This article was updated on 10 July to clarify that swimming isn’t allowed in the lake at any point.

Sadly, a number of fish have died in Wimbledon Park Lake. We understand this will be upsetting for residents and visitors. 

Initial investigations by the Environment Agency and Thames Water indicate that the likely cause is the prolonged period of exceptionally hot weather, which has resulted in unusually high temperatures significantly depleting oxygen levels in the lake. Similar incidents have been seen across the country during the recent heatwave. 

Council officers are working closely with partners to minimise any further impact. This includes installing aeration equipment to help increase oxygen levels in the water. 

There is no evidence to suggest that pollution is responsible, although investigations and water quality monitoring are continuing. 

Dead fish are being removed from the lake as quickly as possible to help protect water quality and minimise any impact on wildlife. 

We appreciate the concern this has caused. The council reminds members of the public that they should not swim in the water for standard health and safety reasons. 

We will continue to monitor the situation closely with our partners and will provide further updates as more information becomes available. 

The council has been working over a number of years to improve the long-term health of the lake, including measures to improve water quality and address historic nutrient build-up from natural sources such as waterfowl. Further improvements, including the installation of an ultrasonic treatment system to help improve water quality and oxygen levels, are due to be introduced shortly.