Blue-Green Algae Red Alert for Mannus Lake

Published on 17 December 2019

BLUE-GREEN ALGAE ALERT Mannus Lake & Creek Update.jpg

Snowy Valleys Council has issued a blue-green algae Red Alert for Mannus Lake and warning signs are in effect at key recreational areas around the lake.

WaterNSW advises people not to enter the water, not to drink untreated water or bathe in water drawn from the lake or creek while the red alert level warning is in place. Livestock owners should monitor stock water supplies and remove stock from waters where surface scum is visible or blue-green algae is suspected.

Council was last week successful in securing funding for the supply, installation and commissioning of a mixer for Mannus Lake to help mitigate the occurrence of blooms.

Council’s Acting Director Mr Kausche said the work undertaken by UTS provided a recommendation that a mixer be installed as a strategy to try and break the link between the thermal stratification of the lake and the occurrence of blue-green algae blooms.

“It was originally intended that the mixer would be installed prior to next summer, however funding became available earlier than anticipated through DPI and Council officers responded to the opportunity to install the mixer now,” he said.

“Although it is not possible to predict how long this red alert will remain in place, it will be interesting to see what impact the new mixer has on the existing algae bloom’s longevity and the appearance of subsequent blooms”.

Council will increase water sampling at the lake and downstream to a weekly monitoring frequency and the Red Alert will be lifted when two consecutive samples fall below the high alert.

Blue-green algae occurs naturally at low levels in lakes and rivers, however they may reproduce quickly in favourable conditions where there is still or slow-flowing water, abundant sunlight and available nutrients.

People who believe they may have been affected by blue-green algae are advised to seek medical advice.

Information updates about blue-green algae blooms and red level warning areas can be obtained from the Regional Algal Coordinating Committee free-call Algal Information Hotline on 1800 999 457 or visit –


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