Described as a "winter fresh" the flows are designed to help maintain the health and functioning of the river.
Goulburn Broken Catchment Management Authority environmental water manager Simon Casanelia said the flow was designed to deposit seed-rich sediment on the banks, which helped stabilising plants to grow, move more sediment from the river bed to maintain habitat for water bugs and native fish and increase the habitat available for native fish, platypus and water bugs by inundating connected anabranches and wetlands.
The flow is managed by Goulburn-Murray Water and determined by the Goulburn Broken CMA in consultation with the Victorian and Commonwealth environmental water holders.
The ‘winter fresh’ is planned to peak late July at approximately 9500 Ml/day (a river height of 5.6 m at Shepparton) before slowly dropping back to approximately 1000 Ml/day (a river height of 2.7 m at Shepparton) in early August. This is well below the minor flood level (9.5 m at Shepparton).
“The fresh aims to utilise natural tributary inflows as much as possible (instead of releases predominately from Lake Eildon) as they are rich in sediment and seed,” Mr Casanelia said.
“If there is heavy rain, environmental flow releases may be reduced or stopped.”
Releases of water for the environment are designed to mimic the natural flows that would have occurred before the river was dammed and regulated, although they are often much smaller than the flows that would have occurred naturally.
The response of vegetation to the water delivery, as well as bank condition, fish and bugs, will be measured as part of the Commonwealth Environmental Water Office’s Monitoring Evaluation and Research (Flow-MER) project.Mr Casanelia said timing of the environmental flows took into consideration delivery orders by irrigators and other water users and feedback from the community via the Goulburn Broken CMA’s environmental water advisory groups.Providing water for the environment is only one way of protecting and improving rivers and wetlands. Fencing and revegetation, erosion control, pest control, returning logs to rivers (re-snagging) for fish and bug habitat, and installation of fishways to allow fish to pass through dams and weirs also help.
To check flows in the Lower Goulburn, view the hydrograph on Goulburn Broken CMA’s website (updated weekly): http://fchmccoys.hydronet.com/
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