£3.6bn tunnel plan proposed to tackle sewage pollution in Windermere

A £3.6bn plan to reduce sewage pollution in Windermere would divert wastewater through a tunnel up to 12 miles (19km) long to a new treatment works. The proposal, backed by water company United Utilities and environmental campaigners, still needs government backing and further assessment.

The plan, called Only Rainwater into Windermere, would connect 12,800 people to the sewage network for the first time and include up to 86 miles (138km) of new infrastructure. Two options are proposed for where treated water would go: the River Leven or, via a tunnel, the Irish Sea at Ulverston.

Windermere receives both raw sewage overflows and treated wastewater. Treatment works can spill raw sewage when overwhelmed, including during heavy rain; treated effluent can also carry high levels of nutrients. The BBC reports that nutrient levels combined with warm temperatures have caused algal blooms in parts of the lake on several occasions in the past five years.

United Utilities chief executive Louise Beardmore described the proposal as a “100 year solution”. Campaigner Matt Staniek called it a milestone, but said it remained a plan rather than definitive action. The government must decide whether to develop it further and whether to accept its cost.

Who would pay?

One option would pass the cost to United Utilities customers, adding up to £3.17 a month depending on the route. Love Windermere campaigner Nigel Wilkinson supports spreading the cost nationally, which the BBC says could add up to 35p a month to bills across England.

The Department for Environment, Food and Rural Affairs said more work was needed to test alternative options. The decision follows a government promise in 2025 to stop sewage entering Windermere; the proposal has not yet been approved or built.