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National Water Account 2019

Melbourne: Statement details

  • Dry conditions for most of the year contributed to low runoff and storage inflows across the region.
  • Total storage at 30 June 2019 was 53% full, the lowest end of year storage since 2010.


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

 

Water assets

Werribee River lower reaches, Melbourne region (Alison Pouliot © 2010)

 

  • Total water asset volumes in the region at 30 June 2019 were 1,603 GL, about two thirds of which is water held in storages.
  • Around 30% of the water assets are inter-region claims and claims on water for the urban system. Less than 5% of the asset volume is water held in rivers, aquifers, and the urban system's wastewater storages.

 

Graph of total storage volume in the region at 30 June 2019 compared with the previous 9 years
Figure S1 Total storage volume in the region at 30 June 2019 compared with the previous 9 years

 

  • Storage volumes decreased from 61% full at 30 June 2018 to 53% full at 30 June 2019. This is the second consecutive decrease in storage volume.
  • The end of year storage volume at 30 June 2019 was the lowest since 2010.

 

Map showing percentage-full volume on 30 June 2019 for each storage and total daily storage volume from 2013–2019 (inset)
Figure S2 Percentage-full volume on 30 June 2019 for each storage and total daily storage volume from 2013–2019 (inset)

 

  • Storage volumes peaked in early-October 2018 following rainfall during the winter months.
  • More detailed information on the individual storages within the region is available on the Bureau of Meteorology's Water Storage website.

 

Water liabilities

Yarra River at Dights Falls, Melbourne region (Alison Pouliot © 2010)

 

  • Water liabilities in the Melbourne region refer to the volume of allocation remaining on licence entitlements at the end of the 2018–19 year.

 

Table S2 Volume of surface water allocation remaining at 30 June 2019
DescriptionIndividual users (ML)Urban system (ML)Transfer: inter-region
 Opening balance at 1 July 20188,408482,0810
add Allocation6,978611,3505,425
less Allocated diversion7,618443,8964,171
less Adjustment and forfeiture1,810207,5941,254
 Closing balance at 30 June 20195,958441,9410

 

Table S3 Volume of groundwater allocation remaining at 30 June 2019
DescriptionIndividual users (ML)Urban system (ML)
 Opening balance at 1 July 201800
add Allocation64,6281,499
less Allocated extraction20,96072
less Adjustment and forfeiture43,6681,427
 Closing balance at 30 June 201900

 

  • As there are no carryover provisions for groundwater supply licences in the region, the portion of water allocation that has not been abstracted at the end of a water year is forfeited and the allocation remaining at the end of the year was 0 ML.
  • A more detailed description of water allocations and associated water rights in the Melbourne region is given in the Water access and use note.

 

Water flows

Werribee river, Melbourne region (Bureau of Meteorology © Brett Anderson)

 

  • Total surface water flows into the region's storages was estimated to be around 783 GL. The key item contributing to surface water inflows was runoff, which made up more than 70% of the total surface water inflows.
  • Runoff was much lower than average (based on modelled data from 1971–2019) and the lowest in more than 10 years due to the relatively poor rainfall across the region. This was the second successive year of below-average runoff across the region.
  • A key item contributing to surface water outflows from the region's storages was river outflow, which made around 44% of the total surface water outflows. River outflow was well below average due to the dry conditions and low runoff across the region.
  • A detailed description on all the water flows associated with the surface water and groundwater stores, as well as the urban water system, is provided in the Water stores note.

 

Unaccounted-for difference

Upper catchment area, Melbourne region (Bureau of Meteorology © Paul Feikema)

 

  • The unaccounted-for difference is the volume necessary to reconcile the opening water storage and closing water storage with the total water inflows and total water outflows reported in the water accounting statements.

 

Table S4 Calculation of unaccounted-for difference for the 2018–19 year
DescriptionVolume (ML)
 Closing water storage at 30 June 20191,097,810
less Total inflows1,899,960
add Total outflows2,193,620
less Opening water storage at 1 July 20181,248,628
 Unaccounted-for difference142,842

 

  • The unaccounted-for difference value is primarily attributed to uncertainties associated with the runoff and river outflow estimates (see Methods).