I don't know the details about the cleaning up of Lake Erie, but I suspect that much of it was just reducing the level of what you were putting into it and letting nature do its work. That and lots of local efforts...and them plaid-clad Canadians probably had a hand in it.
There's got to be a few good examples.... How about the eradication of some diseases like smallpox and polio? A while back, but impressive.... ML
