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Melbourne: Statement of Changes in Water Assets and Water Liabilities

For the water account period 1 July 2023 to 30 June 2024

  • The volume of water in the region's storages decreased by 111 GL in 2023–24, the first decrease in the region's water storages since 2018–19.
  • This decrease represents the change in water volume in the region's surface water storages.

Schematic representation of the Melbourne region. Total water inflows during 2023-24 was 2,970 GL. Total water outflows were 3,038 GL. Change in water storage on 30 June 2024 was 111 GL less 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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 2024 (ML)2023 (ML)2022 (ML)2021 (ML)2020 (ML)2019 (ML)
Water inflows
Surface water inflows1,422,4522,918,4411,905,1141,923,8012,309,949988,812
Precipitation on storages68,34585,52969,14570,68963,85142,283
Precipitation on rivers16,36031,19620,83117,55519,63610,808
Flood return90,712233,111128,856105,667108,30327,127
Inflow outside region212,735212,735212,735296,432214,818126,955
Runoff1,009,0302,345,0221,449,7411,407,6991,885,484767,384
Point return from irrigation2911851109246
Surface water received from other region1,2561,2561,2562,604808356
Treated wastewater discharge from urban water system*23,9859,58122,54223,10416,94013,653
 
Groundwater inflows654,472802,566718,286684,641604,260471,415
Inter-region coastal inflow22,85128,23123,25523,54738,59629,903
Recharge from landscape399,672434,101427,256431,306334,687285,776
Recharge from surface water*189,892312,030230,982204,290205,387122,139
Leakage from urban water system*42,05728,20436,79325,49825,59033,597
 
Urban water system inflows893,066870,924859,122832,175852,922825,974
Delivery of desalinated water04,182125,000125,000118,13222,374
Diversion of surface water*477,338451,104320,263315,125337,915443,896
Extraction of groundwater*518161767273
Wastewater collected415,677415,557413,798391,974396,803359,631
 
Total water inflows2,969,9904,591,9313,482,5223,440,6173,767,1312,286,201
Water outflows
Surface water outflows2,002,3673,676,7212,260,8491,967,1572,029,3401,209,055
Evaporation from storages70,57467,34865,05758,21557,80161,254
Evaporation from rivers19,53726,18319,89916,68115,27712,906
Outflows1,046,1142,294,0401,342,0971,139,9661,163,734495,350
Overbank flow176,776501,922259,298209,730225,98948,069
Recharge to groundwater*189,892312,030230,982204,290205,387122,139
Allocated diversion to individual users8,5188,3118,3118,6648,6517,618
Allocated diversion to inter-region4,5034,1783,3373,6474,2634,171
Diversion to the urban system*477,338451,104320,263315,125337,915443,896
Non-allocated diversion to individual users9,11511,60511,60510,83910,32313,652
 
Groundwater outflows147,078147,443128,104132,333202,728151,342
Inter-region coastal outflow131,455131,041111,262114,699184,378130,311
Allocated extraction to individual users15,57216,32116,78117,55818,27820,958
Extraction to the urban system*518161767273
 
Urban water system outflows888,366824,534857,713830,530837,166810,059
Discharge to sea331,243364,864326,696316,732322,703268,481
Leakage to groundwater*42,05728,20436,79325,49825,59033,597
Other losses9,9367,71618,61012,20510,02310,964
Other wastewater losses12,4578,2338,6889,05412,59318,532
Supply of drinking water for own use2,6142,5072,4471,8312,4162,722
Supply of drinking water to agriculture and irrigation customers000050
Supply of drinking water to commercial and industrial customers104,42070,46393,53589,26199,631109,805
Supply of drinking water to irrigation water schemes00001021,256
Supply of drinking water to other customers2,6782,2802,4082,1472,2261,942
Supply of drinking water to residential customers309,293294,655301,497302,632296,720298,166
Supply of recycled water for own use11,0309,6788,7739,92111,5671,529
Supply of recycled water to agriculture and irrigation customers24,23514,15319,03721,53619,69228,379
Supply of recycled water to commercial and industrial customers3,9623,1234,6225,3805,9955,973
Supply of recycled water to irrigation water schemes7,9836,8667,7758,2457,79312,415
Supply of recycled water to residential customers2,4362,2033,7192,9843,1702,538
Treated wastewater discharge to surface water*23,9859,58122,54223,10416,94013,653
Urban discharge to landscape37857100107
 
Total water outflows3,037,8114,648,6973,246,6662,930,0203,069,2342,170,456
 
Unaccounted-for difference(42,898)163,569(13,701)(287,302)(448,814)(255,630)
 
 
Change in water storage      
Change in surface water storage(110,719)106,803222,291223,002249,260(140,275)
Change in groundwater storage00(6)0190
Change in urban water storage00(130)293(196)390
Total change in water storage(110,719)106,803222,155223,295249,083(139,885)
 
Closing water storage1,789,7141,900,4331,793,6301,571,4751,348,1801,099,097
 
 
Change in water liability
Surface water liability3557,4428,4712225,271(2,450)
Allocation remaining: individual users3557,4228,4712225,271(2,450)
Commitment: inter-region000000
 
Groundwater liability000000
Allocation remaining: individual users000000
Total change in water liability3557,4228,4712225,271(2,450)
       
Net change in water assets(111,074)99,361213,684223,073243,812(137,435)

* between-store flows

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