Logos of each goal in the EMP, with the nutrients logo highlighted in a different colour.

The Eutrophication Index and Water Quality Index supports the collection of data and information to help inform the Nutrients and Pollutants strategy. The Department of Energy, Environment and Climate Action (DEECA) manages the collation of information and formulation to achieve the eutrophication results. Environment Protection Authority Victoria (EPA) leads the monitoring and reporting of the Water Quality report card.

The Eutrophication Index is a nested, hierarchical index which focuses specifically on the effects of

Phot underwater looking up at a pier or jetty.

Photo Credit: Marcia Riederer

nutrient enrichment by reporting on the status, trends, and condition of key ecosystem components. The Eutrophication Index examines indicators that may contribute to a eutrophication event occurring in Port Phillip Bay.  The indicators selected for analysis include (where available): dissolved inorganic nitrogen, dissolved inorganic phosphorus, total nitrogen, total phosphorous, chlorophyll-a and dissolved oxygen (surface). The analysis of long-term trend data assists in highlighting necessary improvements or abatement measures and supports the prioritisation of management investment.

The Water Quality Index (WQI) is an area-weighted averaged index which provides an annual rating of water quality to understand if Port Phillip Bay is meeting objectives set in the Environment Reference Standards for Victoria. The WQI examines the combination of indicators to calculate an overall water quality index score. Indicators selected for the analysis include (where available): algae (chlorophyll-a), dissolved oxygen, metals, nutrients, salinity, pH and water clarity. The scores are summarised at the catchment and bay scale.

While both indices utilise  similar data (from the EPA) and the same 5 status categories (Very Poor through to Very Good), the water quality and eutrophication indices were designed to highlight different aspects of the health of the Bay. The WQI is an assessment of a wide range of water quality measurements against established environmental standards; whereas the Eutrophication Index focusses on both the direct and indirect effect of nutrients, and the extent to which changes in nutrient concentrations may increase the risk of algal blooms, or eutrophication, in different parts of the Bay.

Updated data for 2022-2023 was available and is presented in the Eutrophication Index for Port Phillip Bay. The 2022-2023 Water Quality Index data analysis is still being prepared and will be made available in mid-2024.

Partner agencies and data contributors:

Melbourne Water logo.

EPA Victoria logo.

Page last updated: 17/04/24