Blue-green algae found in Slipper Hill Reservoir

Published Monday, 20th July 2026

Blue-green algae, which can be harmful to humans and highly toxic to animals, has been found in Slipper Hill Reservoir, near Foulridge.

Slipper Hill Reservoir

 

Pendle Borough Council is working with the Environment Agency to ensure people understand the dangers and keep their pets and children away from the water. 

Although the blue-green algal bloom may not be present throughout the whole of the reservoir, regular inspections for scum formation are being made.

Experience has shown that once algal numbers are high, the bloom is likely to persist throughout the season.

Councillor Asjad Mahmood, Leader of Pendle Borough Council, said: “Blue-green algae occur naturally in ponds, rivers, lakes and streams; but during periods of warm, sunny weather, there can be a rapid increase in numbers creating harmful algal blooms or scum.

“The toxins can kill wild animals, farm livestock and pets. In humans, they can cause rashes, eye irritations and illnesses if swallowed. So, we are warning anyone going near Slipper Hill Reservoir to be aware and cautious.”

Posters warning of the dangers are on display, and it’s expected the warnings will be in place until the cooler weather sets in.

Councillor Mohammad Hanif, the Council’s Portfolio Holder for Finance, Health and Leisure Services, said: “The safety of visitors to the reservoir is our number one priority.

“We will work with the Environment Agency over the coming weeks to ensure the reservoir is regularly monitored.”

For more information visit https://www.gov.uk/government/publications/algal-blooms-advice-for-the-public-and-landowners/algal-blooms-advice-for-the-public-and-landowners