The council's safety advice warns that algae can kill pets and livestock and cause illness in humans.

In a warning on social media the council says: "Algae is affecting The Mere at Ellesmere

"It can kill pets and livestock and cause illness in humans.

"Please stay safe and keep out of the water."

The recent Shropshire Triathlon had to cut the event at the Mere into a duathlon with competitors doing a run -bike-run instead of swim-bike-run.