Residents in Brentford have raised concerns about sewage flowing into the local canal network, with dead animals washing up over the summer.

Paul Keane, general manager of watersports charity Brentford Community Boathouse, told the Brentford and Syon Area Forum that the problem had been worsened by the “epidemic of heat” this summer.

The animals were mostly found in the Brentford Lock basin, where the Grand Union Canal meets the River Thames.

“We saw dead foxes, dead ducks and there was a dead cat,” Keane told BBC London.

“Because of the stagnant water and the fact that the water wasn’t travelling anywhere, we were going past them every day in exactly the same spot.”

Brentford Community Boathouse events officer Kelly Everden, who volunteered on a clean-up operation organised by Keane, said the children who used the canal were worst affected.

“It’s really upsetting on behalf of the children, because that’s not anything that they should ever be faced with, especially with a pet cat,” she said.

Keane said the problem was at least partly down to misconnections, where plumbing from housing developments is wrongly linked to surface water drains rather than sewers, sending untreated waste into waterways.

“The big fly in the ointment is sewage coming into the canal,” he said.

“That gets worse in the summer when the water is moving slowly, and some of that is historic, but also a contemporary misdirecting of sewage into storm drains.”

He said he did not believe this was Hounslow Council’s fault, but that it needed attention “if we do want to develop usage of the canal, particularly for children on the water”.

He added: “The water has to be hygienic, and there are times when it simply isn’t. It’s a very difficult issue, but it needs an overall strategy.”

Keane said the animals were predominantly found with E. coli and botulism, and that the most stagnant stretch was within the locks around Boston Manor Park.

Warm, still water holds less oxygen, creating the conditions in which botulism thrives and speeding up the growth of E. coli.

Hounslow councillor Katherine Dunne said officers in Ealing and Brent were examining misconnections through a River Brent catchment group, and committee chair councillor Dan Bowring urged residents to contact their ward councillors.

“All councillors in Brentford will be concerned about this,” he said.

The Canal and River Trust said it aimed to remove any dead animal as quickly as possible. Aquatic weed has been a particular problem at Brentford, it said, because both of its west London weed clearance boats were out of action at the same time.

Thames Water said the area was known to have issues with misconnections and that, while it was not responsible for third-party drainage, it was working with property owners and councils.

The Environment Agency said the area remained in drought, which can affect river health, and that it would continue investigating reports of pollution.

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