NATIONAL WATER-QUALITY ASSESSMENT PROGRAM

Pesticides and Bacteria in an Urban Stream-Gills Creek, Columbia, South Carolina

Significant Findings

Ten different pesticides were detected in the Gills Creek Basin.

Samples from 14 of 16 sites had detectable concentrations of at least one pesticide, and 12 sites had at least five pesticides

detected.

Pesticide detection frequency increased as the percentage of urban land use increased.

Tebuthiuron was detected most frequently (14 sites), followed by diazinon (13 sites), and atrazine (12 sites).

Diazinon, carbaryl, and dieldrin concentrations exceeded aquatic life standards in some samples.

Fecal coliform concentrations exceeded 400 colonies per 100 milliliters at 8 of the 16 sites.

Introduction

As part of the U.S. Geological Survey 

National Water-Quality Assessment Program (NAWQA), water quality in the 

Santee River Basin and coastal drainages 

study area (SANT) is being assessed. 

Gills Creek, an urban stream in Columbia, South Carolina, was studied during a 

low streamflow period in September 

1996. During the study, streamflows 

were in the lower 30 percent of the 1996 

flows in Gills Creek. Samples from 16 

sites were collected over 4 days and analyzed for pesticides and fecal coliform 

bacteria. This fact sheet presents the 

results of the Gills Creek Basin study.

Where is the Gills Creek 

Basin?

The Gills Creek Basin is located in metropolitan Columbia, S.C., and drains about 

60 square miles. The soils are sandy and 

have moderately high permeability. The 

annual mean streamflow at Gills Creek in 

Columbia (site 1, fig. 1) is about 77 cubic 

feet per second (Cooney and others, 

1997). The annual average precipitation 

in Columbia is approximately 50 inches 

per year and is highest during the summer months (South Carolina Department 

of Natural Resources, 1998).

Gills Creek originates from a springfed pond in the northeastern part of the 

basin and passes through forest and wetlands before reaching urban areas (fig. 1). 

Vegetation consists of scrub oak, pine, 

and cactus in the undisturbed areas. Tributaries entering Gills Creek include Rowell Creek, Jackson Creek, Little Jackson 

Creek, Eightmile Branch, Penn Branch, 

and Wildcat Creek. Land uses in the tributaries and lower part of the basin include 

mainly urban and forested areas, with a 

small percentage of barren and agricultural land. Vegetation, where it occurs in the 

urbanized areas, consists of tropical lawn 

grasses and pine trees. The urban landscape consists of residential subdivisions 

and commercial and shopping areas; golf 

courses and lake communities are common. The Gills Creek Basin has been 

experiencing rapid urban development 

since the late 1960's. The bulk of the residential growth has been single-family 

houses with less than 1-acre lot sizes.

Pesticides in the Gills Creek 

Basin

Pesticides are used on a regular basis for 

agricultural, commercial, and domestic 

purposes to control insects and selected 

vegetation. Because of their widespread 

use, pesticides commonly occur in creeks, 

streams, and lakes (Larson and others, 

1997). Pesticides have several potential 

pathways to enter surface waters. Pesticides may enter surface waters as a result 

of direct application of herbicides to 

streams or streambanks to control weed 

growth. Atmospheric deposition results

from precipitation scouring contaminants 

from the air and depositing them on the 

ground or directly into the streams. Nonpoint-source runoff of pesticides occurs 

when rain washes over the ground surface, carrying contaminants into nearby 

streams. Pesticides also can soak into the 

ground and can enter streams in groundwater discharge.

A common "adjusted" method reporting limit (MRL) of 0.01 micrograms per 

liter (jig/L) was used to compare the 

detection frequencies of pesticides having different MRL's. Using an adjusted 

MRL results in a loss of detection information, however, it allows a uniform 

comparison of the pesticide detection frequencies. Of 47 pesticides analyzed, 10 

were detected above the adjusted MRL 

of 0.01 (ig/L. Samples from 14 of the 16 

sites had detectable concentrations of at 

least one pesticide, and 12 sites had at 

least five pesticides detected.

Gills Creek flowing through a commercial area.

U.S. Department of the Interior 

U.S. Geological Survey

USGS Fact Sheet FS-131-98 

March 1999
Tebuthiuron was the most commonly 

detected pesticide (14 sites), followed by 

diazinon (13 sites), and atrazine (12 sites). 

Tebuthiuron is an herbicide used to control weeds in non-cropland areas, right-ofways, and industrial sites. Common trade 

names for tebuthiuron include Brush, Bullet, Graslan, Herbec, Reclaim, and Spike 1 . 

Diazinon is an insecticide used to kill 

cockroaches, silverfish, ants, and fleas in 

residential areas, and on home gardens 

and farms to control a variety of other

Use of trade names does not imply 

endorsement by the U.S. Geological Survey.

insects. Common trade names for diazinon include Basudin, Dazzel, Gardentox, 

Kayazol, Knox Out, Nucidol, and Spectracide. Atrazine is an herbicide used to 

control weeds in cropland and industrial 

areas. Atrazine use is restricted because 

of its potential to contaminate ground 

water. Common trade names for atrazine 

include Aatrex, Alazine, Farmco Atrazine, Primatol, Simazat, and Zeapos.

Other detected pesticides include carbaryl and dieldrin. Carbaryl is a widespectrum insecticide that is used on crops, 

forests, lawns, poultry, livestock, and

pets. Common trade names for carbaryl 

include Adios. Bugmaster. Crunch, Dcnapon, Nac, Sevin, and Tornado. Dieldrin 

is an insecticide that was used widely 

from 1950 to 1970 to control pests on 

crops. In 1974, the U.S. Environmental 

Protection Agency banned all uses of dieldrin except for termite control. In 1987, 

dieldrin was banned for all uses. Because 

dieldrin breaks down slowly, low levels 

are still being detected in the environment. Dieldrin also was detected during a 

study of shallow ground-water quality in 

Columbia during summer 1996 (Reuber, 

1999).

N

EXPLANATION

URBAN

AGRICULTURAL

FOREST

WATER

WETLAND

BARREN

PRIMARY ROAD

BASIN OR SUB-BASIN 

BOUNDARY

SITE LOCATION AND 

NUMBER (see table 1)

Digital land use and land cover data 

modified from U.S Geological Survey 

1970; U.S. Geological Survey, 1990.

2 MILES

J

I I 

0 1 2 KILOMETERS

Gills Creek Basin'

Figure 1. Land use in the Gills Creek Basin.
Table 1. Basin descriptions

Map 

site 

number

1

2

; 3

4

i 5

5A

l 6

7

I 8

9

11

12

1 13

14

1 15

16

Site

Gills Creek at Columbia

Gills Creek below Lake Katherine

Wildcat Creek

Penn Branch

Eightmile Branch below Trenholm Rd.

Eightmile Branch at Covenant Rd.

Gills Crock below Eightmile Branch

Gills Creek above Forest Lake

Gills Creek at Boyden Arbor Rd.

Rowell Creek at Dixie Rd.

Jackson Creek above Decker Blvd.

Little Jackson Creek at Trenholm Rd.

Jackson Creek at Alpine Rd.

Trib. to Little Jackson Creek at Rabon

Little Jackson Creek at Legrande Rd.

Jackson Creek at Leaning Tree Rd.

Drainage 

area, in 

square 

miles

59.4

53.4

5.3

2.9

3.9

2.4

48.2

22.4

18.6

2.5

16.1

7.0

5.2

2.5

3.7

0.5

Percent 

urban land 

use

52

50

68

100

95

92

45

20

14

5

52

66

26

18

71

50

Number of 

pesticides 

detected

7

5

5

9

7

5

7

5

0

0

7

6

5

3

4

5

The number of pesticides detected at a 

site increased as the percentage of urban 

land use increased. Penn Branch (100 percent urban) had the most pesticides 

detected (9), and Gills Creek at Boyden 

Arbor Road (14 percent urban) and Rowell Creek at Dixie Road (5 percent urban) 

had no pesticides detected (table 1).

Are the Pesticide 

Concentrations in the Gills 

Creek Basin Harmful?

Concentrations of three insecticides 

exceeded the chronic criteria to protect 

aquatic life: diazinon, carbaryl, and dieldrin (table 2). Diazinon exceeded the 

chronic criteria for aquatic life in each of 

13 detections; carbaryl exceeded the criteria 8 times in 10 detections; dieldrin 

exceeded the criteria in each of two detections. At sustained concentrations above 

the criteria, aquatic life and reproduction 

may be reduced or impaired. None of the 

pesticides exceeded their respective U.S. 

Environmental Protection Agency maximum contaminant level or health advisory level (finished drinking-water standards).

Fecal Coliform Bacteria

High levels of fecal coliform bacteria in 

streams and lakes may indicate the presence of more serious disease-causing

organisms. Cholera, typhoid fever, bacillary dysentery, and infectious hepatitis 

are some of the well-known waterborne 

diseases that spread through water contaminated with fecal matter and that affect 

human and animal health. Eye, ear, nose, 

and throat infections also can result from 

contact with contaminated water. High 

bacteria concentrations can occur in 

urbanized areas with point-source discharges, landfill leakage, storm drains, 

runoff of pet waste, overflowing sewer 

lines, or failing septic systems.

In South Carolina, water-quality standards state that fecal coliform concentrations may not exceed a geometric mean 

of 200 colonies per 100 milliliters 

(col/100 mL) from five consecutive samples collected during any 30-day period, 

and no more than 10 percent of the total 

samples during any 30-day period can 

exceed 400 col/100 mL (South Carolina 

Department of Health and Environmental 

Control, 1992). Streams or lakes having 

fecal coliform concentrations greater 

than 400 col/100 mL are not considered 

safe for swimming or other direct bodycontact activities.

Fecal coliform concentrations ranged 

from 37 to 1,700 col/100 mL in the Gills 

Creek Basin. Of the 16 sites, 8 had fecal 

coliform concentrations greater than 400 

col/100 mL (fig. 2). Fecal coliform concentrations were lowest in Gills Creek 

above Forest Lake, and highest in the 

downstream section of Jackson Creek 

and at both Eightmile Branch sites. 

Because these samples were collected 

during low streamflow conditions, fecal 

coliform concentrations may have been 

lower than they would have been under 

average or high streamflows. Bacteria 

concentrations often increase during high 

streamflows; therefore, care should be 

taken during recreational use of these 

streams.

Table 2. Pesticides detected in the Gills Creek Basin, September 1996

[--, not established: concentrations in red italics exceed aquatic life criteria]

Pesticide

Tebuthiuron

Atrazine

Simazine

Prometon

Diazinon

Carbaryl

Malathion

Chlorpyrifos

Dieldrin

Methyl parathion

Number of 

detections

14

12

11

9

13

10

5

3

2

I

Maximum Aquatic life 

concentration, criteria, in 

in micrograms micrograms 

per liter per liter

Herbicides

0.177

0.107

0.105

0.178

Insecticides

0.323

0.139

0.032

0.032

0.011

0.012

3 10

30.009

30.02

40.1

40.041

40.0019

40.013

L;fetl Maximum 

Meaitn Contaminant 

, Adv'Ty Level 1 , in Level - in micrograms 

micrograms »

per liter H

500 - !

23 3

4 4

2 100

0.6 flHBB

700

200 - _j

20

"^^^^

-

1 U.S. Environmental Protection Agency, 1996. 

Under review.

3 Freshwater chronic water-quality criteria recommendations from National Academy of Sciences and 

National Academy of Engineering (1973) modified from Nowell and Resek (1994).

4 U.S. Environmental Protection Agency, 1997.
Thirteen additional samples were collected and analyzed for fecal coliform 

bacteria from October 1995 through September 1996 in Gills Creek at Columbia 

(site 1). Concentrations ranged from less 

than 20 col/100 mL to just over 1,100 

col/100 mL, and only two of the 13 samples exceeded 400 col/100 mL.

By Terry L. Maluk

1,800 | r

Lakeside community in the Gills Creek Basin.

Figure 2. Fecal coliform concentrations at synoptic sites in the Gills Creek Basin.

References

Cooney, T.W., Jones, K.H., Drewes, P.A., 

Gissendanner, J.W., and Church, 

B.W., 1997, Water resources data 

South Carolina water year 1996: U.S. 

Geological Survey Water-Data 

Report SC-96-1, 476 p.

Larson, S.J., Capel, P.O., and Majewski, 

M.S., 1997, Pesticides in surface 

waters: Distribution, trends, and 

governing factors: Chelsea, Mich., 

Ann Arbor Press, 390 p.

National Academy of Sciences-National 

Academy of Engineering, 1973, 

Water-quality criteria, 1972: 

Washington, D.C., National Academy 

of Sciences, 594 p.

Nowell, L.H., and Resek, E.A., 1994, 

Summary of national standards and 

guidelines for pesticides in water, bed 

sediment, and aquatic organisms and 

their applications to water-quality 

assessments: U.S. Geological Survey 

Open-File Report 94-44, 115 p.

Reuber, E.J., 1999, Shallow groundwater quality in the coastal plain of 

Columbia, South Carolina, 1996: 

U.S. Geological Survey Fact Sheet 

FS-130-98, 6 p.

South Carolina Department of Health 

and Environmental Control, 1992. 

Water classifications and standards 

(Regulation 61-68): South Carolina 

Department of Health and 

Environmental Control, 35 p.

South Carolina Department of Natural 

Resources, 1998, Climatological 

normals 1961-1990: accessed June 10, 

1998, at URL http://water.dnr.state. 

sc.us/climate/sercc/products/normals 

/381939_30yr_norm.html

U.S. Environmental Protection Agency, 

1996, Drinking water regulations and 

health advisories: Washington, D.C., 

Office of Water, EPA 822-B-96-002, 

26 p.

____1997, TSC195 criteria chart:

Region IV, Water Management 

Division, 6 p.

For More Information

Information on technical reports and 

hydrologic data related to the NAWQA 

Program can be obtained from:

District Chief 

U.S. Geological Survey 

720 Gracern Road 

Columbia, SC 29210-7651

URL http://wwwsc. er. usgs. gov

National Water-Quality Assessment Program

The United States Geological Survey (USGS) is conducting an assessment of 

water quality in the Santee River Basin and coastal drainages (SANT) study area as 

part of the National Water-Quality Assessment (NAWQA) Program. The long-term 

goals of NAWQA are to describe the status of and trends in the quality of a large representative part of the Nation's surface- and ground-water resources and to identify 

major factors that affect the quality of these resources. A total of 59 hydrologic systems are to be studied that include parts of most major river basins and aquifer systems in the Nation. The assessment activities in the SANT study area began in 1994.