A BRIEFING about the Murray-Darling Basin Authority's plan has confirmed fears about a lack of water being returned to the system.
The South Australian government is vowing not to resile from threatened High Court action.
River campaigner Di Bell, from the River, Lakes and Coorong Action Group, who was in Canberra for yesterday's briefing, said the mood was "unhappy".
The long-awaited plan will be released by the MDBA on November 28, nearly 18 months after its proposed release date.
Professor Bell said yesterday's briefing was told the plan would recommend only 2800 gigalitres of water be returned to the system.
"We've always said to show us the science on how the river's health could be restored with 2800GL," Professor Bell said.
But South Australian Premier Jay Weatherill has maintained that unless 4000GL was returned under the plan his Labor government would begin legal action.
Professor Bell said the MDBA had conducted scientific modelling only within 400GL of the 2800GL.
"They have not modelled for the 4000GL - that is the one that needs to be modelled to see if it can meet all the key environmental demands to ensure the long-term health of the basin, especially at the end of the system in South Australia," she said.
"We want an independent scientific review to ensure that the 2800GL can achieve the goals."
Mr Weatherill yesterday warned he would not back away from this threatened High Court challenge if a revised plan did not return 4000GL of water to the system.
"Until we have seen the report and our experts have reviewed it, we won't be speculating about the MDBA's conclusions," Mr Weatherill said.
"However, I do not resile from anything I have said and will not rule out any steps necessary to protect our rights."
But Water Minister Tony Burke last night urged calm.
"Every affected premier has a lot at stake in this reform," Mr Burke said.
"It's completely appropriate for Premier Weatherill to be vigorously pursuing the interests of South Australia.
"This is a once-in-a-generation opportunity to get the reform right and the consultation period will be a critical part of that process."
Wilderness Society spokesman Peter Owen said 2800GL "would not even flush all the salt that gets dumped in the system in South Australia or keep the mouth of the Murray River open".
"The federal government needs to grow a backbone and stand up to the lobby groups in Canberra opposed to more water being returned," Mr Owen said.
The Australian Conservation Foundation called on Mr Burke to set up an independent scientific panel and yesterday released suggested terms of reference.
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