Visitors are being advised to avoid contact a Colwick lake after it was confirmed it contains toxic blue-green algae.
A spokesman for Nottingham City Council warned visitors of the dangers.
They said:”We’ve had confirmed reports of blue-green algae on the West Lake at Colwick Country Park.
“Keep away from the water – this includes dogs and other pets. Blue-green algae can be toxic and potentially fatal to both animals and humans.
“Please ensure your dog does not swim, paddle, or drink from the lake.”
They confirmed the East Lake (Trout Lake) was currently unaffected.
The spokesman nadded: “We’ll continue to monitor the lakes and update people if the situation changes. Please follow all signage and guidance from staff.”