As if we didn't already know; 

Rivers used as 'open sewers', says WWF charity - BBC News

Below is part of a letter received by  RWGA when we we making a nuisance of ourselves with the EA regarding effluent and other noxious discharges and also water abstraction kicences to which we routinely objected..  This is a reply we received from Dafydd Evansthen head of fisheries.  This was back in 2005.  Read it and see if anything has really changed since then.  He makes the point that you cannot expect a pristine environment.

The first part of his letter was over printed and unreadable.  There is a gap too after the first two paragraphs due to inept computer technique. Apologies