BLUE green algae has been found again in Shetland, this time at the Loch of Griesta in Tingwall.
Adjoining landowners, NHS Shetland and Shetland Angling Association have been advised, although at this stage there is no adverse effect on water supply.
Notices will be posted next to the loch warning against contact with algal scum.
It can sometimes cause skin rashes, eye irritations, vomiting, diarrhoea, fever and pains in muscles and joints, while it is known to have killed livestock and dogs.
Blue green algae has already been discovered this year at lochs in Voe, Twatt and near Aith.