A toxic blue-green algae bloom has been found on a beach in Cornwall.
The council says the sand and sea are not contaminated
The algae is in a stream which crosses Porth Beach in Newquay, and the local council has put up warning signs urging people to keep out of the water.
The algae releases toxins in water as it decomposes, and can kill fish and cause skin and eye irritation to humans and domestic animals.
Scientists say the algae bloom occurs if water is polluted with fertilisers or detergents.
It is not uncommon for algal blooms to appear in summer or autumn after a long period of warm weather.
Restormel Borough Council is reassuring people that the problem is isolated to the stream and has said the sea and the sand are safe.
The authority said it has only had to take similar action three times in the past 14 years, but it wanted to act before there was a distressing incident.
Environmental Health Officer Graham Martin said: "Fortunately there is no risk to people who want to go into the sea at Porth, nor to anyone just being on the sand. The warning only applies to playing in the river."
Pet owners are also being warned to keep their animals out of the river.