A blue-green algae alert has been issued for areas around Loch Tay.
Perth and Kinross Council has warned of algal blooms around Kenmore Beach, Dalerb and Acharn.
Members of the public are being warned of the health risks to both themselves and pets.
They should avoid swimming in or drinking affected water. Dog owners are advised to keep their dogs on a lead and stay away from the water in affected areas.
PKC has encouraged residents to use the Bloomin’ Algae App to find and report toxic algal blooms.
A PKC spokesperson said: “We’ve had an alert for blue-green algae for the areas of Kenmore Beach, Dalerb and Acharn in Highland Perthshire.
“Please be aware of the health risks to yourself and your pets that these algal blooms present and avoid swimming in or drinking water affected in this way.”
The blooms appear in freshwater lochs in Perth and Kinross when the temperature increases. As the bloom continues, the water develops a green/turquoise scum on its surface.
The toxic bloom can cause skin rashes, eye irritations, diarrhoea and vomiting, fever and muscle/joint pain.