See the ‘Port Phillip Bay’ page for a detailed description of the Bay.
This Report Card provides an overview of water quality in the Bay from 1 July 2014 to 30 June 2015. These scores were generated using a combination of five standard indicators: nutrients (nitrogen), water clarity (total suspended solids), dissolved oxygen, salinity and algae (chlorophyll-a).
The water quality in Port Phillip Bay for 2014–15 was ‘Very Good’.
Summary Table: The table below shows the percentage of Port Phillip Bay that falls into each scoring category. See scoring method for more information.
Central Bay to the entrance, including the eastern near-shore region
Corio Bay and the western near-shore region
Hobsons Bay region
Newport, directly downstream of highly industrialised activities
Routine monitoring across eight sites accounts for 100% of the bay
See the Monitoring Programs page for changes to the monitoring program
The section 'Changes over time’ compares the Bay’s annual index scores with the Bay's scores from previous Report Cards (since 2002). Results can also be compared to other catchments.
The water quality in Port Phillip Bay for 2014–15 was ’Very Good‘.
Within the Bay, from the Central Bay region to the entrance, including the eastern near-shore areas from Carrum to Dromana had ‘Very Good’ water quality. The water quality of Corio Bay and the western near-shore area was ‘Good’ and Hobsons Bay and Newport were ‘Fair’ and ‘Poor’ respectively. No areas of the Bay had ‘Very Poor’ water quality.
Typically, water quality in the Bay is impacted by stormwater inflow from heavy rainfalls in the river catchments of the Bay. This can wash nutrients and pollutants into the Bay and increase the incidence of algal blooms. This was mostly evident near the major river mouths at Newport and Hobsons Bay (Yarra River), and Long Reef (Werribee River). These areas had higher levels of nutrients, algae and lower water clarity than other areas in the Bay.
The southern area of the Bay, near the entrance is well flushed with clean seawater by the tidal exchange that occurs twice a day. The water quality in this area is always ‘Very Good’.
Short-lived environmental and extreme weather events can impact water quality in the Bay. Heavy rainfalls in early December 2014, and again in January and February 2015, resulted in stormwater impacting the near-shore environment. These impacts only lasted for a day or two and did not affect the long-term water quality of the Bay.
A short-lived and confined algal bloom occurred at Altona beach during February 2015, which caused some concern to bathers, was identified as a non-toxic species. Algal blooms are not uncommon, and are most likely to occur in warm weather following stormwater run-off and river inflow into the bay after heavy rain.
Since 2002, water quality in the Bay has improved.
In years of drought (1995 – late 2009/10) and lower rainfall, improvements in Bay water quality were associated with decreased river discharges and catchment - derived pollutants and nutrients at locations near river mouths and stormwater outlets. Additionally, during periods of extremely low rainfall, the Bay’s salinity increased above the normal range as a consequence of not enough freshwater flowing into the Bay to compensate for water lost though evaporation. This occurred in 2008 and 2009, towards the end of the drought, and was more pronounced on the western side of the Bay and through the Geelong arm.
In 2010, drought breaking rainfall fell over the Bay’s river catchments, increasing stream discharges and increasing the input of pollutants and nutrients at locations near river mouths and stormwater outlets. This resulted in a slight decline in the Bay’s water quality. Water quality around Newport and Hobsons Bay declined, and improvements occurred in Corio Bay and Long Reef as salinity levels returned to within its normal range.
In recent years, rainfall has been below average resulting in a return to ‘Very Good’ water quality in 2013–14. A slight decline has occurred since 2013–14 though water quality is still ‘Very Good’.
The Government, authorities and community have implemented the following initiatives to improve water quality in the Bay:
In addition to the initiatives set out in the Yarra and Bay - Actions, a range of key initiatives are being undertaken by the Government and the community that aim to raise awareness and drive actions to improve water quality in the Bay. These include:
The following figures show a comparison of scores for each identified water quality indicator in the catchments and Port Phillip Bay.