When I was in high school, and rowed and fished the Potomac Rive (and briefly lived on it), you were told to never eat the fish and to go to the hospital if you fell in.
Now, after 40 years of environmental activism and government intervention, the river produces big Largemouth Bass and is a massive commercial and entertainment success. The picture above was taken with my iPhone today, as I crossed Key Bridge. The ducks and the kayakers were taken with the new Nikon, both from a considerable distance.
When you clean up a river, you get wildlife; Ducks, Blue herons, Bald Eagles, Cormorants, and Egrets are all testimony to the healthy fish and plant base in the river.