East Lindsey District Council is urging people not to enter or allow animals in the water.
"If you see it on the sand, please do not touch and keep pets away," the warning states.
According to the Blue Cross for Pets charity, the blooms of blue-green algae can produce harmful toxins which stop a dog’s liver from functioning properly and can kill it in 15 minutes.
It can also cause long term health problems in dogs that survive after drinking or swimming in algae-contaminated water.
Dogs who have been swimming in water can get the algae caught in their fur, and can ingest it while cleaning themselves later on.
Symptoms of blue-green algae poisoning include:
- Vomiting/being sick
- Breathing difficulties
There is no antidote for the toxins produced by the bacteria, but if caught early enough, your vet will likely try to make your dog sick and attempt to flush the toxins from the body before they take hold.
The RNLI have been alerted, who will patrol this beach and mark it as red flag for no bathing.
East Lindsey District Council will continue to monitor and update residents and visitors accordingly.