Wildfowl have been coated in fuel and insects and fish have died after 4,000 litres of diesel spilled into the River Wandle, in South London.
Carshalton MP Bobby Dean told City London News that it is the “worst environmental disaster since 2009.”
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A volunteer from The Swan Sanctuary said the impact on wildlife would be ‘”devastating”.
Ecologists from the National Trust told a local reporter at Westside Radio they were particularly concerned having seen a dead eel, a species that is resilient to poor quality water – suggesting that the pollution levels in the river are particularly high.
London Fire Brigade had been working to contain the spill, with fire trucks and officers “trying their best to stop the flow and take the pollutants out of the river”, according to a post by local Labour councillor Stuart Neaverson.
This morning, the Environment Agency has installed floating barricades in the water to soak up diesel that floats on the surface.
However, ecologists have said the real impact will come when the fuel breaks down and disperses into the water.
The River Wandle, which is nine miles (14km) long, begins in the North Downs and flows through Sutton, Croydon, and Wandsworth before entering the Thames.
It is one of London’s few chalk streams, and popular with anglers for its brown trout, chub, barbel and roach.
