Windermere £3.6bn sewage tunnel plan wins backing but awaits approval

England's largest lake has a plan to stop sewage discharges, but it is not yet approved. A feasibility study has set out a £3.6 billion scheme to connect homes around Windermere to a new sewage network and build a huge tunnel to carry waste away from the lake. The report was drawn up by Stantec with the local water company, regulators and local authorities.

Under the proposal, the tunnel would be four metres wide and up to 19 kilometres long, running along the east side of the lake. It would connect 12,800 homes to a single sewerage network. Sewage would be taken away for treatment at a wastewater centre at Leven or Ulverston and then discharged in or near the Irish Sea. The feasibility study sets out a £3.6 billion option to take sewage to the River Leven around Newby Bridge and a £3.7 billion option to go further south to Ulverston. If approved, the project is expected to take seven years to build.

Windermere has suffered algal blooms in summer, turning parts of the water putrid green. The blooms are caused by warming temperatures and nutrients entering the lake, in part from agriculture but mainly from sewage. Sewage acts as fertiliser for algae, and the algae can be toxic to wildlife and people. In 2022 campaigners shared footage of turquoise water caused by algae growing at speed and then decaying, which sucks oxygen out of the water that wildlife need to survive.

The plan is backed by United Utilities and by campaigners who have long called for action. Nigel Wilkinson, who runs a fleet of boats on the lake, said Windermere has national and international significance because of its World Heritage status and should be treated as a national asset and funded accordingly. Ian Doig, who runs sailing tours, said people will not want to swim or jump off boats if the water is not clean. Save Windermere campaigner Matt Staniek said the tunnel is probably the most environmentally friendly way to tackle the problem and called for construction to start as quickly as possible.

Who pays is still unresolved. Those behind the project say it could be funded either by a £3 a month increase on local bills or by a rise of about 35p a month levied on everyone across England. One report put the nationwide figure at just over 30p a month per household. United Utilities chief executive Louise Beardmore acknowledged that bill increases are sensitive and said the company had invested hundreds of millions of pounds in the past but clearly not enough. She said shareholders gave the company £800 million in March and that it is delivering £13.5 billion of investment in the North West, supporting 30,000 jobs.

United Utilities has faced repeated criticism over raw sewage spills into Windermere, and the feasibility study identifies regulated public infrastructure as the most significant and controllable source of nutrient inputs. The company says £200 million of investment over the next five years will reduce combined sewer overflows into the lake, and it aims to meet a 2050 target by 2029. In Wigan, residents asked by one channel said the general public should not pay and that shareholders and profits should be looked at first.

The government has not approved the project. It says it is determined to protect Windermere and cut sewage spills, but it wants more work done and alternatives tested. The decision now rests with ministers, and the cost and who pays remain central to whether the tunnel goes ahead.