A 12-year plan to restore Australia’s largest and most complex river system to a sustainable level cannot be delivered on time.

An independent assessment of the Murray-Darling Basin Plan has shown there is no pathway to deliver it by June 2024.

The plan will also fall about 750 gigalitres short of legislated targets to recover 2750 gigalitres from farming and industry for the environment.

“While we recognise that the Basin Plan has delivered significant outcomes, the authority’s view is that full implementation of the Basin Plan will not be possible by 30 June 2024 under the current settings,” the Murray-Darling Basin Authority said on Tuesday.

“There are many reasons why implementation has been slower and even more challenging than originally anticipated, and why both the Commonwealth and Basin states have found it difficult to meet timeframes and milestones.”

The management of the river system, which runs through four states and sustains dozens of town and cities, was overhauled in 2012 after years of overuse and the devastating millennium drought.

Sustainability has become more pressing in recent years with CSIRO modelling showing climate change could reduce river flows by 30 per cent by 2050.

Some 36 projects were supposed to be complete by next June but the Murray-Darling Basin Authority expects 16 will not meet the deadline.

That position has worsened since the July 2022 update.

Environment Minister Tanya Plibersek says the federal government remains committed to delivering the plan in full but accuses the previous government of waging a “decade-long guerrilla war” against the plan.

“No government can catch up on nine years’ sabotage in just two years,” she said on Tuesday.

“As the independent advice tells us, we have to extend the time frames. That’s the reality of what we inherited.

“The next terrible drought is knocking on the door. El Nino is coming back. Delivering this plan has to be a priority.”

The basin authority said last month water resource plans in Victoria, Queensland, South Australia and the ACT remained on track.

But NSW was lagging after the new Labor government withdrew seven programs from formal assessment.

The water resource plans were meant to be developed by mid-2019 as part of the goal to keep the rivers and environment at sustainable levels.

– AAP