Lake Ainsworth Blue Green Algae Status

 No Alert as at 8 October 2019 

Overall blue green algae levels are at No Alert levels. Potentially toxic Microcystis aeruginosa has NOT been detected. Council is not aware of any slicks and scums forming. Council has now commenced sampling for the 2019/2020 swimming season.

Users should always obey all signage erected by Council.

The aerator is currently switched on twelve hours a day (7 pm to 7 am) from October to May.

  A Red Level Action Mode is in place 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. At Red Mode, local and health authorities should be contacted to assess risks to recreational users and appropriate measures should be taken to warn water users.
Water should not be used for primary recreation.

Amber Level Alert Mode is triggered when Microcystis aeruginosa concentrations are between 5000 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.

  Green Level occurs above 5000 cells/mL of Microcystis aeruginosa or >0.04 mm3/L of total cyanobacterial biovolume but below the Amber alert level. At this level routine sampling for algae should be undertaken.
No restrictions on recreational use of the water.


Lake users should note any signage at the site and should report any sign of algae which may appear like a green paint spill on the surface of the water to Ballina Shire Council's Environmental Health Unit.

Enquiries: Development and Environmental Health Group, Ph 02 6686 1210.

Algal Information Line: 1800 999 457

To report algal blooms after hours 02 6626 6954

What are blue green algae?

Blue green algae are single celled organisms of ancient origin. Otherwise known as cyanobacteria there are about 40 species known in this country. A selected number of these exhibit toxic properties from time to time.

The algae may sometimes (but not always) be seen as a bluish green scum on the surface of the water or the shoreline when the water is calm.

What species affect Lake Ainsworth?

Species that have been identified from time to time in Lake Ainsworth include: anabaena, microcystis, lyngbya, and oscillatoria.

How can blue green algae affect me?

Skin and eye irritation is a common reaction. At stronger concentrations nerve and liver toxins may be present. Some people are more likely than others to suffer as a result of contact with blue green algae. Anyone who is aware that they are acutely allergic to blue green algae should avoid contact with the waters of Lake Ainsworth during the summer months. To learn more about this organism, how it forms, and what it can do to you, click on the Department of Natural Resources (DNR) information.

Council follows the protocols set by the North Coast Regional Algal Coordinating Committee (NCRACC) for recreational water when determining whether health warnings are necessary.

Warning signs are erected:

  • when blue green algae concentrations exceed the NCRACC protocols.
  • and/or when concentrated algal slicks and/or scums appear.

The signs are removed:

  • when blue-green algal concentrations fall below the NCRACC protocol levels, and slicks and/or scums are no longer present.

Sampling is undertaken by environmental health officers in accordance with NCRACC protocols and analysed by a NATA accredited laboratory. Results are generally available within 24 hours. Testing is stepped up in summer and may be carried out several times a week when algae blooms appear imminent or are in progress.

Lake Ainsworth Aerator

An aerator operates in the Lake 12 hours a day from April to October. This circulates the water to prevent the Lake stratifying, which can help to minimise algae blooms. 

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