Remember the ’56 flood? How much water flows to the environment in the Barwon Darling system?

Irrigation Murray-Darling Basin Water conservation Conservation Rivers Disasters Murray-Darling Basin New South Wales Bourke Menindee

Controversy is raging around Murray Darling Basin water issues following allegations of large-scale water theft that were aired on Four Corners aired in July 2017. In particular, government and departmental management of the Barwon-Darling river system is under scrutiny.

Defending the management of the Barwon-Darling, current and former NSW Ministers for Water, Niall Blair and Kevin Humphreys have claimed that only 6% of water in the Barwon-Darling is available for production, leaving 94% for the downstream communities, uses and the environment. This claim is deeply flawed as it:

• Appears to be based on flows at Bourke, not Menindee, which are substantially higher.

• Is based on average flows since 1944, of 3,300,000 megalitres (ML). This includes the 1950 and 1956 floods, two years that had flows almost equal to the driest 50 years. Average flows this century average just 1,800,000 ML.

• Ignores that under the Barwon-Darling Water Sharing Plan, producers are allowed to take 300% of a water access licence, in any one year, every year.

In fact, upstream producers can take 41% of the average flows at Menindee1 , based on the average flow this century, leaving just 59% for downstream users and the environment.

Even this is misleading. Discussion of average flows is of only limited use in relation to a river like the Barwon-Darling, one of the most variable in the world. Each year needs to be assessed based on the water available. In the driest year, the amount of water theoretically available for producers is 1,652% of flows, while in the wettest years the environment could theoretically receive 99% of flows.

Water management is complex, and arrangements for the equitable sharing of the water resource are not simple. The challenges in implementing the Basin Plan are not assisted by politicians citing figures that are wildly misleading.



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