IT LOOKS like a pool of blood, but more than likely this striking red water discovered at Allambie Heights is algae.

Allambie Heights residents David and Pat Parsons first noticed the red water Tuesday afternoon at a detention basin near their home.

media_camera Is it or isn’t it red algae? Pic: Braden Fastier

The water was still red when the Manly Daily went to press this afternoon.

Mr Parsons said he was startled by what he saw.

“You go: ‘what they hell is going on here?’,” he said.

Mr Parsons contacted the paper amid concerns that the coloured water would end up in Manly Dam.

“Nobody can say it’s not dangerous,” he said.

media_camera Red algae at Clovelly Beach in 2013 Pic: Craig Greenhill

Warringah Council, however, is confident there is nothing for people to worry about.

“Warringah Council’s environment officers have taken samples of the water at the detention basin in Allambie Heights and preliminary results suggest that it is Euglena,” a spokeswoman said.

“This red algae is present in most freshwater dams and thrives in organically enriched water.

“It is normally dispersed through the catchment during rain events and is completely harmless.”

EUGELNA

■Euglena can be khaki or reddish and this may change during the day

■The red algae is present in most freshwater dams and thrives in organically enriched water

■Euglena is completely harmless

■You can find out more about it and other algae blooms at water.nsw.gov.au