The 18,000-acre New Bedford site is an urban tidal estuary with sediments that are highly contaminated with polychlorinated biphenyls (PCBs) and heavy metals. From the 1940s until EPA’s PCB ban in the 1970s, facilities associated with the production of electrical devices discharged industrial wastes containing PCBs directly and indirectly into the harbor. As a result, PCBs contaminate the harbor in varying degrees for at least six miles, from the upper Acushnet River into Buzzards Bay. A five-acre northern portion of the Acushnet River Estuary contaminated with high levels of PCBs (the "hot spot" area) was dredged in 1994 and 1995. Bioaccumulation of PCBs within the marine food chain has resulted in closing the entire site area to lobstering and fishing, and recreational activities and harbor development have been limited by the widespread-PCB problem.