While the situation in Lake Erie didn’t gain media exposure until 2014-2016, when studies and articles came out about the toxic algae blooms making the water undrinkable for thousands, many agencies have been monitoring the lake for decades. In one study, Mercury was detected in all 15 bed-sediment samples and 11 fish-liver samples, posing risks for human consumption. Between the 1970s and 1990s toxaphene, a chemical known for being able to “damage people’s nervous system, livers, kidneys and cause death”, was used as a pesticide. It was finally banned in 1990 and now toxaphene levels are virtually non-existent in the lake.
Total chlordane, total DDT, dieldrin, heptachlor epoxide, mercury, and total PCBs were detected in the tissues of carp, rock bass, and northern hog suckers collected in 1996–97.
However, despite the success in reducing toxaphene and the Great Lakes Water Quality Agreement signed by the U.S. in 1972, phosphorus levels have been on the rise.
More recently, dissolved phosphorus from Roundup caused a toxic algae bloom in 2014 that left 400,000, and hospitals, without drinkable tap water in the middle of summer. For more information, look at the current dangers posed by the lake.