Rivers, streams and freshwater marshes are being "devastated" by agricultural waste, raw sewage, pollution and flooding, according to a new report from environmentalists.
Bodies of water across England, Wales and Northern Ireland are being polluted by storm and sewage overflows, and chemical run off from mines and pesticides, the report said.
The public is unaware of the perilous state of our waterways with just under half believing they are in a good condition, the report by the Royal Society of Protection of Birds (RSPB), the National Trust and the Rivers Trust said.
It said otters, swallows, tail butterflies and salmon are in great decline with some species facing extinction due to the contaminated waters.
Percentage of rivers that meet "good ecological status":
• England - 14%
• Wales - 46%
• Northern Ireland - 31%
Poorly regulated use of pesticides and fertilisers in farming is one of the key causes behind the water pollution.
Water companies discharged raw sewage into rivers 400,000 times in England and 100,000 times in Wales in 2020 despite laws stipulating this should only happen under exceptional circumstances. Chemical run off from mines has also polluted 932 miles (1,500km) of rivers in England alone.
According to an online YouGov poll, 88% of those in England, Wales and Northern Ireland agree freshwater habitats are a "national treasure".
Deputy director of policy for the RSPB Jenna Hegarty said: "It is no surprise so many people think of our waterways are a national treasure and revel in the magical sight of otters playing in our streams, dragonflies hovering like jewels above our lakes and the vibrant flash of kingfishers in flight.
"But nature is in crisis and the incredible freshwater wildlife people marvelled at as they explored our countryside this summer is a fraction of what should be there.
"It is disturbing how it has become so normal for our waterways to be polluted and contaminated, and that many people do not realise there is something wrong."