A sewage spill that killed 200 fish was deliberately directed into the river following heavy rainfall

Thames Water has admitted that a raw sewage spill, which resulted in the death of at least 200 fish, was deliberately directed into the river.

The spillage occurred on Friday 3 July after heavy rain lead to an overflow of sewage at the Mogden Sewage Treatment Works in Isleworth, leading to devastating consequences for local wildlife.

Tanya Houston, fisheries officer at the Environment Agency, said, “This is a serious incident, which has caused the death of hundreds of fish. Unfortunately we may never know the exact numbers of fish that have died.”

But Thames Water said it had no other option than to release the sewage into the river, “This legally consented discharge took place following a very heavy downpour, after which there was literally nowhere else for the storm sewage to go,” a statement said. “We very much regret the impact on the river, but this was not an accident. The system is designed to work like this in such conditions.”

Thames Water said that had it not taken such drastic action the sewage would have ended up in people’s homes. But it also said every measure was taken to minimise the impact on the river, including injecting oxygen into the river and releasing additional water at Teddington Lock in an attempt to improve freshwater quality further downstream.

The statement from Thames Water said, “This incident shows why we and the Environment Agency are keen to increase the treatment capacity of Mogden Sewage Treatment Works. Hounslow Borough Council recently granted planning permission to extend the works. This will boost capacity by 40 per cent, making incidents like this far less likely.”