Buffalo is lucky because Lake Erie is the shallower of the Great Lakes so it takes about 10 years to turn over all the water. By comparison Ontario is one of the deeper lakes and takes about 100 years. Also, some invasive species also helped. The mussels invaded and ate everything they could which helped clean up some pollution. Then another invasive fish came in that ate all the mussels further cleaning up the lake. So Lake Erie is actually relatively clean. By far cleanest of the Great Lakes.
I learned some of this on a sailing/ wine/ booze thing, so some of my stats may be a little off. 😏