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Sydney: Supporting information

  • Rainfall during the 2021–22 year was the region's third wettest year on record, contributing to high runoff and storage inflows across the region.
  • Total storage volumes remained stable at 97% full, the same as the previous year. 
  • 2% of surface water allocations and 33% of groundwater allocations were taken in 2021–22.

Schematic representation of the Sydney region. In 2021–22, runoff was 224% more than average. Storage volumes at 30 June 2022 were 97% full, same as the previous year. 2% of the total surface water allocation (179 GL) was taken. 33% of the total groundwater allocation (134 GL) was taken.

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

 

Water assets

Cataract Dam, Sydney region (WaterNSW © 2012)

 

  • Total water asset volumes in the region at 30 June 2022 was 2,680 GL, around 99% of which was water held in surface water storages. The remaining amount was water held in rivers.
  • There are no groundwater or urban water assets in the Sydney region.

 

Table S1 Accessible storage volume in the Sydney region at 30 June 2022 compared with the previous seven years
  2022 2021 2020 2019 2018 2017 2016 2015
Avon 144,187 140,637 124,082 76,951 97,389 137,843 146,486 135,152
Cataract 83,710 78,624 69,467 28,048 40,988 93,944 94,468 81,527
Cordeaux 91,757 92,606 69,209 38,277 44,829 88,077 90,913 87,018
Fitzroy Falls 6,667 9,815 8,256 8,158 4,526 5,447 3,735 8,463
Greaves Creek 295 260 208 132 153 185 207 179
Lake Medlow 107 124 133 141 160 147 297 284
Lower Cascade 299 236 190 218 182 157 183 205
Middle Cascade 160 160 112 111 111 116 114 160
Nepean 65,412 63,617 44,306 31,316 41,068 61,996 66,045 64,619
Prospect 30,649 32,337 29,295 31,366 29,972 30,649 30,602 29,570
Tallowa 84,661 85,342 87,541 82,864 79,336 83,350 83,940 84,253
Upper Cascade 1,333 1,637 1,736 1,202 1,360 1,445 1,444 1,755
Warragamba 1,962,347 1,977,702 1,668,856 1,078,670 1,451,499 1,898,074 2,009,678 1,888,110
Wingecarribee 20,119 20,934 19,728 13,796 15,819 21,443 18,156 14,500
Woronora 71,270 60,147 45,017 30,830 49,648 71,339 68,958 69,048
Accessible total 2,562,973 2,564,178 2,168,136 1,422,080 1,857,040 2,494,212 2,615,226 2,464,843
Dead storage 108,430 108,430 108,430 108,430 108,430 108,430 108,430 108,430
Total storage 2,671,403 2,672,608 2,276,566 1,530,510 1,965,470 2,602,642 2,723,656 2,573,273
Total capacity 2,766,470 2,766,470 2,766,470 2,766,470 2,766,470 2,766,470 2,766,470 2,766,470
% full 96.6% 96.6% 82.3% 55.3% 71.0% 94.1% 98.5% 93.0%

 

  • Storage volume did not change from the previous year (97% full at 30 June 2021 and 2022).
  • Water in Lake Burragorang (which is formed by Warragamba Dam) makes up more than 75% of the region's total surface water storage.

 


Figure S1 Percentage-full volume on 30 June 2022 for each storage and total storage volume from 2009-2022 (inset)

  • Storage volume remained around 95% full during the first six months of the 2021-22 year (July - December 2021), and fluctuated between 95% and 100% full for the remainer of the 2021-22 year (January to June 2022).
  • Heavy rainfall in August 2021 and March 2022 helped maintain the high storage volume throughout the 2021-22 year. 
  • Tallowa Dam spilled twice during the 2021-22 year, resulting in 4,877 GL flowing over the dam's wall during July 2021, and 4,044 GL in December 2021. 
  • More detailed information on the individual storages within the region is available on the Bureau of Meteorology's Water Storage website.

 

Water liabilities

Coastline near Gerringong, Sydney region (Bureau of Meteorology © Merryn Coutts)

 

  • Water liabilities in the Sydney region refer to the volume of allocation remaining on licence entitlements at the end of the 2021–22 year.

 

Table S2 Volume of surface water allocation remaining at 30 June 2022
Description Surface water (ML)
  Opening balance at 1 July 2021 0
add Allocation 179,393
less Allocated diversion 2,796
less Adjustment and forfeiture 176,597
  Closing balance at 30 June 2022 0

 

Table S3 Volume of groundwater allocation remaining at 30 June 2022
Description Groundwater (ML)
  Opening balance at 1 July 2021 0
add Allocation 134,210
less Allocated diversion 43,826
less Adjustment and forfeiture 90,384
  Closing balance at 30 June 2022 0

 

  • The water supply licences for the region have a water management year that ends on 30 June. The portion of water allocation that has not been abstracted at the end of the water year is either forfeited or is carried over into the next water year.
  • As the carryover cannot be quantified, the unused portion of the allocation is assumed to be forfeited and the allocation remaining at the end of the year was 0 ML in the Sydney region.
  • A more detailed description of water allocations in the Sydney region is given in the Water use section below.

 

Water flows

Hawkesbury River, Sydney region (istock © Leadinglights)

 

  • Total water inflows into the Sydney region was 20,839 GL, 43% more than last year and the highest for the past eleven years.
  • Surface water inflows contributed 16,717 GL (80%) of the total water inflows. Runoff contributed to 97% of the total surface water inflows.
  • Groundwater inflows contributed 2,897 GL (14%) of the total water inflows. Recharge from landscape contributed to 98% of the total groundwater inflows.
  • Urban water inflows contributed 1,226 GL (6%) of the total water inflows. Wastewater collected contributed to 57% of the total urban water inflows, followed by diversion of surface water contributing 41% of the total urban water inflows.
  • Total water outflows from the Sydney region was 20,537 GL, 28% more than last year and the highest for the past eleven years.
  • Surface water outflows contributed 19,265 GL (94%) of the total water outflows. Outflow contributed to 77% of the total surface water outflows.
  • Groundwater outflows contributed 44 GL (<1%) of the total water outflows. Allocated extraction to individual users contributed to 100% of the total groundwater outflows.
  • Urban water outflows contributed 1,228 GL (6%) of the total water outflows. Discharge to sea contributed to 40% of the total urban water outflows, followed by supply of drinking water to urban users contributing 38% of the total urban water outflows.
  • A more detailed breakdown of inflows and outflows is given in the Statement of Changes in Water Assets and Water Liabilities for the Sydney urban region.

 

Water availability

 

Table S4 Annual surface water available in the Sydney region at 30 June 2022 compared with the previous seven years
  2022 2021 2020 2019 2018 2017 2016 2015
Water availability 18,938,491 13,699,743 8,248,064 3,487,350 3,601,748 7,642,114 9,124,671 9,103,090
Water accessible 715,357 702,134 659,251 754,929 798,820 755,395 718,008 705,884
Water taken 538,760 544,890 508,122 608,910 654,082 614,546 608,140 600,352

 

  • Physical surface water availability is calculated as the sum of storage volumes at the start of the year (see Water assets) and estimated inflows into storages and rivers during the year.
  • Surface water availability in the Sydney region in 2021–22 was well above average for the second consecutive year and the region's highest in more than ten years.
  • Surface water accessible is calculated as the sum of surface water allocations and other statutory rights, plus carryover at the start of the year.
  • Water taken during the year is influenced by the physical water available. Typically, water taken from surface water resources is lower than water availability and water accessible.

 

Water use

Wollongong Water Recycling Plant, Sydney region (Sydney Water Corporation © 2010)

 

Consumptive use

 

Table S5 Surface water taken for consumptive use in Sydney region for the previous four years
Surface water 2022 2021 2020 2019
Individual users 2,796 2,146 8,260 13,370
Urban system 503,707 510,487 467,605 563,283
Statutory rights 32,257 32,257 32,257 32,257
Total 538,760 544,890 508,122 608,910

 

Table S6 Groundwater taken for consumptive use in Sydney region for the previous four years
Groundwater 2022 2021 2020 2019
Individual users 43,826 16,918 19,914 3,409
Total 43,826 16,918 19,914 3,409

 

  • Water taken from surface water and groundwater resources for consumptive use was 582,586 ML.
  • Total surface water diverted in the region was 538,760 ML, slightly less than last year.
  • 93% of the total surface water diverted was for urban system supply, almost entirely to the Sydney Water Corporation. 6% was for inter-region users under a statutory right while less than 1% was for individual users (comprising allocated and non-allocated diversions).
  • Total groundwater extracted in the region was 43,826 ML, 159% more than last year, all of which was for individual users. 

 

Allocations and diversions

 

Table S7 Surface water allocations and diversions in the Sydney region for the year ending 30 June
Surface water (ML) 2022 2021 2020 2019
Individual users
Carryover 0 0 0 0
Allocated announcements 179,393 159,390 159,389 159,389
Allocated diversions 2,796 2,146 8,260 13,370
% used 2% 1% 5% 8%

 

  • In 2021–22, total surface water allocation was 179,393 ML, all for individual users. 2% of the allocated surface water was taken.
  • Total allocations for individual users were 13% more than last year, and the highest over the last four years.
  • Total diversions were 30% more than last year because of the favourable wet climate conditions.

 

Table S8 Groundwater allocations and diversions in the Sydney region for the year ending 30 June
Groundwater (ML) 2022 2021 2020 2019
Individual users
Carryover 0 0 0 0
Allocated announcements 134,210 84,534 83,623 76,954
Allocated extractions 43,826 16,918 19,914 3,409
% used 33% 20% 24% 4%

 

  • In 2021–22, total groundwater allocation was 134,210 ML, all for private and commercial use. 33% of the allocated groundwater was taken.
  • Total groundwater allocation were 59% higher than last year.
  • Total groundwater extractions for individual users was 159% more than last year; a reflection of the volume of water available in the region. 

 

Urban supply system

 

Table S9 Water sources used in the Sydney's urban supply system at 30 June 2022 compared with the previous eight years
  2022 2021 2020 2019 2018 2017 2016 2015
Surface water 501,523 509,116 464,608 556,608 597,959 560,032 550,661 539,827
Inter-region 2,184 1,371 2,997 6,675 9,215 3,712 4,448 3,068
Desalinated water 22,480 19,609 71,147 7,793 0 0 0 0
Total urban water supplied 526,187 530,096 538,752 571,076 607,174 563,744 555,109 542,895

 

  • Total inflow to the urban supply system was 526,187 ML, slightly lower than last year.
  • Around 95% of the total urban supply was from surface water storages. Desalinated water made up roughly 4% of urban supply, while inter-region inflows made up the remaining amount of urban water supplied. 
  • The contribution of desalinated water to the urban supply system was 15% higher than last year, but 68% lower than 2020.
  • For more information on the use of desalinated water for the Sydney region, please visit Sydney's Desalination Plant webpage.