Murray-Darling Basin Authority report echoes farmers’ fears irrigators are causing the river to run dry, not the weather

This article is more than 2 years old

This article is more than 2 years old

Most of the Murray-Darling system has been placed on red or amber alert for outbreaks of blue-green algae as a new report finds that the increasing incidence in low-flow or no-flow events is due to irrigators extracting more water from the system.

A draft report by the Murray-Darling Basin Authority, dated November, which is being circulated for comment with the federal and NSW governments, confirms what farmers in the lower Darling and in the stretch of river between Walgett and Brewarrina have been saying for years: that upstream extractions for irrigation of cotton are prolonging low-flow events downstream.



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Grazier Rob McBride, whose sheep and cattle station, Tolarno, is in the lower section of the Darling, near Pooncarie, said the report “just showed the corruption in the system”.

He has been trying to get the raw data from the MDBA for years to have it analysed, but has been refused access to the detailed flow data.

But McBride has seen the impact in the Darling which flows past his property.

Since the expansion of irrigation around Bourke, he says there have been 15 events during which the river has stopped flowing entirely. The only time historically the river had stopped flowing was in 1946-47, he says.

In 2015-16 the river stopped flowing for eight months.

“It was just soul-destroying. Staff had to go 200 kms for a shower. You watch your stock die. The sheep don’t have lambs.”

The McBrides have seen signs of blue-green algae in the Darling at their property for several weeks this summer. The river serves as the source of water for grazing and for residential use, though in recent years they have installed bores to deal with the increasingly long dry river events.

There is now a red alert for the deadly algae at Pooncarie, near Tolarno.

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McBride wants a royal commission into the management of the Murray-Darling and has written to the prime minister, Malcolm Turnbull.

The MDBA report appears to confirm his concerns that the reason behind the river running dry is over-extraction, not weather.

It looked at flow behaviour in the Barwon-Darling system from 1990 to 2017 and analysed more than 2,000 individual flow events, focussing on the measurements between gauges during dry spells.



“The results presented here suggest a change to the hydrologic behaviour of the Barwon-Darling has occurred since the turn of the millennium (particularly in the midsections of the system),” the report said.

It found that that periods of low and no flow had increased significantly in length for gauges downstream of Bourke post-2000.



“Flow events recorded at Walgett (and Geera) at the upstream end or midsections of the river were found to have disappeared completely with no corresponding flow recorded 50 kms downstream at Brewarrina,” the report said.

The scientists at the MDBA said “river extraction” appeared to be the leading contributor to the “heavy attenuation of these events.”



Since 2000, there has been significant development of the cotton industry around Walgett and Bourke.

The NSW government also introduced a new water-sharing plan for the Barwon-Darling in 2009, which downstream graziers say has led to massive over-extraction from the river.

In July last year, ABC’s Four Corners program aired allegations of water theft in the Barwon-Darling and pumping during the release of environmental flows, which was permitted under NSW’s administration of the system.

So far no charges have been laid.

The MDBA said the report was undergoing quality assurance processes prior to publication, with a formal release on its website likely soon.

Last month the Senate disallowed a proposal backed by the MDBA to cut the environmental water recovery target by 70 gigalitres. But the debate over changes to the $13bn Murray-Darling Basin plan is likely to continue, with Labor signalling it was willing to negotiate with the government over the changes. The issue is expected to surface again in the Senate in May.



