Update: 30 January 2025
The Gellibrand River estuary was artificially opened to the sea on Friday 24 January by Parks Victoria to prevent flooding and blocking of a critical bushfire evacuation route on the Great Ocean Road over the long weekend and extreme fire danger rating day on Monday 27 January.
Corangamite Catchment Management Authority (CMA) worked closely with Parks Victoria to advise on potential risks to environmental values.
Water quality testing conducted by both an independent contractor and EstuaryWatch volunteers in the Gellibrand River just prior to the opening indicated water quality was poor, with low dissolved oxygen levels throughout the water column. A small fish death event of approximately 40 fish had already been reported to EPA on 21 January prior to the artificial estuary opening.
“Given the warm, dry conditions over the long weekend, we expected water quality to continue to deteriorate in the estuary even if the estuary was not artificially opened. These conditions could have also led to further fish deaths over time,” a Corangamite CMA spokesperson said.
“Approximately 50 fish deaths were observed by Parks Victoria and reported to the EPA over the long weekend.
“On the evening of Wednesday January 29, monitoring was undertaken by an independent contractor via boat. The contractor observed more than a hundred and possibly up to a few hundred dead fish. They are mostly localised to one area downstream of Old Coach Road on the eastern shoreline, in thick reeds making it difficult to determine exact numbers. The additional fish deaths will be reported to the EPA.”
Current research indicates that wherever possible it is best to leave estuaries to operate naturally to maintain the health of waterways, vegetation and wildlife.
“However, in this instance, maintaining the safe passage of vehicles along the Great Ocean Road and potentially other roads along the estuary was critical so that visitors and residents could safely evacuate in the event of a bushfire,” the spokesperson said.
The artificial estuary opening lowered the water level in the Gellibrand River estuary and allowed safe passage of vehicles over the long weekend.
“The estuary is currently still open, we’ve seen some good tidal activity, and dissolved oxygen levels in the water have also improved. We will continue to assess monitoring data and undertake further field investigations if required.”
Corangamite CMA is working with agencies and the community to reduce the need to artificially open estuaries over time and to investigate options to improve flows in the Gellibrand River. Corangamite CMA continues to work with landholders and community groups to fence and revegetate the Gellibrand River and communicate the importance of improving waterway health to improve water quality.
As the sea level continues to rise over the coming decades, more land and assets will become inundated more frequently and it will become increasingly difficult to safely open estuary entrances out to the sea. Also, modelling suggests that the effectiveness of artificial estuary openings in the future may decline. This is why we must urgently continue our work to understand and communicate the future impacts of climate change and sea level rise for coastal communities.
Original article published 24 January 2025:
Corangamite CMA today released a statement saying that the Gellibrand River estuary may be artificially opened to the sea within the next 24 hours.
“To prevent flooding and potential damage along the Great Ocean Road in Princetown, Parks Victoria plans to artificially open the Gellibrand River estuary within the next 24 hours if conditions allow for a safe and effective opening," a Corangamite CMA spokesperson said.
The Gellibrand River estuary is currently closed to the sea, however water levels are rising slowly, and there is an imminent risk the Great Ocean Road will become inundated before the estuary naturally opens.
“Multiple agencies are working together to monitor the situation and keep the Great Ocean Road accessible in case of an emergency such as a bushfire," the spokesperson said.
This weekend will see an increase in traffic and visitors along the Great Ocean Road with Monday being a public holiday. Weather is forecast to be hot and there is an extreme fire danger rating on Monday in the southwest region.
Maintaining the safe passage of vehicles along the Great Ocean Road and potentially other roads alongside the estuary is critical during the fire danger period so visitors and residents can safely evacuate in the event of a bushfire.
Water quality in the Gellibrand River estuary is currently very poor and there have already been reports of fish deaths.
“Corangamite CMA is working closely with Parks Victoria to advise on any potential risks to environmental values."
An opening under current conditions has a very high risk of adverse impacts to some fish species and birds. However, under the current warm and dry conditions, it is expected that water quality will continue to deteriorate in the estuary even if the estuary is not artificially opened. These conditions can lead to further fish deaths over time.
Fish deaths in Victoria should be reported to the EPA via their hotline 1300 372 842 or website.
64 Dennis Street, Colac VIC 3250
PO Box 159, Colac, VIC 3250
Hours: 8:30am – 5pm, Monday to Friday
T: 1800 002 262
E: info@ccma.vic.gov.au
BARWON WATER OFFICES
Hours: 8:30am – 5pm, Monday to Friday
All mail must be sent via our Colac office
PO Box 159, Colac, VIC 3250
T: 1800 002 262
E: info@ccma.vic.gov.au