The commission has called for more state and federal government accountability in its first interim review of the plan in five years.

“Very little progress has been made on water recovery, or on supply and constraints-easing measures,” associate commissioner Chris Guest said.

“The plan is central to securing a healthy working Basin. Basin governments need to be more transparent and accountable for delivering the plan.”

The Murray-Darling plan outlines the amount of water that can be taken from the basin each year, while allowing for an environmentally sustainable amount to remain.

The original proposal aimed to return 450 gigalitres of additional water to the environment by June 2024, but new laws would push back the deadline to December 2027.

Environment Minister Tanya Plibersek in August unveiled a new plan with all basin states except for Victoria after it was revealed the old agreement was not on track to meet its water recovery targets.

A Senate committee will examine legislation to amend the Basin Plan in coming days and report back by November 8.

The commission’s 254-page report looked at how the actions of governments are tracking against the time-frames set out in the plan.

It found progress had stalled because of weak governance in a changing water market and the costs of achieving enhanced environmental outcomes through water recovery had risen substantially.

The federal government needs to renew its efforts to save the plan, the report found. The interim report said “resetting the balance” of the basin has slowed since 2018 and will not be completed by the original deadline of July 2024.

It found the federal government needs to renew its efforts to save the plan, including not funding unviable schemes like the Menindee Lakes project.

The federal water minister should report annually to parliament on the progress, feasibility and cost of projects and decide on their future, Commissioner Joanne Chong said.

While the proposed legislation will provide more time and allow new supply measures and voluntary water purchases, a significant water recovery shortfall is still likely, the commission found.

The legislation did not address all the factors that have contributed to the lack of progress across the range of projects.

“Escalating costs, across both water recovery and the supply projects, also means resetting the balance will cost taxpayers considerably more than originally expected,” the report said.

It concluded the Australian government needed to be more accountable “on the supply, constraints easing and toolkits projects during the next phase of implementation.”

The commission also recommends strengthening the roles of Aboriginal and Torres Strait Islander people in the Basin plan and noted minimal progress on the Aboriginal Water Entitlements Program.

The commissioners have called on the federal government to begin a renewed program of water recovery including staged voluntary water entitlement purchases.

They also want consideration given to a new government-owned corporate entity to undertake water recovery and implement some supply projects.

Previous warnings about the plan had not led to change, they noted.

-with AAP