Groundwater Protection Program

As part of the state's goal of protecting the public's health and the environment, Clemson University's Department of Pesticide Regulation (DPR) initiated a groundwater-sampling program for pesticides and nitrate in the fall of 1991. The purpose of the program is to determine whether chemicals used in farming, landscape management and home gardening are impairing South Carolina's groundwater resources. Wells located on private and public land have been sampled for 22 commonly used pesticides and nitrate, a common component of fertilizer.

DPR researched which pesticides would have the highest probability to impact groundwater during normal use. EPA's list of leachable pesticides was cross-referenced with crop and use patterns in South Carolina. From EPA's list, 22 leachable pesticides were picked for routine analysis in all groundwater samples because of their high usage in the state's agriculture. Nitrate-nitrogen was also chosen for analysis, because its presence can be used as an indicator that surface applied chemicals are able to reach groundwater. In addition to the 22 leachable pesticides, the samples are also analyzed for any pesticide listed by the well owner as being used within 500 feet of the well.

Prior to sampling, DPR, in cooperation with the South Carolina Department of Health and Environmental Control (SCDHEC) and the Clemson Cooperative Extension Service, performed a risk analysis for groundwater vulnerability to pesticide and nitrate contamination. Crop patterns, pesticide usage, population and groundwater vulnerability data were combined to estimate which areas of South Carolina had the greatest risk of groundwater contamination from pesticide use. Review of the data revealed that eighteen counties, located in South Carolina's Coastal Plain, fall into the area of the state identified as having high groundwater vulnerability as well as medium to high pesticide usage.

Sampling began in the 18 most vulnerable counties in September 1991 and continued through December 1992. Results from groundwater tested in these high vulnerability counties showed little detection of pesticides and nitrate at levels of concern to the public's health. In 1993, DPR expanded its groundwater sampling efforts to all 46 counties in South Carolina. The groundwater-sampling program is an ongoing project and it is now in its 15th year of sampling. Each year DPR collect between 150 and 200 groundwater samples from wells across the state. DPR plans to continue testing wells as a public service as long as funds for the project are available.

For more information on the sampling program, please contact Jerry Moore.