More than 50bn litres of effluent from sewage treatment plants in the Lake District have flowed into Windermere and the rivers and smaller lakes which surround it since 2017, new figures from Save Windermere have revealed.

An activist whose “watched sewage destroy” Lake Windermere has trekked deep into the Lake District’s mountains to find the source of England’s “crown jewel”.

Matt Staniek embarked on a journey to show Britons “what water in the Lake District should look like” amid an ongoing battle with water company United Utilities.

Waters have carved out the landscape of the Lake District, giving many of us a playground rivalling mountain regions around the world. Culminating in a powerful call to arms, the new film from the Save Windermere campaign is essential watching for anyone who has ever visited Lakeland and marvelled in its beauty.

More than one illicit spill or leak was recorded per week around Lake Windermere last year, revealing the scale of the pollution crisis at one of England’s most-beloved nature sites.

A total of 68 “pollution incidents” were recorded by the Environment Agency (EA) in the Windermere catchment last year. The incidents included multiple occasions of blue-green algae.

Documents and data shared with BBC News from inside England's much criticised environment watchdog show an agency struggling to monitor incidents of serious pollution.

Matt Staniek is a water quality campaigner in the Lake District and cited several incidents where he says the EA took explanations from the local water company about sewage spills at face value, which later through his own data requests were proved wrong.

"The Environment Agency has not been holding United Utilities accountable," he says. "And the only way that we get them to properly turn up to pollution incidents and now actually try and do a proper investigation is by going to the media with it, and that should not be the case."

United Utilities has underspent by more than £50m on vital work in Windermere and elsewhere in north-west England, to connect private septic tanks to the mains network and reduce sewage pollution. Save Windermere, the campaign group that submitted the request, has mapped where private sewerage systems are likely to be significantly affecting water quality.

Untreated sewage and waste water continuously discharged near England's largest lake for eight days during prolonged rainy weather.

Storm overflows at a water treatment plant in Cumbria released water into Cunsey Beck, which runs into Windermere, from 15 to 23 September, information from water company United Utilities showed.

The founder of the Save Windermere Campaign Matt Staniek blamed "insufficient investment" for discharges and said sewage pollution was causing "irreparable damage" to the lake.

Campaigners trying to stop raw sewage being pumped into Lake Windermere, which is supposed to be a pristine monument to nature, are envious of Lake Annecy in France.

Volunteers testing the water quality of Windermere have found “really concerning” pollution in England’s largest and most famous lake. The analysis, in which 350 “citizen scientists” took samples of water at more than 100 locations around the lake, found “hotspots” of phosphorus, which causes algal blooms, and two types of bacteria that cause illness.

The Big Windermere Survey, involving 350 volunteers and over 1,000 water samples, has revealed consistently poor water quality across England’s largest lake. Concentrations of faecal bacteria in the lake were found to peak in summer but there were high levels throughout year.

Organisers of Kendal Calling have pledged to donate £100,000 to Lake District conservation projects over the next five years.

To kickstart the commitment, the music festival has donated £10,000 to Save Windermere.

A campaigner has accused a water firm and green regulator of “painting a fictitious picture” of Lake Windermere’s pollution. United Utilities (UU) previously claimed a 50% reduction in phosphorus discharges into England’s largest lake, in Cumbria, following investment between 2015 and 2020.

But Save Windermere founder Matt Staniek alleged this figure is based on “unverified assumptions rather than concrete data”. The Environment Agency (EA), in a blog post last year, said that phosphorus levels have declined by approximately 30% since 2020 – contradicting the claims made by the water company.