Fish deaths in Menindee

Responding to mass fish deaths at Menindee

NSW Government agencies, along with the Australian Government and local partners have been undertaking water quality monitoring since early Spring 2022 to review dissolved oxygen conditions across NSW, identify potential risks to ecological communities, implement mitigating measures to evolving blackwater occurrences and respond to the mass fish death event in the Darling-Baaka River that occurred in March 2023.

The immediate causes of the fish deaths are believed to be attributed to hypoxia, caused by a combination of hypoxic blackwater, a high biovolume of algae, and a significant biomass of fish, as a result breeding following three wet years. Hypoxic blackwater is a naturally occurring phenomenon which causes extremely low dissolved oxygen levels. The Office of the Chief Scientist and Engineer also found that mass fish deaths are symptomatic of degradation of the broader river ecosystem over many years.

Taking action to address the Office of the Chief Scientist and Engineer report

The NSW Government has released its full response PDF, 14271.64 KB to the Office of the Chief Scientist and Engineer report into mass fish deaths on the Darling-Baaka River near Menindee in March 2023. This follows from the first formal response PDF, 5698.64 KB that was released in November 2023.

The NSW Government has accepted the recommendations made in the report and is committed to rehabilitating the Darling–Baaka River, committing $25 million in new funding over 4 years for the actions outlined in this full response, including:

• More than $6.5 million to trial state-of-the-art temporary fish passage technologies such as a new retrofitted tube design which allows fish to pass over weirs and river barriers to escape poor water quality events and reduce the chance of future mass fish deaths.
• $6 million to complete a detailed business case for permanent fish passage in the Lower Darling and Menindee Lakes system which could restore 518 km of connectivity between the northern and southern Murray–Darling Basin.
• Nearly $4.5 million to design and implement a Menindee-specific mass fish death event response sub plan to clearly explain triggers, agency and community responsibilities in the event of an incident.
• Nearly $3 million to install new real-time multi-parameter water quality monitoring buoys and data loggers, undertake a scientific study on the impacts of mass fish deaths on Weir 32 water quality and develop new hydrodynamic modelling to improve knowledge and understanding of the river.
• $1 million towards ongoing maintenance and operation of real-time water quality sensors and other water quality monitoring in the weir pool to allow decision makers to respond rapidly to changing conditions.
• Over $1.7 million to set up a new governance model which will coordinate integrated management of land use, water and natural resources to improve ecological outcomes.
• $600,000 for strategic planning for on-ground rehabilitation works to improve water quality, ecological and cultural outcomes, such as new fending, trees, erosion control methods that reduce sediment entering the river and more Aboriginal access to riparian areas.
• $720,000 to provide on-the-ground resources in Menindee to support the program.
• More than $1 million to develop a new water quality monitoring framework to make our data easier to navigate and identify knowledge gaps.

The full response also provides a progress update on the initial actions outlined in the November 2023 response.

• Read the full government response PDF, 14271.64 KB
• Read the initial response (November 2023) PDF, 5698.64 KB