I have a guy in my family who worked to remove dams over a small tributary river of the Seine, in Normandy, France. It took him several years to remove the 300+ dams, the oldest ones being easily 150 years old. The very first year after his work was completed the salmons came back.<p>Now he works in the environmental police, and is often called to handle cetaceans getting lost in the Seine delta. People freak out because it is an unusual sight nowadays, but he told me this is just a return to how things were. They are stories of dolphins swimming as far back as Paris in the past centuries.<p>I guess this means we're doing something right, I hope one day we'll be rid of this poisonous brown opaque water flowing through our cities. I really hope one day to be able to see this "clear water" my grandpa told me he learned to swim in.