High levels of the potentially toxic algae have been detected at Lake Hume, Lake Mulwala and numerous sites along the river all the way to, and including, Torrumbarry Weir, near Echuca.

The Murray Regional Algal Co-ordinating Committee issued the warning yesterday and chairman Richard Scott said it was the largest blue-green algae bloom the committee had experienced since it was established in 1994.

He said the committee, along with eight others across the state, was set up after a 1200km bloom in the Darling River in the early 90s.

“It’s not common to have a bloom at them all simultaneously,” Mr Scott said.

“But with the drought, weather and the lower water levels, we’re not getting flows down the river that help dilute it.

“We’re at the mercy of Mother Nature, we need her to help.

“Cold weather would retard its ability to grow.”

The species of blue-green algae detected could cause gastroenteritis in humans if swallowed or skin and eye irritations.

People are advised not to enter the water or drink and bathe in untreated water drawn from the river.

Mr Scott said people should not enter the water even if it looked clear.

Water supplies for towns along the affected stretch of the river are being treated and are safe for human consumption.

North East Water operations manager Fiona Smith said the corporation’s treatment plants were equipped to remove any algae from the water.

“Each of the towns we supply along that reach have activated carbon dosing facilities as part of the treatment process, which removes that algae,” she said.

Ms Smith said the corporation had also boosted monitoring of the raw water supply to ensure treatment processes were adjusted according to the algae levels.

Updates about blue-green algae blooms and red level warning areas are available from the Algal Information Hotline on 1800 999 457.