New research released today by The Australia Institute shows that estimates of impacts on South Australia from proposed changes to the Murray Darling Basin Plan have been changed multiple times by the Murray Darling Basin Authority (MDBA).
These changes appear to be based more on political convenience than best available science.
“Initial versions of the MDBA’s Northern Basin Review suggested that giving more water to northern users would see flows to South Australia reduce by 20 gigalitres (GL) per year,” said Maryanne Slattery, Senior Water Researcher at The Australia Institute.
“35 GL per year would have been lost from Menindee Lakes, the water supply for Broken Hill NSW. Such a large impact would almost certainly have been rejected by South Australia.
“These numbers were altered several times. Suddenly, South Australia would only lose 4 GL and Menindee Lakes 7 GL.
“No modelling was released to support these changes. When some analysis was finally released, the impact on Menindee was back at 22.5, with no data for South Australia.
Estimates of impacts on flows into Menindee Lakes and SA under Northern Basin Review
“Published later still, another model result saw the numbers back to 7 GL and 4 GL. Despite almost 18 months passing since the Northern Basin Review was published, there has been no disclosure of why most of these changes were made, or presentation of analysis or modelling to support them.
“The reasons for these changes and the working behind them are unclear, but they give the impression that large reductions in water to South Australia have been avoided, without actually making any changes upstream.
“The Senate should disallow the Northern Basin Review until transparent analysis is presented around the impacts to South Australia and the Lower Darling.
“With so many scandals around allegations of water theft, corruption and mismanagement of our greatest river system, the MDBA’s analysis must be fully transparent to restore confidence in the work of the MDBA and the implementation of the Basin Plan,” Ms Slattery said.