Analysis found high levels of Escherichia coli (E.coli) and Intestinal Enterococci (IE), indicating sewage pollution, at the time when the lake is busiest for swimming and watersports. The Big Windermere Survey (BWS) saw 350 citizen scientists collect more than 1,000 samples over two and a half years at more than 100 locations - many of which had never been tested before. Campaigners want "decisive action" to improve the lake. The Department for Environment, Food and Rural Affairs (Defra) has committed to getting water quality back to normal.

It said there was "a lot of damage to undo". The Freshwater Biological Association (FBA), which co-ordinated the citizen science project with the University of Lancaster, said the elevated concentrations of E.coli and IE in summer were "particularly concerning as they indicate an increased risk of gastro-intestinal illness if water is ingested". Simon Johnson, the FBA's executive director, said: "When you see a place you love so much, that is so important, when the water quality of that place is below what I think society expects and demands, then that's really concerning." He said Windermere was one of the world's most famous lakes and if the issues could not be solved there, it did not bode well for the future of other equally important but less famous sites in the Lake District. (BBC)