CPS Enviro technical report to The Commonwealth Environmental Water Office
About the document
In 2016–17, approximately 120 gigalitres of water for the environment was delivered to the Lower Darling River and almost 100 gigalitres was delivered down the Great Darling Anabranch. The purpose of these deliveries was to promote population recovery from the near catastrophic drying conditions that occurred throughout 2015–16 by:
- supporting breeding opportunities for Murray cod in the Lower Darling River
- facilitating the dispersal of golden perch from the Menindee Lakes nursery grounds into the Lower Darling River, Great Darling Anabranch and Murray River populations.
The design of the hydrograph delivered in the Lower Darling River was designed based on scientific advice and was adjusted in response to real-time monitoring information in conjunction with stakeholders.
Key findings of this study included:
- Delivery of water for the environment supported a strong spawning response (when considered to other spawning events across the Murray–Darling Basin), with 885 Murray cod larvae collected.
- Spawning responses from both golden and silver perch recorded in response to elements of the optimised hydrograph.
- The Lower Darling population census in winter 2017 showed ‘young-of-year’ Murray cod were present at each monitored Lower Darling River site and that these represented a significant proportion (~10 per cent) of the population.
- The Menindee Lakes is a major golden perch nursery and performs an important hydrological function within the Murray–Darling Basin or golden perch recruitment.
This report presents the scientific foundations of the successful environmental flow design and the monitoring program that was undertaken to evaluate the fish responses to its delivery in the Lower Darling River. It provides an evaluation of the environmental flows’ success in meeting its objectives and provides recommendations for best practice river management to support fish populations in the LDR, applicable to rivers throughout the MDB, into the future.