Blue-green algae (cyanobacteria) are bacterial organisms that have some of the characteristics of bacteria and some of algae. They are present in almost all aquatic ecosystems in Australia, including rivers, lakes and estuaries.
Blue-green algae blooms
Under certain environmental conditions, blue–green algae concentrations in water can rapidly increase and form visible blooms or scums. Blooms are usually dark green to yellowish brown, and can make the water look greenish.
Blooms generally occur during summer and autumn, often when nutrient levels are high, temperatures are warm, and the water is relatively still or flows slowly with low turbulence. Weather conditions, nutrient levels and water flow will affect how long a bloom will last.
For the latest information on blue-green algae blooms, contact the manager of the affected water body. Managers may be located at local councils, water corporations, or the Department of Environment, Land, Water and Planning.
Blue-green algae health effects
Water affected by blue-green algae may be unsuitable for drinking, recreational activities such as swimming and fishing, and agricultural uses.
Some species of blue-green algae produce toxins that are harmful to humans and animals when they are eaten or inhaled, or contact the skin. Toxins have affected seafood in the Gippsland Lakes in recent years.
Direct contact with blue–green algae-affected water may cause skin irritation, mild respiratory effects and hayfever-like symptoms.
Avoid contact with algae-affected water, particularly in areas with visible scums or discoloured water. Follow advice on any information signs in affected areas and avoid contact with the water until authorities advise there is no longer a health risk.
If you do have contact with affected water, remove any clothing and wash yourself thoroughly with clean water after coming ashore. Rinse wetsuits before wearing them again to remove any traces of algae.
Seek medical advice if you have any health effects after recreational water activities.
Dogs can be poisoned or die from contact with some types of blue–green algae. It is safest not to let your dog swim or drink in algae-affected areas. If they do come in contact with the water, wash them thoroughly with fresh water and dry them to prevent them grooming themselves and ingesting algal residues. If you are concerned, take your dog to a vet.
Blue-green algae in water supplies
Blue-green algae can cause taste and odour issues in water supplies.
If your local water corporation supplies your drinking water, risks from blue-green algae are managed through their risk management plan.
Never drink untreated water. Boiling algae-affected water will not inactivate algal toxins. Affected water will also be unsuitable for domestic purposes such as preparing food, bathing, showering and brushing teeth.
To prevent algae from affecting your private drinking water supply, ensure that light does not penetrate any pipes or fittings to your water tank and that your water tank is sealed.