MAIN SOURCES OF SEWAGE POLLUTION

After monitoring the issue for years, local zoologist Matt Staniek calculates that 40% of the phosphorus comes directly from storm outflows run by United Utilities, the regional water company; a further 30% from unregulated septic tanks linked to hotels, B&Bs and holiday cottages. Modern sewage plants clean effluent, but many hotels and guesthouses are not on mains drainage and rely on smallscale treatment works, some of which date to the Victorian era. Up to 1,500 septic tanks are located within the Windermere catchment and the Environment Agency doubts many tanks have been emptied in decades. Household shampoos and detergents also add phosphate to the lakes.

Natural factors and farming

Geological processes play a role, whereby sediment and rock from the mountains filter into the lakes. This natural process, thousands of years old, is being exacerbated by people and, increasingly, climate change. Historic land drainage and the creation of channels has disconnected rivers from their natural floodplain, so that fine sediments remain in the river channels, to be deposited in the lakes. Sheep grazing on the fells means that water – and sediment, pesticides and animal waste – is washed more quickly into water courses. In heavy rains, the substrate run-off from the fells can raise a riverbed by a metre. Poorly built or badly located sileage plants or slurry stores are also contributors. Jim Ratcliffe of the Environment Agency cautions: “We can’t make farmers the whipping boys for this – most farmers do the right thing.”