WATER levels in Lake Keepit and Split Rock Dam could fall to as a low as 2 per cent and 5 per cent by the end of the year.
WaterNSW says the catchments are already at “critical levels” and could worsen “without significant inflows”.
On Saturday, WaterNSW began a transfer of almost 35 gigalitres of water downstream from Split Rock Dam to Lake Keepit to maintain supply to the Lower Namoi.
In a statement, WaterNSW said “in the Lower Namoi it is possible that some stock and domestic customers and irrigators will not receive any more water while conditions persist, and remaining customers will be severely restricted in what water can be extracted.”
WaterNSW executive manager of systems operations, Adrian Langdon, said “hard decisions” would be made in the coming months to ensure the remaining water was distributed fairly.
“WaterNSW has been working closely with water users in the Upper and Lower Namoi to manage supply,” Mr Langdon said.
“Our management plan and the co-operation from customers has enabled us to extend supply under arguably the state’s most severe drought conditions.”
Without further inflows, releases from Lake Keepit will likely cease in December, leaving water users reliant on groundwater supplies where available.
“With government, and in collaboration with the critical water advisory panel, we are implementing strategies to extend vital supply as long as possible and sharing the hardship as fairly as we can in line with water sharing plan rules until the drought breaks,” Mr Langdon said.