As the summer heats up there has been an increase in the blue-green algae at Lake Ainsworth near Lennox Head and an ‘amber alert’ has been flagged by Ballina Shire Council.
Restrictions of recreational use are not triggered for this level of alert, however, users should obey all signage erected by Ballina Council. The average water temperature at the lake is currently 28 degrees celcius.
Amber level alert mode is triggered when Microcystis aeruginosa concentrations are between 5,000 and 50,000 cells/mL or the biovolume of all cyanobacteria is between 0.4 and 4mm3/L. At this alert level investigations into the causes and increased sampling of algae should be undertaken.
‘Council will continue to monitor weekly, however, care should be taken to avoid any slicks or scums should they develop,’ said a spokesperson for the Ballina Shire Council.
Slicks and scums are present as they are areas of concentrated algae and may present a health risk. There are currently no restrictions on the recreational use of the lake.
Red alert
At the next level, a ‘red alert’, the lake should not be used for recreation.
This is triggered when >50,000 cells of Microcystis aeruginosa are present or a biovolume of all toxin-producing cyanobacteria exceeds 4 mm3/L, or if the total of all cyanobacteria (toxic and non toxic) exceeds 10 mm3/L, or scums are present for long periods.
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