The most discussed pollution of the Hudson River is General Electric's contamination of the river with polychlorinated biphenyls (PCBs) between 1947 and 1977. This pollution caused a range of harmful effects to wildlife and people who ate fish from the river or drank the water. In response to this contamination, activists protested in various ways. A group of fishermen formed an organization in 1966 that would later become Riverkeeper, the first member of the Waterkeeper Alliance. Musician Pete Seeger founded the Hudson River Sloop Clearwater and the Clearwater Festival to draw attention to the problem. Environmental activism led to passage of the federal Clean Water Act in 1972 as well as federal government designation of the river as a Superfund site in 1984. Other kinds of pollution, including mercury contamination and discharges of partially-treated sewage, have also caused problems.