Untreated sewage is killing the river Windrush, creating a health risk to paddlers, children and pets according to campaigners who say that the river is ‘literally dying’.

Thames Water’s own figures record that in 2019 its treatment plant at Witney pumped raw sewage into the river for a total of 1,395 hours.

“That’s the equivalent of nearly two months of continuous flow. 24 hours a day, seven days a week. This river is being absolutely hammered,” said Soraya Wooller of Witney Against Sewage Pollution.

The latest figures for 2020 show a rise from that to 1,563 hours..

Many new houses are being added to a system in West Oxfordshire that is already failing, said WASP.

Ms Wooller said: “We have seen untreated sewage spilling into the Colwell Brook in Witney and filling it with sewage fungus for months on end in a public place used by many people, with dog walkers particularly at risk as their dogs often swim in it.

“WASP is in the process of establishing how many more tonnes of untreated sewage will be dumped into the Windrush and other rivers because no measures have yet been taken to cope with the extra load.”

Ms Wooller said the government has all the legislation it needs to stop this, but the Environment Agency enforcement policy dictates that only a tiny fraction of incidences can be investigated and potentially prosecuted.

“It is time they [the Environment Agency] looked at the whole picture of decline that has happened on their watch as we now have only 14 per cent of rivers in good ecological status and huge increases in the amount of untreated sewage being dumped in our rivers,” added Ms Wooller.

An Environment Agency spokesman said: “Water companies have a legal duty to avoid pollution, informing the Environment Agency of all sewage discharged into our waterways. They must act quickly to reduce any damage that happens as a result of their activities.

“We are investigating potentially-illegal sewage discharges into the River Windrush and Colwell Brook and Emma’s Dyke streams in Oxfordshire between October 2019 and April 2021. However, we believe the main reason the Windrush appears cloudy is natural geology.

“Anyone who suspects pollution in our waterways can report it to our free, 24-hour incident hotline: 0800 807060.”

There is, however, some good news.

With pressure from WASP, Thames Water is starting to acknowledge the scale and severity of the problem.

Ms Wooller said: “We have secured an agreement from Thames Water to commit to an ambitious recovery project for the River Windrush and we need to hold them to that.

A spokesperson for Thames Water said plans to upgrade Witney Sewage Works were now progressing.

“The health of the river is as important to us as it is to the community that enjoys it. We funded an independent study into the murky appearance of the Windrush and will be working in partnership with the campaign group WASP to help improve water quality.

“While the report supports our belief that sewage discharges are not solely responsible for water quality problems, we accept they are a factor.

“We see all discharges as unacceptable and want to accelerate work to stop them being necessary. The upgrade of Witney sewage works will go a long way towards that, as will the project with WASP, which will build on current work in a number of different ways to help the river.”

The spokesperson added: “The design is still being finalised, but the project will increase the treatment capacity of the works - by at least a third. Although originally scheduled for delivery by April 2025, we are working as fast as possible and now expect to complete late in 2023.”

Ms Wooller said: “While we welcome news of plans to upgrade the Witney Sewage Treatment works, this is work that should have happened years ago.

“Pollution will continue until the work is complete, by which time there will be an increase in demand on the system.”

Witney MP Robert Courts has also said Thames Water is not ‘doing enough’ to tackle sewage overflows.

He said: “I am clear about the importance of ensuring healthy local rivers and have been campaigning to end pollution from storm overflows in West Oxfordshire.

“I have been pressuring Thames Water to urgently upgrade West Oxfordshire’s sewerage infrastructure, in particular the vital expansion of Witney Sewage Treatment Works. While I welcome their promise of accelerating the delivery of these upgrades, I will continue to press Thames Water to ensure they are delivered as soon as possible and are effective.”

Ms Wooller added: 'I want my son to be able to find fish in the Windrush. People should be able to paddle without getting infected by pollution. Dogs should be able to swim without getting sick from sewage.

"Above all, the Windrush should be a haven for wildlife: a river for all of us."