A criminal investigation is being carried out into sewage dumping into Witney's rivers, it has been confirmed.

The Environment Agency is investigating Thames Water over allegedly releasing “significant” levels of pollution which affected Colwell Brook and Queen Emma’s Dyke which flow into the River Windrush in Witney.

It was revealed by Robbie Moore, the minister for water and rural growth, at a Westminster Hall debate tabled by Layla Moran MP on Wednesday (February 7).

During the debate Ms Moran slammed Thames Water's "shoddy performance" and called for the supplier to become a public interest company.

She said sewage was flowing from 28 of its sewage treatment works in Oxfordshire, including at Combe, Church Hanborough, South Leigh, Stanton Harcourt, Standlake, Appleton, Oxford, Kingston Bagpuize, Drayton, Clanfield, Faringdon, Wantage and Didcot.

Dr Alex Lipp, an environmental scientist at the University of Oxford, created a website to show where the sewage is being pumped in and where it ends up.

According to his data sewage was discharged from Witney for over 2,000 hours in 2023.

An Environment Agency spokesperson said: "We are carrying out a criminal investigation into alleged sewage discharges and significant sewage pollution incidents at Colwell Brook and Emma’s Dyke in Witney.

“If members of the public suspect pollution incidents in our rivers and other watercourses, they can contact our free 24-hour incident hotline on 0800 80 70 60." 

The Environment Agency spokesperson added: "We will always seek to hold those responsible for environmental harm to account.

"If we identify illegal discharges from storm overflows, we investigate them, and any appropriate enforcement action will be considered."

The Environment Agency spokesperson also said not in relation to this investigation, but it is a statement of fact that the Environment Agency has prosecuted Thames Water 12 times since 2017 for river pollution, including in Oxfordshire. Courts have fined Thames Water £35.7m for those offences, with costs of almost £1.2m in that time.

Mr Moore also confirmed during the debate that work to increase treatment capacity at Witney treatment works is due to be completed by March 31, 2025 at the latest.  

This is being upgraded at a cost of over £17million and will give a 66 per cent increase in treatment capacity.

A spokesperson for Thames Water said they regard all discharges as "unacceptable" and plans were in place to upgrade 250 of its sewage treatment works and sewers.

They added: "Taking action to improve the health of rivers is a key focus for us and we want to lead the way with our transparent approach to data."

Thames Water is believed to be the first company to provide live alerts for all untreated discharges throughout its region, the spokesperson said.

They explained: "This 'near real-time' data is available to customers as a map on our website and is also available through an open data platform for third parties, such as swimming and environmental groups to use."