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19 WGCMA – The flow down on estuaries
THE FLOW DOWN ON ESTUARIES...
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West Gippsland’s rivers begin in the mountain headwaters and wind their way to the sea. The areas where the saltwater rises to meet the fresh rivers and creeks are known as estuaries and that’s where you will find West Gippsland Catchment Management Authority’s Coastal Waterways Officer Callum Edwards on most days.
“Put simply, an estuary is a body of water that has both fresh and salt waters and is the interface between the rivers and the ocean,” says Callum who started work at West Gippsland Catchment Management Authority (CMA) in 2021.
Within these dynamic systems lives a wide range of plants and animals – with those adapted to fresh water living in the upper reaches and the more salt tolerant species closer to the river mouth. In between these two zones, you find plants and animals adapted to both fresh and saline conditions. “That’s what makes estuaries so cool - they are so varied.”
Most estuaries within the West Gippsland CMA region are tidal - meaning they are open to the sea. Waterways such as Powlett River near Wonthaggi and Merriman Creek near Seaspray open and close intermittently, operating as tidal systems when they are open and are no longer tidal when the mouth is closed. Intermittently closed estuaries naturally close over during periods of low river inflow and high wave heights which transport sand across the mouth. When the estuary can no longer get rid of that sand, due to the low flow of water, sand builds up until the river mouth is completely closed over. On the flip side, when there is enough rain or water coming over the ocean side, the water will eventually break open the sand barrier.
“Sometimes stakeholders request artificial opening of estuaries, mainly to reduce flooding risks,” explains Callum.
“West Gippsland CMA plays a role in managing intermittently closed estuaries and regulates artificial openings. We keep an eye on what the river mouth is doing – whether it is open or closed and respond to any risks that arise from that. There is a lot of work and planning that goes into any opening events.”
The team also works closely with landholders, partners and community to care for these special parts of rivers through working with Traditional Owners, stock exclusion, fencing and revegetation works in estuaries across the region. Controlling the weed, spartina, is also a key focus in Corner, Anderson and Shallow Inlets and their estuaries. “Spartina is a particularly large threat because it covers and takes away the intertidal areas that birds and animals need to feed.”
Image by Darryl Whittaker | Powlett River
Image by Darryl Whittaker | Powlett River
THE FLOW DOWN ON ESTUARIES...
All estuaries are highly significant with many recognised nationally and internationally for their role as habitat for wildlife, notably migratory birds, their high cultural values and for providing recreation and nature-based activities for communities and visitors.
The Powlett River estuary flows southwest from the Strzelecki Ranges near Korumburra and enters Bass Strait between Kilcunda and Wonthaggi. It is a Nationally Important Wetland due to its extensive saltmarsh and wetland communities and heritage values. It is also a priority waterway for the West Gippsland Region as it is a significant part of Victoria’s environment with value to the agricultural sector, private landholders, recreational users, Traditional Owners and the community.
This year, West Gippsland CMA will begin a project to work collaboratively with landholders and partners to develop a plan that will reduce risks such as the effects of pest plants and animals and the effects of climate change on the river system – including the Powlett estuary.
“We will also continue our monitoring and works across other estuaries in the region including Wreck Creek in Inverloch and Bourne Creek near Kilcunda. Further east in Gippsland, estuaries include Merriman Creek which flows east from the Strzelecki Hills and out to sea near the township of Seaspray.”
Image by John Morgan | Merriman Creek Mouth
“I love my job - estuaries have such cultural, environmental and social benefits, and I also really enjoy going kayaking in them,” reflects Callum.
And, along with contributing to major projects, such as at the Powlett, Callum will continue to visit the estuaries of West Gippsland, checking on their overall health and going with the flow...
Follow the story and keep up to date on projects www.wgcma.vic.gov.au
Image by John Morgan | Merriman Creek Mouth
Image by John Morgan | Merriman Creek Mouth
