South Australia Premier Jay Weatherill has urged Victorians to back his campaign to return more water to the Murray-Darling Basin.
Visiting Melbourne to drum up support, Mr Weatherill said he had "given up" on Victorian Premier Ted Baillieu and Water Minister Peter Walsh.
He told The Age it was crucial to appeal to people in Victoria and New South Wales who wanted a good outcome for the river system.
Mr Weatherill said the best available science finds 3500 to 4000 billion litres of water had to be returned to the Murray-Darling to meet its environmental needs. The current version of the proposed basin reform plan recommends 2750 billion litres, and Mr Weatherill has threatened a High Court challenge if it is not substantially changed.
The Victorian government is calling for a target of 2100 billion litres, saying its modelling shows similar environment gains can be achieved in conjunction with investment in works and measures.
"I think we have given up on Ted and Peter, we are focusing on the federal decision makers," Mr Weatherill told The Age in an interview.
"They have not indicated any willingness to grapple with the central issues, they are talking about putting less water in the river."
Mr Weatherill rejected the "trimmed down analysis" from irrigator groups that said less water would equal less jobs in basin communities as simplistic and wrong.
"By investing in water technologies, by adding value to food and fibre, we can have thriving basin communities," he said.
Mr Walsh said Mr Weatherill's campaign would not be popular in Victoria as he was effectively proposing the closure of irrigation industries in Northern Victoria, which would have a major hit on gross state product.
State governments are expected to receive the latest iteration of the basin plan in early August.