Murray-Darling Basin Authority chief executive officer Phillip Glyde said the recommendation came after four years of “extensive research and consultation”.
The proposed reduction will take the Northern Basin’s Sustainable Diversion Limit from 390GL to 320GL, in a bid to reduce economic and social impacts driven by productive water losses in the Dirranbandi and St George regions of Qld as part of the MDB Plan.
A MDBA spokesperson said the amendment would result in a “very small change to the amount of water flowing into the Southern Basin”.
“The changes will affect the Menindee Lakes’ long-term average inflows by 0.3 per cent,” they said. “This also translates to a minuscule 0.05pc change to long-term average flows to SA.
“Our analysis has found it will have no impact on the health of the rivers and day-to-day river operations.”
The SA government has also assured the amendments would have no negative impact on the Southern Basin.
“MDBA CEO Phillip Glyde has said the recommended amendments will not impact on the Southern Basin,” a spokesperson said.
“The state government is not backing down on its insistence on the 450GL for the health of our river – that has not changed with these amendments.”
But Nick Xenophon Team leader Nick Xenophon said SA needed to remain “extra vigilant we don’t get done over down the track”.
“Provided the MDBA’s decision was based on the science, we have to accept that, but making up the shortfall should not come at the expense of SA,” he said.
“There needs to be a renewed effort to ensure that government water-saving projects proceed and are effective and that constraints are dealt with.
“There are also too many examples upstream of open, unlined irrigation channels and dams, which is just incredible in this day in age.”
Local Member for Chaffey Tim Whetstone agreed SA must remain vigilant to ensure the environment and communities remained sustainable.
He said more government works and measures needed to be undertaken “instead of using irrigators’ water to prop up the Basin Plan”.