Lower Darling pushed into drought three years early because of sheer volume of water extraction by just a few licence holders

This article is more than 1 year old

This article is more than 1 year old

A handful of big irrigators are responsible for 86% of water extracted from the Barwon-Darling river system, pushing the lower Darling into drought three years early, an expert report has found.

The NSW Natural Resources Commission released the report by the Australian Rivers Institute professor Fran Sheldon on Monday night, after it received criticism for the claim that extraction of water by cotton growers had pushed the river system into hydrological drought three years early.

Sheldon found that of the 158 licence holders in the Barwon-Darling, just 10 control 86% of the water extracted and four control 75%.

These four include the Harris family, which faces prosecution for extracting during low flows, and the publicly listed Webster Ltd.

Barwon-Darling river ecosystem on path to collapse, review warns Read more

The report found that the combination of the 2012 water-sharing rules and changes in climate have increased the warming and drying trend in the basin and that these factors were combining to pose serious risks to the Barwon-Darling system.

“The most significant risk is the failure of water management approaches to meet the ‘maintenance’ flows for the Barwon-Darling, resulting in a loss of ecosystem resilience,” the report found.

“The volume of water extracted under the A Class Licence rules [the highest level of water rights] has increased since 2012 due to changes in access arrangements made in 2012, with a marked increase in the volume between 2014- 2017,” the report found.

“Extraction patterns that occur in the low flows and base-flows are most severe when they intersect with larger climate phenomena, such as the onset of El Niño conditions,” Sheldon said.

The 2012 water-sharing rules have been highly contentious. Then water minister Katrina Hodgkinson made changes to rules after they had been put on public exhibition, following lobbying by the cotton industry.

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This included changes to when irrigators could pump during low flow events and changes to the rules that allowed them to take up to 300% of their entitlement in one year. This has resulted in enormous volumes being extracted upstream during the drought.

Sheldon concluded that these two rules had pushed the Lower Darling, below Bourke’s cotton farms, into hydrological drought three years early.

Sheldon said she had used multiple lines of evidence to conclude that “these extractions from the base flow band could have essentially pushed the Barwon-Darling system below Bourke into very low flow conditions three years earlier than the river upstream.”

The Independent Commission against Corruption is believed to have looked at events around the finalising of the plan as part of its investigation into allegations of water theft by irrigators raised by Four Corners. It is unclear whether Icac plans to hold a public inquiry.

The rules are now being reviewed and the Natural Resources Commission has recommended urgent changes to save the Barwon-Darling from ecological collapse.

Sheldon said new rules were needed to protect flows throughout the year by restricting pumping levels for A-class licences.

The federal government committed in April to buy back A-class licences in the Barwon Darling, after an independent report into this year’s fish kills recommended a major refinement of basin management.

A change in the rules would affect the value of the licences, as Class A licences would no longer be able extract water during very low flows.

The Australian Financial Review has reported that several cotton growers are offering to sell B-class licences, but these would yield water savings only when the river is flowing. The major issue in the Barwon Darling is the A-class licences and the generous rules that allow the holders to access water during low flows.