I know, the great lakes are all amazing. I'm just messin. Even down south further where the water was pretty bad a while ago it's been cleaned up alot in the last 30 years or so.
Even the Cayuhoga river, which did catch on fire near the refineries and mills, is clean up.
The one benefit from the invasive Zebra Mussels has been that Lake Erie is said to be very clear now. The mussels have filtered out a lot of pollutioin, and also organisms that are food for larger forms of life. The also clog water intakes, grow on docks, and have to be removed from boats.