Factsheets
At low numbers algae cause no problems and are in fact part of the natural microscopic plankton of water. Occasionally, the algae can grow very fast or "bloom" and accumulate into dense, visible patches near the surface of the water. Such blooms occur in slow moving, warm water that is high in nutrients such as phosphorus and nitrogen, and can be a serious public health and an environmental problem in many waterways throughout Western Australia, particularly in river and estuarine systems.
Frequently asked questions
Are there any detrimental health effects from having contact with an algal bloom?
Contact with an algal bloom (both toxic and non-toxic species) may cause a number of human health problems including:
- skin rashes
- eye irritation and redness
- ear aches
- itchiness
- swollen lips
- hayfever symptoms
- asthma
- possible skin tumours
- gastroenteritis
Certain species of algae can also produce toxins that can contaminate shellfish and make them unsafe to eat. See the Environmental Health Factsheet ‘ Wild shellfish collection ’ for further details.
How will I know if there is an algal bloom in the water?
Some “tell tale” signs which indicate that the water may be polluted with an algal bloom include:
- brightly coloured water
- blue/green scums on the water surface
- brown discoloured water
- oily films on the water surface
If you notice any of these signs it is recommended that you do not go swimming.
Does anyone test for algal blooms?
The Department of Water (External link) monitors a number of waterways in Western Australia for the presence of algae, including the Swan, Canning (for the Swan River Trust (External link)), Murray, Serpentine and Vasse Rivers. When an algal bloom of human health concern is detected at potentially harmful levels the Department of Health is advised and a public warning may be issued. Warning signs will be located in affected areas and messages will be broadcast on television, radio, in local or regional newspapers and on our website (External link).
Who do I contact if I suspect that there is an algal bloom in the water?
If you observe or suspect that there is an algal bloom in a waterway, you can contact the following agencies:
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