A big flush of fresh water
The Goulburn River is about to get a big dose of fresh water as part of the Goulburn Broken Catchment Management Authority’s program for environmental watering.
Depending on natural conditions, including rainfall, the CMA could be applying up to 60 Gl of water.
The extra flow is designed to provide plants on the banks of the lower Goulburn River a well-needed late summer drink and encourage golden perch to migrate from the Murray River to the Goulburn.
Goulburn Broken CMA environmental water manager Simon Casanelia said an environmental water ‘‘fresh’’ would be delivered along the Goulburn River below the Goulburn Weir from late February and through March.
‘‘The annual monitoring that we’ve been conducting shows that using environmental water to ‘top up’ the water that is being delivered to irrigators and other users at this time of the year has helped bank-stabilising plants establish along the lower Goulburn,’’ Mr Casanelia said.
‘‘And, because of this vegetation, we saw far less bank slumping and erosion during the natural flooding we experienced late last year than we did during 2010 to 2012.’’
Water for the increased flow is due to be released from Goulburn Weir from February 26, with the peak of about 4600 Ml/day reaching McCoy’s Bridge by March 9.
The flow will be well below minor flood level. In the event of heavy rain, the timing and size of the environmental flow could change.
The water will come from an Inter-Valley transfer and from Commonwealth and Victorian environmental water.
If the water from the transfer is low, about 60 Gl of environmental water could be used, or if the water available from the transfer is high, then only 14 Gl may be required.
The CMA said these estimates were assuming no rainfall and no inflows from tributaries such as the Broken River, so they were at the highest possible range of water required to be released.
The environmental water will improve water quality and provide food and shelter for water bugs and native fish.
‘‘During the hot, dry weather it’s important to have refuge pools for aquatic animals,’’ Mr Casanelia said.
‘‘Improved water quality will also help crayfish, shrimps, water bugs and native fish continue to recover after the blackwater event earlier this year.
‘‘We’re keen too to see if the higher flows in the Goulburn River at this time of the year attract native fish, particularly golden perch, to move here from the Murray.’’
In past years, environmental water delivered in spring has triggered golden perch spawning in the Goulburn River.
‘‘While we’ve found lots of eggs in the Goulburn, only low numbers of young fish have been reported,’’ Mr Casanelia said.
‘‘The reason for this is unclear, although it seems highly likely that the eggs and juvenile fish move downstream into the Murray. We hope the higher flows in the Goulburn at this time of the year will attract more young perch back into the Goulburn.’’
As part of the monitoring program funded by the Commonwealth Environmental Water Office, fish ecologists from the Arthur Rylah Institute will use acoustic tracking to determine if fish move into the Goulburn from the Murray in response to the fresh. For more information, visit www.gbcma.vic.gov.au
Refreshed . . . The Goulburn will get a fresh flush of water soon.
Helping hand . . . Golden perch could benefit from the extra flow planned.