Algae Alerts NSW map

Alert level definitions

Red

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.

People should not eat mussels or crayfish from Red Alert warning areas. A precautionary approach should be applied to fishing during bloom events. Any fish caught should be cleaned and washed thoroughly in uncontaminated water and any internal organs disposed of before consumption. Fish fillet meals from algal bloom affected areas should be limited to 1-2 servings per week. Avoiding fishing in a bloom location is the best way to minimise risk, particularly catching and eating fish from locations with severe blooms that last extended periods of time.

Amber

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.

Green

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.

For marine and estuarine blooms

The algae guidelines for coastal waters for recreational uses are only based on a few species due to limited knowledge on toxic algae.

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.