The almost 800-acre Barite Hill site southwest of town on the state's western edge was mined from 1989 through 1994. The mining company is bankrupt and the state does not have the money to clean the site.
The EPA announced Wednesday that water and sediment at the site, as well as in nearby Hawe Creek where people fish, are contaminated with metals including lead, mercury, arsenic and cadmium.
Superfund is the federal program that cleans complex or abandoned hazardous sites. There are 25 other Superfund sites in South Carolina.