Thames fish die after storms force sewage discharge

The Thames has witnessed a massive fish kill after tens of thousands of tonnes of sewage washed into the capital's river during a heavy storm last night.

Dead fish were seen floating on the river at Kew, Brentford and Isleworth in west London, according to the Environment Agency (EA).

It is estimated that 600,000 tonnes of untreated sewage washed into the river after massive downpours – 42mm were recorded in just one hour – overwhelmed drainage systems.

Thames Water said it was working with the EA to minimise the impact of the pollution.

Currently Thames Water helps fish to survive storm discharges to the Thames by deploying two 'Bubbler' vessels, which pump extra oxygen into the river.

As the system currently stands, the safety valve of letting the dilute sewage go to the river during storms, though regrettable, is preferable to the flooding backing up out of the sewers into London's streets, Thames Water said.

Robin Clarke, Director of Waste Water Operations at Thames Water, said the organisation "deeply regretted" the incident.

"The scale of the fish loss last night was very rare - a very unfortunate side effect of the exceptionally heavy rainfall," he said.

"Despite events such as last night, the Thames remains one of the cleanest metropolitan rivers in the world. This is directly linked to Thames Water's £1 billion investment at sewage treatment works, which has paved the way for wildlife to return the river, which was biologically dead for many years."

Thames Water said that it has been in close contact with Defra on the issue of storm discharges to the Thames Tideway. The company is represented on the independently-chaired steering group, which recently submitted a report to Defra outlining the options for tackling the issue in the long term, including a new £2-3 billion tunnel to accommodate the storm flows.

Climate change and population growth accentuate the need to focus investment on replacing Victorian water mains in London and reducing the risk of sewer flooding to customers properties, the company said.

(gmcg)