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Melbourne: Statement of Changes in Water Assets and Water Liabilities

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

  • The volume of water in the region's storages increased during 2022-23 for the fourth consecutive year.
  • This increase represents the change in water volume in the region's surface water storages.

Schematic representation of the Melbourne region. Total water inflows during 2022-23 was 4,301 GL. Total water outflows were 4,676 GL. Change in water storage on 30 June 2022 was 107 GL more than the previous year.

The Statement of Changes in Water Assets and Water Liabilities is provided in the table below.
The statement presents the actual water flows associated with the region's water stores, as well as the changes in water assets and water liabilities that occurred during the year.

 

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  2023 (ML) 2022 (ML) 2021 (ML) 2020 (ML) 2019 (ML) 2018 (ML)
Water inflows
Surface water inflows 2,774,678
 1,758,368 1,923,801 2,309,949 988,812 1,272,711
Precipitation on storages 85,616 69,145 70,689 63,851 42,283 51,094
Precipitation on rivers 31,180 20,903 17,555 19,636 10,808 13,890
Runoff 2,348,796 1,450,021 1,407,699 1,885,484 767,384 976,431
Flood return 234,065 130,608 105,667 108,303 27,127 44,852
Inflow outside region 64,000
 63,758 296,432 214,818 126,955 157,667
Point return from irrigation 140
 135 51 109 246 57
Surface water received from other region 1,300
 1,256 2,604 808 356 757
Treated wastewater discharge from urban water system* 9,581 22,542 23,104 16,940 13,653 27,963
 
Groundwater inflows 798,166
 718,938 684,644 604,260 471,415 549,886
Inter-region coastal inflow 23,000
 23,255 23,547 38,596 29,903 28,471
Leakage from urban water system* 28,204 36,793 25,498 25,590 33,597 39,891
Recharge from landscape 434,230 427,307 431,309 334,687 285,776 338,560
Recharge from surface water* 312,732 231,583 204,290 205,387 122,139 142,964
 
Urban water system inflows 727,924 859,122 832,175 852,922 825,974 820,043
Delivery of desalinated water 4,182 125,000 125,000 118,132 22,374 14,972
Diversion of surface water* 451,104 320,263 315,125 337,915 443,896 443,736
Extraction of groundwater* 81 61 76 72 73 72
Wastewater collected 272,575 413,798 391,974 396,803 359,631 361,263
 
Total water inflows 4,300,768
 3,336,428 3,440,620 3,767,131 2,286,201 2,642,640
Water outflows
Surface water outflows 3,692,473 2,276,167 1,967,157 2,026,501 1,202,685 1,413,233
Evaporation from storages 67,348 65,057 58,215 54,962 54,884 60,103
Evaporation from rivers 26,241 20,110 16,681 15,277 12,906 15,345
Outflows 2,308,491 1,353,566 1,139,966 1,163,734 495,350 641,505
Overbank flow 502,637 261,645 209,730 225,989 48,069 86,097
Recharge to groundwater* 312,732 231,583 204,290 205,387 122,139 142,964
Diversion to the urban system* 451,104 320,263 315,125 337,915 443,896 443,736
Non-allocated diversion to individual users 11,620
 11,605 10,839 10,323 13,652 12,243
Allocated diversion to inter-region 4,000
 4,027 3,647 4,263 4,171 3,849
Allocated diversion to individual users 8,300
 8,311 8,664 8,651 7,618 7,391
 
Groundwater outflows 129,111
 130,256 132,334 202,728 151,344 153,431
Extraction to the urban system* 81 61 76 72 73 72
Inter-region coastal outflow 110,000
 111,262 114,699 184,378 130,311 132,349
Allocated extraction to individual users 19,030
 18,933 17,559 18,278 20,960 21,010
 
Urban water system outflows 854,212 857,713 830,531 837,168 810,059 822,311
Supply of drinking water to residential customers 294,655 301,497 302,632 296,720 298,166 287,249
Supply of drinking water to commercial and industrial customers 100,141 93,535 89,261 99,631 109,805 109,542
Supply of drinking water to agriculture and irrigation customers 0 0 0 5 0 0
Supply of drinking water to irrigation water schemes 0 0 0 102 1,256 1,507
Supply of drinking water to other customers 2,280 2,408 2,147 2,226 1,942 1,807
Supply of drinking water for own use 2,507 2,447 1,831 2,417 2,722 3,481
Discharge to sea 364,864 326,696 316,732 322,703 268,481 277,668
Leakage to groundwater* 28,204 36,793 25,498 25,590 33,597 39,891
Other losses 7,716 18,610 12,205 10,023 10,964 11,218
Other wastewater losses 8,233 8,688 9,054 12,593 18,532 18,028
Supply of recycled water to residential customers 2,203 3,719 2,984 3,170 2,538 2,083
Supply of recycled water to commercial and industrial customers 3,123 4,622 5,380 5,995 5,973 5,930
Supply of recycled water to agriculture and irrigation customers 14,153 19,037 21,537 19,693 28,379 21,871
Supply of recycled water to irrigation water schemes 6,866 7,775 8,245 7,793 12,415 12,224
Supply of recycled water for own use 9,678 8,773 9,921 11,567 1,529 1,596
Treated wastewater discharge to surface water* 9,581 22,542 23,104 16,940 13,653 27,963
Urban discharge to landscape 8 571 0 0 107 253
 
Total water outflows 4,675,796
 3,264,136 2,930,022 3,066,397 2,164,088 2,388,975
 
Unaccounted-for difference 481,993
 151,174 (287,303) (451,651) (261,998) (337,660)
 
 
Change in water storage            
Change in surface water storage 106,702
 222,367 223,002 249,260 (140,275) (83,388)
Change in groundwater storage 263
 1,099 0 19 0 0
Change in urban water storage 0 0 293 (196) 390 (607)
Total change in water storage 106,965
 223,466 223,295 249,083 (139,885) (83,995)
 
Closing water storage 1,901,906
 1,794,941 1,571,475 1,348,180 1,099,097 1,238,982
 
 
Change in water liability
Surface water liability (300)
 1,005 222 5,271 (2,450) (2,587)
Allocation remaining: individual users (300)
 1,005 222 5,271 (2,450) (2,587)
Commitment: inter-region 0
 0 0 0 0 0
 
Groundwater liability 0
 0 0 0 0 0
Allocation remaining: individual users 0
 0 0 0 0 0
Total change in water liability (300)
 1,005 222 5,271 (2,450) (2,587)
             
Net change in water assets 107,265
 222,461 223,073 243,812 (137,435) (81,408)

* between-store flows

Note: quantification approaches used to derive each item volume are provided in the Methods