Algae are a natural part of aquatic ecosystems. However, some algae can produce toxins that can be damaging to humans, domestic animals and livestock. Exposure through drinking or contact with the water can have impact on animals as well as to organisms living in water. These algae can be found in freshwater as well as brackish and marine waters.

Blue-green algae (also known as cyanobacteria) are the only group of algae to be toxic in freshwaters. They are microscopic bacteria living in water and are capable of photosynthesising which is why they are often called ‘algae’.

Though microscopic, when they form colonies and accumulate together they can become visible to the naked eye. Blue–green algae can produce potent liver and neurotoxins as well potentially being skin irritants. However, not all blue–green algae are toxic. Potentially toxic species do not always produce toxins.

Toxic marine and estuarine algae can also affect recreational water use. Some of these algae produce toxins that can cause illness if ingested and others can cause skin irritations. These algae are often microscopic but some cause red coloration to water a phenomenon known as red–tides.

For further information on identification of algal blooms, dangers and problems and prevention and control see the WaterNSW website.

Algal alerts and contacts

Current algal alerts are published by WaterNSW.

Contact the relevant regional Co-ordinator at WaterNSW to report an algal bloom.

State strategy for algal management

The role of the department in algal management is to:

  • Co-ordinate and support the State Algal Advisory Group
  • Provide advice on algal issues and the government strategic direction of algal management and planning in NSW

The State Algal Advisory Group provides the over-arching policy advice and framework for the management of fresh water and marine blooms.  Membership of the State Algal Advisory Group is made up of the relevant NSW State Agencies, NSW local government and the Murray Darling Basin Authority.

Information for water utilities

A framework for raw waters used as a source for potable supply is available at Water Quality Research Australia  (PDF, 2072 KB).