The Environment Agency is warning people visiting the lakes and rivers in Cumbria to be on the look out for blue green algae.
Blue Green Algae is a naturally occurring environmental phenomenon that becomes more likely during periods of warm, settled, dry weather but can also form after periods of heavy rain.
The algae poses a small risk to humans but it can be deadly to animals, particularly dogs if they drink or swim in the water.
Nicki Ruston, Environment Manager at the Environment Agency said: “Blue green algae can cause stomach pains, vomiting, diarrhoea, and skin rashes though the risk to people is relatively small.
"Animals such as dogs can, however, be more seriously affected and we would urge dog owners to keep their pets out of the water if they suspect that blue green algae may be present."
Current reported areas include:
Grasmere and Rydal
If you suspect Blue Green Algae please contact the Environment Agency’s 24 hour hotline on 0800 80 70 60.