Below average rainfall and corresponding extremely low inflows have beset dams across many regions of NSW, with Burrendong sitting at 20 per cent of capacity and Windamere 39 per cent.

Inflows to Burrendong Dam since August 2017 total about 38 gigalitres (GL) - only 26 per cent of the previous record low inflow of about 143GL for the 15 months ending in October - confirming that the Macquarie system has entered a new drought-of-record.

Initially, the transfer was scheduled to occur in November, but a government decision to temporarily quarantine 30 per cent of carryover water and plans to introduce more stringent conditions on water ordering by customers have reduced demand forecasts for the two dams.

Windamere and Burrendong storages provide water security for customers in the Macquarie Valley.

Transfers occur from Windamere to Burrendong when the storage levels drop to ensure reliability of supply to all customers.

Executive manager system operation, Adrian Langdon, said in a statement that any transfer must leave at least 70 gigalitres in Windamere and would be reviewed in the event of substantive inflows into Burrendong.

“The water transfer is provided for under the Macquarie-Cudgegong water sharing plan in the event of prolonged dry conditions placing water security in the Macquarie Valley under pressure,” Mr Langdon told Fairfax Media.

“Should rainfall deliver substantial inflows into Burrendong there is every likelihood that the transfer date will be pushed further into the future.

“WaterNSW is talking to water users including Cudgegong Valley Water Security Committee and Midwest Regional Council to ensure they are aware of the timing of the bulk water transfer and what safeguards are in place to ensure water security for Windamere users is provided for,” Mr Langdon said. 

Last month, the NSW Government announced that WaterNSW will conduct a study into construction of a new regulating storage between Narromine and Warren and report its findings to government.

The assessment of a new mid-Macquarie storage site is part of wider investigations into potential options for improving the security, reliability and delivery efficiency of water in the Macquarie Valley.

This includes infrastructure and non-infrastructure measures.

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