Warnings have been issued after a suspected case of blue-green algae growth at Clickimin Loch.
The council’s environmental health department received notification of the growth on Thursday and hope to have laboratory confirmation today (Friday).
As a precautionary measure notices have been posted along footpaths warning against contact with algal scum.
The algae can cause skin rashes, eye irritation, vomiting and diarrhoea. It is also said to have caused the death of livestock and dogs.
Adjoining landowners, NHS Shetland and the Scottish Environmental Protection Agency have all been advised of the situation. There have been no adverse effects on water supplies.