A scientist says the parched Murray-Darling has started to die, turning into acid capable of burning human flesh.
A leaked scientific report to governments has warned parts of the river system, particularly the lower lakes, are on their last legs.
Mike Young from the University of Adelaide says parts of the Murray-Darling Basin are becoming acidic as underwater soils became exposed to the sun.
"If you put your hands in it you get burnt.
"This is sulfuric acid.
"Once you get to there, then there's no turning back. Those systems are now dead forever."
Professor Young has joined environmental groups and political parties today, calling for governments to dramatically speed up efforts to save the Murray-Darling.
A report by the Natural Resource Management Board of the South Australian Murray-Darling Basin has set an October deadline on action to return water to the rivers.
Federal and state water ministers aren't due to meet until November, sparking criticism they are moving too slowly on the crisis.
But federal Water Minister Penny Wong says governments are ready to take action, and she is actively looking at ways to tackle the problems outlined in the report.
"I have asked for urgent advice on what we can do in the short term.
Ms Wong said action in response to the report had not been deferred until November.
"If urgent decisions need to be made by the ministerial council, that can occur out of session," she said.
