Plan Unveiled to Keep Sewage Out of Windermere Lake

A plan worth £3.6bn to stop sewage being discharged into Windermere has been unveiled, according to BBC News. The proposal is backed by United Utilities and clean water campaigners.

The plan would see a tunnel up to 12 miles (19km) long built to carry sewage away from the lake. Right now, both raw sewage and treated effluent (water that has been cleaned at a treatment works) are discharged into Windermere.

Campaigners say this discharge causes parts of the lake to turn green each summer through algal blooming (a fast growth of tiny plants that colours the water). High nutrient levels and warm temperatures have caused algal blooming on several occasions in the last five years.

Windermere is in the Lake District, which is a Unesco World Heritage site and attracts close to 18m visitors each year. The lake holds around 300bn litres of water. Water entering one end can take 9 months to reach the other end.

The sewage network around the lake is fragmented, with homes served by public treatment works, private treatment facilities and septic tanks (underground tanks that store waste). Overwhelmed treatment works, such as during heavy rain, can spill raw sewage.

The proposal, called "Only Rainwater into Windermere" (ORiW), would connect 12,800 people to the sewage network for the first time. It includes up to 86 miles (138km) of new sewage infrastructure and a single wastewater treatment works. Two route plans are proposed, one discharging treated effluent into the River Leven and the other into the Irish Sea at Ulverston.

Louise Beardmore, chief executive of United Utilities, called the proposals a "100 year solution for this lake". Activist Matt Staniek called the proposal a "milestone".

One funding option would pass the cost to United Utilities' customers, adding up to £3.17 to monthly bills depending on the route. Nigel Wilkinson of the Love Windermere group would like the cost spread nationally, which would increase bills in England by up to 35p a month.

Steve Reed, who was then Environment secretary, promised in March 2025 to stop all sewage going into Windermere. The government must now decide whether the plan can be developed further and whether the £3.6bn cost is acceptable. The Department for Environment, Food and Rural Affairs said further work is needed to test alternative options.