Arsenic, chromium, and lead exceeded guidelines in a few samples. Although concentrations were not high in sediment samples, data suggest that mercury is accumulating in fish and clams in concentrations that are harmful to humans or animals that eat them. Sampling by State agencies has resulted in fish-consumption advisories for mercury in 49 rivers and reservoirs in South Carolina. Most of the 3.5 million people in the Santee Basin live in urban areas. Eighty-six percent of the water used in homes and for industry is treated surface water withdrawn from rivers or reservoirs.
Ground water is the main water source for rural households.
Organochlorine pesticides were detected frequently in bed sediment and tissue. Most of these compounds have been discontinued for use for many years but continue to be detected because they are persistent in the environment. A derivative of DDT was detected at concentrations exceeding aquatic-life standards in sediment at three agricultural sites. Bacteria levels frequently exceeded South Carolina standards for contact recreation in streams in forested, urban, and agricultural areas. Standards were exceeded more frequently in small streams than in large rivers.