Frustrated campaigners have voiced their concerns over the “unpredictable” flood risks surrounding a planned new reservoir following several flood alerts.

The Group Against Reservoir Development (GARD) has claimed that more flooding research needs to be carried out by Thames Water ahead of the planned building of its reservoir between Steventon, Drayton, Marcham and East Hanney.

The calls come after nearly 20 flood alerts were issued for Oxfordshire, including in the area where the reservoir is proposed to be built.

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Secretary of the anti-reservoir group Deborah Bennett said: “Nobody knows the consequences of severe flooding once the reservoir is in place, because the research hasn’t been done.

“We now know Thames Water is proposing to build the reservoir at 50 per cent extra capacity on top of its original plans.

“But the studies on flooding for a structure of this size have not been done. This new, larger reservoir will take up so much land that there won’t be any space to control flooding.

“Thames Water need to research the flooding and possible damage done if there’s a breach in the wall of this massive structure – this needs to be done before construction.”

The water company has argued that the reservoir may even improve flood risks in the area, which houses an essential floodplain.

A Thames Water spokesperson said: “The reservoir will not increase the risk of flooding in the area. 

“It would be built on some of the existing floodplain associated with tributaries of the River Ock and therefore flood compensation measures will be included in the design to leave flood risk at a lower level than if the project hadn’t taken place.    

“In addition, the reservoir could potentially improve flood risk management in the Abingdon area and as part of the Thames Valley flood risk management strategy.

"Work is ongoing with the Environment Agency on this. This work will be shared in an open and transparent way when it is complete.”

Ms Bennett highlighted that new houses are being built in East Hanney, which come right up to the edge of the planned reservoir’s dam.

She said: “All that would be needed is a six-foot crack to appear in the hillside dam and torrents of water would come gushing through.

“It would be flowing for about 20 days, and the people in those houses would have about 90 seconds to evacuate.”

The spokesperson for Thames Water added: “Thames Water and the UK water industry has an excellent record of reservoir safety.

“The design would meet the requirements of the Reservoirs Act, be reviewed by an independent Reservoir Advisory Panel, and adopt appropriate security measures.  

“We would work with specialist industry contractors in the design and construction of the reservoir to ensure that visually, operationally and in terms of public access and enjoyment the reservoir would be a facility we could all be proud of.”


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This story was written by Matthew Norman, he joined the team in 2022 as a Facebook community reporter.

Matthew covers Bicester and focuses on finding stories from diverse communities.

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