South Australian Premier Jay Weatherill has called on the prime minister to recommit to the Murray rescue plan or face a reinvigorated public campaign to save the river.
Mr Weatherill says any such campaign would target Malcolm Turnbull directly as he also called on the PM to put his deputy Barnaby Joyce "back in his box" after he questioned how the deal can be delivered.
The premier accused the federal government of "ratting" on the agreement, including a promise to deliver another 450 gigalitres in environmental flows.
"We're going to stand up and fight for the river," Mr Weatherill told reporters on Monday.
"The prime minister has a clear ultimatum. Recommit to this agreement or we will start up our fight for the Murray campaign and it will be directed at him."
The agreement to help save the Murray was secured partly on the back of a major social media and public campaign by South Australia, which drew strong popular support.
It also included a threat to take the matter to the High Court.
Mr Weatherill's strong stand comes after his water minister Ian Hunter clashed with Mr Joyce and other state water ministers last week, with Mr Hunter storming out of an informal meeting after delivering a foul-mouthed tirade.
Mr Hunter was rebuked by the premier and apologised for his language but Mr Weatherill said the sentiments behind his outburst were entirely appropriate.
After Mr Hunter's outburst, Mr Joyce said he was only stating the "bleeding obvious" when he told South Australia the plan for extra flows down the Murray could not be delivered under the current arrangements which called for there to be no social or economic harm to river communities.
Mr Joyce said he was open to suggestions but Mr Weatherill described the commonwealth's current attitude to the plan as a fundamental breach of trust.
"We've been dudded for 100 years. We had an agreement which essentially secured our future and we've got some bloke who thinks he can tear it up without a consequence," the premier said.
"Well there is a consequence."