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Key Water Blog

NSW Groundwater allocation statement

DPIE bought out the following announcement in relation to groundwater allocations for the 2020-2021 water season. The graph down the bottom shows groundwater sources that could expect reduced allocations on 1 July 2020

NSW Groundwater allocation statement; Water allocation update

The extreme dry conditions experienced for the last two to three years across NSW continued into the beginning of 2020. The rainfall map below shows that, for the six months from August 2019 to the end of January 2020, most of NSW had very much below average rainfall. Some areas recorded the lowest rainfall on record for this time of year. With very little surface water available, there was a heavy reliance on groundwater across all areas of the state.

However, since February 2020 there has been some good rainfall across much of the state. The
second map below shows large areas of the state having received much higher than average
rainfall for the three months to the end of April. This rainfall has alleviated the pumping pressure on
groundwater to finish the irrigation season.
Although soil moisture deficits have been reducing with passing storms and catchments are
beginning to generate an improved runoff response, large inland storages are still very low, with
most less than 20 per cent full. Coastal valleys have fared much better. Overall, the seasonal
rainfall outlooks are providing some optimism for NSW surface water users.

Water sharing plans allow groundwater to be temporarily pumped for some years at higher volumes than the annual limit. This provides some operational flexibility to respond to variations in climate conditions, including droughts. However, the plans also set limits on the period that this higher level of extraction can continue. To prevent unacceptable resource depletion, once this compliance trigger is reached, groundwater allocations are reduced until the extraction is back within the plan’s annual limit. It’s anticipated that the new groundwater sharing plans for the Murray-Darling Basin area of NSW will start on 1 July 2020, once approved by the Minister for Water with the concurrence of the Minister for the Environment. For several groundwater sources these new plans change the period that extraction can exceed the plan’s annual limit. The water allocation outlook provided here is based on the changed compliance triggers in the new plans. These new compliance rules will be adopted for 2020-2021.

Water allocation outlook

Under water sharing plan rules, allocations must be reduced in a groundwater source when the average annual extraction exceeds the plan’s compliance trigger. Reduced allocations are intended to return groundwater extraction to within long term average sustainable limits. The calculations for compliance with extraction limits, and therefore the need to reduce allocation, are based on the volumes pumped in the current and previous years to determine the average annual extraction over the five-year compliance period. The plans have varying exceedance levels, typically 5 per cent or 10 per cent above the extraction limit. Those groundwater sources that have higher exceedance levels over which the average extraction is calculated could require longer periods of reduced allocation to return the water source to sustainable levels of extraction once exceedance is triggered. The 1 July water allocations are currently being calculated. For two groundwater sources, their plan’s compliance trigger has already been reached and allocations for 2020-2021 will be reduced.

Reduced allocations for Aquifer Access entitlements may also be expected in some other groundwater sources (Table1). WaterNSW is prioritising the processing of metering data for groundwater systems that have extraction levels approaching their plan’s compliance trigger. This will ensure we have the best available information on which to base the water allocation determinations. Groundwater entitlements in highly connected alluvial systems can also expect a reduced allocation on 1 July if the linked surface water allocation is reduced.

Click here to read the whole allocation statement

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