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Perth: Statement of Water Assets and Water Liabilities

as at 30 June 2020

  • Water availability in the Perth region's storages decreased during 2019–20.
  • Water availability is represented by the net water assets, which are the volume of water assets minus the water liabilities.

Schematic representation of the Perth region. Total water assets at 30 June 2020 was 392 GL. Total water liabilities was 143 GL. Closing net water assets at 30 June 2020 was 249 GL, 18% less than last year.

The Statement of Water Assets and Water Liabilities is provided in the table below. The statement presents the volume of water assets, and water liabilities at the start and end of the reporting year.




Select comparative year

 2020 ML2019 ML2018 ML2017 ML2016 ML2015 ML
Water assets
Surface water 360,128415,416390,226297,520262,516334,828
Urban water system000000
Claims: surface water*000000
Claims: groundwater*000000
Irrigation scheme31,83140,63438,14141,08135,37249,142
Claims: surface water*31,83140,63438,14141,081**35,372**49,142
Total water assets391,959456,050428,367338,601**297,888**383,970
Water liabilities
Surface water liability40,35349,15646,66349,60343,89257,579
Allocation remaining: individual users8,5228,5228,5228,5228,5208,437
Allocation remaining: urban system*000000
Allocation remaining: irrigation scheme*31,83140,63438,14141,081**35,372**49,142
Groundwater liability102,375102,375102,375102,374107,255109,093
Allocation remaining: individual users102,375102,375102,375102,374107,255109,093
Allocation remaining: urban system*000000
Total water liabilities142,728151,531149,038151,977**151,147**166,672
Net water assets
Net surface water assets319,775366,260343,563247,917218,624277,249
Opening net surface water assets366,260343,563247,917218,624**277,249**290,852
Change in net surface water assets(46,485)22,69795,64629,293**(58,625)**(13,603)
Closing net surface water assets319,775366,260343,563247,917**218,624**277,249
Net groundwater assets(102,375)(102,375)(102,375)(102,374)(107,255)(109,093)
Opening net groundwater assets(102,375)(102,375)(102,374)(107,255)(109,093)(116,430)
Change in net groundwater assets00(1)4,8811,8387,337
Closing net groundwater assets(102,375)(102,375)(102,375)(102,374)(107,255)(109,093)
Net urban water assets000000
Opening net urban water assets000000
Change in net urban water assets000000
Closing net urban water assets000000
Net irrigation water assets31,83140,63438,14141,08135,37249,142
Opening net irrigation water assets40,63438,14141,08135,372**49,142**41,670
Change in net irrigation water assets(8,803)2,493(2,940)5,709**(13,770)**7,472
Closing net irrigation water assets31,83140,63438,14141,081**35,372**49,142
Total closing net water assets249,231304,519279,329186,624**146,741**217,298
Total change in net water assets(55,288)25,19092,70539,883**(70,557)**1,206


* between-store claims / liabilities

** different to published volume in historical accounts (see Governance for more information)

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