See the ‘Port Phillip Bay’ page for a detailed description of the Bay.
The Report Card for the Bay provides water quality index scores for the period July 2012 to June 2013. These scores are generated using a combination of five standard indicators: nutrients (nitrogen), water clarity (total suspended solids), dissolved oxygen, salinity and algae (chlorophyll-a).
These are sampled monthly across eight sites in the Bay as part of the bay monitoring program.
The following section 'Changes over time’ compares these annual index scores and indicators with the Bay's scores from 2000. Results can also be compared to other catchments in the section below ‘Compared to other catchments’.
Site-specific details about indicators can be found via the site lists or can be accessed directly from the map.
Summary Table: The table below shows the area-weighted distribution of site scores based on marine zones specific to each monitoring site. See scoring method for more information.
Entrance, Dromana and central bay
Near-shore areas infrequently affected by stormwater
Near-shore areas affected by stormwater
Routine monthly monitoring across 8 sites accounts for 100% of the bay
The overall water quality in Port Phillip Bay for 2012 - 13 was ‘Very Good’ to ‘Good’.
Central Bay and two southern near shore sites (Popes Eye and Dromana) achieved ‘Very Good’ water quality. Similarly, near-shore areas at Carrum (Patterson River), Long Reef and Corio Bay scored ‘Good’ water quality. Hobsons Bay and Newport were scored ‘Fair’.
Typically, water quality in the Bay is impacted by storm water inflow following heavy rainfalls in the river catchments of the Bay. This can increase the incidence of algal blooms. Thanks largely to dry conditions, there was only one algal bloom noted in the 2012-13 reporting period.
The Report Card's water quality index is based on monthly sampling which can mean short-lived environmental and weather events that can impact water quality are not always captured. This section highlights events for the 2012-13 reporting period.
A short-lived and confined bloom of the tropical algae Lyngbya occurred at Mothers Beach in Mornington, which caused some concern to bathers but was identified as a non-toxic species. This happened during a period of low catchment inflows.
During the period 2000 to 2013 the Bay's condition has been mainly influenced by significant climate variations: from record-breaking drought in 2000-09 to summer deluges in 2010-12; with a return in 2012-13 to more average conditions. Water quality at monitoring sites closer to the catchments’ inflows such as Newport, Hobsons Bay, Patterson River and Long Reef revealed greater sensitivity to the influence of these climatic shifts, and better water quality conditions during years of low water inflow.
A comparison of water quality's current condition to that in the earlier drought years (peaking through 2006-09) indicates that increased catchment inflows in 2010-12 have increased the amount of nutrients and sediment in the Bay along with a corresponding increase in algal blooms at this time.
The salinity index is a good measure of climate extremes and highlights the poorer results during drought conditions when salinity levels are increased and during heavy rain periods when salinity levels drop too low.
The ‘Actions’ section below outlines projects and initiatives that will contribute toward addressing the issues outlined above.
Driven by the key water quality issues identified for the region, major projects were implemented to improve water quality in the Bay and included the following initiatives.
In addition to the initiatives set out in the A Cleaner Yarra River and Port Phillip Bay - A Plan of Action, a range of key initiatives are being undertaken by government and the community that aim to raise awareness and improve water quality for 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.