Figures showing how much water SA should get in Murray River ‘changed without explanation’

“RUBBERY” water figures that show billions of litres difference in what South Australia should get have been changed without explanation, The Australia Institute says.

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“RUBBERY” water figures showing billions of litres difference in what South Australia should get from Murray River flows have been changed without explanation, The Australia Institute says.

But the Murray-Darling Basin Authority says different models were explored before deciding on one that was best for SA.

In a report to be released today, the Institute says initial reports showed SA would miss out on 20GL of water if changes upstream went ahead. The reported figure then dwindled to 4GL.

Senior water researcher Maryanne Slattery said the numbers were “altered several times” with no supporting modelling.

“The Senate should disallow the Northern Basin Review until transparent analysis is presented around the impacts to SA and the Lower Darling,” she said.

The number is critical because it is the amount of water SA will lose if legislation to let Queensland and NSW use an extra 70GL goes ahead.

The Federal Government, farmers and irrigators want the 70GL and say the impact on SA will be tiny because it is only 4GL. The Institute says if the number is bigger it makes a crucial difference.

The NBR legislation is already in place, but today a vote to overturn it is set to happen in federal Parliament.

SA Greens Senator Sarah Hanson-Young has spearheaded the disallowance motion, and the Greens will likely be able to block it with the help of Labor and SA Best (federal).

State Water Minister Ian Hunter said the Authority updated and firmed up its estimates and that the final advice is that the average reduction will be about 4GL a year.

A MDBA spokesman said the authority undertook detailed analysis including the development of multiple scenarios to test alternative forms of water recovery on hydrological flows across the northern Basin.

“The MDBA did not adjust down any scenario modelled and any suggestion otherwise is misleading,” he said.