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National Water Account 2019

Sydney: Statement details

  • Dry conditions contributed to very low runoff and storage inflows across the region.
  • End of year storage volume dropped to 52% full, the lowest in more than 10 years.

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

 

Water assets

Cataract Dam, Sydney region (WaterNSW © 2012)

 

  • Water asset volumes in the region at 30 June 2019 were 1,452,030 ML, more than 99% of which is water held in storages; less than 1% is inter-region claims and water held in rivers.

 

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 71% full at 30 June 2018 to 52% full at 30 June 2019, the third consecutive decrease in storage.
  • The end of year storage at 30 June 2019 was the lowest in more than 10 years.
  • From 1 June 2019, Sydney has been on Level 1 Water Restrictions due to the region's low storage volumes.
  • Water in Warragamba Reservoir (Lake Burragorang) makes up more than 70% of the region's total surface water storage.

 

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

 

  • Storage volumes declined throughout almost the entire year for the third consecutive year.
  • Warragamba—the largest storage in the region—dropped to 53% full by the end of the year. This is the lowest volume in the reservoir since 2010.
  • More detailed information on the individual storages within the region is available on the Bureau of Meteorology's Water Storage website.

 

Water liabilities

Warragamba Dam, Sydney region (WaterNSW © Adam Hollingworth)

 

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

 

Table S1 Volume of surface water allocation remaining at 30 June 2019
DescriptionIndividual users (ML)Urban system (ML)
 Opening balance at 1 July 201800
add Allocation159,3891,040,554
less Allocated diversion13,370563,283
less Adjustment and forfeiture146,019477,271
 Closing balance at 30 June 201900

 

Table S2 Volume of groundwater allocation remaining at 30 June 2019
DescriptionIndividual users (ML)Urban system (ML)
 Opening balance at 1 July 201800
add Allocation76,954142
less Allocated diversion3,4090
less Adjustment and forfeiture73,545142
 Closing balance at 30 June 201900

 

  • The water supply licences for the region have a water management year that ends on 30 June. The portion of water allocation that has not been abstracted at the end of the water year is either forfeited or is carried over into the next water year.
  • As the carryover cannot be quantified, the unused portion of the allocation is assumed to be 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 Sydney region is given in the Water access and use note.

 

Water flows

Hawkesbury River, Sydney region (istock © Leadinglights)

 

  • Total surface water flows into the region's storages was estimated to be around 1,550 GL. The key item contributing to surface water inflows was runoff, which made more than 90% of the total surface water inflows.
  • Runoff was much lower than average (based on modelled data from 1971–2019) due to the relatively poor rainfall across the region. This was the second successive year of well below-average runoff across the region.
  • A key item contributing to surface water outflows from the region's storages was river outflow, which made up almost 40% of the total surface water outflows. Although river outflow was higher than last year, it was still 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 store, as well as the urban water system, is provided in the Water stores note.

 

Unaccounted-for difference

 

  • 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 S3 Calculation of unaccounted-for difference for the 2018–19 year
DescriptionVolume (ML)
 Closing water storage at 30 June 20191,452,030
less Total inflows3,391,336
add Total outflows3,574,438
less Opening water storage at 1 July 20182,047,235
 Unaccounted-for difference (412,103)

 

  • The relatively high unaccounted-for difference volume is primarily attributed to uncertainties associated with the runoff estimate and groundwater recharge from surface water (see Methods).