Hotspots of bacteria and phosphorus at England's most famous lake must be addressed urgently, the authors of a study into its water quality warned on Tuesday.
Volunteers collected 1,020 samples from Windermere in the Lake District National Park in northwest England between June 2022 and November 2024.
The Big Windermere Survey released its summary report on Tuesday, finding "poor" standards of bathing water quality in some parts of the lake owing to "hotspots" of illness-causing bacteria like E.coli and intestinal enterococci.
The problem was particularly acute during the summer, when thousands of visitors swim and play watersports in the lake.
The Freshwater Biological Association, which carried out the study with Lancaster University, said hotspots "must be addressed urgently" by those responsible for improving water quality, and laid out a four-step plan.
"The first priority must be to identify and address causes of high nutrient and bacterial concentrations," said the report.
More investment is also needed to enforce regulations and for investigation work, while monitoring needs to be increased in waters used for recreation, it added.
Around seven million people visit Windermere each year, attracted by its scenery and cultural heritage.
But concerns over pollution from wastewater, farming and sewage have risen over recent years, with the government promising to "clean up Windermere".
