Blue-green algae has been found in parks and lakes across the West Country.
The algae, which is toxic to animals and humans, has been spotted at several locations in North Somerset.
Councils are now warning pet owners to keep their dogs from drinking from or swimming in the water at several popular parks and lake grounds as investigations continue.
Where has blue-green algae has been seen in the South West?
ITV News West Country has received reports of the toxic algae in Wiltshire, Gloucestershire and North Somerset.
Portishead Lake Grounds, North Somerset
North Somerset Council is investigating a bloom of algae at the town’s lake grounds and is advising people and their pets not to enter the water.
The water is now being tested, but Portishead Town Council has warned it is toxic to fish, birds, other animals and humans.
They said: “We have been advised by North Somerset Council that they have noted an algal bloom in the lake at the lake grounds.
"As a precaution, they will be asking people to not go into the lake or allow their pets to do so."
A number of birds at the lake – including the ducks – have become ill and died as a result of the algae in previous years. In 2016, parts of the lake had to be cordoned off and bales of barley straw were put into the water to break the algae down.
Lydiard Park, Wiltshire
On Wednesday (August 17), rangers at Lydiard Park put signs up to advise people they had found blue-green algae in the lakes.
A park ranger said it's "one of the first times blue-green algae has been spotted at the park," due to a mixture of recent high temperatures and lack of flowing water.
River Frome, Gloucestershire
Pictures of algae blooms were sent to ITV West Country by community organisation Friends of Frome. It is currently unknown whether they are toxic.
How to spot if algae is toxic?
It is impossible to see how toxic algal bloom is just by looking at it, so the Environment Agency says people should assume it is.
It said: “Cyanobacteria, or blue-green algae, is a type of blooming algae which can produce toxins that have the capacity to kill wild animals, livestock and pets.
"They can also harm people, producing rashes after skin contact and illness if swallowed.
“Algal blooms block sunlight from reaching other plants in the water. They also use up oxygen in the water at night which can suffocate fish and other creatures. Oxygen is also used up when the bloom decays.”