Scientists are urging major dam projects in NSW and Queensland be abandoned, warning of significant environmental and agricultural consequences.
ANU Professor Jamie Pittock, a member of the Wentworth group of concerned scientists, said he Wyangala dam proposal in NSW is expected to cost more than $2 billion dollars, with alternatives not properly explored.
"There are many alternatives to increase water security for all ... it can't be full to supply water and empty to catch a flood," Professor Pittock told a conference on Wednesday.
He called on the NSW government to abandon Wyangala expansion plans, as well as Dungowan Dam near Tamworth, and Queensland to abandon the Hells Gates project.
"The proposal to raise Wyangala Dam is an exemplar of why these dam-building projects are crazy," he told AAP.
"It was proposed without a business case."