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Alert information

For information on current recreational alerts see the status reports below, call the NSW algae hotline on 1800 999 457, or view the media releases in our Newsroom.

Algal blooms can cause waters to be unsafe for recreation in both freshwater and marine water environments. Algal alerts are issued by Regional Algal Coordinating Committees (RACCs) who are responsible for local management of algal blooms. Algal alerts reported on this web page are for recreational water use.

Current Algal Alerts

The below algal alerts map displays all current alerts collated by the RACCs across NSW. Algal blooms may be present and not reported to the RACCs. This map does not contain data from water storages managed by water supply authorities where there is no public access. Water users should use caution and be aware of signage placed around waterbodies, particularly during the warmer months.

NSW Health advises that any domestic use (including drinking) of surface water without appropriate treatment should be avoided at all times.

Algal alerts in NSW map

Please click on a site to view additional algal alert details across New South Wales. Use the search bar to search for a site, address or other location. Click the basemap tool to toggle between aerial photography and other topographic layers.

Alerts are declared where algal cell numbers exceed the triggers identified in the Guidelines for Managing Risk in Recreational Waters (1.2MB PDF) published by the National Health and Medical Research Council (NHMRC 2008).

Additional advisory

  • A Red Alert has been issued for Lake Yandel'ora in Mt Annan after sampling by Camden Council showed high levels of potentially toxic blue-green algae. Warning signs are in place and recreational users are advised to avoid all contact with the water. Camden Council are notifying all nearby residents and will continue regular monitoring.
  • A new  Red Alert level warning (high alert) for potentially toxic blue-green algae has been issued for the lower Murray River from Lock 11 at Mildura to Lock 10 at Wentworth. This declaration of a red alert follows testing undertaken by local water authorities. Levels of blue green algae in other sections of the river continue to fluctuate.
  • A Red Alert is in place for Walka Water Works in Maitland until further notice.
  • Stockton Beach Shellfish Harvest Area is currently closed due to exceeding levels of diarrhetic shellfish toxins caused by Dinophysis spp. found in Pipis. The alert was issued on Friday 1st November by the NSW Food Authority. Further sampling by the harvesters will resume once the bloom is believed to have subsided.

Alert level definitions

Red alert levels represent 'bloom' conditions. The water may appear green and may have strong, musty or organically polluted odours. Blue-green algae may be visible as clumps or as scums. The 'blooms' should be considered to be toxic to humans and animals, and the water should not be used for drinking (without prior treatment), stock watering, or for recreation.

A red level alert is in place when >50,000 cells of Microcystis aeruginosa are present or a biovolume of all toxin producing cyanobacteria exceeds 4 mm3/L. A red alert level is also triggered if the total of all blue-green algae (toxic and non-toxic) exceeds 10 mm3/L or scums are present for long periods. At red alert level a waterbody should not be used for primary recreation. Waterbody managers should notify the public through signage and media avenues. Results should be forwarded to the appropriate Regional Algal Coordinating Committees (RACCs) for further dissemination and assistance in management of blooms.

At amber alert levels blue-green algae may be multiplying in numbers. The water may have a green tinge and musty or organic odour. The water should be considered as unsuitable for potable use and alternative supplies or prior treatment of raw water for domestic purposes should be considered. The water may also be unsuitable for stock watering. The water remains suitable for recreational use, however algal concentrations can change rapidly. Water users should use caution and avoid water where signs of blue-green algae present.

Amber level alerts are triggered when Microcystis aeruginosa concentrations are between 5000 and 50,000 cells/mL or the biovolume of all blue-green algae is between 0.4 and 4 mm3/L. At this alert level investigations increased sampling of algae is undertaken.

At green alert levels blue-green algae are present in the water at low densities, possibly signalling the early stages of the development of a bloom, or a period where a bloom is declining. At these densities, the blue-green algae do not pose a threat to recreational, stock or domestic use.

A green level alert occurs above 500 cells/mL of Microcystis aeruginosa or >0.04 mm3/L of total blue-green algae biovolume but below the amber alert level. At this level routine sampling for algae should be undertaken.

For marine and estuarine blooms

The NHMRC algae guidelines for coastal waters for recreational uses are only based on a few species due to limited knowledge on toxic algae. Red level alerts are triggered when Karenia brevis levels exceed 10 cells/mL or when Lyngbya or Pfiesteria species are in high numbers.

A caution alert may also be issued where highly visible blooms elicit public and media inquiries and samples have not been identified or have been identified as non-toxic species.


Friday 13 December
1,160,726 ML
2,596,150 ML
10,201 ML
1,458 ML
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Friday 13 December