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Daly: Supporting information

For the water account period 01 July 2022 - 30 June 2023

  • Total annual rainfall was above average, following the region's eighth-wettest year on record, increasing runoff and surface water inflows across the region.
  • Approximately, 33% of surface water allocations and 34% of groundwater allocation were taken in 2022-23.

Schematic representation of the Daly region. In 2022-23, runoff was 30% more than average. Aquifer storage data was unavailable for the 2022-23 year. 33% of the total surface water allocation (10 GL) was taken. 34% of the total groundwater allocation (145 GL) was taken.

For further information on the regions water accounting statements scroll down this page or click on the links below:

 

Water assets

 

Surface water assets

  • Total surface water asset volume in the Daly region at 30 June 2023 was 14 GL, all of which was held in rivers.
  • The volume of water in the region's storages (see Region description) could not be quantified, however this volume is very small compared with the volume of water in rivers.

Groundwater assets

  • The volume of water stored in the region's aquifers cannot be quantified, however information on the total annual change in aquifer storage is available.

 

Table S1 Total annual change in aquifer volume in the Daly region over the past six water accounting periods ending 30 June
 Groundwater **2023 2022 2021 2020 2019 2018
Change in aquifer volume - (684,230) 280,500 (490,890) (599,000) (460,000)

** The total change in aquifer volume has increased by 3 metres. The change in volume in GL is not available for 2022-23.

 

Water liabilities

Katherine River, Daly region (NT Tourism © anonymous)

 

  • Water liabilities in the Daly region refer to the volume of allocation remaining on licence entitlements at the end of the 2022-23 year.

 

Table S2 Opening and closing balance of surface water allocations for individual users in the Daly region over the past six water accounting periods
Description 2023 2022 2021 2020 2019 2018
 Opening balance at 01 July 0 0 0 0 0 0
add Allocation 10,364 14,441 8,884 9,430 9,774 9,284
less Allocated diversion 3,399 3,832 3,473 3,721 2,912 3,699
less Adjustment and forfeiture 6,965 10,609 5,411 5,709 6,862 5,585
 Closing balance at 30 June 0 0 0 0 0 0

 

Table S3 Opening and closing balance of groundwater allocations for individual users in the Daly region over the past six water accounting periods
Description 2023 2022 2021 2020 2019 2018
 Opening balance at 01 July 0 0 0 0 0 0
add Allocation 144,548 144,473 143,993 146,663 123,082 123,589
less Allocated extraction 48,613 46,314 37,289 48,609 34,665 34,436
less Adjustment and forfeiture 95,935 98,159 106,704 98,054 88,417 89,153
 Closing balance at 30 June 0 0 0 0 0 0

 

  • Most surface water and groundwater licences have a management year that ends of 30 June.
  • The portion of water allocated that was not abstracted during the 2022-23 year was forfeited, with no allocation remaining (carryover) being carried over to the start of the 2023-24 year.
  • A more detailed description of water allocations in the Daly region is given in the Water use section below.

 

Water flows

Katherine River in flood, Daly region (DENR © Sean Lawrie)

 

  • Total water inflows into the Daly region was 12,090 GL, double that of the previous year.
  • Surface water inflows contributed 11,807 GL (98%) of total water inflows, with runoff accounting for 89% of the total water inflows into the region.
  • Runoff into the region's surface water storages was 30% above average (based on modelled data from 1971 to 2022), and the highest since 2016-17, reflecting the above-average rainfall across the region.
  • Groundwater inflows contributed 282 GL (2%) of total water inflows, with recharge from landscape accounting for 96% of total groundwater inflows.
  • Total water outflows from the Daly region was 10,614 GL, more than double from last year.
  • Surface water outflows contributed 9,816 GL (92%) of total water outflows, with outflow to sea accounting for 87% of the total water outflows from the region.
  • Outflow to sea was 12% above average (based on modelled data from 1971 to 2022), reflecting the increase in rainfall across the region, restoring river outflows during the year.
  • Groundwater outflows contributed 798 GL (8%) of total water outflows, with discharge to surface water accounting for 93% of total groundwater outflows.
  • A more detailed breakdown of inflows and outflows is given in the Statement of Changes in Water Assets and Water Liabilities for the Daly region.

 

Water use

Daly River, Northern Territory (Bureau of Meteorology © Bradley Wood)

 

Consumptive use

 

Table S4 Surface water taken for consumptive use in the Daly region over the past six water accounting periods ending 30 June
Surface water 2023 2022 2021 2020 2019 2018
Agriculture users 1,307 1,150 780 949 881 1,081
Cultural users 164 216 - - - -
Industrial users 40 105 80 75 133 72
Other users 5,415 5,369 5,369 5,369 5,369 5,369
Urban users 2,068 2,541 2,793 2,877 2,078 2,726
Total 8,994 9,381 9,022 9,270 8,461 9,248

 

Table S5 Groundwater taken for consumptive use in the Daly region over the past six water accounting periods ending 30 June
Groundwater 2023 2022 2021 2020 2019 2018
Agricultural users 46,873 44,293 36,142 47,320 33,833 33,232
Cultural users 402 1,160 456 535 126 -
Industrial users 300 310 293 377 423 925
Mining users 143 86 - - - -
Other users 4,280 4,280 4,280 4,280 4,280 4,280
Urban users 895 465 398 377 283 279
Total 52,893 50,594 41.569 52,889 38,945 38,716

 

  • Water taken from surface water and groundwater resources for consumptive use was 61,887 ML, 3% more than last year.
  • Total surface water diverted in the Daly region was 8,994 ML, around 4% less than last year, mostly from the Katherine River.
  • Around 54% of the surface water was taken for other users, while urban users accounted for 22% of the total surface water diversions taken.
  • Total groundwater extracted in the Daly region was 52,893 ML, 5% more than last year, mostly from the Oolloo Dolostone and the Tindall Limestone water allocation plan areas.
  • Around 89% of the groundwater extractions were for agriculture users, while urban users accounted for 8% of the total groundwater extractions taken.

 

Allocations and diversions

 

Table S6 Surface water allocations and diversions for individual users in the Daly region over the past six water accounting periods ending 30 June
Surface water 2023 2022 2021 2020 2019 2018
Individual users
Carryover 0 0 0 0 0 0
Allocated announcements 10,346 14,441 8,884 9,430 9,774 9,284
Allocated diversions 3,399 3,832 3,473 3,721 2,912 3,699
% used 33% 27% 39% 39% 30% 40%

 

  • In 2022-23, total surface water allocation was 10,364 ML, mostly from the Katherine River for town supply. This was a decrease of 28% from the previous year.
  • While there was a significant decrease in surface water allocation, surface water diversions in the Daly region only decreased by 11% to 3,399 ML (33% of the allocated surface water).
  • In 2018–19, surface water allocations were increased as a precautionary measure in case groundwater supply to Katherine was further limited by the presence of per- and poly-fluoroalkyl substances (PFAS) and more surface water was needed to meet the town's water supply requirements.

 

Table S7 Groundwater allocations and extractions for individual users in the Daly region over the past six water accounting periods ending 30 June
Groundwater 2023 2022 2021 2020 2019 2018
Individual users
Carryover 0 0 0 0 0 123,589
Allocated announcements 144,548 144,473 143,993 146,663 123,082 33,232
Allocated extractions 48,613 46,314 37,289 48,609 34,665 1,204
% used 34% 32% 26% 33% 28% 4%

 

  • In 2022-23, total groundwater allocation was 144,548 ML, mostly from the Oolloo Dolostone and Tindall Limestone aquifers for agricultural purposes.
  • Groundwater extractions in the Daly region was 48,613 ML, 5% more than last year. This equates to 34% of groundwater allocations being taken.
  • During the past five years, groundwater supply to the town of Katherine has been limited due to a requirement for groundwater to be filtered to remove per- and poly-fluoroalkyl substances (PFAS) before transfer to the urban system (see Water restrictions below for more detail).

 

Water restrictions

 

  • A per- and poly-fluoroalkyl substances (PFAS) treatment plant commenced operation in the region in October 2017 to remove higher levels of PFAS identified in the town of Katherine's groundwater supply. Groundwater extracted from the Tindall Limestone Aquifer was filtered to remove PFAS prior to transfer to the urban system.
  • The PFAS removal process has meant that groundwater supply to the town of Katherine has been limited during the last five years. Although most of the town water supply for Katherine comes from surface water, the drop in groundwater contribution meant total water usage in Katherine needed to reduce by 20% to ensure a sustainable water supply.