Sewage makes River Thames swim spots unsafe after heavy rain

Sewage pollution is making popular swimming spots on the Thames unsafe after rainfall, a study has found.

Oxford Rivers Project found that during months with heavier rainfall bacteria levels were, on average, twice the recommended safety threshold.

As a result, there was enough bacteria to cause people to become ill, it said.

Thames Water said it was planning enhancements to its sewage treatment works and sewer network to improve the situation in the river.

The main source of bacteria was found to be treated and untreated sewage, the study showed.

Treatment works are only allowed to put sewage into waterways after wet weather, and when they are close to capacity.

Thames Water data showed raw sewage was released into the upper Thames for 50,000 hours in 2021.

Claire Robertson, of Oxford Rivers Project, said the group was "concerned" about the bacteria levels, especially with increasingly heavy rain during the summer, due to climate change.

The study, jointly funded by The Rivers Trust, Thames Water and Oxford City Council, used water samples from Port Meadow, and Longbridges and Kennington Meadows.

The water was then tested for bacteria in Thames Water's laboratories.

Richard Aylard, of Thames Water, said: "We are planning major expansions of a number of our sewage treatment works in the area, including at Witney and Oxford, as well as improvements to the sewer network."

Oxford City Council is expected to apply in October to make Port Meadow a designated bathing water area. The government is due to make a decision in early 2022.

Once a site is designated, the landowner and water company have five years to reduce bacteria levels in summer months.

Mary Clarkson, of the city council, said it was "worrying" there were times when the water quality was "very poor" given how popular the site was.

"We hope and expect that the Thames at this site will be given bathing water status so it can receive greater funding, testing and improvement," she said.

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