What is blue-green algae?
What causes a blue-green algae bloom?
Problems with blue-green algae
Managing blue-green algae blooms

What is blue-green algae?

Blue-green algae or cyanobacteria are tiny micro-organisms found in aquatic habitats such as rivers, lakes and watercourses. Different species of blue-green algae can exist in both salt and freshwater.

Blue-green algae is an important part of a healthy ecosystem and typically exist in low numbers during normal conditions. Thick, dense algal colonies, known as an algae bloom, may form rapidly under favourable conditions. Signs of a bloom include:

• Green, soupy looking water
• Surface scums, mats or films
• Swampy or fishy smell.

Blue-green algae factsheet

What causes a blue-green algae bloom?

Blooms of blue-green algae can occur rapidly under the right conditions which includes:

• Warm water temperatures
• Increased nutrient levels
• High sunlight; and
• Stagnant and drought conditions.

Problems with blue-green algae

Blue-green algae blooms may accumulate in certain areas of waterways due to wind and water currents, including at the waters edge. Some species of blue-green algae release toxins as they breakdown which are a potential health risk to humans, pets and aquatic wildlife. Algae blooms can also discolour the water and create an unsightly and foul-smelling scum on the surface.

Managing blue-green algae blooms

Most blue-green algae blooms are natural events that cannot be stopped however high nutrient loads may increase the frequency and severity of algae blooms. Residents can assist with reducing nutrient pollution and algae blooms by using and disposing of fertilisers appropriately, washing cars on the lawn and preventing soil erosion around the home and garden.

Where Council becomes aware of blue-green algae blooms, residents should follow advice provided by signage and communications. If a bloom is present:

• Do not drink, swim in or allow pets to enter the water
• If you or your pets have come in contact with affected water, wash thoroughly
• If you, or your pets become sick after contact, see your doctor or veterinarian.