Something similar happened close by my old neighborhood. The river was highly contaminated by close by industry. In the 80s a new initiative started to improve the quality of the river.

Nowadays, there is promenade along the river and it is easy to see many birds around. People goes there to do jogging or cycle. The river is creating as much economic value as natural one.

But it is nor inviting nor healthy to swim in the river, there is much more work to be done.