A draft report says the Murray-Darling Basin Authority (MDBA) could be split into two separate institutions.

The Productivity Commission has released a draft report on the effectiveness of the MDBA, which also covers future challenges for Basin governments.

“Governments have agreed to invest in a package of complex, interdependent supply projects,” said the Productivity Commission's commissioner for water, Jane Doolan.

“Planning has fallen behind already, and in some cases the timetable to deliver some of them is unrealistic.”

The report says Basin governments should seek independent opinions on more credible timelines, and ensure the promised water recovery is still achieved if they fail.

The Productivity Commission estimates not completing projects on time could cost up to $480 million.

“More water would have to be recovered from irrigators, it'll cost taxpayers more money and will damage community confidence in the Plan,” Ms Doolan said.

It also questioned the role of the MDBA itself.

The authority is meant to provide advice and support to Government in implementing the Basin Plan, but also acts as a regulator.

Ms Doolan said the roles are conflicted.

“On one hand they need to be the Government's trusted advisor, helping them work through those complex supply measures and meet their objectives,” the commissioner said.

“But on the other hand, as of June 2019, they'll also be the Basin Plan regulator — judging whether those supply project meet their targets or not.”

The report proposes splitting its functions into two separate bodies, but Australian Conservation Foundation campaigns director Dr Paul Sinclair says that would be pragmatic.

“Reading between the lines of this report, what it makes really clear is that there's been a failure of governance in the Murray-Darling Basin, and a lack of transparency around implementation of water recovery that needs to be fixed,” he said.

“We agree with the recommendation for the MDBA to be broken into two because they cannot deliver their advice role and their regulatory role at the same time.

“That's something we've been deeply concerned about for some time.”

National Irrigators’ Council CEO Steve Whan says the report provides a wake-up call.

“It would be hard to argue with the draft report’s statement that the next five years of basin plan implementation will be ‘challenging’,” Mr Whan said.

“However, in contrast to some of the doom and gloom scenarios raised by opponents of the Basin Plan, the PC report tells us that the plan is fundamentally on track and is making; ‘significant practical progress’.

“The wake-up calls come for all Basin Governments and communities and reflect concerns NIC has frequently expressed on the ability to meet certain tasks within the time frames remaining.

“On the positive side, NIC welcomes the focus on the need for maximum flexibility and consultation in implementing the 36 Sustainable Diversion Limit Adjustment Measures projects.

“We also cautiously welcome the recommendations relating to the 450GL of so called ‘up-water’ which is to be obtained via efficiency projects that come with either positive or at least no negative socio-economic impacts.”