THE Murray Darling Basin Authority has identified NSW water regulations as a decisive factor for a drop off in low flow events making it downstream from Bourke since 2000.
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A draft MDBA hydrological investigation – leaked this week and expected to be released in full in the coming days - indicated that even taking into account the Millennium drought and climate change, human intervention had “significantly” impacted the passage of small flows through irrigation country in the Barwon Darling.
But water theft was not a concern, the MDBA said.
The MDBA studied hydrological history for the past 18 years as well as the catchment's environmental needs.
Modelling the impact of extraction on river flow is complex and the MDBA was unable to conclude if altered pumping regulations, or perhaps changes to use of carryover entitlements was the major factor reducing low flows.
The leaked report period covers the Millennium drought, and starts 12 years before NSW’s 2012 controversial Barwon Darling Water Sharing Plan started.
Flow gauge data showed dry conditions – particularly between Walgett and Brewarrina – had persisted for longer than the area was affected by the drought.
Word of its draft findings has sparked allegations that agency failed to provide the information at a crucial time.
NSW government reportedly had access to the draft document before last month’s Senate disallowance motion on a proposal to downgrade Northern Basin recovery targets by 70 gigalitres.
Speaking to the report, MDBA chief executive Phillip Glyde said his agency identified state water regulations as the main drain on low flows, not irrigator theft.
“There are no allegations of illegality, but we do know that low flows are being pumped out” said MDBA chief executive Phillip Glyde.
“Drought and climate change don’t explain it. It’s evident the extraction rules in place are part of the decline.”
Mr Glyde denied the timing of the report’s release was politically motivated and said two initiatives are under way to improve low flows down the Darling.
Changes contained in the MDBA’s Northern Basin amendment, which NSW has committed to, were designed to address the low flow issues in the Barwon Darling, which are also known as ‘toolkit measures’.
The Basin Plan also requires states to develop new water resource regulations, to replace their existing water sharing plans, which must be signed off by the MDBA by mid-2019.
NSW regional Water Minister Niall Blair has been contacted for comment.
