As of March 26, 2010, there were two Superfund sites on the National Priorities List in South Dakota.[2] No sites are currently proposed for entry on the list. Two sites have been cleaned up and removed from the NPL.[2]
Sulfide waste rock and exposed ore zones contain heavy metals, including arsenic, cadmium, chromium, copper, lead, nickel, silver and zinc. These heavy metals, in addition to cobalt and manganese, have been found in Strawberry Creek. Elevated nitrates and sulfates are also present in heap leach residues.[8][9]
On-site shallow monitoring wells downgradient from the landfills and burn pit are contaminated with 1,1-dichloroethane, 1,2-dichloroethylene, trichloroethylene, arsenic, and chromium.[12][13]
Sediment in the 7 foot deep unlined pit measuring 9 feet by 9 feet contains barium, beryllium, chromium, copper, iron, lead, zinc, benzene, toluene, xylene, polynuclear aromatic hydrocarbons, and pesticides. Ground water near the pit is contaminated with 4,4'-DDD, 4,4'-DDT, gamma-chlordane, beta-BHC, and lead.[14][15]