By Nick Bryant
BBC News, Sydney
Australia is facing is worst drought in a century
Parts of Australia's vital Murray-Darling river basin will be beyond the point of recovery unless they receive water by October.
That is the verdict of an expert panel whose leaked report warns of dire consequences like the loss of wetlands, vegetation and some fish species.
The Green party has hit out at the government for deferring consideration of the report until November.
Australia remains in the grip of its worst drought in a century.
The hope is for heavy winter rainfalls.
'Decades to recover'
The Murray-Darling is Australia's most important river system. Crossing much of southeast Australia, it irrigates much of the country's food bowl.
So when scientists warn that parts of the basin will be "beyond the point of recovery" unless they receive water by October, it becomes a matter of serious national concern.
In stark language, the leaked report raises the spectre of an ecological disaster in the lower reaches of the Murray River - wetlands drying out, vegetation lost, some fishes species forced into extinction. Some might already have died out.
Parts of the ecosystem could take decades to recover - parts might be irreversibly lost.
Ministers were presented with the report in May, but decided to defer consideration of its implications until November - a month after the scientists' deadline.
According to the Green Party, that is an act of environmental vandalism.
It is demanding to know why the government intends to wait seven months until it addresses the report, when its authors have warned of a calamity in six months' time.