Ruislip Lido Closed After Dozens of Dead Fish Wash Up

Dozens of dead fish have washed up on the shores of Ruislip Lido, a 60-acre reservoir in west London. Residents discovered the fish carcasses on Monday. The Environment Agency (EA) has tested the water and believes a recent algal bloom, likely caused by the prolonged heat this summer, has led to a drop in oxygen levels.

Lake Closure and Aeration Efforts

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Hillingdon Council has closed the lake to fishing to protect fish stocks while aeration work is carried out. Councillor Philip Corthorne, a Conservative councillor for Hillingdon, stated that it may take three to four days to stabilise the lake, after which the EA will reassess the situation. Swimming is already banned at Ruislip Lido due to hazards including potentially toxic blue-green algae, submerged objects, and vegetation.

The EA has provided Hillingdon Council with three aerators to re-oxygenate the lake, concentrating efforts on areas where fish tend to gather. These devices create ripples to prevent stagnation, aid fish respiration, and encourage beneficial bacteria while controlling algae growth. An EA spokesperson confirmed that while the fishing lake is privately owned and the owner's responsibility, the agency is providing aeration equipment and ongoing advice to help restore oxygen levels.

Impact of Heatwaves on Waterways

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This summer has been exceptionally warm, with the Met Office indicating it is likely to be the hottest on record. Multiple heatwaves have occurred, with temperatures exceeding heatwave thresholds on numerous occasions. Increased water temperatures reduce the amount of oxygen water can hold, leading to less oxygen available for aquatic life and subsequent fish deaths. A similar incident occurred at Wimbledon Park lake, where hot weather was also cited as the initial cause for fish deaths.