Blue-Green Algae

Visitors and local residents are advised to be aware that blue-green algae can occasionally be present in lakes and other bodies of water throughout the Lake District, particularly during periods of warm weather.

Blue-green algae are naturally occurring bacteria that can multiply rapidly under certain conditions, forming blooms on the water’s surface. These blooms can vary in appearance, often looking like green scum, paint, foam, or streaks floating on the water. While not all blooms are visible, some can produce toxins that may be harmful to people and animals.

Extra care should be taken around children and dogs. Dogs are particularly at risk as they may drink affected water, swim in it, or ingest algae while grooming themselves after entering the water. Exposure can cause serious illness and, in some cases, may be fatal. Children should also be supervised closely and discouraged from swimming or paddling in areas where algae is present.

If you suspect blue-green algae is present, avoid contact with the water and keep pets away from the shoreline. If a person or animal becomes unwell after contact with affected water, seek medical or veterinary advice immediately.

Conditions can change quickly, and visitors are encouraged to check the latest information before enjoying lakeside activities. For the most up-to-date guidance and advice, please see the links below.

Cumbria & Lancashire Blooms | Spot, snap, and report blue-green algae | Engage Environment Agency

Recent Blooms in Windermere and Coniston;

Windermere & Coniston – Confirmed Blue Green Algal Blooms (updated 16/07/2026)

Blue Green Algal Blooms have been confirmed at the following locations, see table above for further details: 

  • Coniston – SD 29110 91215 (19/04/2026)

  • Windermere – North Basin (09/07/2026 + 15/07/2026)

  • Windermere – Fell Foot (15/07/2026)

The date shown on the map is the date on which the bloom was confirmed as blue-green algae by the Environment Agency. Unsettled conditions can disperse blooms or move them around the lake. We encourage water users to check for signs of blue-green algae before entering the water. 

If you wish to report an algal bloom, please contact the Environment Agency’s Incident Hotline on 0800 807060 or report via UKCEH’s Bloomin Algae App. If you have any concerns, please contact the Environment Agency’s Incident Hotline on 0800 807060.

Last updated 17/07/2026