An algal bloom has been detected on Lough Derg, prompting a public warning from Tipperary County Council.
The council, in consultation with the HSE, is advising people to exercise caution following inspections this week which found significant blooms in areas of the lake.
The blue-green algae can produce harmful toxins and is most easily recognised when it forms a bright, pea-green, paint-like scum on or close to the shoreline.
People are being advised to avoid contact with the bloom as it may cause skin irritation.
They are also being urged to keep animals, particularly dogs, away from affected areas and to ensure they have an alternative source of drinking water.
The public advisory is effective immediately and will remain in place until Monday, 28 September.
