What image comes to mind when you think of a sewage treatment plant? Did you picture a thriving ecosystem and internationally recognised bird habitat? Well, the Western Treatment Plant is just that. 

Located in Werribee, the Western Treatment Plant treats half of Melbourne’s sewage. You may be surprised to know that it is also home to almost 300 species of birds. In fact, it is one of Victoria’s most popular birdwatching sites, welcoming birds from as far away as Siberia.

The plant’s grasslands, lagoons and coastline provide an ideal habitat, with permanent water, plenty of food and a variety of plants and landforms. The Ramsar Convention has recognised much of the surrounding areas as a wetland of international significance. 
Image credit - Jamie Davies

Melbourne Water highlights several rare and threatened species hosted by the Western Treatment Plant.

Threatened species

  • The treatment plant is one of the few places where the orange-bellied parrot can be seen in winter. These parrots are an extremely rare and critically endangered species.
  • Brolgas have been seen nesting in saltmarshes next to the treatment plant, moving with their chicks to forage on the plant’s grasslands. Victoria’s Flora and Fauna Guarantee Act lists the Brolga, which is considered endangered in Victoria.


  • Some of Australia’s rarest shorebird species have been seen at the Western Treatment plant, including the buff-breasted sandpipe and the Asian dowitcher.
  • The red-kneed dotterel is a small plover. Up to 250 red-kneed dotterels have been seen at the plant at a single time.
  • The red-necked avocet is one of eight shorebird species that breed at the plant. 
  • Thousands of red-necked stints arrive at the plant from their breeding grounds in Siberia. The red-necked stint is the smallest and most abundant migratory shorebird in Australia. 


The treatment plant is an important haven for waterfowl.

  • The Western Treatment Plant supports the most chestnut teal in south-eastern Australia.
  • Australia’s rarest duck species called the freckled duck can be seen regularly at Lake Borrie within the plant.
  • The ponds of the plant support up to 40,000 pink-eared ducks during late summer.

The State of the Marine and Coastal Environment 2021 Report takes a closer look at Victoria’s waterbirds in the Biodiversity chapter. You can discover more about the Western Treatment Plant in the report’s Water Quality and Catchment Inputs chapter.