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Port Phillip Bay

Bay and Catchments

Water quality index
Land Use




Water Quality Index

Very Good




Very Poor

Citizen Science Data

Citizen Science monitoring site

See the ‘Port Phillip Bay’ page for a detailed description of the Bay.

Report Card for July 2012 – June 2013

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.

Area Score

Very Good
Near-natural high quality waterways

Entrance, Dromana and central bay


Meets Victorian water quality standards

Near-shore areas infrequently affected by stormwater


Some evidence of stress

Near-shore areas affected by stormwater


Under considerable stress


Very Poor
Under severe stress

Routine monthly monitoring across 8 sites accounts for 100% of the bay

What does this mean?

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.

Bar chart showing WQI and indicator scores for Port Phillip Bay Bar chart showing WQI and indicator scores for Port Phillip Bay

PortPhillipBayEPA.jpg Litter on the beach, Port Phillip Bay. Source: EPA Victoria

PortPhillipBayEPAVictoria.png Healthy seagrass meadows are an indicator of good water quality in Port Phillip Bay. Source: Parks Victoria

Changes over time

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.

Plot of WQI history for Port Phillip Bay Plot of WQI history for Port Phillip Bay


What's happened?

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.

  • EPA partnered with Frankston City Council and Mornington Peninsula Shire to proactively identify and address high-risk pollution sources that may impact water quality and contribute to algal blooms at beaches.
  • A partnership between the Victorian Government and Life Saving Victoria in 2013/14 resulted in water quality forecasting signage being rolled out at 10 bayside beaches (Seaford, Half Moon Bay, Beaumaris, Sandridge, Altona, St Kilda, Elwood, Mentone, Mordialloc and Frankston) as part of the Victorian Government's A Cleaner Yarra River and Port Phillip Bay - A Plan of Action.
  • EPA's reporting to the community about water quality has been expanded to now include: alerts about pollution, fish deaths and algal blooms. These are now reported via a new website: Cleaner Yarra and Bay.
  • The Melbourne Water 10,000 Raingardens Program was launched in 2008 and has since worked with homes, schools and businesses across the Port Phillip and Westernport region to build more than 10,000 raingardens. Raingardens help filter pollutants from stormwater and to slow down the strength of its flow which prevents erosion and habitat destruction.
  • Project funding as part of the Living Victoria Fund which focuses on reducing polluted water and stormwater runoff and includes major benefits for Port Phillip Bay.
  • Provided almost $140,000 in grants supporting community action to improve water quality in the Yarra River and Port Phillip Bay.
  • Announced round three of the Communities for Nature Grants Program, which focuses on projects to improve water quality in the Yarra River and Port Phillip Bay.
  • Instigated EPA's summer litter campaign ‘A cleaner Victoria is in your hands', which encourages people to report litter thrown from vehicles via EPA's online reporting tool or mobile apps. It is specifically aimed at creating awareness about the impact of litter on our natural assets such as the Bay and its catchments.
  • Achieved court-ordered funding from Mobil Refining Australia Pty Ltd following an environmental prosecution by EPA to pay $250,000 to Port Phillip EcoCentre for various community awareness campaigns regarding pollution impacts on marine life in the Bay. See Baykeepers video documentary.
  • Beach litter associated with stormwater inflows is also being addressed directly by councils and government through a range of litter management programs. Community stakeholders around the Bay have continued in 2012-13 to be active in beach cleaning programs such as Beach Patrol to routinely collect and monitor litter in Port Phillip Bay.

What's planned

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:

Compare to other Catchments

The following figures show a comparison of scores for each identified water quality indicator in the catchments and Port Phillip Bay.

Diagram of nutrient score history for catchments and bay

Diagram of oxygen score history for catchments and bay

Diagram of water clarity score history for catchments and bay

Diagram of salinity score history for catchments and bay

Diagram of algae score history for catchments and bay

Diagram of metals score history for catchments and bay

Program Partners

Department of Environment and Primary Industries Environmental Protection Agency Melbourne Water