As part of the U.S. Geological Survey National Water-Quality Assessment Program (NAWQA), water quality in Gills Creek, an urban stream in Columbia, South Carolina was studied during a low streamflow period in September 1996. Sixteen sites were sampled for pesticides and fecal coliform bacteria.

Gills Creek originates from springs and passes through forest and wetlands before reaching urban areas in the middle and lower part of the basin. The urban landscape consists of suburban housing, golf courses, and commercial shopping areas. There are several impoundments along Gills Creek where lakeside communities have developed.

Significant results of the sampling include:

• Ten different pesticides were detected in the Gills Creek Basin.

• Fourteen of the 16 stations had detectable concentrations of at least one pesticide, and 12 stations had at least five pesticides detected.

• Pesticides were detected more frequently at stations with high percentages of urban land use.

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

• Diazinon, carbaryl, and dieldrin concentrations exceeded U.S. Environmental Protection Agency aquatic life standards.

• Fecal coliform concentrations ranged from 37 to 1,700 colonies per 100 milliliters and exceeded the South Carolina water-quality standard at 8 of the 16 stations.

--- March 1999

To order SANT NAWQA publications, please email or call:

Celeste A. Journey
SANT NAWQA Project Chief
cjourney@usgs.gov
(803) 750-6141