Upstream of the bathing site there is a combined sewer overflow and a sewage pumping station, and agency investigations also found that three nearby rainwater drains were not correctly connected to the sewage system, leading to increased pollution in the river.

Pollution from sewage and agriculture

Testing suggested the bacteria was coming from a mixture of human and animal sources, suggesting pollution from sewage and from agriculture.

A report by campaigners recently found that children missed school for sickness after swimming in the Wharfe in 2018.

Last year John Leyland, the Environment Agency’s chief of staff, said rivers were “not there for human swimming” despite the rising popularity of wild swimming.

Campaigners have pushed for more rivers to be made designated bathing sites to pressure agencies and water companies to clean them up.

The Ilkley Clean River Campaign said: “We continue to challenge the orthodoxy that no-one should be enjoying the riverbank and river with their children in the summer.

“In cleaning up the river for people, we also aim to prevent the use of the Wharfe as an open sewer and return it to being a thriving habitat for wildlife.”

Overall improvement of water quality

The data were released as part of the Environment Agency’s annual update on bathing water status, which showed an overall improvement, with 99 per cent of sites passing water quality tests, up from 98.3 per cent in 2019.

The Wharfe is the UK’s only official river bathing site after being classified in 2020, with all others found in lakes or coastal areas.