Funny enough, this topic came up on the radio today, from a Toronto station.
That Lake Ontario is polluted, is a misconception from decades passed. Today, Lake Ontario is much cleaner. Granted, certain areas of Hamilton (and ironically, some of the places that look most appealing to swim, like Bayfront Park) have poor water currents, leaving the water quality suffering due to eutrophication. This is due to the shape of the waterfront however.
ODDLY enough, the same radio station host went on to cite places like cottage country having much poorer water quality. While they're not scientists, I can get behind it because generally cottage country lakes have less flow than the open body of Lake Ontario, and less water in general, and when you add regular boating activities and the outflow of all the lake's occupants, it can get pretty bad.
But don't my word for it.
https://www.theswimguide.org/#43.185...33259375001/12