Lake Erie had beautiful clear water when I first saw it in the 1980’s. I know it had the reputation of being dirty but that must have been a long time ago.
Enormous amounts of money were spent cleaning it up. Sewers, paper mills, steel mills and refineries routinely dumped their wastes into this lake for decades. The water is clean now and supports a great walleye population, which you can see, is well guarded by the bordering states.