A protest is being planned after wild swimmers in Oxford claim they ended up ploughing through raw sewage on Christmas Day.

The outdoor swimming group Brrrrr! were not told about a sewage release from Witney Sewage Treatment Works in the early hours of Christmas Day until 24 hours later.

It meant swimmers gathering for the annual Christmas group swim on Oxford's Port Meadow had no idea of the health risks of entering the water.

Despite signing up for advanced warnings, swimmer and protest organiser Jo Sandelson said nobody in the group received notifications until Boxing Day.

She said: "Thames Water dumped us in it. My swim group were swimming in raw sewage on Christmas Day and weren't alerted until 24 hours later about that sewage release."

Ms Sandelson, who is a wild swimmer and Lib Dem candidate for Oxford City Council, added: "Notifications of more dumping are happening now on an almost daily basis and this is illegal outside of heavy rain events.

"We are protesting against the endless stream of sewage being pumped into our precious river by Thames Water. It's destroying our wildlife habitat, our well-being.

"Even if we aren't river users, we've had enough of our rivers and waterways being turned into open sewers.”

Thames Water has released sewage at least 16 times since that day and the company has advised that each time it can take four days to clear.

Ms Sandelson said the Environment Agency "is underfunded and lacks the resources to monitor the hundreds of spillages every year".

"This local and national scandal should be resolved immediately," she said. "When will Thames Water tell us why their billions of pounds in profits are paid in dividends to shareholders, rather than in essential reinvestment in infrastructure to save our wildlife and ourselves from this rank stench?

A Thames Water spokesperson said no dividends have been paid to external shareholders in the last four years.

"Our shareholders are in it for the long term, and have not taken a dividend for four years to prioritise investment in improving service for customers and to protect the environment."

She added: “We’re sorry for the delay in the Witney discharge notification being sent to river users, which was due to an error in our automated email alert system which is currently being trialled across six sites in Oxford.

"We’re working to make our alerts as accurate as possible, but there might be times during the trial where there are slight inaccuracies or delays in email alerts reaching those who’ve signed up for them.

“Our aim will always be to try and do the right thing for our rivers and for the communities who love and value them. We’re increasing sewage treatment capacity at our sewage works in the area, including Witney and Oxford, and we’re also committed to continuing our industry-leading trial to provide real-time alerts of sewage discharges in 2022.”

The Environment Agency said its staff respond to pollution incidents 24/7 and water companies are legally required to report any breaches of their permits.

"We will always seek to hold those responsible for environmental harm to account. Specific action will depend on the nature of the offence, up to and including prosecution," said a spokesperson.

Oxford MP Layla Moran has called on the Government to take action and clean up the Thames in a Westminster Hall debate she secured in November.

The protest starts at 11.30am on Sunday January 23. Meet at the car park in Lower Wolvercote for protest on Port Meadow near the weir.