Windermere: Warning after potentially toxic green algae infects lake

Cyanobacteria can be harmful to humans, animals and the environment. The Fresh Water Biological Association says there are several reasons for its return including the Lake District's recent hot, dry spell, Phosphorus from wastewater from treatment works and climate change influencing the intensity of cyanobacterial blooms.

Dr Lynsey Harper, of the Freshwater Biological Association, said: "Not all species of cyanobacteria produce toxins and a given species may not produce toxins all of the time. However, it is not possible to say whether a cyanobacterial bloom on Windermere is producing toxins without detailed laboratory analysis.

"Therefore, as a precautionary measure, it is recommended to stay out of the water, and to keep pets out of the water if a cyanobacterial bloom is present and especially inshore areas and bays where scums or slicks have formed on the surface of the water."

Reports flooded into environmental conservation group Save Windermere this week stating it is "all over" the lake. The group says excessively high nutrient levels are destroying England’s largest lake and it demands an end to all treated and untreated sewage discharges into the Windermere catchment.

A spokesperson said: "The single largest input of phosphorus into Windermere, which is feeding the algal blooms, is sewage coming from United Utilities waste water treatment works. Windermere in its natural state is oligotrophic which means it would be so low in nutrient that algal blooms would be incredibly rare or would not happen at all. What we are seeing is from anthropogenic pressure on the lake. 

"As the summer progresses and rain continues to elude the catchment. We want to see more warnings placed around the lake to ensure that people understand the risks that harmful algal blooms pose to their health and the health of their pets. If a bloom is extensive enough then this can threaten the wildlife of the lake.

"Save Windermere is calling for an end to all treated and untreated sewage going into Windermere following the success of sewage removal from Lake Annecy in France."

A United Utilities spokesperson said: "The factors affecting water quality in Windermere are complex and, without targeted action by multiple sectors, we will not see the changes we all want.

“We are determined to play our part by improving our operations and their contribution to the overall health of Windermere. In the last five years we have halved the amount of phosphorus that is now entering the lake from our processes.

"We know there is more to be done though and in the next two years we are making an early start on reducing storm overflow operations at Elterwater pumping station, Ambleside, Hawkshead and Near Sawrey wastewater treatment works.

"We will also work with the wider community to tackle the various factors that affect Windermere."

Visitors to the lake are advised to look out for signage and keep out of the water. To report sightings, visit the UKCEH Bloomin’ Algae app.