Index of Estuary Condition

Estuaries are semi-enclosed waterbodies where freshwater from streams and rivers mixes with saltwater from the ocean. Estuaries have unique vegetation, provide important habitat for waterbirds and are nursery grounds for many fish species.

The Department of Energy, Environment and Climate Action (DEECA) developed a condition assessment method for estuaries called the Index of Estuary Condition (IEC). The IEC was applied to estuaries throughout Victoria to document their current condition and establish a baseline for future assessments. This supports guiding the management of Victoria’s estuaries.

Estuarine Index

The IEC focuses on 5 components of estuaries: physical form, hydrology, water quality, flora, and fish. The Arthur Rylah Institute was involved in the fish, flora and water quality themes:

Fish - used as representative of the broader community of estuary animals, as fish respond to environmental, ecological, physical, and hydrological factors and are an important estuary component of broad interest to communities.
Flora - includes the structure of vegetation along shorelines and whether submerged vegetation is predominantly seagrass or macroalgae.
Water quality - includes clarity, which influences the type and extent of submerged vegetation, and chlorophyll-a concentration, which is indicative of primary production that is responsive to nutrient inputs and is important for estuarine health. This component was assessed in partnership with catchment management authorities and citizen scientists to draw on valuable local knowledge of our estuaries.

The first state-wide IEC assessment for Victorian estuaries was delivered in 2021. This project was part of an investment by the Victorian Government funded through the Water and Catchments group to improve the health of waterways and catchments. The IEC plays an important role in improving knowledge about our estuaries and sharing the importance of estuary health, and waterways in general, with the community.

Access the assessment on DEECA's Water and Catchments estuaries page.

For more information on the IEC assessment contact waterway.monitoring@delwp.vic.gov.au (Water and Catchments Group).