The South Australian Government has labelled a series of New South Wales Murray-Darling demands as "irrational", and has called for a "mature" discussion over the basin plan.

Key points: The NSW Government has threatened to walk away from the basin plan

The NSW Government has threatened to walk away from the basin plan SA Water Minister David Speirs has hit back, describing the NSW stance as "posturing"

SA Water Minister David Speirs has hit back, describing the NSW stance as "posturing" Federal Water Minister David Littleproud says all basin states need to agree on the plan

The NSW Government yesterday threatened to walk away from the agreement if it was not exempted from contributing to an additional 450 gigalitres of environmental flows.

It also wants barrages on South Australia's lower lakes lifted to allow seawater back into Lake Alexandrina.

SA Water Minister David Speirs has lashed out at demands made by the Berejiklian Government and warned against "threats and posturing" over the basin.

He said removing the barrages was "nonsense" and it would not deliver water savings.

"The South Australian Government will not be agreeing to the New South Wales National Party's latest irrational list of demands," Mr Speirs said.

"People who rely on the Murray-Darling Basin are tired of the threats and posturing that do nothing for our environment, irrigators and communities.

"Mature, balanced leadership from all basin jurisdictions is what is needed now more than ever to deliver what has been agreed."

The Berejiklian Government has threatened to walk away from the basin plan. ( ABC News: Ian Cutmore )

Last month, the SA Government committed to helping drought-ravaged NSW farmers by cranking up Adelaide's little-used desalination plant.

The decision means 40 gigalitres of water can be returned to the river and used for the upstream drought relief.

However, there has long been tension between SA and NSW over the basin plan, with the Berejiklian Government yesterday claiming it needed to have more flexibility in times of drought.

"We just don't have any more water to give," NSW Deputy Premier John Barilaro said.

"We have a commitment of 450 gigalitres of water to go back into the system which we can't achieve, we want that taken off the table and out of the plan."

The NSW Government has also demanded all water resource plans, which were required as part of the agreement, to be put on hold until after the drought is broken.

Removing barrages 'won't deliver water savings'

The conflict comes as a convoy of farmers travelled to Canberra on Monday urging the Federal Government to 'Can the Plan'.

'Can the Plan' protesters gathered outside Parliament House in Canberra. ( ABC Rural: Kath Sullivan )

Protesters said on Tuesday that the convoy had prompted Federal Water Minister David Littleproud to seek a review of state-based water sharing arrangements.

Mr Speirs said South Australia would seek further detail about the proposed review, but would only be interested in changes to improve long-term outcomes for all jurisdictions.

"We will not accept any less water flowing down the river and talk of removing the barrages at the lower lakes is nonsense that won't even deliver any water savings," he said.

Mr Speirs has slammed a list of demands made by the NSW Government. ( ABC News )

"We've advocated for the creation of the inspector-general position and we support all efforts to improve compliance and delivery of the Murray-Darling Basin Plan."

Mr Littleproud yesterday responded to the NSW Government's demands by saying the Federal Government did not have the power to make those changes and that all basin states needed to agree on the plan.

"While everybody points their guns at us, they've got to understand that my job in many respects is to herd the cats and the real power comes in us having cooperation," he said.

'We would have just a cesspool'

Lesley Fischer is a retired farmer from the lower lakes region in South Australia and said removing the barrages would further impact a region that had already suffered.

"We're sitting here, we watch what happens all the way up the river," she told ABC Radio Adelaide.

"It would ruin everything, it would ruin everything in the lakes.

"We would have just a cesspool out there because there won't be water coming in all the time from the ocean."

Ms Fischer said if something was not done to help lower lakes locals, more people would be forced to leave the region.

"The fisherman are going to be going, in the Millennium Drought the dairies left — we've got three left here just around the lakes," she said.

"Those people upstream have just got no idea.

"We've lost a lot, we're really fighting back and we deserve a go like every other town or community along the system."