A DAM on the Thames north of Oxford needs to be replaced this year or it will fail, causing flooding or boats grounded on riverbeds.

That was the warning made by Environment Agency officials this week about the weir at Godstow Bridge.

The weir, known as Godstow Weir B, is just south of the Grade-II listed bridge as it crosses from the east bank of the river next to the Trout Inn.

Oxford City Council's west area planning committee agreed to allow the Environment Agency to replace the current weir, built in 1937, when it met on Tuesday.

But that was not before warnings of why the work was important from Environment Agency officials.

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Mark Hill, the area lead for the EA said: "If it is not replaced it will fail, it could be this year it could be two or three years time, but it will happen.

"The weir is essentially for the EA to manage the river levels in the Thames for both navigation and flood risk

"If the weir as it is fails in an open position general navigation would not be possible between Osney and Kings Lock and vessels using permanent moorings in these regions would be grounded out on the riverbed."

Trout in a river. Picture: Pixabay

Trout in a river. Picture: Pixabay

His colleague Nick Leishman added work needed to begin this spring so it could be completed before winter, when floods are likely.

Planning committee member Liz Wade had concerns about a 'fish pass' on the weir: a long, sloping channel which allows fish and eels to swim upstream to lay their eggs, and asked if a fish pass was needed there, and not just at Godstow Weir A, the other side of Trout Island.

The Lib Dem councillor was worried about the impact the new weir would have on nearby historic buildings, including the medieval bridge, the nearby Godstow Abbey.

Mr Leishman explained the agency had a duty under law 'to provide fish passage' through weirs.

He added: "Fish aren’t clever enough to know there’s another passage a bit downstream and swim back to it. They just get stuck and go nowhere."

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Committee member Alex Hollingsworth said the new weir would 'strike a balance' between maintaining the river's wildlife and its built environment.

He added: "The gap opened up will allow people to see the bridge in a way they have not been able to see it in hundreds of years, certainly decades

"Things like weirs which make rivers navigable and in fact create in many ways the visual elements of waterways which we celebrate are also the things that make it difficult for the wildlife of rivers."

The committee unanimously supported the plans.

It had been called in for a closer look by the committee by six councillors concerned about its impact on nearby historic buildings.