A major hub for manufacturing and transportation, the Great Lakes and their tributaries were once an easy dump site for their waste products that included organic toxins, mercury, PCBs, and dioxins. As a result of the Federal Clean Water Act (1972) most of the direct pollution discharges from known point sources have stopped, but the legacy pollutants remain because many are trapped in lake and stream sediments. Other dissolved pollutants have long residence times because less than one percent of the water in the Great Lakes exits the lake system annually. Discharge from sewage treatment systems remains a problem, particularly where stormwater and sewage systems are combined in large urban areas. The inland fish habitats of the Upper [...]
