Algal blooms at Edwardes Lake

Latest monitoring shows no toxic blue-green algae in Edwardes Lake. However, algal blooms are still a sign of poor water quality, and conditions can change.

Always follow signage at the lake for the latest advice.

An algal bloom happens when algae grow rapidly in water. This usually occurs when environmental conditions favour their growth, such as:

• warm temperatures
• high sunlight and low shade
• nutrient pollution (e.g. fertilisers, runoff, waste)
• poor water movement
• lack of aquatic plants. 

Algal blooms can:

• reduce water quality
• cause harm to fish, turtles, frogs, and birds
• disrupt the natural balance of the lake.

Some algae, such as blue-green algae, can produce toxins that are harmful to people, pets, and wildlife.

Pollution and runoff

When it rains, pollutants from streets, homes, and parks wash into drains and flow into the lake. These include:

• fertilisers (nitrogen)
• detergents and chemicals (phosphorus)
• pet waste
• litter and other contaminants.

These nutrients act like fertiliser for algae, causing them to grow rapidly.

Loss of vegetation

Healthy waterways have plants in and around them:

• Aquatic plants absorb nutrients from the water.
• Trees and shrubs provide shade and keep water cooler.

When vegetation is reduced, algae have more favourable conditions to grow.

Climate change

Warmer temperatures and more variable rainfall are expected to:

• increase the frequency of algal blooms
• make blooms more intense
• affect overall lake health and wildlife.

Simple everyday actions can make a big difference:

Reduce pollution

• Always put rubbish in the bin.
• Pick up after your dog.
• Avoid washing chemicals into drains (e.g. don't wash your car on the driveway).
• Use phosphate-free detergents.

Protect waterways

• Avoid using fertilisers or herbicides before rain.
• Sweep paths instead of hosing them down.
• Check your car for fluid leaks.

Support healthy ecosystems

• Don’t feed birds (this increases waste and pollution in the lake).
• Care for local plants and wildlife.
• Get involved with groups like Friends of Edwardes Lake.

Report issues

• Follow lake signage for health advice.
• Report injured wildlife to Wildlife Victoria: 03 8400 7300.