That wouldn't surprise me, I know Lake Erie is one of the filthiest bodies of water on the planet, all the sh*t from Ohio drains straight in there.
You haven't seen Lake Erie in a number of years have you? Despite all the problems zebra mussels cause, they sure clean up a lake. In Port Colborne's harbour - upstream entry to the Welland Canal and once home to an Inco processor - you can see mussels on piers, seawalls and piles - through cupric-tinted but very clear water