Blue-Green Algae

Blue-green algae (cyanobacteria) are naturally occurring bacteria that live in lakes and waterways.

The presence of sufficient nutrients, warm temperatures, and high levels of sunlight, together with calm waters, provide optimal growing conditions for blue-green algae.

Excessive growth, called an algal bloom, generally occurs during summer and autumn, however blooms can happen at any time.

Cool, cloudy and windy weather can help reduce blue-green algae levels.

Blue-green algae impacts water quality, and some species produce toxins that can be harmful to people and animals.

Algae and associated toxins may be present in lakes and lagoons without being visible to the naked eye.

Sometimes algae can be mixed in the water column, or produce a smelly, thick scum on the water surface.

Algal blooms can occur every year with varying severity and can persist for weeks, months or even an entire season if the right conditions exist.

Potential health hazards are related to the way people are exposed to the toxins:

• Swallowing water containing algae toxins may cause gastroenteritis symptoms such as vomiting, diarrhoea, fever and headache.
• Inhaling affected water droplets may cause respiratory problems and flu-like symptoms.
• Skin contact with water, including sensitive areas such as the eyes, ears, mouth and nose, may cause irritation, skin rash, flu-like symptoms, and fever.
• Eating fish and other food caught in algae-affected waters may present a health risk.
• Boiling algae-affected water will not remove algae toxins or make the water safe to drink.

Importantly, children and pets are more susceptible to the effects of toxins. Do not allow either in the water, and seek medical advice if you are concerned about their health.

• Council has been liaising with WaterNSW who coordinate and support Regional Algal Co-ordinating Committees (RACCs).
• We have been regularly monitoring the Coomaditchie Lagoon for levels of blue-green algae and reporting to WaterNSW under the NSW Guidelines to Management Response to Freshwater, Marine and Estuarine Harmful Algal Blooms.
• Council has also undertaken water sampling.
• Algae warning signs have been placed around the lagoon.
• Regular and on-going communication with key stakeholders groups to keep them up to date.
• Council will be installing aerator pumps as a low-impact management action in an attempt to reduce algal levels.
  • Aeration increases water circulation and oxygen concentrations throughout the water column, of which blue-green algae do not survive well in. It also creates an environment that allows other diatoms and good algae to proliferate and outcompete the blue green algae.
• We will continue to conduct regular monitoring of the lagoon until high levels dissipate.

As a community, we can help prevent blue-green algal blooms by limiting the amount of nutrients in the water and promoting ecological health.

Detergents and fertilisers contain a high concentration of nitrogen and phosphorus. We can all play our part by:

• Preventing nutrients from washing into roadside drains that flow into local waterways, for example, by washing your car on the lawn rather than on the road.
• Using phosphorus-free detergents.
• Reducing the use of fertilisers where possible.
• Helping to rehabilitate waterways.