Horsham Rural City Council technical services director John Martin said council would continue to monitor  levels on a weekly basis until the algae was cleared.

“An inspection on Wednesday revealed that high levels of blue-green algae were present and visible on the surface across most of the lake,” Mr Martin said.

“Testing the water supply would have shown high levels still present.

“We’re hoping that weather conditions change soon. Winds chop the surface of the lake and help the algae to disperse.”

The popular recreational lake was closed to the public during the Easter long weekend after tests identified the potentially toxic bacteria last Wednesday.

This is the second time since the start of the year that the lake has been closed due to blue-green algae.

In January, the lake was closed to the public for almost a month.

Mr Martin said people should continue to avoid contact with the lake’s water supply.

“We have put many signs up around the lake warning people about the algae.

“I want to urge people to please heed the signs and avoid the lake water. 

“In the past people have reported skin irritation after coming in contact with contaminated water.”

Green Lake has a long history with blue-green algae outbreaks. The bacteria was first detected in 1990, while further blooms occurred in 1993, 1994, 1997, 2012, 2013 and 2015.

“Outbreaks can be caused by a number of things, warm sunny days for instance,” he said.

“Green Lake doesn’t have a flow through it and lakes that do have flows don’t get that build up of bacteria.”

Lake users are advised that other recreational activities such as bushwalking, boating and sightseeing aren’t affected by the outbreak.

Direct contact with blue-green algae can cause allergic reactions such as skin rashes, and sore eyes, ears and nose.

If swallowed, contaminated water can cause gastroenteritis, nausea or vomiting.