Macquarie valley drought plan on to next phase as dam falls

Macquarie valley drought plan on to next phase as dam falls

13 May 2019

WaterNSW has begun investigations into a range of measures to address the impacts of drought in the Macquarie Valley and secure water supply for critical needs.

Under current conditions regulated river flows beyond Warren will cease from early spring 2019 to conserve water for town water supply and high security users.

Temporary modifications to Warren weir and the regulators at Duck and Crooked Creeks will be required to raise the weir pools to permit water to be supplied to Nyngan and Cobar.

These changes will be temporary and reversible to enable flows from rainfall events to be directed to downstream customers when possible.

The preliminary Warren weir works commenced last Thursday (9 May) and come as Burrendong Dam reaches 6.2% of storage capacity and record drought conditions in the valley cut inflows to unprecedented lows.

Even with a further water transfer from Windamere Dam (33.2%) via the Cudgegong River, and pumping water from below the dam outlets, Burrendong could run dry before June 2020 without significant rainfall.

A meeting of key stakeholders on the new Macquarie River Operations Stakeholder Consultation Committee will occur in Narromine on 16 May, following an update to Dubbo Regional Council on 14 May.

Current outlook:

  • Already no allocation for general security in 2018-19 and 30% of irrigation carryover and environmental water is withheld pending further inflows. No general security irrigation allocation will be available in 2019-20 if conditions remain dry.
  • Without inflows high security customers including the Cobar mines, Dubbo abattoirs, permanent plantings, Western Plains Zoo and Dubbo golf club are at risk of having reduced access to water after July. WaterNSW is working with these customers to identify alternative water sources.
  • Regular river flows beyond Warren may also cease in early spring if no inflows are received.
  • Landholders’ access to water for stock and domestic use will depend on dam inflows and tributary flows and are likely to be only intermittent from July, especially downstream of Warren.
  • Burrendong dam is likely to be unable to release water by gravity by March 2020 at which point WaterNSW would be required to pump the remaining water from the storage to continue to supply water to towns downstream. Even with all these measures the system could cease to flow by June 2020 if there are no inflows to the system.

March Inflows from tributaries between Burrendong Dam and Warren have been directed into the Lower Bogan River, Marra Creek and Lower Macquarie River for critical human needs.

WaterNSW executive manager for system operations, Adrian Langdon said the Macquarie valley is in the grip of one of the worst droughts on record.

“With ongoing low inflows and storage levels continuing to decrease, the Macquarie Valley is a priority catchment for drought response and WaterNSW is working hard to extend the supply of water to regional towns for as long as possible.

“We are looking at a range of options including temporary modifications to the Warren weir and our regulators at Duck Creek and Crooked Creek.

“These temporary works would help us to minimise any system losses and extend existing limited water supplies for Warren, Nyngan and Cobar,” he said.

WaterNSW is working closely with state and federal government agencies to ensure the options meet the critical water needs of regional towns and that the social, environmental and economic impacts are being monitored and effectively managed.

“Across the state, WaterNSW’s management of the storages and river system has delayed the worst effects of the drought,” Mr Langdon explained.

“If not for the efficient storage of the 2016 flood inflows in our northern dams, many of these river systems would have ceased to flow a long time ago.”

Read more on WaterNSW drought operations.

Media Contact – Tony Webber 0428 613 478.

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