most improved" rivers, according to the Environmental Agency.
Once merely a sewer, this urban river has been turned round and is now packed with wildlife. I remember stopping when I saw a [sorry bit hopeless at species of water fowl, probably a coot or cormorant] struggling with an eel almost as long as it was.
On last year's kayak down it the water was clearly good and filled with growing things. The only slight qualification was that it was packed with litter and needed a good clear up, but even here the Wandle Trust is doing its bit (I should go along to their events too).
More background at The Guardian and The Telegraph.