Translucent flow payback
Native fish, platypus and other aquatic species are currently seeing the benefits of increased flows in the Severn River downstream of Pindari Dam.
Water that would ordinarily be released as ‘translucency flows’ under the NSW Border Rivers Water Sharing Plan has instead been held in storage so repairs could be made to a release valve on the dam.
WaterNSW have made these flows available as a ‘payback account’ for use up until the end of June 2021.
A total of 10.8 gigalitres of water has been accrued in the payback account. Under normal circumstances, this water would have already passed through Pindari Dam to contribute to environmental outcomes, making up a portion of what is also known as planned environmental water.
Senior Wetlands and Rivers Conservation Officer Matthew Miles said a working group had been established to develop a strategy for use of the water. The working group is made up of representatives from Department of Planning Industry and Environment – Environment Energy and Science, NSW Department if Primary Industries – Fisheries, Department of Planning Industry and Environment – Water and the Commonwealth Environmental Water Office (CEWO).
‘A portion of the payback water is currently being used to contribute to base flows of approximately 50 megalitres per day when dam releases are required of less than 50 megalitres per day in the Severn River,’ Mr Miles said.
‘These base flows are aimed at maintaining water quality in refuge pools downstream of Pindari over the warmer months and improving conditions for larval and juvenile Murray cod and eel-tailed catfish.
‘These base flows may also provide spawning opportunities for generalist species such as Australian smelt which are an important food source for larger species including Murray cod.
‘The payback volume may be used to supplement natural events to achieve environmental outcomes as described in the Long-Term Watering Plan for the Border Rivers and the ecological objectives of the Water Sharing Plan for the NSW Border Rivers Regulated River Water Source.
‘Should conditions become dry through summer and water quality issues become apparent the base flow delivery rate maybe increased to address water quality issues.
‘Any remaining volume in autumn will be used to deliver a small fresh event to increase productivity and provide ideal conditions for native fish to improve conditions leading into winter,’ he said.
Developing options for the release of the translucency payback account, has considered a range of factors including cold water pollution, potential for a blackwater event with high flows and overall volume in storage.
The management of this translucency payback account will not have any impact on existing irrigation orders, nor will it impact the opportunity to order water throughout the rest of the water year. The volume ‘paid back’ should have been released as it flowed into Pindari, therefore making no contribution to the volume of water in storage for water users.