Fife Council is warning locals that blooms of toxic blue-green algae have been reported in several lochs and ponds.
The bacteria, which can turn the water a distinctive blue or green colour, can be lethal if it is ingested by animals.
Locals have been told that the algae has been reported in three places across Fife, including at Clatto Reservoir south of Cupar.
Blue-green algae, or cyanobacteria, can be harmful to humans, sometimes causing severe illness as well as problems like eye irritation and vomiting.
Fife Council says suspected blooms have also been reported at Lochore Meadows and Beveridge Park in Kirkcaldy.
A spokesperson said: “Blue-green algae pose risks to public and animal health when they form blooms and scums in freshwater in warm summer months.
“Please keep yourselves and your dogs away from affected water bodies.”
While the algae can develop anywhere, it is more common in still or slow-moving water like ponds.
Cyanobacteria often has a much more serious effect on animals, with several cases reported in Scotland this year where dogs have died after coming into contact with it.
Fife Council warn locals of blue-green algae blooms
Bute and Cowal Vets in Dunoon in Argyll and Bute shared a warning to pet owners in July after a dog they treated died after exposure to blue-green algae.
In a post warning people about the dangers, bosses wrote: “Call your vet immediately if you think your dog has blue-green algae poisoning, the sooner your dog gets treatment the better their chance of survival.
“If your dog comes into contact with blue-green algae, don’t allow them to lick their fur, wash them (if possible) and call your vet ASAP.
“The more toxins your dog takes in, the worse their poisoning will be.”
Fife Council says any member of the public who finds areas of water affected with blue-green algae should inform economy, planning & employability services on 03451 55 00 22.