The trial
The trial seeks to protect environmental water from the northern to the southern Murray–Darling Basin by protecting environmental water recovered in the northern Basin when it arrives in the Menindee Lakes.
The trial means environmental flows can be protected from Queensland all the way to the Murray Mouth. Outside of the trial, environmental inflows to Menindee Lakes are reshared equally to NSW and Victorian entitlement holders when the lakes are a shared resource, and entirely to NSW when the lakes fall below 480 GL and until they rise above 640 GL.
The environmental inflow is additional water that would not have reached Menindee Lakes without the active management rules introduced in December 2020. To date, water users in the Murray and Lower Darling water sources have benefited from this additional water. Under the trial, the additional water is recognised and protected for the environment.
The trial is testing water accounting arrangements to protect environmental water into Menindee Lakes, the key gap in protection from the northern to southern Basin, while ensuring no impact to other entitlement holders.
In November 2025, the Basin Officials Committee approved the trial arrangements until 30 June 2028. The committee facilitates cooperation and coordination between the Commonwealth, the Basin states and the Murray–Darling Basin Authority in funding works and managing the Basin water and other natural resources.
How the trial will work in practice
Trial arrangements
The Murray–Darling Basin Authority have developed trial arrangements with input from Basin states, building on the information gathered during the 2024 initial trial release. These arrangements focus on operational issues and bulk scale water management to avoid impacts on state-sharing arrangements. The trial arrangements do not cover the retail mechanisms which Victoria and NSW are separately developing.
Tracking environmental inflows and release
The MDBA will track inflows of active environmental water from the Barwon-Darling, the evaporation loss applied to stored active environmental water in Menindee Lakes and any releases or spills of active environmental water. The Water Liaison Working Group, a Basin Officials Committee subcommittee, will agree to the volumes available for release for environmental purposes and will manage potential risks, including risks to water quality or state sharing arrangements.
Coordination
The trial requires NSW and Victoria to release their respective shares of the environmental inflows for environmental purposes.
When Menindee Lakes is a shared resource, MDBA will co-ordinate the implementation of the trial with oversight from the Water Liaison Working Group with input from the relevant agencies in each jurisdiction.
When Menindee Lakes is a NSW-only resource, clause 95 of the Murray–Darling Basin Agreement allows NSW to use the stored water as it requires. The drought management principles defined in the NSW Murray and Lower Darling Incident Response Guide (IRG) will be used to guide any release of environmental water from the lakes.
Initial trial release 2024
Report
An initial trial release occurred in 2024-25. The NSW report from this first trial details the successful improvement in water quality as the protected environmental water moved through the lower Darling-Baaka River to the Murray River.