A WARNING has been issued after multiple blooms of a bacteria that is potentially lethal to pets were spotted this month in one of the national park's lakes. 

The presence of blue-green algal blooms has been confirmed at three locations on Windermere.

The Environment Agency (EA) says bloom- and scum-forming blue-green algae can produce toxins that can kill animals. It can cause rashes in humans if it comes into contact with the skin, and illness if swallowed.

The Lake District National Park Authority has issued a warning in the wake of the sightings on Windermere. 

A spokesman said: "It's impossible to tell if the algae is the dangerous kind just by looking at it, so it's best to not enter the water if you suspect there is algae.

“Please look out for signs on lake shores and call the Environment Agency on 0800 80 70 60 to report your sighting.

"Do not enter, drink or swallow the water. Also keep children and pets away from the water."

Blooms of blue-green algae, which is a form of bacteria, have been confirmed at five locations in the national park. 

Three of these sightings - at YMCA Lakeside, Millerground and Cunsey Beck - occurred on Windermere this month.

There was another confirmed sighting close to Lakeside Wood at Bassenthwaite at the beginning of May.

A fifth confirmed report dates back to the end of March and relates to Killington Lake. 

The EA says illness that blue-green algae can cause includes rashes, eye irritation, vomiting, diarrhoea and fever and muscle and joint pain. 

"These haven’t led to long-term effects or death but, in some cases, the illnesses were severe," says a spokesman in an online information pack.  

"Although algal scum isn’t always harmful, avoid contact with it and the water close to it."

The spokesman says: "Blooms can have a negative effect on the appearance, quality and use of the water. 

"It may become green, blue-green or greenish-brown, and several species can produce musty, earthy or grassy odours.

"Blooms can also cause foaming on the shoreline – sometimes confused with sewage pollution."

He says algal scums can 'look like paint, jelly or form small clumps' and may be 'blue-green, grey-green, greenish-brown or, occasionally, reddish-brown' in colour.

Sightings of blue-green algae can also be reported via the UK Centre for Ecology and Hydrology's Bloomin' Algae mobile application.