Fife Council has urged members of the public to stay out of the water at Lochore Meadows after huge amounts of algae was discovered.
The loch in central Fife is a popular place for paddle boarding, wild swimming, and fishing, but those visiting at the weekend were met with a warning notice about the plant that can make people "severely" sick. High concentrations of blue-green algae have been found in the water and Fife council have advised people and their animals to keep out temporarily.
Swallowing the water or having contact with algal scum can cause harmful effects such as rashes, vomiting, diarrhoea, muscle or joint pain. The bacteria that contains dangerous toxins potentially fatal to pets, livestock and birds if ingested even in small quantities.