The Green party and the celebrity chef Hugh Fearnley-Whittingstall are calling for a “protection zone” to be placed around one of the UK’s most beautiful but threatened rivers and have demanded “drastic” nationwide changes to the water industry’s management and regulation.

At a wild-swimming event on the River Wye on Wednesday, Fearnley-Whittingstall and the Green party’s candidate for North Herefordshire, Ellie Chowns, both took dips, but only after measuring the level of pollution in the water.

Fearnley-Whittingstall, who is a Green party member, said: “I love swimming in rivers and the sea. It makes me angry we have to check that it’s safe before we get in.”