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

Introduction to the marine water quality of Western Port

Western Port’s marine and coastal environments are of national and international significance.  Its environmental diversity and productivity arise from unique combinations of:


These environments are often in close proximity, their interrelationships further supporting Western Port’s extraordinary biodiversity.

Western Port is a Ramsar-listed wetland and the subject of JAMBA* and CAMBA* agreements covering 330 indigenous, resident and migratory birds.  Western Port’s natural values also include internationally significant animal communities, seal and penguin colonies and nurseries for important fish species. 

Western Port holds 4 marine protected areas; the Churchill Island, French Island and Yaringa Marine National Parks and the Mushroom Reef Marine Sanctuary off the ocean coast near Flinders.  In addition, the San Remo Marine Community is listed under the Flora and Fauna Guarantee Act.

Quality marine water underpins all of Western Port’s assets.  Its waters sustain all its biota, nutrient cycling and the ecological services that make the bay important.  Quality water is also the asset most vulnerable to catchment-based impacts.  This places it clearly within the scope of this strategy.

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

The nature of Western Port’s physical environment makes the quality of its marine waters particularly vulnerable to adjacent agriculture, residential, industrial and port development.  Some 50 million cubic metres of earth are estimated to have been transported to Western Port by eroding tributary streams between the 1920s and 1970s .   An estimated 62,000 tonnes of fine sediments are still deposited in Western Port each year from its rural catchments  and from erosion of nearly 20km of its northern and north-eastern coasts. 

High marine sediment loads are believed to be the major cause of the loss of 70% of Western Port’s seagrass during 1970s and 80s.  Sediment is also filling the deep tidal channels that are important to the bay’s habitat diversity.  Pest plants and animals also pose major threats to Western Port’s Ramsar site values.

Climate change risks to Western Port centre on future coastal inundation and rising sea temperatures. Inundation of Western Port’s northern coast will make efforts to improve water quality through coastal erosion control more risky and expensive. Increasing water temperatures 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 crustaceans and planktons to create their calcium-based 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
These historical legacies and the impacts of expected future developments and climate change are major barriers to attaining this Strategy’s target for Western Port’s marine waters.

The marine water quality in Western Port has been assessed (Method & Condition).  Lead organisations are committed to achieving the targets (Targets) and 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.

*JAMBA: Japan Australia Migratory Birds Agreement.  CAMBA: China Australia Migratory Birds Agreement