The Federal Greens have announced their intentions to push for the establishment of a Senate inquiry into the Murray Darling Basin Authority’s draft plan.


"We want an answer to the basic question why did the MDBA choose 2,750 GL when the science says the river system needs at least 4,000 GL," Greens' water spokesperson, Sen. Sarah Hanson-Young, said.


"The basin authority has yet to justify that figure.


"There's $9 billion of taxpayers' money at stake and it will be a national tragedy if it doesn't result in a healthy, working river system now and in the future.


Ms Hanson-Young has urged caution in the signing off of the plan, saying that more must be done to understand the ramifications of the proposed 2,600 GL being allocated for groundwater extraction.