Darling River running dry due to over extraction not climate change: ANU

The Australian National University study found the principal cause of river flow decline on the Darling River is not due to a drying climate but rather ongoing and "large-scale" management failures.

ANU professor and lead author Quentin Grafton said the analyses separated the various reasons for the reduced flows of the Darling, and found more than half of the decline during the past four decades was due to "factors other than higher temperatures or less rainfall".

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"Our principal finding is that much of the river flow decline on the Darling River over the past 40 years has not been because of climate change but almost certainly a result of increased water extractions," Prof Grafton said.

"Further evidence in support of this conclusion can be drawn from the large, unmetered, and possibly increasing, water extractions associated with floodplain harvesting in the order of hundreds of billions of litres per year in the northern Murray-Darling Basin, some of which may be illegal."

The Darling has had high rates of extraction for decades, driven by water allocation and provided by 15 main channel weirs and more than a thousand small weirs along its 1000km length.

During the last drought, the river ran dry in many places. UNSW professor and study co-author Richard Kingsford said the findings show that although climate change was clearly happening it couldn't be used as an "excuse" for the negative impacts poor water management was having on the Darling River.

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"Climate change shouldn't be used as a get out of jail card or treated as an act of God to excuse bad decision-making and poor planning decisions," Prof Kingsford said.

"We have no excuses for claiming that climate change is primarily or solely responsible for declining flows on Darling River when it's not."

Prof Grafton said the study supported the need for reduced extraction and water reallocation to ensure minimum river flows for downstream communities and critically important environments.

"This task is urgent if we, as a nation, are to achieve what we agreed to with the basin plan a decade ago; healthy sustainable working rivers," he said.