 is 39 percent, 

with percent difference computed as 

100 , (4)

2

||

21

21 ×





 



 +

− = xxxx PercentDifference

where

x1 is highest 7Q10 estimate from the periods analyzed, 

and

x2 is lowest 7Q10 estimate from the periods analyzed.

To show the effect of how the 7Q10 can be influenced 

under a different set of hydrologic conditions and the significant influence that period of record can have on streamflow 

statistics, a similar analysis was done using a synthesized 

record of annual minimum 7-day average flows. The synthesized flows were generated by reversing the annual minimum 

7-day average flows from station 02175000. Under these 

conditions, the streamflow record begins in a significant dry 

period. As can be seen in figure 14, the 7Q10 computed from 

the first 10 years of record is 197 ft3/s, which is 38 percent 

of the 7Q10 based on the first 10 years of record from the 

measured data at station 02175000. Because the synthesized 

record began in a period that was the driest based on the next 

60 years of record, the 7Q10 shows a pattern of continuing to 

increase until the value of 347 ft3/s was again obtained in CY 

2008. The percent difference between the highest and lowest 

7Q10 computed in this analysis is 55 percent. This percent 

difference emphasizes that, although the 7Q10 value at the 

end of the record was the same for both the measured data and 

the synthesized data, the intermittent values were sometimes 

substantially different based on a rearrangement of the hydrologic conditions (starting in an historic dry period as opposed 

to starting in a relatively normal period). Thus, as the length 

of record at a streamgaging station increases, the low-flow 

statistics are moving toward the values that would be expected 

to be obtained from the population. As the period of record 

increases, the streamflow statistics tend to be less influenced 

by extreme conditions, whether wet or dry.

Additional Considerations

As the information in the preceding section indicates, the 

Saluda, Reedy, and Congaree Rivers are complex with respect 

to the varying degrees of regulation and other influences that 

can impact low-flow statistics. Variability in low-flow statistics 

is related to the length of record available at the CR stations 

in addition to geologic, topographic, and climatic differences 

among the various stations being analyzed, even in the same 

basin (Bloxham, 1979). For the Piedmont region, Bloxham 

(1979, 1981) reported a decrease in the unit annual minimum 7-day streamflows from the northern part of the region 

to the southern part with unit values reported from 0.72 to 

0.01 (ft3

/s)/mi2 for 7Q2 and from 0.46 to 0 (ft3/s)/mi2 for 7Q10. 
Considerations for Accuracy of Low-Flow Statistics 21

1

10

100

1,000

10,000

Daily mean flow, in cubic feet per second

Climate year

Figure 10. Daily mean flow for stations 02165000, Reedy River near Ware Shoals,

South Carolina, and 021650905, Reedy River near Waterloo, South Carolina.

Jan. 1939

Dec. 1940Dec. 1942Dec. 1944Dec. 1946Dec. 1948Dec. 1950Dec. 1952Dec. 1954Dec. 1956Dec. 1958Dec. 1960Dec. 1962Dec. 1964Dec. 1966Dec. 1968Dec. 1970Dec. 1972Dec. 1974Dec. 1976Dec. 1978Dec. 1980Dec. 1982Dec. 1984Dec. 1986Dec. 1988Dec. 1990Dec. 1992Dec. 1994Dec. 1996Dec. 1998Dec. 2000Dec. 2002Dec. 2004Dec. 2006Dec. 2008Dec. 2010

Station 02165000, Reedy River near

Ware Shoals, South Carolina

Station 021650905, Reedy River

near Waterloo, South Carolina

Figure 10. Daily mean flow for U.S. Geological Survey South Carolina 

streamgaging stations 02165000, Reedy River near Ware Shoals, and 

021650905, Reedy River near Waterloo.
22 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams Annual minimum 7-day average flow, in cubic feet per second Ratio

Climate year

Median weekday flow / median

7-day weekly flow

Median weekend flow / median 

7-day weekly flow

A

B

EXPLANATION

0

50

100

150

200

250

0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1930 1940 1950 1960 1970 1980 1990 2000 2010

Figure 11. (A) Annual minimum 7-day average streamflow

and (B) ratio of the median weekday to median weekly

streamflow and the median weekend to median weekly

streamflow for the combined records of U.S. Geological

Survey South Carolina streamgaging stations 02165000,

Reedy River near Ware Shoals, South Carolina, and

021650905, Reedy River near Waterloo, South Carolina.

Figure 11. (A) Annual minimum 7-day average 

streamflow and (B) ratio of the median weekday 

to median weekly streamflow and the median 

weekend to median weekly streamflow for the 

combined records of U.S. Geological Survey South 

Carolina streamgaging stations 02165000, Reedy 

River near Ware Shoals, and 021650905, Reedy 

River near Waterloo.

Annual minimum 7-day average flow,

in cubic feet per second Ratio

Climate year

Median weekday flow / median

7-day weekly flow

Median weekend flow / median 

7-day weekly flow

A

B

EXPLANATION

0

1930 1940 1950 1960 1970 1980 1990 2000 2010

Figure 12. (A) Annual minimum 7-day average streamflow

and (B) ratio of the median weekday to median weekly

streamflow and the median weekend to median weekly

streamflow for U.S. Geological Survey streamgaging

station 02169500, Congaree River at Columbia, South Carolina.

Median weekday flow / median

7-day weekly flow

Median weekend flow / median 

7-day weekly flow

EXPLANATION

1,000

2,000

3,000

4,000

5,000

6,000

7,000

0

0.2

0.4

0.6

0.8

1.0

1.2

Figure 12. (A) Annual minimum 7-day average 

streamflow and (B) ratio of the median weekday 

to median weekly streamflow and the median 

weekend to median weekly streamflow for U.S. 

Geological Survey streamgaging station 02169500, 

Congaree River at Columbia, South Carolina.
Comparison with Previously Published Low-Flow Statistics 23

Similar variation can be seen from the low-flow statistics 

reported in this study for stations along the Saluda and Reedy 

Rivers (table 7). Thus, along with the anthropogenic influences 

on the low-flow statistics, other natural influences on variability should be considered as well when comparing values 

among various sites or when considering the appropriateness 

of estimating a low-flow statistic at an ungaged location based 

on the unit flow from a gaged location.

Comparison with Previously Published 

Low-Flow Statistics

The last systematic update of low-flow statistics in South 

Carolina included data through March 1987 (the 1986 CY). 

Since that time, several droughts have occurred, including 

the severe drought between 1998 and 2002 and a more recent 

drought from 2006 to 2009 (South Carolina Department of 

Natural Resources, 2012). Other droughts were reported in 

1988, 1990, 1993, and 1995 (Mizzell, 2008). At all stations 

included in this report that experienced the 1998-2002 and 

(or) the 2006-2009 droughts, the results were lower annual 

minimum 7-day average streamflow. That excludes regulated 

stations where the annual 7-day average is more dependent 

on flow releases from the dams and stations that were established or discontinued during or before the droughts. Stations 

02162350, Middle Saluda River near Cleveland; 02166970, 

Ninety-Six Creek near Ninety Six; and 02172640, Dean 

Swamp Creek near Salley were discontinued in 2003, 2001, 

and 2000, respectively and, therefore, those records do not 

fully reflect the droughts noted above. Factors other than 

droughts that likely influenced the differences in the 7Q10 

values are record extensions, which were used in this study but 

were not used in previous studies; whether the 7Q10 analyses 

were mathematical, as was the case in this study, or graphical; 

and changes in the basin that, although not necessarily substantial enough to indicate trends in the data, could still have 

some influence on the low-flow statistics.

Of the 25 stations included in this study, 18 had low-flow 

statistics that were previously published by Bloxham (1979) or 

Zalants (1991b). In addition, the records for two stations were 

combined with the records of stations that were previously 

published: station 02163001, Saluda River near Williamston 

was combined with station 02163000, Saluda River near 

Pelzer; and station 021650905, Reedy River near Waterloo 

was combined with station 02165000, Reedy River near Ware 

Shoals. The results of these two stations were compared to 

the low-flow statistics of the previously published stations 

(02163000 and 02165000, table 8); therefore, low-flow statistics were compared for 20 stations. The most recently published 7Q10 values for these 20 stations were compared with 

the current values, and differences, in percent, were computed 

as follows:

Percent difference = [(current 7Q10 – previous 7Q10) / 

 previous 7Q10] x 100.

As computed, the percent difference indicates the percent 

of change from the previously published 7Q10 value. The percent differences ranged from -84.0 to 38.9 (table 8). The negative-percent differences for 18 stations indicate that the 7Q10 

values decreased, and the positive-percent differences for 

2 stations indicate that the 7Q10 values increased. The smallest change in the 7Q10 flow values from the previous investigation was for station 02169630, Big Beaver Creek near St. 

Matthews, which shows a decrease of -2.0 percent (from 5.0 

to 4.9 ft3/s). It should be noted, however, that the additional 

data for that station only extended from March 1988 through 

March 1993. The two stations having an increase in the 7Q10 

value were station 02169000, Saluda River near Columbia 

and station 021650905, Reedy River near Waterloo (compared to station 02165000, Reedy River near Ware Shoals). 

As previously discussed, an agreement between SCDHEC and 

the SCE&G set a minimum streamflow for the Lake Murray 

Dam which is upstream from station 02169000, Saluda River 

near Columbia. A minimum streamflow release from the dam 

will be reflected in the 7Q10 as higher minimum streamflow 

values. Additionally, station 02169000 was evaluated for the 

period of record from April 1, 1989, through March 31, 2009, 

because the flow patterns prior to this period were significantly 

different from the selected period of analysis.
24 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams Annual minimum 7-day average flow, in cubic feet per second 

Climate year

Annual minimum 7-day

average flow

7Q10

EXPLANATION

1930 1940 1950 1960 1970 1980 1990 2000 2010

Figure 13. Annual minimum 7-day average streamflow

and 7Q10 estimates at U.S. Geological Survey streamgaging station 02175000, Edisto River near Givhans,

South Carolina.

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

7Q10, in cubic feet per second

Figure 13. Annual minimum 7-day average 

streamflow and 7Q10 estimates at U.S. Geological 

Survey streamgaging station 02175000, Edisto River 

near Givhans, South Carolina.

Annual minimum 7-day average flow,

in cubic feet per second 

Number of climate years

Annual minimum 7-day

average flow

7Q10

EXPLANATION

0 10 20 30 40 50 60 70 80

Figure 14. Annual minimum 7-day average streamflow

and 7Q10 estimates from a synthesized dataset where

the annual minimum 7-day average streamflows from

U.S. Geological Survey streamgaging station 02175000,

Edisto River near Givhans, South Carolina, were reversed

for the period of record.

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

7Q10, in cubic feet per second

Figure 14. Annual minimum 7-day average 

streamflow and 7Q10 estimates from a synthesized 

dataset where the annual minimum 7-day 

average streamflows from U.S. Geological Survey 

streamgaging station 02175000, Edisto River near 

Givhans, South Carolina, were reversed for the 

period of record.

Table 7. Unit annual minimum 7-day average streamflow with a 2- and 10-year recurrence interval 

for U.S. Geological Survey streamgaging stations on the Saluda and Reedy Rivers, South Carolina.

[(ft3/s)/mi2, cubic feet per second per square mile]

Station name and number Unit 7Q2, in (ft3/s)/mi2 Unit 7Q10, in (ft3/s)/mi2

Saluda River

02162500, Saluda River near Greenville 0.74 0.33

a

02163001, Sulada River near Williamston 0.66 0.26

02163500, Saluda River near Ware Shoals 0.53 0.22

02168504, Saluda River below Lake Murray 

Dam near Columbia 0.16 0.10

02169000, Saluda River near Columbia 0.19 0.12

Reedy River

02164000, Reedy River near Greenville 0.43 0.23

02164110, Reedy River above Fork Shoals 0.66 0.41

b

021650905, Reedy River near Waterloo 0.35 0.20

a

 Station combined with U.S. Geological Survey station 02163000, Saluda River near Pelzer.

b

 Station combined with U.S. Geological Survey station 02165000, Reedy River near Ware Shoals.
Comparison with Previously Published Low-Flow Statistics 25

Table 8. Differences between the annual minimum 7-day average streamflow with a 10-year recurrence 

interval in this report and previously published values for continuous-record streamgaging stations in the 

Saluda, Congaree, and Edisto River basins of South Carolina.—Continued

[USGS, U.S. Geological Survey; ft3/s, cubic feet per second; CY, climatic year; ND, not determined]

USGS streamgaging station number and name

Previous estimate 

from Bloxham (1979), 

in ft3

/s

Previous estimate 

from Zalants 

(1991b), in ft3/s

Current (CY 2008) 

estimate, in ft3

/s

Percent difference 

from most recent 

estimate to current 

estimate

02162350, Middle Saluda 

River near Cleveland

ND 11 9.3 –15.5

02162500, Saluda River 

near Greenville

130 160 99 –38.1

a

02163001, Saluda River 

near Williamston

168 ND 106 –36.9

02163500, Saluda River 

near Ware Shoals

190 190 130 –31.6

02164000, Reedy River 

near Greenville

16 16 11.0 –31.3

b

021650905, Reedy River 

near Waterloo

36 36 50 38.9

02165200, South Rabon 

Creek near Gray Court

6.4 7.8 1.5 –80.8

02166970, Ninety-Six 

Creek near Ninety Six

ND 0.25 0.04 –84.0

02167000, Saluda River 

near Chappells

320 ND 258 –19.4

02169000, Saluda River 

near Columbia

260 ND 304 16.9

02169500, Congaree 

River at Columbia

1,800 ND 1,210 –32.8

02169570, Gills Creek at 

Columbia

9.8 5.6 3.9 –30.4

02169630, Big Beaver 

Creek near St. Mathews

5.0 5.0 4.9 –2.0

02172500, South Fork 

Edisto River near 

Montmorenci

65 ND 55 –15.4

02172640, Dean Swamp 

Creek near Salley

ND 16 14 –12.5

02173000, South Fork 

Edisto River near 

Denmark

211 200 175 –12.5
26 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

Table 8. Differences between the annual minimum 7-day average streamflow with a 10-year recurrence 

interval in this report and previously published values for continuous-record streamgaging stations in the 

Saluda, Congaree, and Edisto River basins of South Carolina.—Continued

[USGS, U.S. Geological Survey; ft3/s, cubic feet per second; CY, climatic year; ND, not determined]

USGS streamgaging 

station number 

and name

Previous estimate 

from Bloxham (1979), 

in ft3

/s

Previous estimate 

from Zalants 

(1991b), in ft3/s

Current (CY 2008) 

estimate, in ft3

/s

Percent difference 

from most recent 

estimate to current 

estimate

02173500, North Fork 

Edisto River near 

Orangeburg

02174000, Edisto River 

near Branchville

02174250, Cow Castle 

Creek near Bowman

02175000, Edisto River 

near Givhans

225

455

0.74

442

230

480

0.70

500

209

406

0.26

347

–9.1

–15.4

–62.9

–30.6

a

 Compared to station 02163000, Saluda River near Pelzer, because of the proximity of the two stations, the similarity in 

drainage area, and the different period of record for the two stations, their records were combined.

b

 Compared to station 02165000, Reedy River near Ware Shoals, because of the proximity of the two stations, the similarity 

in drainage area, and the different period of record for the two stations, their records were combined.

Summary

This report, prepared in cooperation with the South 

Carolina Department of Health and Environmental Control, 

provides updated low-flow statistics at continuous-record 

streamgaging stations operated by the U.S. Geological Survey 

in the Saluda, Congaree, and Edisto River basins of South Carolina. The continuous-record streamgaging stations included in 

this study were analyzed based on four categories of stations: 

(1) long-term record stations, (2) short-term record stations 

that have at least 10 years of record, (3) stations that have 

between 5 and 10 years of record and were analyzed for a limited set of low-flow statistics using techniques typically used 

in analyzing partial-record stations, and (4) regulated stations. 

The Maintenance of Variance Extension, Type 1, method was 

used for the record-extension analyses and the partial-record 

type analyses. Based on the length of record available at the 

continuous-record streamgaging stations, low-flow frequency 

statistics were estimated for annual minimum 1-, 3-, 7-, 14-, 

30-, 60-, and 90-day average flows with recurrence intervals 

of 2, 5, l0, 20, 30, and 50 years. Additionally, daily flow durations for the 5-, 10-, 25-, 50-, 75-, 90-, and 95-percent exceedances were computed for the stations.

Of the 25 streamgaging stations included in this study, 20 

had low-flow statistics that were published in previous U.S. 

Geological Survey reports. Of those 20 stations, only 2 of the 

stations had an increase in the 7Q10 value. The percent difference of 7Q10 values computed for this report and previously 

published U.S. Geological Survey reports ranged from –84.0 

to 38.9 percent. 
Selected References 27

Selected References

Barker, A.C., 1986, Base-flow measurements at partial-record 

sites on small streams in South Carolina: U.S. Geological 

Survey Open-File Report 86-143, 97 p.

Bloxham, W.M., 1976, Low-flow characteristics of streams in 

the Inner Coastal Plain of South Carolina: South Carolina 

Water Resources Commission Report No. 5, 41 p.

Bloxham, W.M., 1979, Low-flow frequency and flow duration 

of South Carolina streams: South Carolina Water Resources 

Commission Report No. 11, 90 p. 

Bloxham, W.M., 1981, Low-flow characteristics of ungaged 

streams in the Piedmont and Lower Coastal Plain of South 

Carolina: South Carolina Water Resources Commission 

Report No. 14, 48 p.

Bloxham, W.M., Siple, G.E., and Cummings, T.R., 1970, 

Water resources of Spartanburg County, South Carolina: 

South Carolina Water Resources Commission Report No. 3, 

112 p.

Eidson, J.P., Lacy, C.M., Nance, Luke, Hansen, W.F., Lowery, M.A., and Hurley, N.M., Jr., 2005, Development of a 

10- and 12-digit hydrologic unit code numbering system 

for South Carolina, 2008: U.S. Department of Agriculture, 

Natural Resources Conservation Service, 38 p., including 

plate.

Feaster, T.D., and Guimaraes, W.B., 2009, Low-flow frequency and flow duration of selected South Carolina 

streams in the Pee Dee River basin through March 2007: 

U.S. Geological Survey Open-File Report 2009-1171, 39 p.

Federal Energy Regulatory Commission (FERC), 1995, Order 

issuing new license for South Carolina Electric & Gas’s 

Buzzard’s Roost Project No. 1267: Issuance 19951226-

0063, Docket No. P-1267-000, 33 p.

Guimaraes, W.B., and Feaster, T.D., 2010, Low-flow frequency and flow duration of selected South Carolina 

streams in the Broad River basin through March 2008: U.S. 

Geological Survey Open-File Report 2010-1305, 47 p.

Helsel, D.R., and Hirsch, R.M., 1992, Studies in environmental science 49—Statistical methods in water resources: 

Amsterdam, Elsevier Science, 529 p.

Hirsch, R.M., 1982, A comparison of four record extension 

techniques: Water Resources Research, v. 18, no. 4, 

p. 1081–1088.

Hydrology Subcommittee of the Interagency Advisory Committee on Water Data, 1982, Guidelines for determining 

flood frequency: U.S. Geological Survey Bulletin 17B, 

183 p.

Johnson, F.A., Siple, G.E., and Cummings, T.R., 1968, A 

reconnaissance of the water resources of Pickens County, 

South Carolina: South Carolina Water Resources Commission Report No. 1, 69 p.

Lake Conestee Nature Park, 2012, A lake in transition: 

Accessed July 5, 2012, at http://conesteepark.com/history/

a-lake-in-transition.

Langbein, W.B., and Iseri, K.T., 1960 General introduction 

and hydrologic definitions. Manual of hydrology, part I: 

General surface water techniques (3d ed.): U.S. Geological 

Survey Water-Supply Paper W1541A, 29 p.

Lins, H.F., Hirsch, R.M., and Kiang, Julie, 2010, Water—the 

Nation’s fundamental climate issue: A white paper on the 

U.S. Geological Survey role and capabilities: U.S. Geological Survey Circular 1347, 9 p., available at http://pubs.usgs.

gov/circ/1347. 

Mizzell, Hope, 2008, Improving drought detection in the 

Carolinas—Evaluation of local, State, and Federal drought 

indicators: Department of Geology, University of South 

Carolina, Ph. D dissertation 149 p.

Nielsen, J.P., 1999, Record extension and streamflow statistics for the Pleasant River, Maine: U.S. Geological Survey 

Water-Resources Investigations Report 99-4078, 22 p.

Ries, K.G., III, 1994, Estimation of low-flow duration discharges in Massachusetts: U.S Geological Survey WaterSupply Paper 2418, 50 p.
28 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

Ries, K.G., III, and Friesz, P.J., 2000, Methods for estimating 

low-flow statistics for Massachusetts streams: U.S. Geological Survey Water-Resources Investigations Report 00-4135, 

81 p.

Riggs, H.C., 1972, Low-flow investigations: U.S. Geological Survey Techniques of Water Resources Investigations, 

book 4, chap. B1, 18 p.

Riggs, H.C., 1985, Streamflow characteristics: New York, 

Elsevier, 249 p.

SAS Institute, Inc., 1989, SAS user’s guide: Statistics: Cary, 

N.C., 583 p.

Searcy, J.K., 1959, Flow-duration curves, manual of hydrology—part 2. Low-flow techniques: U.S. Geological Survey 

Water-Supply Paper 1542-A, p. 1-33.

South Carolina Department of Health and Environmental Control, 2009, Watersheds and TMDLs: Accessed 

February 19, 2009, at http://www.scdhec.net/environment/

water/shed/prog.htm. 

South Carolina Department of Natural Resources, 2012, South 

Carolina current drought status: Accessed July 12, 2012, at 

http://www.dnr.sc.gov/water/climate/sco/Drought/drought_

current_info.php#

Stallings, J.S., 1967, South Carolina streamflow 

characteristics—Low-flow frequency and flow duration: 

U.S. Geological Survey Open-File Report, 83 p.

Stedinger, J.R., and Thomas, W.O., Jr., 1985, Low-flow 

frequency estimation using base-flow measurements: U.S. 

Geological Survey Open-File Report 85-95, 22 p.

Telis, P.A., 1991, Low-flow and flow-duration characteristics 

of Mississippi streams: U.S. Geological Survey WaterResources Investigations Report 90-4087, 214 p.

U.S. Army Corps of Engineers, 2007, National inventory of 

dams: Accessed May 21, 2007, at https://nid.usace.army.

mil.

U.S. Environmental Protection Agency, 2009, Pollution 

prevention and control—Polluted runoff: Appendix: Case 

studies: Accessed June 27, 2009, at http://www.epa.gov/

owow/nps/urbanize/appendix.html.

U.S. Geological Survey, 1979, Office of Surface Water 

Technical Memorandum Number 79.06: Accessed April 26, 

2007, at http://water.usgs.gov/admin/memo/SW/sw79.06.

html.

U.S. Geological Survey, 1985, Office of Surface Water 

Technical Memorandum Number 86.02: Accessed May 7, 

2007, at http://water.usgs.gov/admin/memo/SW/sw86.02.

html.

U.S. Geological Survey, 2009, National Streamflow 

Information Program (NSIP) : Accessed July 11, 2009, at 

http://water.usgs.gov/nsip/history1.html.

Wachob, Andrew, Park, A.D., and Newcome, Roy, Jr., 

eds., 2009, South Carolina State water assessement (2d 

ed.): Columbia, South Carolina Department of Natural 

Resources, Land, Water and Conservation Division, 407 p.

Zalants, M.G., 1991a, Low-flow characteristics of natural 

streams in the Blue Ridge, Piedmont, and upper Coastal 

Plain Physiographic Provinces of South Carolina: U.S. 

Geological Survey Water-Resources Investigations Report 

90-4188, 92 p.

Zalants, M.G., 1991b, Low-flow frequency and flow duration 

of selected South Carolina streams through 1987: U.S. 

Geological Survey Water-Resources Investigations Report 

91-4170, 87 p.
Table 2 29

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey] 

Notes: The station low-flow statistics are presented in the following pages in numerical order by station number. See figure 2 for location of 

the streamgaging stations.

STATION NAME AND NUMBER.—02162350 Middle Saluda River near Cleveland, SC

LOCATION.—Lat 35o

07'12", Long 82o32'16", referenced to North American Datum of 1927, Greenville County, SC, Hydrologic Unit 

03050109, at State Road 41 bridge, 3.9 mi north of Cleveland, and 5.0 mi east of Caesers Head.

DRAINAGE AREA.—21.0 mi2

, approximately.

PERIOD OF RECORD.—October 1980 to September 2003. 

PERIOD OF ANALYSIS.—April 1981 to March 2003.

REMARKS.—Based on review of withdrawal and discharge data provided by the SCDHEC, there are no significant diversions upstream. 

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence Lowest average flow for indicated number of consecutive days intervals (cubic feet per second) (years)

1 3 7 14 30 60 90

2 16 16 17 18 20 23 25

5 11 11 11 12 14 16 18

10 8.8 9.0 9.3 10 11 13 15

20 7.4 7.6 7.9 8.5 9.4 11 13

30 6.7 7.0 7.2 7.8 8.7 9.6 10

DURATION OF DAILY FLOW

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

135 104 70 44 27 18 15

Table 2
30 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square miie; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey] 

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.--02162500 Saluda River near Greenville, SC 

LOCATION.—Lat 35o50'32'', long 82o28'51'', referenced to North American Datum of 1927, Pickens County, SC, Hydrologic Unit 03050109, 

on right bank 700 ft upstream from bridge on State Road 124, 1.6 mi downstream from Saluda Lake Dam, 2.4 mi upstream from Georges 

Creek, 4.6 mi west of city hall in Greenville, and at mile 132.0. 

2

DRAINAGE AREA.--295 mi .

PERIOD OF RECORD.—January 1942 to September 1978, and March 1990 to current year. 

PERIOD OF ANALYSIS.—April 1942 to March 1978 and April 1990 to March 2009.

REMARKS.—Based on review of discharge data provided by the SCDHEC, there are no significant point-source discharges upstream. Based 

on review of withdrawal data provided by the SCDHEC, the potential exists for significant withdrawal upstream. However, adequate data 

are not available to quantify this diversion. No adjustment was made to the data used in the frequency analysis. Some regulation of low to 

medium flow by powerplants upstream. Greenville Water diverts water for municipal supply upstream. 

MAGNITUDE AND FREQUENCY OF ANNUAL FLOWS

Recurrence intervals (years)Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2

5

10

20

30

50

173

101

72

54

45

37

195

114

81

59

49

40

217

135

99

75

64

53

232

146

109

83

72

60

255

166

128

101

88

75

289

189

146

116

102

88

322

211

164

131

116

100

DURATION OF DAILY FLOW

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

1,410 1,100 753 495 321 223 162
Table 2 31

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey] 

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.--02163001 Saluda River near Williamston, SC 

LOCATION.--Lat 34o 36' 35'', long 82o 26' 39'', referenced to North American Datum of 1927, Greenville County, SC, Hydrologic Unit 

03050109, 1,300 ft downstream from Pelzer Mills dam, and 2 mi east of Williamston, SC

DRAINAGE AREA.-– 414 mi2

.

PERIOD OF RECORD.—May 1995 to current year.

PERIOD OF ANALYSIS.—April 1930 to March 1971, and April 1996 to March 2009. 

REMARKS.—Daily mean flows are combined with streamgaging station 02163000, Saluda River near Pelzer, SC (October 1929 to 

September 1971) to extend the period of record. The drainage areas of the two stations are within 2.2 percent of each other. Based on review 

of withdrawal data provided by the SCDHEC, the potential exists for significant withdrawal upstream. However, adequate data are not 

available to quantify this diversion. No adjustment was made to the data used in the frequency analysis. Some regulation of low to medium 

flow from upstream Pelzer Mills dam. Greenville Water diverts water for municipal supply upstream. 

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence 

intervals (years)

Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2 212 254 275 285 305 345 377

5 101 138 158 171 196 226 252

10 59 87 106 121 149 175 200

20 35 55 71 87 116 139 163

30 25 41 55 71 101 122 145

50 17 30 42 57 86 106 127

DURATION OF DAILY FLOW

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

1,830 1,360 916 608 408 294 241
32 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey]

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.—02163500 Saluda River near Ware Shoals, SC 

LOCATION.--Lat 34o23'30'', long 83o13'25'', referenced to North American Datum of 1927, Greenwood County, SC, Hydrologic Unit 

03050109, on downstream side of U.S. Highway 25 bridge, 1.4 mi southeast of Ware Shoals, 1.8 mi downstream from Ware Shoals Dam, 

5.7 mi upstream from Turkey Creek, and at mile 84.4.

DRAINAGE AREA.–580 mi2. 

PERIOD OF RECORD.–March 1939 to current year.

PERIOD OF ANALYSIS.—April 1939 to March 2009.

REMARKS—Based on review of discharge data provided by the SCDHEC, there are no significant point-source discharges upstream. Based 

on review of withdrawal data provided by the SCDHEC, the potential exists for significant withdrawal upstream. However, adequate data 

are not available to quantify this diversion. No adjustment was made to the data used in the frequency analysis. Some regulation of low to 

medium flow from upstream Ware Shoals Dam. City of Greenville diverts water for municipal water supply upstream. 

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence intervals (years)Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2 203 263 309 338 373 426 470

5 99 150 183 207 238 276 314

10 61 105 130 150 180 211 247

20 38 76 94 112 140 166 199

30 29 63 78 93 121 144 176

50 21 50 63 77 102 123 154

DURATION OF DAILY FLOW

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

2,360 1,750 1,140 724 474 302 238
Table 2 33

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey]

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.—02164000 Reedy River near Greenville, SC

LOCATION.-- Lat 34o48'00'', long 82o21'55'', referenced to North American Datum of 1927, Greenville County, SC, Hydrologic Unit 

03050109, on right bank, 375 ft downstream from bridge on Interstate Highway 85, 0.5 mi upstream from Brushy Creek, 2.5 mi upstream from 

dam at Conestee, 3.9 mi southeast of City Hall in Greenville, and at mile 48.5.

DRAINAGE AREA.—48.6 mi2

. 

PERIOD OF RECORD.—November 1941 to September 1971, and June 1987 to current year.

PERIOD OF ANALYSIS.—April 1942 to March 1971, and April 1988 to March 2009.

REMARKS.—Based on review of withdrawal and discharge data provided by the SCDHEC, there are no significant diversions upstream. 

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence intervals (years)Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2 19 19 21 24 28 33 39

5 12 13 14 16 19 24 28

10 9.3 10 11 13 16 20 23

20 7.4 8.1 9.2 10 13 17 20

30 6.5 7.2 8.2 9.3 12 16 18

50 5.6 6.3 7.2 8.2 11 15 16

DURATION OF DAILY FLOW

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

214 136 79 50 33 23 18
34 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey] 

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.—02164110 Reedy River above Fork Shoals, SC

LOCATION.—Lat 34o39'10'', long 82o17'52'', referenced to North American Datum of 1927, Greenville County, SC, Hydrologic Unit 

03050109, at Jenkins Bridge Road bridge, 0.1 mi northeast of intersection of Road 418 and Road 146, and 2.4 mi north of Fork Shoals and at 

mile 36.1.

DRAINAGE AREA.—110 mi2

.

PERIOD OF RECORD.—September 1993 to current year.

PERIOD OF ANALYSIS.—April 1994 to March 2009.

REMARKS.—Based on review of withdrawal data provided by the SCDHEC, there are no significant withdrawals upstream. Based on review 

of point-source discharge data provided by the SCDHEC, the potential exists for significant discharge upstream. However, adequate data are 

not available to quantify this diversion. No adjustment was made to the data used in the frequency analysis. Diversion into basin by the city of 

Greenville, SC, from the Saluda River upstream from station 02162500, Saluda River near Greenville, SC

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

 Recurrence intervals (years)Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2

5

10

20

69

51

42

36

71

52

43

36

73

55

45

38

77

58

49

42

85

66

56

49

99

76

65

57

113

85

71

60

DURATION OF DAILY FLOW

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

510 306 189 136 98 73 61
Table 2 35

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey] 

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.—021650905 Reedy River near Waterloo, SC

LOCATION.— Lat 34o 23' 29'', long 82o 08' 22'', referenced to North American Datum of 1983, Laurens County, SC, Hydrologic Unit 

03050109, at upstream from State Road S-30-36 bridge, 6.0 mi northwest of Waterloo, SC, 7.8 mi downstream from Boyd Mill Pond Dam.

 DRAINAGE AREA.—251 mi2

.

PERIOD OF RECORD.—November 2004 to current year.

PERIOD OF ANALYSIS.—April 1988 to March 2009. 

REMARKS.--Daily mean flows are combined with streamgaging station 02165000, Reedy River near Ware Shoals, SC (April 1939 to 

March 2005) to extend the period of record. The drainage areas of the two stations are within 6.0 percent of each other. Based on review of 

withdrawal data provided by the SCDHEC, there are no significant withdrawals upstream. Based on review of point-source discharge data 

provided by the SCDHEC, the potential exists for significant discharge upstream. However, adequate data are not available to quantify this 

diversion. No adjustment was made to the data used in the frequency analysis. Some regulation of low to medium flow from upstream dams. 

Sewage effluent discharged into the Reedy River about 500 ft below station 02164000. 

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence intervals (years)Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2

5

10

20

30

50

54

38

32

27

25

22

75

52

42

35

32

29

88

61

50

42

38

34

102

72

59

50

44

40

121

84

67

55

49

43

151

101

79

63

56

48

162

109

86

70

61

54

DURATION OF DAILY FLOW

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

900 634 375 256 157 90 66
36 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey]

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.—02165200 South Rabon Creek near Gray Court, SC

LOCATION.-- Lat 34o31'12'', long 82o09'06'', referenced to North American Datum of 1927, Laurens County, SC, Hydrologic Unit 03050109, 

at left bank, 125 ft upstream from U.S. Highway 76, 2.5 mi upstream from North Rabon Creek and 7.0 mi southwest of Gray Court.

DRAINAGE AREA.—29.5 mi2

.

PERIOD OF RECORD.—January 1967 to September 1981, and May 1990 to current year. 

PERIOD OF ANALYSIS.—April 1968 to March 1981, and April 1991 to March 2009.

REMARKS.--Based on review of withdrawal and discharge data provided by the SCDHEC, there are no significant diversions upstream. 

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence 

intervals 

(years)

Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2 9.0 9.2 9.6 11 12 13 14

5 3.0 3.1 3.4 4.0 5.6 7.1 8.2

10 1.3 1.3 1.5 1.8 3.1 4.3 5.6

20 0.51 0.55 0.63 0.79 1.7 2.6 3.9

30 0.29 0.32 0.36 0.46 1.1 1.9 3.1

50 0.15 0.17 0.20 0.26 0.72 1.3 2.4

DURATION OF DAILY FLOW

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

85 57 37 24 15 8.9 5.6
Table 2 37

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey]

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.—02166970 Ninety Six Creek near Ninety Six, SC 

LOCATION.--Lat 34o07'57'', long 81o59'48'', referenced to North American Datum of 1927, Greenwood County, SC, Hydrologic Unit 

03050109, 10.1 mi southeast of Greenwood, and at Road 288 bridge 3.3 mi southeast of Ninety Six, SC

DRAINAGE AREA.—17.4 mi2

. 

PERIOD OF RECORD.—October 1980 to September 2001.

PERIOD OF ANALYSIS.—April 1981 to March 2001. 

REMARKS.—Based on review of withdrawal and discharge data provided by the SCDHEC, there are no significant diversions upstream. 

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence 

intervals 

(years)

Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2 0.27 0.29 0.36 0.37 0.46 0.70 1.1

5 0.10 0.11 0.10 0.13 0.18 0.28 0.42

10 0.06 0.06 0.04 0.07 0.12 0.17 0.25

20 0.0 0.0 0.02 0.04 0.08 0.11 0.16

30 0.0 0.0 0.01 0.03 0.06 0.09 0.12

DURATION OF DAILY FLOW

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

52 21 8.9 3.8 1.2 0.41 0.21
38 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey]

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.—02167000 Saluda River at Chappells, SC 

LOCATION.--Lat 34o10'28'', long 81o51'51'', referenced to North American Datum of 1927, Saluda County, SC, Hydrologic Unit 03050109, 

on downstream side of bridge on State Highway 39 at Chappells, 6.7 mi downstream from dam at Lake Greenwood, 9.8 mi upstream from 

Little River, and at mile 52.3.

DRAINAGE AREA.—1,360 mi2. 

PERIOD OF RECORD.—October 1926 to current year.

PERIOD OF ANALYSIS.—April 1983 to March 2009. 

REMARKS.—Based on review of discharge and withdrawal data provided by the SCDHEC, the potential exists for significant discharge and 

withdrawal upstream. However, adequate data are not available to quantify this diversion. No adjustment was made to the data used in the 

frequency analysis. Flow regulated since 1940 by Lake Greenwood, which has a usable capacity of approximately 7,640,000,000 ft3

.

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence 

intervals 

(years)

Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2 257 347 402 437 496 583 647

5 176 256 301 326 359 399 427

10 144 218 258 277 299 321 338

20 122 191 225 240 256 265 276

30 111 177 209 222 234 238 246

DURATION OF DAILY FLOWS

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

4,430 3,350 1,840 1,040 593 372 301
Table 2 39

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey] 

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.—02167450 Little River near Silverstreet, SC 

LOCATION.--Lat 34o12'34'', long 81o45'48'', referenced to North American Datum of 1927, Newberry County, SC, Hydrologic Unit 

03050109, near center span on downstream side of bridge on U.S. Highway 34, 3.4 mi downstream from Mud Lick Creek, 2.8 mi upstream 

from mouth, 2.9 mi west of Silverstreet, SC

DRAINAGE AREA.—230 mi2

.

PERIOD OF RECORD.—March 1990 to current year.

PERIOD OF ANALYSIS.—April 1991 to March 2009.

REMARKS.—Based on review of withdrawal and discharge data provided by the SCDHEC, there are no significant diversions upstream. 

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence 

intervals 

(years)

Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2 16 16 17 20 25 33 38

5 4.5 4.9 5.9 7.6 11 16 19

10 2.0 2.2 2.9 4.1 6.6 10 12

20 0.89 1.1 1.5 2.4 4.0 6.9 8.1

DURATION OF DAILY FLOWS

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

524 297 153 82 45 21 13
40 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey]

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.—02167582 Bush River near Prosperity, SC 

LOCATION.--Lat 34o10'07'', long 81o36'38'', referenced to North American Datum of 1927, Newberry County, SC, Hydrologic Unit 

03050109, on downstream side of bridge on County Road 244, 5.2 mi southwest of Prosperity, and 7.2 mi south of the center of 

Newberry, SC

DRAINAGE AREA.—115 mi2

. 

PERIOD OF RECORD.—February 1990 to current year.

PERIOD OF ANALYSIS.—April 1990 to March 2009.

REMARKS.—Based on review of withdrawal and discharge data provided by the SCDHEC, there are no significant diversions upstream. 

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence intervals (years)Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2 10 11 12 13 16 21 24

5 5.9 6.4 6.9 7.6 9.5 12 13

10 4.3 4.6 5.0 5.5 6.9 8.3 9.3

20 3.2 3.5 3.8 4.1 5.2 6.0 6.8

DURATION OF DAILY FLOWS

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

362 181 83 42 23 13 8.6
Table 2 41

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey]

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.—02168504 Saluda River below Lake Murray Dam near Columbia, SC 

LOCATION.--Lat 34o03'03'', long 81o12'35'', referenced to North American Datum of 1927, Lexington County, SC, Hydrologic Unit 

03050109, on left bank, approximately 1,000 ft downstream from Lake Murray Dam on the Saluda River, and at mile 9.7. 

DRAINAGE AREA.—2,420 mi2

.

PERIOD OF RECORD.—October 1988 to current year.

PERIOD OF ANALYSIS.—April 1989 to March 2009.

REMARKS.—Based on review of discharge and withdrawal data provided by the SCDHEC, the potential exists for significant discharge 

and withdrawal upstream. However, adequate data are not available to quantify this diversion. No adjustment was made to the data used in 

the frequency analysis. Flow regulated since 1929 by Lake Murray, usable capacity 70,300,000,000 ft3

, and since 1940 by Lake Greenwood, 

which has a usable capacity of 7,640,000,000 ft3. A minimum flow release agreement was established between South Carolina Department 

of Health and Environmental Control and the South Carolina Electric and Gas Company in April 1988 (Wade Cantrell, South Carolina 

Department of Health and Environmental Control, written commun., May 18, 2011)..

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence intervals (years)Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2 248 318 382 440 571 704 889

5 192 236 285 334 400 465 550

10 168 199 240 288 340 376 423

20 151 171 205 254 301 317 339

DURATION OF DAILY FLOWS

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

8,430 5,290 2,710 1,290 544 424 322
42 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey]

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.—02169000 Saluda River near Columbia, SC 

LOCATION.--Lat 34o00'50'', long 81o05'17'', referenced to North American Datum of 1927, Richland County, SC, Hydrologic Unit 

03050109, on left bank 0.4 mi upstream from site of Old Saluda Mill, 1.6 mi upstream from confluence with the Broad River and 3.3 mi west 

of the State Capitol in Columbia, and at mile 1.67.

DRAINAGE AREA.—2,520 mi2

.

PERIOD OF RECORD.—August 1925 to current.

PERIOD OF ANALYSIS.—April 1989 to March 2009.

REMARKS.—Based on review of discharge and withdrawal data provided by the SCDHEC, the potential exists for significant discharge 

and withdrawal upstream. However, adequate data are not available to quantify this diversion. No adjustment was made to the data used in 

the frequency analysis. Flow regulated since 1929 by Lake Murray, usable capacity 70,300,000,000 ft3

, and since 1940 by Lake Greenwood, 

which has a usable capacity of 7,640,000,000 ft3. A minimum flow release agreement was established between South Carolina Department 

of Health and Environmental Control and the South Carolina Electric and Gas Company in April 1988 (Wade Cantrell, South Carolina 

Department of Health and Environmental Control, written commun., May 18, 2011).

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence intervals (years)Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2 351 406 477 535 662 807 987

5 266 313 361 410 484 562 647

10 229 268 304 355 419 470 516

20 202 234 260 314 376 407 427

DURATION OF DAILY FLOWS

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

8,540 5,550 2,930 1,420 637 495 422
Table 2 43

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey] 

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.—02169500 Congaree River at Columbia, SC 

LOCATION.--Lat 33o59'35'', long 81o03'00'', referenced to North American Datum of 1927, Lexington County, SC, Hydrologic Unit 

03050110, on right bank at Columbia, 1,000 ft downstream from Gervais Street Bridge, 1.4 mi downstream from confluence of the Broad 

and Saluda Rivers, and at mile 174.8.

DRAINAGE AREA.—7,850 mi2

.

PERIOD OF RECORD.—October 1939 to current year.

PERIOD OF ANALYSIS.—April 1980 to March 2009.

REMARKS.—Based on review of withdrawal and discharge data provided by the SCDHEC, there are no significant diversions upstream. 

Consequently, no adjustment was made to the data used in the frequency analysis. Flow regulated since 1929 by Lake Murray, usable capacity 

70,300,000,000 ft3

, and since 1940 by Lake Greenwood, which has a usable capacity of 7,640,000,000 ft3. Low to medium flow also regulated 

by powerplants on Broad River. Municipal supply for the City of Columbia diverted above station from Broad River.

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence intervals (years)Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2

5

10

20

30

1,310

917

756

643

587

1,730

1,220

1,000

836

756

2,120

1,490

1,210

1,010

914

2,420

1,690

1,360

1,130

1,010

2,760

1,890

1,520

1,250

1,120

3,250

2,180

1,700

1,360

1,200

3,630

2,410

1,890

1,510

1,330

DURATION OF DAILY FLOWS

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

22,400 14,800 8,710 5,480 3,420 2,050 1,590
44 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey] 

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.—02169570 Gills Creek at Columbia, SC 

LOCATION.--Lat 33o59'22'', long 80o58'28'', referenced to North American Datum of 1927, Richland County, SC, Hydrologic Unit 

03050110, on left bank, downstream side of bridge on U.S. Highways 378 and 76 (Devine Street) at Columbia, 0.75 mi downstream from Lake 

Katherine, and at mile 7.7. 

DRAINAGE AREA.—59.6 mi2

.

PERIOD OF RECORD.—October 1966 to current year. 

PERIOD OF ANALYSIS.—April 1967 to March 2009.

REMARKS.---Based on review of discharge data provided by the SCDHEC, there are no significant point-source discharges upstream. Based 

on review of withdrawal data provided by the SCDHEC, the potential exists for significant withdrawal upstream. However, adequate data are 

not available to quantify this diversion. Natural flow subject to temporary influence from private lakes upstream. 

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence 

intervals 

(years)

Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2

5

10

20

30

50

8.4

4.5

3.1

2.2

1.8

1.4

9.0

4.9

3.4

2.5

2.0

1.6

10

5.5

3.9

2.8

2.3

1.9

12

6.8

4.9

3.7

3.1

2.6

17

9.2

6.4

4.7

3.9

3.2

23

13

9.6

7.3

6.3

5.3

29

17

13

9.6

8.2

7.0

DURATION OF DAILY FLOWS

Flow equaled or exceeded for indicated percentage of time

5 10 25 50 75 90 95

217 147 83 45 25 13 9.4
Table 2 45

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey] 

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.—02169630 Big Beaver Creek near St. Matthews, SC 

LOCATION.--Lat 33o44'12'', long 80o57'30'', referenced to North American Datum of 1927, Lexington County, SC, Hydrologic Unit 

03050110, on downstream side of bridge on U.S. Highway 21, 0.1 mi below Rock Branch and 11.6 mi northwest of St. Matthews, Calhoun 

County, SC

DRAINAGE AREA.—10.0 mi2

.

PERIOD OF RECORD.—July 1966 to September 1993. 

PERIOD OF ANALYSIS.—April 1967 to March 1993. 

REMARKS.—Based on review of withdrawal and discharge data provided by the SCDHEC, there are no significant diversions upstream. 

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence 

intervals 

(years)

Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2 6.5 6.7 7.0 7.3 8.0 8.8 9.3 

5 5.1 5.3 5.5 5.8 6.3 7.0 7.4

10 4.5 4.7 4.9 5.1 5.6 6.2 6.6

20 4.1 4.2 4.4 4.6 5.1 5.6 6.0

30 3.9 4.0 4.2 4.4 4.8 5.3 5.7

DURATION OF DAILY FLOWS

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

27 22 16 12 8.9 7.1 6.4
46 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey] 

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.—02172500 South Fork Edisto River near Montmorenci, SC 

LOCATION.--Lat 33o34'35'', long 81o30'50'', referenced to North American Datum of 1927, Aiken County, SC, Hydrologic Unit 03050204, 

near the center span on downstream side of bridge on State Highway 302, 0.4 mi upstream from Cedar Creek, 1.0 mi upstream from Shaw 

Creek, 7.6 mi northeast of Montmorenci, SC, and at mile 167.3.

DRAINAGE AREA.—198 mi2

.

PERIOD OF RECORD.—April 1940 to September 1966. 

PERIOD OF ANALYSIS.—April 1940 to March 1966. Period of record was extended to include climatic years 1932 to 1939, 1966 to 1970, 

and 1981 to 2008 by using streamgaging station 02173000, South Fork Edisto River near Denmark, SC, as an index station. The MOVE.1 

technique was used to augment the record. 

REMARKS.—Based on review of discharge data provided by the SCDHEC, there are no significant point-source discharges upstream. Based 

on review of withdrawal data provided by the SCDHEC, the potential exists for significant withdrawal upstream. However, with respect to 

adjusting the low-flow statistics, adequate data are not available to quantify this diversion.

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence 

intervals 

(years)

Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2

5

10

20

83

59

49

42

85

61

51

44

91

65

55

47

97

70

58

50

111

81

68

58

125

92

77

66

135 

100

84

72

DURATION OF DAILY FLOWS

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

453 369 261 186 133 99 79
Table 2 47

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey] 

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.—02172640 Dean Swamp near Salley, SC 

LOCATION.--Lat 33o35'21'', long 81o21'57'', referenced to North American Datum of 1927, Aiken County, SC, Hydrologic Unit 03050204, 

on dirt road, Richburg Villa, South of County Road 27, 1.2 mi south of intersection of County Roads 14 and 270.

DRAINAGE AREA.—31.2 mi2

.

PERIOD OF RECORD.—October 1980 to March 1987, then February 1988 to October 2000. 

PERIOD OF ANALYSIS.—April 1981 to March 1987, then April 1988 to March 2000.

REMARKS.—Based on review of withdrawal and discharge data provided by the SCDHEC, there are no significant diversions upstream. 

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence 

intervals 

(years)

Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2 17 18 18 19 20 22 22

5 15 15 15 16 18 19 19

10 13 14 14 14 16 17 17

20 12 13 13 13 15 16 16

DURATION OF DAILY FLOWS

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

36 32 27 24 20 18 16
48 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey] 

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.—02173000 South Fork Edisto River near Denmark, SC 

LOCATION.--Lat 33o23'35'', long 81o08'00'', referenced to North American Datum of 1927, Bamberg County, SC, Hydrologic Unit 

03050204, on left bank on downstream side of bridge on U.S. Highway 321, 360 ft downstream from Seaboard Coast Line Railroad Bridge, 

1.8 mi downstream from Little River, 4.8 mi north of Denmark, and at mile 136.6.

DRAINAGE AREA.—720 mi2

.

PERIOD OF RECORD.—August 1931 to September 1971, then October 1980 to current year. 

PERIOD OF ANALYSIS.—April 1932 to March 1971, then April 1981 to March 2009.

REMARKS.—Based on review of discharge data provided by the SCDHEC, there are no significant point-source discharges upstream. Based 

on review of withdrawal data provided by the SCDHEC, the potential exists for significant withdrawal upstream. However, adequate data are 

not available to quantify this diversion. No adjustment was made to the data used in the frequency analysis.

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence 

intervals 

(years)

Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2

5

10

20

30

50

267

194

164

142

131

121

271

198

168

145

135

124

284

207

175

152

 140

129

305

223

188

163

150

138

343

252

212

182

167

153

390

286

240

206

189

172

420

308

257

220

202

183

DURATION OF DAILY FLOWS

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

1,640 1,290 872 616 442 317 256
Table 2 49

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey] 

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.—02173051 South Fork Edisto River near Bamberg, SC 

LOCATION.--Lat 33o20'13'', long 81o01'08'', referenced to North American Datum of 1927, Bamberg County, SC, Hydrologic Unit 

03050204, on downstream side of upstream bridge, on U.S. Highway 301/601, 3.0 mi north of Bamberg, and at mile 127.2.

DRAINAGE AREA.—807 mi2

.

PERIOD OF RECORD.—April 1991 to current year. 

PERIOD OF ANALYSIS.—April 1932 to March 2009. Period of record was extended to include climatic years 1932 to 1970 and 1981 to 

1990 by using streamgaging station 02173000, South Fork Edisto River near Denmark, SC, as an index station. The MOVE.1 technique was 

used to augment the record. 

REMARKS.—Based on review of withdrawal and discharge data provided by the SCDHEC, there are no significant diversions upstream. 

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence 

intervals 

(years)

Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2 277 281 299 331 388 461 510

5 195 199 211 232 271 316 349

10 163 165 175 191 221 256 279

20 139 142 150 163 185 212 231

30 128 131 137 148 168 191 208

50 117 119 125 135 151 171 184

DURATION OF DAILY FLOWS

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

2,550 1,940 1,220 796 521 349 271
50 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey] 

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.—02173500 North Fork Edisto River at Orangeburg, SC 

LOCATION.--Lat 33o29'00'', long 80o52'25'', referenced to North American Datum of 1927, Orangeburg County, SC, Hydrologic Unit 

03050203, on left bank, under bridge on U.S. Highway 301 at Orangeburg, 0.5 mi upstream from Seaboard Coast Line Railroad bridge, 

1.5 mi downstream from Caw Caw Swamp and at mile 22.1.

DRAINAGE AREA.—683 mi2

.

PERIOD OF RECORD.—December 1938 to current year. 

PERIOD OF ANALYSIS.—April 1939 to March 2009.

REMARKS.—Based on review of withdrawal and discharge data provided by the SCDHEC, there are no significant diversions upstream. 

Consequently, no adjustments were made to the data used in the frequency analysis. City of Orangeburg diverts municipal water supply 

upstream, but this diversion was determined to not be significant.

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence 

 intervals 

(years)

Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2

5

10

20

30

50

331

239

198

167

153

137

336

242

201

170

155

140

347

252

209

178

162

147

365

265

221

188

171

155

396

292

244

209

191

173

441

324

271

232

212

193

473

346

288

245

223

202

DURATION OF DAILY FLOWS

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

1,550 1,240 883 646 467 350 284
Table 2 51

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey] 

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.—02174000 Edisto River near Branchville, SC 

LOCATION.--Lat 33o10'35'', long 80o48'05'', referenced to North American Datum of 1927, Bamberg County, SC, Hydrologic Unit 

03050205, 400 ft downstream from bridge on U.S. Highway 21 and 5.2 mi south of Branchville.

DRAINAGE AREA.—1,720 mi2

.

PERIOD OF RECORD.—October 1945 to September 1996. 

PERIOD OF ANALYSIS.—April 1940 to March 2009. Period of record was augmented to include climatic years 1940 to 1944, and 1997 

to 2009 by using streamgaging station 02175000, Edisto River near Givhans, SC, as an index station. The MOVE.1 technique was used to 

augment the record.

REMARKS.—Based on review of withdrawal and discharge data provided by the SCDHEC, there are no significant diversions upstream. 

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence 

intervals 

(years)

Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2 699 706 725 758 817 910 961

5 481 488 505 537 592 662 707

10 384 390 406 437 490 556 596

20 313 319 334 363 415 479 515

30 277 283 298 326 377 441 475

50 244 249 263 290 340 403 435

DURATION OF DAILY FLOWS

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

5,100 3,850 2,490 1,580 1,060 761 607
52 Low-Flow Frequency and Flow Duration of Selected South Carolina Streams

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey] 

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.—02174250 Cow Castle near Creek near Bowman, SC 

LOCATION.--Lat 33o22'43'', long 80o42'00'', referenced to North American Datum of 1927, Bamberg County, SC, Hydrologic Unit 

03050206, 400 ft downstream from bridge on U.S. Highway 21 and 5.2 mi south of Branchville.

DRAINAGE AREA.—23.4 mi2

.

PERIOD OF RECORD.—October 1970 to September 1981, and October 1995 to current year. 

PERIOD OF ANALYSIS.—April 1971 to March 1981, and April 1996 to March 2009.

REMARKS.—Based on review of discharge data provided by the SCDHEC, there are no significant point-source discharges upstream. Based 

on review of withdrawal data provided by the SCDHEC, the potential exists for significant withdrawal upstream. However, adequate data are 

not available to quantify this diversion. No adjustment was made to the data used in the frequency analysis.

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence 

intervals 

(years)

Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2 0.77 0.83 0.94 1.1 1.5 2.0 2.6

5 0.33 0.37 0.43 0.53 0.79 0.98 1.2

10 0.19 0.22 0.26 0.33 0.52 0.68 0.84

20 0.08 0.10 0.11 0.15 0.26 0.50 0.61

30 0.0 0.0 0.0 0.0 0.0 0.43 0.51

DURATION OF DAILY FLOWS

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

69 43 18 6.9 2.7 1.4 0.87
Table 2 53

Table 2. Low-flow statistics for continuous-record streamgaging stations in the Saluda, Congaree, and Edisto River basins of 

South Carolina.—Continued

[lat, latitude; long, longitude; ft, feet; mi, mile; mi2, square mile; SCDHEC, South Carolina Department of Health and Environmental Control; USGS, U.S. 

Geological Survey] 

Note: See figure 2 for location of the streamgaging stations.

STATION NAME AND NUMBER.—02175000 Edisto River near Givhans, SC 

LOCATION.--Lat 33o01'40'', long 80o23'30'', referenced to North American Datum of 1927, Dorchester County, SC, Hydrologic Unit 

03050205, on downstream side of bridge on State Highway 61, 2.3 mi downstream from Four Hole Swamp, 2.8 mi west of Givhans, and at 

mile 59.9.

DRAINAGE AREA.—2,730 mi2

.

PERIOD OF RECORD.—January 1939 to current year. 

PERIOD OF ANALYSIS.—April 1940 to March 2009.

REMARKS.—Based on review of discharge data provided by the SCDHEC, there are no significant point-source discharges upstream. Based 

on review of withdrawal data provided by the SCDHEC, the potential exists for significant withdrawal upstream. However, adequate data 

are not available to quantify this diversion. No adjustment was made to the data used in the frequency analysis. City of Charleston diverts 

municipal water supply upstream.

MAGNITUDE AND FREQUENCY OF ANNUAL LOW FLOWS

Recurrence 

intervals 

(years)

Lowest average flow for indicated number of consecutive days

(cubic feet per second)

1 3 7 14 30 60 90

2

5

10

20

30

50

625

422

332

268

236

206

634

428

337

272

239

209

649

439

347

281

248

217

677

459

364

296

262

230

738

504

403

331

296

262

859

566

450

370

332

295

968

626

491

399

355

314

DURATION OF DAILY FLOWS

Flow equaled or exceeded for indicated percentage of time

(cubic feet per second)

5 10 25 50 75 90 95

7,330 5,240 3,050 1,700 1,000 670 524
Prepared by:

USGS Publishing Network

Raleigh Publishing Service Center

3916 Sunset Ridge Road

Raleigh, NC 27607

For additional information regarding this publication, contact:

 USGS South Carolina Water Science Center

 Stephenson Center, Suite 129

 720 Gracern Road

 Columbia, SC 29210-7651

Or visit the USGS South Carolina Water Science Center Web site at:

 http://sc.water.usgs.gov

Feaster and Guimaraes—Low-Flow Frequency and Flow Duration of Selected South Carolina Streams—Open-File Report 2012–1253