Millions of litres of sewage illegally dumped in Windermere

The Environment Agency has launched a “complex and ongoing” investigation and says it is committed to improving the water quality in Lake Windermere

A BBC investigation has found that over 140 million litres of waste was illegally dumped into Unesco world heritage site, Lake Windermere by United Utilities between 2021 and 2023. Most of it was unreported.

In certain conditions during wet weather, the Environment Agency (EA) permits the release of raw sewage into Lake Windermere. United Utilities pumps at least 245 litres a second to nearby Glebe Road pumping station in Bowness-on-Windermere, and analysis found that it discharged sewage into the lake at times when it had not been pumping the required amount for treatment.

The company retrospectively reported some discharges from October 2023 onwards, but the investigation revealed United Utilities failed to report 118 hours during which illegal sewage was pumped into Windermere between 2021 and 2023. Estimates suggest between 143 million and 286 million litres was illegally dumped in the lake, with at least 102 million litres unreported.

While United Utilities acknowledges that some of its releases were "potentially non-compliant", it reported "over 94% of potential pollution incidents to the Environment Agency."

A spokesperson said: “We have reported all discharges including any potential non-compliant discharges to the Environment Agency...As part of our ongoing work to reduce spills, in January 2024 we discovered an engineering issue on the configuration of the Windermere system that meant some of the discharges recorded by our Event Duration Monitors were potentially non-compliant. Even though these spills were happening when it was wet and our storage system was already full and spilling, we reported them to the Environment Agency as soon as we became aware of the situation.”

“If any water company is found to be in breach of an environmental permit, [the EA] will take the appropriate enforcement action up to and including a criminal prosecution.”

An EA spokesperson said: “As soon as this incident was brought to our attention, we launched a thorough investigation. This investigation is complex and ongoing, and we are examining further evidence received from United Utilities. If any water company is found to be in breach of an environmental permit, the Environment Agency will take the appropriate enforcement action up to and including a criminal prosecution.”

The spokesperson stated that the EA is “absolutely committed to improving the water quality in Lake Windermere” and is working closely with the local community to reduce pollution from different sources.

United Utilities says it has implemented engineering changes to the system to prevent a reoccurrence of this issue and has started construction for additional storage and treatment facilities around Windermere, to cope with increased rainfall, population growth and the impacts of climate change.

Sewage discharge contains pathogens like bacteria and viruses, nutrients like nitrogen and phosphorous, toxic chemicals and heavy metals. These can cause several problems, including environmental damage, harmful algal blooms and the death of fish and other animals in the lake.

Professor Andrew C. Johnson from UK Centre for Ecology and Hydrology said: “Adding phosphate to lakes is undesirable as unlike rivers, they can stay in the system for longer and sustain more plant growth. There are other worrying things happening in lakes that could be playing a major role in blue green algae blooms such as higher temperatures due to climate change.”