Matt Staniek from the Save Windermere campaign, says treated sewage from places like the Langdale Wastewater Treatment Plant are part of the problem. It has a permit to emit more than 1m litres a day of treated effluent into the River Brathay, which feeds into Windermere. There are other similar outflows around the catchment area, and while the wastewater treatment plants can remove some of the phosphorus, some of it is also flows out into the river.