Melbourne: Statement of Changes in Water Assets and Water Liabilities

for the year ended 30 June 2022

  • The volume of water in the region's storages increased during 2021–22 for the third 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 2021–22 was 3,459 GL. Total water outflows was 3,250 GL. Water storage at 30 June 2022 was 223 GL same as 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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2022 (ML) 2021 (ML) 2020 (ML) 2019 (ML) 2018 (ML) 2017 (ML)
Water inflows
Surface water inflows 1,756,754 1,920,671 2,308,953 987,194 1,271,445 1,899,347
Precipitation on storages 69,151 68,455 62,854 40,655 49,828 54,736
Precipitation on rivers 20,925 17,526 19,636 10,808 13,890 20,202
Flood return 130,662 105,660 108,303 27,127 44,852 92,791
Inflow outside region 63,758 296,432 214,818 126,955 157,667 196,912
Point return from irrigation 135 51 109 246 57 61
Runoff 1,448,324 1,406,838 1,885,484 767,384 976,431 1,514,144
Surface water received from other region 1,256 2,604 808 356 757 3,058
Treated wastewater discharge from urban water system* 22,543 23,105 16,941 13,653 27,963 17,443
Groundwater inflows 718,814 685,751 604,260 471,415 549,886 618,040
Inter-region coastal inflow 23,255 23,547 38,596 29,903 28,471 28,713
Leakage from urban water system* 36,793 25,498 25,290 33,597 39,891 33,770
Recharge from landscape 427,029 431,118 334,687 285,776 338,560 357,716
Recharge from surface water* 231,737 205,588 205,387 122,139 142,964 197,841
Urban water system inflows 984,122 957,175 971,054 848,347 835,015 860,976
Delivery of desalinated water 125,000 125,000 118,132 22,374 14,972 46,209
Diversion of surface water* 445,264 440,125 456,047 466,270 458,708 436,848
Extraction of groundwater* 60 76 72 72 72 60
Wastewater collected 413,898 391,974 396,803 359,631 361,263 377,859
Total water inflows 3,459,690 3,563,597 3,884,267 2,306,956 2,656,346 3,378,363
Water outflows
Surface water outflows 2,281,264 2,033,832 2,088,829 1,277,770 1,492,617 1,913,795
Evaporation from storages 65,056 58,459 55,123 58,169 62,462 60,153
Evaporation from rivers 20,131 16,696 15,277 12,906 15,345 17,922
Allocated diversion to individual users 8,311 8,664 8,651 7,618 7,391 8,234
Allocated diversion to inter-region 4,027 3,647 4,263 4,171 3,849 3,792
Diversion to the urban system* 320,264 315,125 337,915 443,896 443,736 390,639
Non-allocated diversion to individual users 11,605 10,839 10,323 13,652 12,243 12,042
Outflow 1,357,809 1,204,767 1,225,901 567,150 718,530 1,045,396
Overbank flow 262,324 210,047 225,989 48,069 86,097 177,776
Recharge to groundwater* 231,737 205,588 205,387 122,139 142,964 197,841
Groundwater outflows 130,255 132,334 202,728 151,343 153,431 154,939
Allocated extraction to individual users 18,933 17,559 18,278 20,960 21,010 20,222
Extraction to the urban system* 60 76 72 72 72 60
Inter-region coastal outflow 111,262 126,277 184,378 130,311 132,349 134,657
Urban water system outflows 838,636 808,995 817,476 781,681 800,440 788,685
Discharge to sea 326,696 316,732 322,703 268,481 277,668 301,846
Leakage to groundwater* 36,793 25,498 25,590 33,597 39,891 33,770
Other losses 18,610 12,205 10,023 10,964 11,218 13,125
Other wastewater losses 8,649 9,054 12,593 18,532 18,028 17,411
Recycled water delivery to irrigation users 7,775 8,245 7,793 12,415 12,224 5,049
Supply of drinking water for own use 2,447 1,831 2,417 2,722 3,481 230
Supply of drinking water to irrigation users 0 0 107 1,256 1,507 756
Supply of drinking water to urban users 397,440 394,040 398,577 409,913 398,598 386,147
Supply of recycled water for own use 8,773 9,921 11,567 1,530 1,596 5,384
Supply of recycled water to urban users 8,339 8,364 9,165 8,511 8,012 7,334
Treated wastewater discharge to surface water* 22,543 23,105 16,941 13,653 27,983 17,443
Urban discharge to landscape 571 0 0 107 253 190
Total water outflows 3,250,155 2,975,161 3,109,033 2,210,794 2,446,488 2,857,419
Unaccounted-for difference 13,936 (365,147) (526,151) (236,049) (293,851) (434,340)
Change in water storage
Change in surface water storage 222,372 222,996 249,260 (140,277) (83,386) 87,406
Change in groundwater storage 1,099 0 19 0 0 0
Change in urban water storage 0 293 (196) 390 (607) (802)
Total change in water storage 223,471 223,289 249,083 (139,887) (83,993) 86,604
Closing water storage 1,794,940 1,571,469 1,348,180 1,099,097 1,238,984 1,322,977
Change in water liability
Surface water liability 1,005 222 5,271 (2,450) (2,587) (2,429)
Allocation remaining: individual users 1,005 222 5,271 (2,450) (2,587) (2,429)
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 1,005 222 5,271 (2,450) (2,587) (2,429)
Net change in water assets 222,466 223,067 243,812 (137,437) (81,406) 79,121

* between-store flows

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