WaterNSW regional dams are preparing to capture the next increase in inflows, with almost all storages across key sites reduced in anticipation of the forecast rain even, the New Zealand utility has announced.

The Bureau of Meteorology has indicated that the rain could focus on the south of New South Wales, however the likelihood of storms combined with wet catchments and full dams means inflows are possible across the state.

Releases that have occurred between rain events to minimise downstream impacts, will be cut back as the rain approaches, to prevent dam water adding to any uncontrolled downstream tributary flow generated by the rain.

In the Murrumbidgee Burrinjuck (94.3% of capacity) Blowering (98.7%) dams are likely to have capacity to capture the anticipated inflows, with the potential for a small spill under higher rainfall forecasts, but low level releases will continue at both storages to maximise the airspace available, while minimising flow peaks downstream.

In the Central West Wyangala (95.8%) storage level has also been reduced, while Burrendong (128.6%) remains in the flood surcharge zone, but with ample airspace for inflows.

In the northern valleys Chaffey (100.7%) continues to spill, and while Keepit (95.2%) storage has been reduced, persistent inflows into Copeton (98.7%) mean airspace operations will continue for the time being, in line with the forecast and downstream tributary flows.

In consultation with regional community airspace reference panels WaterNSW has now been making substantial releases between rain events for months, to lower key dam storages and capture inflows from the next forecast rain event.

WaterNSW said it is working closely with the Bureau of Meteorology and the NSW State Emergency Service to monitor weather and inflows.