A popular loch for fishermen, dog walkers and swimmers in Caithness has toxic blue-green algae which is harmful to humans and animals.
Highland Council’s environmental health team is advising caution as blooms have been found in Loch Watten.
Samples taken at the popular loch have indicated the presence of blue-green algae.
Loch Watten is regarded by many anglers as “the Leven of the north”, due to its abundance of wild brown trout.
Earlier this year two dogs died after swimming in a loch in the Western Isles that had blue-green algae.
What is blue-green algae and is it harmful?
A Highland Council spokesman said: “During this current period of prolonged warm weather, the chance of blue-green algae (cyanobacteria) affecting water courses, particularly ponds, lochs and canals as well as rivers, increases significantly.
“Sometimes the blue-green algae can form blooms, which can release toxins into the water.
“Contact with blue-green algae can have health effects for humans and animals.
“The situation is being investigated by The Highland Council’s environmental health team, in partnership with NHS Highland public health and wider colleagues.”
He warned: “As a precautionary measure contact with the algal scum should be avoided by people and pets.
“Notices will be posted next to the loch warning that contact with the algal scum should be avoided. ”
You can find more information about blue-green algae at Public Health Scotland’s website – https://www.hps.scot.nhs.uk/a-to-z-of-topics/blue-green-algae/