Algal Alert Level Definitions
GWMWater uses the following 3-step scale to alert customers of blue-green algae levels:
Blue-green algae is present at high concentrations (bloom conditions) that may pose human health risks.
Water is non-potable (not drinkable), unless treated by a Water Treatment Plant which is designed to treat algae, and is not suitable for domestic or recreational use.
What should I do?
Rural pipeline customers are advised to seek veterinary advice prior to watering stock during a red alert.
Blue-green algae is present in the water at concentrations that may pose human health risks.
Water is non-potable (not drinkable), unless it is treated through a Water Treatment Plant which is designed to treat algae, but remains suitable for recreational use.
What should I do?
Rural pipeline customers are advised to seek veterinary advice prior to watering stock during an amber alert. Regular sampling is undertaken at this alert level.
Blue-green algae is present in the water at low concentrations.
Water is potable (drinkable) provided it is supplied through a Water Treatment Plant and is considered safe for recreational, stock and domestic use.
For warnings for the Murray River, refer to algal information issued by the NSW Department of Primary Industries.
Blue-green algae warnings
We advise the public to avoid direct contact with water bodies that have been issued a blue-green algae warning. Monitoring has detected levels of blue-green algae above levels considered safe for recreational use.
- Avoiding all contact with affected water.
- Affected water not be used for cooking, drinking, washing/showering or any other domestic use. Boiling the affected water will not make it safe to use.
- People who come into contact with the affected water should wash skin immediately in clean water. Characteristic signs of algae contact are skin rashes or itchiness, sore eyes, ears and nose; or if swallowed, nausea or vomiting.
- Those experiencing any health issues after being in contact with blue-green algae affected water, please seek medical advice immediately.
- Pet owners should prevent pets from drinking or having direct contact with blue-green algae affected water.
High levels of blue-green algae produce toxins that can affect the health of humans, animals, birds and livestock as well as harm the environment.
Blue-green algae blooms occur naturally and can reproduce quickly in still or slow-flowing water in rivers and lakes. Blooms can be triggered by a combination of:
- nutrients in the water
- low water inflows and storage levels
- warmer weather conditions
It is not possible to predict how long blue-green algae levels will remain high.
In the event of an algae bloom in one of our waterways, we may issue a warning (depending on the blue-green algae levels as identified in the above table). We will continue to regularly monitor the water quality in line with our Blue-green Algae Regional Coordination Plan.
It's important that you respect any changes to recreational activities at lakes, reservoirs, rivers and wetlands where warnings are issued.
Anglers wanting more information are recommended to visit Victorian Fisheries Authority’s website.
How to recognise a blue-green algae bloom
Blue–green algal blooms often cause a green/red/brown discolouration of the water. Sometimes scum forms on the water surface and an earthy or musty smell may be present.
Although algae blooms can sometimes be seen, water samples need to analysed to know for sure.
If you suspect a blue-green algae bloom, contact us immediately on 1800 188 586.
Blue-green algae Regional Coordination Plan
GWMWater is the Regional Coordinator for a major blue-green algae outbreak for a number lakes, reservoirs, rivers and wetlands within our region.
More about our Blue-Green Algae Regional Coordination Plan.
Further information on blue-green algae
Department of Environment, Land, Water and Planning (DELWP) https://www.water.vic.gov.au/waterways-and-catchments/rivers-estuaries-and-waterways/blue-green-algae
Australian Drinking Water Guidelines https://nhmrc.gov.au/about-us/publications/australian-drinking-water-guidelines