The Murray-Darling is so starved of water that it may not be possible to save South Australia's parched Coorong wetlands and lower lakes, says a Senate committee report.
The drought, climate change and overallocation to farmers higher up the river meant that not enough was available to allow sufficient flows, said the committee's majority report, endorsed by Labor senators and released late yesterday.
But a dissenting minority report produced by the committee argued that lakes Albert and Alexandrina could be saved if less water was allocated to irrigators in NSW and Victoria.
The minority report, written by Greens senators with the South Australian independent Nick Xenophon, said keeping back 60 gigalitres from irrigators over the next year would stop the lakes drying out and becoming acidic.
The majority report said the extra water was not available.
The report examined flooding the lakes with seawater in an attempt to keep their ecosystems on life support.
It said that solution may "become necessary", subject to an investigation into the environmental effects.
The possibility of using seawater in the lakes was rejected in the minority committee report.
A Greens senator, Rachel Siewert, said that the problem could only be tackled by permanently reducing water use along the length of the river.
"We can no longer simply pray for rain - we must plan for drought," Ms Siewert said.
Water Minister, Senator Penny Wong, said the inquiry had shown how difficult the situation is across the Murray-Darling Basin, including around the Murray River’s mouth.
"For too long, we have overdrawn the scarce water supplies of the Murray-Darling Basin, and with years of drought and the onset of climate change, the Basin’s rivers and wetlands are in serious trouble," Senator Wong said.
"The evidence presented to the inquiry indicated there is very little fresh water available right now for either the Lower Lakes or for the numerous other icon sites throughout the Basin.
"Even if some fresh water were immediately available from the northern Basin, around 70-80pc of it would be lost in transmission before it could reach the Lakes."