The NSW Department of Planning, Industry and Environment (DPIE) released its June water allocation statement, which shows an increase of 1.9 per cent, a total allocation of 90.5 per cent for the current water year.

All other categories in the Upper and Lower Namoi Regulated River Water Source remain unchanged, with full allocations.

During May, between 25 to 50mm of rainfall fell across the catchment, which is considered below average to average.

The updated levels for Split Rock Dam show it is currently 29.3 per cent full, while Keepit Dam sits at 67 per cent full.

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The Bureau of Meteorology's seasonal outlook for winter indicates that rainfall is likely to be above average across the catchment.

"Both daytime and overnight temperatures are also likely to be above average for winter," the statement read.

Critical requirements for Manilla and Barraba townships are secure for the next 24 months and beyond, based on assumed minimum future inflows to Split Rock Dam.

Drought stages for both Upper and Lower Namoi rivers remain at the minimum level - stage 1 - which reflects normal river operation.