According study published by The Times
86 per cent of rivers fall short of the EU’s pollution standards and none of them are tested regularly enough to be officially deemed safe for swimmers.
Thankfully we’ll soon be out of the EU and then the growing number of essentially self-regulated US-style ‘mega-farms’ will be better placed to look after all of our waterways 👍🏼
Anecdote: I sometimes swim in the River Clun, looks beautiful, but quality is noticeably changing and set to lose it’s Special Area Of Conservation status due to phosphates, nitrates etc. The freshwater pearl mussels in the lower reaches are now in decline. This year I got out mid-swim as eyes were stinging and there was a weird taste in the water. It’s beyond depressing IMO, after decades of trying to turn things around from the dirty 20th Century we actually seem to be struggling not to head backwards.
The Taff here in Cardiff seems good
I’d take a closer look, pretty sure when I was researching the Clun that I saw the Taff and the Ely both mentioned as areas of concern.
*Edit
last year a large part of the Ely was classed as “bad” – the worst water quality classification from the EU’s Water Framework Directive – and a survey found hundreds of fly-tipping hotspots and previously unknown sewage pipes.
Five sections of the River Taff and one section of the River Rhymney were also classified as “poor”.
A council report said it was due to human activity, including sewage, industrial pollution, and incorrectly plumbed toilets and showers. It is hard to pinpoint a source as the litter can be washed-up from miles away.
https://www.bbc.co.uk/news/uk-wales-south-east-wales-44398892