Burrendong Dam's last gasp in the worst drought on record will help keep water flowing down the Macquarie River until at least May 2020.
Tenders have been called for the installation of a network of pumps to retrieve water sitting below the dam's outlet valve. Water will be moved to the valve for release into the river.
Burrendong Dam will need to be at zero per cent capacity when the pumping begins.
Accessing the remnant storage is step two in a plan that aims to buy time for Dubbo Regional Council to extend its groundwater resources and find alternative water sources with $30 million from the state government.
Step one is the "likely" transfer of water from Windamere Dam to Burrendong Dam late this year.
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Burrendong Dam is expected to run dry in November without significant inflows.
Pumping of water out of remnant storage would be a first for the 52-year-old dam which holds 1188 gigalitres (GL) of water when full.
In August the state government announced $7.7 million for the works. At the time of the announcement Member for the Dubbo electorate Dugald Saunders said the project would "extend water availability in the Macquarie River to Dubbo for an extra four months".
"A survey by WaterNSW has confirmed around 21 GL of water can be accessed by pumping out the remnant storage, and planning is already under way to make that happen, including an upgrade of the power supply," he said.
Australian media outlets jumped on WaterNSW modelling at the weekend, declaring Dubbo with "34,000 residents" would run dry by November.
WaterNSW released a statement revealing its projects to extend the availability of water from Burrendong Dam to communities in the Macquarie Valley were "well advanced".
"WaterNSW forecasts indicate that without these projects, and with no inflows into the dam, surface water supply to communities in the Macquarie Valley would be insecure by November 2019," a spokesman said.
"However, works under way such as temporarily raising Warren weir, and preparing to pump the remnant storage left in Burrendong Dam, pushes that worst-case scenario into 2020."
The spokesman reported that the weir project had been completed and tenders called this month to install the pumping network.
"With the addition of water transferred from Windamere Dam via the Cudgegong River, even with zero inflows into Burrendong there is sufficient dam water supply for towns and critical human needs until at least May 2020," he said.