The Guardian reports that testing by citizen scientists of a beck that feeds into Windermere has revealed a huge loss in invertebrate life in the lake in Cumbria that campaigners say is being caused by sewage discharges.

Save Windermere and WildFish carried out testing for invertebrates in Cunsey Beck, a site of special scientific interest (SSSI), in order to assess the impact on its freshwater ecology of the Near Sawrey wastewater treatment works, owned and operated by United Utilities.

Their first year results showed a decline of 76% in riverfly species and a 33% reduction in riverfly diversity in samples taken below the sewage outlet compared with samples taken above it.

They said the permit issued by the Environment Agency – outlining when raw sewage can be discharged legally from the treatment works and providing limits for toxic pollutants – is not fit for purpose. The Environment Agency denies this.

Save Windermere and WildFish say their findings suggest chronic damage to Cunsey Beck as a result of the regulatory failure of the EA. The stream was hit by a serious pollution event in 2022 that killed hundreds of fish, while Lake Windermere has become the focus of national concerns over sewage dumping and extensive algae.

Like all rivers in England Cunsey Beck is being affected by pollution from sewage – both raw and treated – and agricultural runoff. No river in England passes pollution tests for chemical and biological pollutants.

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More details on the Save Windemere campaign website