I lived in Toronto in the 70's and 80's The Don, at that time was a festering sewer. Along the banks of the lower Don there used to exist heavy industry, soap factories, brick works, etc.. The lower was a dead river. In the 70's the river was so toxic that mere contact with the water would get you sick. It was years before anybody would even consider doing a shoreline cleanup. DO they still dump road snow below the Bloor Viaduct?
I used to work for the cemetaries. Pine Hills had a beautiful nature trail along the East Don. Yes we occasionaly spotted trout. The portion north of Hog's Hollow used to be absolutely beautiful. York cemetary backs onto the valley. I've fished there as well. I only remember big chubs back then. Small trout in the upper portions of Black Creek befor Vaughan was turned into a giant strip mall. People used to think I was strange fishing the Ross Lord reservoir. That was over20 years ago.