What is an estuary?
An estuary is the place where freshwater from a river mixes with saltwater from the sea. Estuaries are a great spot to spend time swimming, walking, canoeing or having a picnic.
Importantly, they also act as buffers to protect shorelines from erosion, flooding and provide essential food and habitat for birds, fish and other wildlife.
Estuaries are unique and dynamic environments that include some of the most complex ecosystems on earth – we are so lucky to live near these ecosystems in the Corangamite region.
When should an estuary be opened or closed?
Many of Victoria’s estuaries close from time to time as part of a natural process. This is important for supporting estuary ecosystems, plants and animals. Under some conditions, artificial estuary openings are considered to manage the risk of flooding to built infrastructure and agriculture land.
This Estuary Low Flows Fact sheet has been developed by Victoria’s coastal catchment management authorities, to provide further insight into how estuaries function in low-flow periods.
Who can artificially open an estuary?
Only permit holders can be authorised to artificially open an estuary. Anyone who opens an estuary so without a permit can be fined up to $33,000 and/or imprisoned for up to 10 years under the Land Act 1958, Water Act 1989, Catchment and Land Protection Act 1994, Fisheries Act 1995 and Marine and Coastal Act 2018.
Why are estuaries artificially opened?
Permit holders can request to artificially open an estuary if they deem it necessary. Considerations include inundation of human assets such as properties, roads, bridges, campgrounds and playgrounds.
Will the Corangamite CMA artificially open an estuary?
No. Estuaries are artificially open due to inundation of human assets. The Corangamite CMA do not intervene in natural processes, so do not open or close estuaries.
What is the process behind artificially opening an estuary?
Once the decision has been made to open an estuary, the Corangamite CMA is notified and undertakes a risk-based assessment to inform the permit holder when and how the estuary can be opened. Environmental, social and economic factors are considered.
The permit holder is responsible for conducting water quality testing pre-opening and the physical removal of the sand berm (sand bar) to allow the estuarine water to flow into the ocean.
Acid events in the Anglesea River
In recent years, the condition of the Anglesea River has been the subject of concern, due to the frequency and duration of acid events and several related fish death events. A review conducted by Professor Maher in 2011 concluded that acidic or low pH water in the Anglesea River results from natural processes in the catchment and that rainfall intensity and timing is the key determinant of whether or not an acid flush occurs.
If you notice dead or dying fish, crustaceans or eels contact the Environment Protection Authority on 1300 372 842 in the first instance. The Corangamite CMA, EPA and Surf Coast Shire Council will be in constant liaison during an acid event and will be adhering to the Acid Event Response Plan.
Where can I find more information about the estuaries in our region?
You can find more information about the estuaries in the Corangamite region, such as, studies, reports and estuary management plans in the Publications and Knowledge Base section of the website.
How to monitor your local estuary
Join EstuaryWatch, a community-based citizen science program which monitors the condition of 11 estuaries in the Corangamite region.