The Presque Isle site is located on the Presque Isle State Park peninsula in Erie County, Pennsylvania. In the early 1970s, the Erie County Health Department noted a seep near Beach No. 7 that was discharging a noxious hydrogen sulfide-bearing black liquid. The discharge released hydrogen sulfide into the air and a black fluid containing hazardous substances into the soil and shallow groundwater. This discharge continued until the early 1980s. The source of the discharge was found to be an unplugged natural gas well that had been dug in 1910 and abandoned in 1920. The well intercepts a geologic formation known as the Bass Island formation. The Pennsylvania Department of Environmental Protection (PADEP) plugged the well in 1982. EPA took the site off the Superfund program�s National Priorities List (NPL) in December 1989.