The NSW Minns Labor Government must immediately release the valley-by-valley modelling and departmental advice underpinning its decision to lift the Menindee Lakes trigger from 195GL to 250GL of active storage.
Under the new 250GL trigger, irrigators will be prevented from harvesting water until Menindee Lakes reach a substantially higher storage level than under the previous 195GL setting.
Through a co-signed omnibus amendment to multiple water sharing plans, the Minister for Water and the Minister for Environment have altered the rules governing access to overland flows in the Gwydir, Macquarie, Cudgegong, and Border Rivers systems.
This change will inevitably reduce the number of days or weeks in which water can be lawfully captured in affected valleys.
Shadow Minister for Water, Steph Cooke, said the government's claim that the change does not affect allocations, and therefore does not trigger compensation provisions under the Water Management Act, demands a detailed public explanation.
"The Water Management Act establishes a clear statutory framework around allocation reliability and compensation where reliability is reduced beyond prescribed thresholds," Ms Cooke said.
"If increasing the Menindee trigger reduces the frequency or duration of access to overland flows, the government must demonstrate how that does not translate into reduced long-term allocation reliability."
Ms Cooke said if the government is confident the decision has no material impact on reliability, it should release the underlying evidence.
"That means publishing the valley-by-valley modelling, the projected change in access days, the long-term yield analysis and any assessment undertaken against the compensation provisions of the Act," Ms Cooke said.
"This is not a minor administrative adjustment; it is a structural rule change affecting multiple Northern Basin systems."
Ms Cooke also raised concerns about how the 250GL trigger has been calculated, including whether it is based solely on active storage and how dead storage within the Menindee Lakes system has been treated.
"These technical settings matter because small changes in modelling assumptions can have significant real-world consequences for Basin communities."
"Water policy must be transparent, evidence-based, and provide long-term certainty for farmers and regional communities. Our farmers make multi-year cropping and capital-investment decisions based on predictable water conditions.
"Protecting communities and the environment is essential, but those objectives must be pursued transparently, with full disclosure of impacts and proper consultation."
Ms Cooke is calling on the Ministers for Water and Environment to:
1. Release all modelling, assumptions and departmental advice underpinning the 250GL active storage decision.
2. Publish valley-by-valley analysis of projected impacts on access frequency and long-term allocation reliability.
3. Confirm whether the decision has been formally assessed against the compensation provisions of the Water Management Act.
4. Detail the consultation undertaken prior to the amendment.
"If this decision stacks up, the Government should have no hesitation in releasing the facts," Ms Cooke said.
"Regional water users deserve certainty, transparency and accountability."
