Dangerous blue-green algae has been spotted at several bays on Loch Lomond.

Loch Lomond and The Trossachs National Park have warned people to be aware of the algae blooms which produce toxins harmful to humans and potentially fatal to animals.

Dog owners are advised to keep their beloved pooches out of the water because it can kill them.

Death can occur within a few minutes or a few days, depending on the type of exposure.

Reports came from bays on the Loch’s east and around the Duncan Mills Memorial Slipway in Balloch.

Social media users reported seeing the distinctive blue-green colour of water at Lomond shores, Luss and Balmaha.

Lea-anne Bovill wrote: “It’s everywhere.

“Canny believe how bad it is.”

Dawn Diggines wrote: “I’m actually scared to walk [my dog] anywhere again.”

The National Park said West Dunbartonshire Council and the Scottish Environment Protection Agency (SEPA) are aware and warning signs have been issued.

The algae can form and then dissipate within just hours or days, depending on weather and water temperature.

Lynsey Galloway posted online: “Just walked around Balloch Park - no signs up at all.

“But then I understand that although there was algae seen yesterday, due to water movement and rain fall, there might be none today.

It can change from hour to hour.”

In humans, the algae can cause rashes after skin contact and illnesses if swallowed.

If you see warning signs by the shore then keep yourself, pets and livestock away from the water.

Further information is available on the National Park’s website, lochlomond-trossachs.org, or their Facebook.

If you have spotted blue-green algae and there are no warning signs on the shore, please contact the environmental health team at the local council.