Algal blooms are composed of tiny floating marine plants. They can look like a murky, sludge-like substance floating in marine waters and washing onto beaches. Water affected by algal blooms can become temporarily discoloured and have an unpleasant smell. Algal blooms vary in colour and can be red, pink, white, green or brown.

Algal blooms in Port Phillip Bay often occur after heavy rain, and often coincide with warm weather or light winds. They are generally localised and last only a few days.

Blooms of toxic algae in Port Phillip Bay are very uncommon. Most blooms occurring in the Bay are not the same as toxic blue-green algae that occur in Victoria's lakes, dams and rivers. They usually dissipate within a short period of time. People should avoid contact with algal blooms.

Some species of algae that can produce toxins have been found in the Bay and these can concentrate in shellfish. Commercial fish and shellfish harvested from the Bay are subject to quality assurance programs that include active monitoring of shellfish harvesting areas.

What you should do

  • Avoid water that looks murky or sludgy.
  • Wash thoroughly with clean water if you or your pets come into contact with algal blooms.
  • Report suspected algal blooms, discoloured water or floating slicks to the Environment Protection Authority (EPA) on 1300 372 842.

Visit the Yarra and Bay website to find up to date information on algal blooms in Port Phillip Bay.

Page last updated: 28/07/21