Windermere hit by toxic spills once a week as bathers warned of harmful algae
Data also revealed that the Environment Agency was failing to attend around a third of pollution incidents in person
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, according to data released as part of a Freedom of Information request and shared with The i Paper.
The incidents included multiple occasions of blue-green algae, which can be toxic to humans. Swimmers have been warned to avoid the iconic lake when algal blooms are spotted.
It’s the highest number of recorded incidents since at least 2019, which local campaigners say is likely a result of more people calling in incidents to the EA.
The data also revealed that the EA was failing to attend around a third of pollution incidents in person.
“We are actually seeing the true scale of what has been basically covered up for 30 years,” said Matt Staniek, founder of the Save Windermere campaign.
Staniek said the regulator had previously “turned a blind eye” to pollution and public scrutiny was forcing it to “properly do its job”.
There are signs the situation is improving this year, with 20 pollution incidents recorded in the first half of 2025.
Sewage spills and toxic algae
A pollution incident is any unauthorised leak of a substance, such as sewage or chemicals, that could have a negative impact on the environment.
Of those recorded in Windermere last year, 36 (53 per cent) were leaks from the sewerage system operated by United Utilities, by far the largest source of incidents.
A United Utilities spokesperson said the water company had “hugely ambitious plans for Windermere” and has cut pollution incidents by 54 per cent this year compared to 2024.
The vast majority were classed as category 3 or 4 incidents, meaning the impact on the environment was considered minimal.
Three category 2 incidents, which are assessed as having a significant impact on the environment, were recorded last year. No category 1 incidents occurred.
The three category 2 incidents were recorded following sightings of blue-green algae at various spots around Windermere in June and October last year.
Blue-green algae can be toxic, causing problems including diarrhoea, nausea and rashes for humans and animals that come into contact with it.
Algae blooms can also cause fish kills by absorbing the oxygen in a water body and suffocating any aquatic life below it.
Windermere has been regularly blighted by blue-green algae in recent years, caused by an excess of nutrients in the water.
These nutrients come from a number of sources, including sewage discharges and agriculture.
EA failing to attend incidents
The data has also revealed that the EA is failing to attend all pollution incidents in person.
In 2024 officials attended 48 (71 per cent) of recorded pollution incidents, and in the first half of 2025 it attended 13 (65 per cent).
This is an improvement on previous years, where the watchdog failed to attend the vast majority of cases.
The i Paper previously revealed the EA did not attend 90 per cent of pollution events in 2022, including over 60 per cent of the most serious incidents.
The situation has started to improve since the previous Conservative government boosted the EA’s enforcement resources in response to the public outcry over the sewage crisis.
However, Staniek said the EA must “be there on the ground” for all incidents around Windermere in order to properly police polluters.
“The Environment Agency has more resource now and for places like Windermere that hold such natural significance they should be attending every pollution incident and getting to the bottom as to what’s caused it,” he said.
An EA spokesperson said the agency “responds to every incident we receive” and was on track to deliver 10,000 inspections next year.
A sewage-free Windermere?
In March, the Government announced a long-term ambition to end sewage discharges into Lake Windermere.
This would see an end to both untreated and treated sewage being dumped into the lake and would require a redesign of the sewerage network in the area.
Save Windermere has campaigned for such a solution, modelled on the clean up Lake Annecy in France between 1944 and 1976.
Staniek said the Government is yet to announce further details of its plans, adding that Emma Reynolds, who replaced Steve Reed as Environment Secretary in September, has not commented on the Windermere situation.
“We want to see the Government and future governments committing to protecting Windermere for the people of this nation forever,” he said.
A spokesperson for the Department for Environment, Food and Rural Affairs said: “This Government shares the nation’s concern at unacceptable levels of pollution in this iconic landscape.
“We remain firmly committed to ending sewage pollution into Windermere.”
