(AP) — The aquifer under central Hockessin, Delaware, has been formally added to the federal program to cleanup of the country's most contaminated sites.

The U.S. Environmental Protection Agency made the announcement Tuesday for six sites throughout the country named as Superfund sites. They included groundwater or former industrial areas of South Carolina, Indiana, Minnesota and Texas.

The aquifer made the list due to the presence of dry-cleaning pollutants, which have lingered in area groundwater for decades.

The 32-acre area straddles Lancaster Pike through the core of the Hockessin business district.

Regulators emphasize that drinking water drawn from Hockessin wells by the public utility, Artesian Resources Corp., is known to be safe because it is filtered and regularly tested.