Recent water samples taken at Loch Branahuie, on the Braighe isthmus near Stornoway, have indicated the presence of blue-green algae, which can be a health threat..
The bloom has the potential to discharge on to Melbost Beach. Dog walkers using the beach should take care that their dogs do not come into contact with the algal scum.
Swallowing the water or algal scum can cause stomach upsets or more serious health effects. Contact with the water or algal scum can also cause skin problems.
A spokesman for Comhairle nan Eilean Siar said: "It is a sensible precaution for you, your children and your animals to avoid contact with the scum and the water close to it. For further information, contact the Environmental Health Team of Comhairle Nan Eilean Siar on 01851 822 694."
As a precautionary measure, notices have been posted next to the lochs warning that contact with the algal scum should be avoided. Adjoining landowners and fishing interests have been advised of the situation as have the Consumer & Environmental Services Section of Comhairle nan Eilean Siar and NHS Western Isles.
Blue-green algae exist in fresh waters in Great Britain and throughout the world; they are noticed when their concentrations increase to form “blooms” and when they form scums – looking like blue-green paint – or when they collect on the shore line.
Some blue-green algae may give rise to adverse medical effects – but not always. Effects on people coming into contact with toxic scums include skin rashes, eye irritations, vomiting and diarrhoea, fever and pains in muscles and joints. Toxic algae have caused deaths of livestock and dogs. The treatment of water supplies removes blue-green algae and additional treatment may be applied to destroy or remove toxins should they arise. The level of its toxicity can fluctuate; it can appear one day, be dispersed by the wind and mixing and re-accumulate at any time.