2019
Download
About the document
This monitoring project was commissioned and funded by Commonwealth Environmental Water Office with additional in-kind support from Charles Sturt University and NSW Office of Environment and Heritage. The production of this report and expert advice by Darren Baldwin during the 2019 Murrumbidgee refuge environmental watering action was funded by the Murray-Darling Basin Authority.
In response to severe declining water quality in the lower Murrumbidgee River in January 2019, Commonwealth, NSW and The Living Murray Water (TLM) environmental water was made available to maximise survival of native fish, provide refuge and attempt to improve dissolved oxygen concentrations and water quality. Between 30 January and 9 April 2019, 27,600 ML of environmental water (3,300 ML Commonwealth; 8,200 ML NSW EWA; and 16,100 TLM) was delivered in-channel in the Lower Murrumbidgee River and onto the Lowbidgee floodplain.
In late January, prior to the commencement of this environmental watering action, a fish kill, of several thousand fish consisting of Murray cod, golden perch, silver perch, bony bream and carp, were observed in Redbank Weir on the Murrumbidgee River.
This monitoring report was commissioned to address the following objectives:
- Determine the proximate cause or causes of the fish kill that occurred at Redbank Weir in late January 2019.
- Examine management responses to the fish kill, specifically the use of environmental water, to improve fish habitat and mitigate poor water quality conditions in Redbank Weir and, prevent other fish kills in Maude and Balranald Weir pools.
- Report on monitoring efforts before, during and immediately after the fish kill in order to inform future monitoring programs.
- Make recommendations on potential ways the river can be operated into the future to minimise fish kills.
Thirteen recommendations in relation to monitoring and reporting, river management and knowledge gaps have been made in this report to prevent and/or mitigate against weir pool stratification (the establishment of a thermocline, with warmer, oxygenated water above and cooler, low dissolved oxygen below). These recommendations will help to inform future watering actions and management decisions in the Murrumbidgee catchment and may also be applicable to other catchments in the Murray-Darling Basin.