Our Region, Our Environment, Our Future.
State Government Victoria
The Regional Catchment Strategy for the Port Phillip & Western Port region

Introduction to marine water quality in Port Phillip Bay

Port Phillip Bay is arguably the single most important environmental, social and economic asset in the region; possibly in all of Victoria.  Its ecological services - aesthetic seascapes, fishing, transport, wastewater purification, swimming and boating, are irreplaceable.

The Bay features 4 marine protected areas; the Port Phillip Heads Marine National Park and the Jawbone, Ricketts Point and Point Cook Marine Sanctuaries.  The Port Phillip Heads national Park comprises Mud Islands, Point Nepean, Popes Eye and the Portsea Hole.  (Also Swan Bay and Point Lonsdale in the Corangamite CMA region)  The Bay’s western coast wetlands are internationally recognised for their migratory bird habitats under the Ramsar convention.

Rocky reefs occur on the Bay’s margins and at the Heads while the central basin is an extensive marine plain of sand and silt.  Seagrass meadows cover the seabed in shallower waters.  These diverse environments provide habitat for around 300 fish species, several hundred species each of molluscs, crustaceans, bristle worms, jellyfish, corals, etc and sponges, 2 species of seagrass and at least 200 species of seaweeds.

Port Phillip Bay is Victoria’s largest marine bay with an area of 1,950 km2.  The vast majority of the Bay is under 10m in depth and water exchange with the open ocean is highly restricted. 

Quality marine water underpins all of Port Phillip Bay’s myriad assets.  Its waters sustain all its biota, nutrient cycling and the ecological services that make the bay so important.  Quality water is also the asset most vulnerable to catchment-based impacts. 

Accordingly, this strategy sets targets that aim to maintain current water quality in each of the Bay’s segments defined by Victoria’s State Environment Protection Policy.

The Bay has proved to be a resilient natural system.  But it is critical that the water-borne nutrients, suspended solids and pollutants carried to the Bay from the region's six catchments do not exceed the Bay’s assimilative capacity.  Major investments over the past decade have successfully reduced nutrient loads to the Bay but projected urban growth is estimated to make it difficult to prevent future load increases.

Climate change will increase water temperatures. Warmer waters are already changing marine animal and plant distributions and advantaging some species over others. Increasing atmospheric CO2 concentrations will increase water acidity. This will have particular impacts on the ability of shellfish, crustaceans and planktons to create their calcium-based external skeletons and shells./>
Water quality in Port Phillip Bay has been assessed (Method & Condition). Targets have been set (Targets) and lead organisations are committed to achieving the targets (Leadership). Arrangements are in place to monitor and report on progress and success (Monitoring & Reporting).  Targets and leadership arrangements are determined in consultation with relevant departments, agencies and delegated land managers.