The basin states – Queensland, New South Wales, Victoria and South Australia – as well as the federal government, are due to meet on Tuesday in Brisbane amid threats from the NSW Nationals that it will walk away from the plan unless major changes are made.

“We simply can no longer stand by the Murray-Darling Basin plan in its current form, the plan needs to work for us, not against us,” NSW Nationals’ leader John Barilaro warned last week.

“NSW is being crippled by the worst drought on record and our future is at risk. The plan should be flexible, adaptive and needs to produce good environmental outcomes for this state.”

NSW has already flagged that it will be asking to be relieved of its remaining contributions towards the environmental water target – it has committed to saving a further 450GL – while Victoria is balking at meeting its commitments as well.

There have also been calls from various ministers to end environmental flows during the drought and to instead allocate more water for agriculture. In particular is unhappiness from NSW at the amount of water stored in the lower lakes in South Australia. That will be fiercely resisted by SA.

And with record low inflows into the Darling from its tributaries, there will be questions asked about how Queensland (and NSW) have managed floodplain harvesting and the growth of on-farm storages, which are blamed for the fact that what little rain that’s fallen in the last two years has failed to reach the river.

Meanwhile, the Australian Competition and Consumer Commission is investigating allegations of profiteering by companies that invest in water. Under the plan water has become a tradable commodity. In a drought, when water is scarce, the price has, unsurprisingly, gone up.

It adds up to an explosive cocktail of grievances about the way the Murray-Darling Basin plan operates.

But before anyone rips up the plan, it may also be a case of being careful what you wish for.

Walking away from the plan, even if it is flawed, could create worse problems, as it could trigger a free for all on water use.

“The basin plan is a long-term reform that remains a once in a lifetime opportunity to restore and protect the health of this great river system,” MDBA chief executive, Phillip Glyde warned this week.

It’s had the enduring support of all basin governments and this bipartisan commitment is more important than ever to deliver for communities from the top of the system to the bottom.”

But despite the pleas of the MDBA, Tuesday’s meeting could well be a turning point, with numerous potential flash points.

Politics rules OK

The Nationals in NSW have been the loudest critics of the plan, fuelled in part by the political heat they are feeling from the Shooters Fishers and Farmers and from One Nation, particularly in the Riverina.

The irrigators in the Riverina have got the ear of recently elected Shooters MP, Helen Dalton, who is being advised by Deb Buller, an irrigator and advocate for NSW Rice Growers and a former president of Murrumbidgee Food and Fibre.

One Nation’s Malcolm Roberts has also been conducting a “listening tour” of the region and is promoting a simplistic view that environmental water should be given back to farmers. NSW One Nation MP Mark Latham has also jumped on the bandwagon.

NSW is also the state that has the most left to do under the plan.

NSW still has to deliver up 450GL for environmental flows, much of which is planned to be achieved through efficiency projects, known as the sustainable diversion limit (SDL) projects. These aim to deliver equivalent environmental outcomes as water buybacks by using water more efficiently.

NSW and Victoria plan to present a report to Tuesday’s meeting that criticises the program and explains why they cannot deliver on commitments. (In Victoria’s case it’s about removing constraints that prevent environmental water being used efficiently).

They can expect strong pushback from the federal government and the MDBA which warned the projects are progressing far too slowly to meet the 2024 deadline.

Lately Barilaro has upped the rhetoric, threatening to pull out of the plan if NSW is not given concessions. NSW water minister, Melinda Pavey (also a National), appears to have a more nuanced view and appears to appreciate the possible consequences of blowing it up.

The Nationals are also under pressure from their own tribe: major cotton growers in the north west who face tougher limits on their extractions under future NSW water sharing plans that must be drawn up by early 2020.

The old plans have been criticised because they allowed irrigators to take water during low flow events. These rules have been blamed by scientists for the prolonged periods of no flows in the lower Darling which contributed to the mass fish deaths at Menindee and have left graziers and towns in the region on their knees.