Between 1947 and 1977, General Electric polluted the Hudson River by dispensing polychlorinated biphenyls (PCBs), causing a range of harmful effects to wildlife and people who eat fish from the river or drink the water. In response to this contamination, activists protested in various ways; for instance, musician Pete Seeger founded the Hudson River Sloop Clearwater and the Clearwater Festival to draw attention to the problem. The activism led to the site being designated as one of the Superfund sites. Other kinds of pollution, including mercury contamination and sewage dumping, have also caused problems.
The New York State Department of Environmental Conservation (NYSDEC) has listed various portions of the Hudson as having impaired water quality due to PCBs, cadmium, and other toxic compounds. Hudson River tributaries with impaired water quality (not necessarily the same pollutants as the Hudson main stem) are Mohawk River, Dwaas Kill, Schuyler Creek, Saw Mill River, Esopus Creek, Hoosic River, Quaker Creek, and Batten Kill. Many lakes in the Hudson drainage basin are also listed. Other ongoing pollution issues affecting the river include: accidental sewage discharges, urban runoff, heavy metals, furans, dioxin, pesticides, and polycyclic aromatic hydrocarbons (PAHs).