Economic rationalists: Productivity Commission backs irrigator water buyouts

The federal Productivity Commission has said irrigator water buyouts are one of most “cost-effective” methods of recovering environmental water.

Relaxing constraints to funnel an extra 450,000 megalitres down the Murray River to get 60,000ML a day across South Australian border is pointless, according to Victorian government modelling.

The Productivity Commission has come out in favour of federal irrigator buyouts to recover Murray-Darling Basin environmental water.

Associate Commissioner Chris Guest said “in the five years since the last commission review, very little progress has been made on water recovery, or on supply and constraints-easing measures”.

“Despite the prospect of more time, a significant water recovery shortfall is likely. The Australian government should commence a renewed program of water recovery, using the most cost‑effective methods, including staged voluntary water entitlement purchases.”

“This should occur alongside a commitment from Basin governments to support communities to adjust, where warranted.”

In releasing its interim report reviewing the Murray–Darling Basin Plan’s implementation the commission has recommended a new arm’s length government-owned corporation would be one option for undertaking water recovery and implementing some supply projects.

The report also finds that further effort should be made to ease river constraints on environmental water delivery.

“Constraints-easing measures are critical to the success of the Basin Plan. Governments should implement them through a dedicated, stand-alone program,” Commissioner Guest said.

But updated river modelling by the Victorian government has shown relaxing constraints to funnel an extra 450,000 megalitres down the Murray River to get 60,000ML a day across the South Australian border is pointless.

“Modelling suggests relaxing constraints will result in no change in the frequency of environmentally desirable higher flow rates in the Murray River at the South Australian border under all relaxed constraints scenarios tested,” according to the latest Hydrological Outcomes report, modelling Goulburn and Murray River flows.

The modelling also showed relaxing constraints to get more water down the Goulburn and Murray rivers, by flooding more than 3000 riverside properties, would also reduce the chances of piggybacking environmental flows on spills from Hume, Dartmouth and Eildon dams.

“The MDBA modelling suggests the impact of relaxing constraints at the South Australian border for the higher flow levels (greater than 60,000ML/day) is minimal and may reduce peak flow events compared to current operations due to the higher use of the environmental water portfolio resulting in reduced spills,” the modelling found.

One of the main goals of the MDBA Plan is to achieve flows of 80,000ML/day for a month, during spring, three times a decade, which would require targeted flows to be co-ordinated across the Murray and its tributaries.

But DEECA’s 31-page Hydrological Outcomes report warns boosting flows during spring would coincide with “peak productive pasture growth, meaning that extended periods of inundation during this time may have significant impacts on the enterprises of affected landowners”.

The 80,000ML target is not far below SA border flows during the 2016 floods, which peaked at 95,000ML/day.

Read the full PC interim report and make a submission at pc.gov.au