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Canberra: Supporting information

  • Dry conditions in the latter half of 2019 contributed to below-average annual runoff across the region.
  • End-of-year storage was only slightly less than last year due to some rainfall relief in early 2020.
  • 72% of the allocated water was taken in 2019–20, primarily for residential use.

Schematic representation of the Canberra region. In 2019–20, runoff was 58% less than average. Storage volumes at 30 June 2020 were 56% full, slightly lower than the previous year. 73% of the total surface water allocation (79 GL) was taken. 43% of the total groundwater allocation (2 GL) was taken.

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

 

Water assets

Aerial cityscape, Canberra region (Bureau of Meteorology © Andrew Terracini)

 

  • Water asset volumes in the region at 30 June 2020 were 199 GL, about 80% of which is water held in storages. The remaining amount is water held in lakes, rivers, and the urban distribution pipe network.

 

Bar graph of annual storage volume in the Canberra region at 30 June for the years 2010–2020. Accessible storage plus dead storage is plotted against the storage capacity to show percentage full at 30 June each year. Storages at 30 June 2020 were 56% full, slightly lower than the previous year. Since 2010, the highest end-of-year storage volume was in 2017 when storages were 84% full, the lowest was in 2010 when storages were 55% full.
Figure S1 Total storage volume in the region at 30 June 2020 compared with the previous 10 years

 

  • Storage volumes decreased slightly from 57% full at 30 June 2019 to 56% full at 30 June 2020.
  • The end-of-year storage volume at 30 June 2020 was the lowest since 2010.
  • In 2013 the Cotter Reservoir was enlarged, increasing the region's total storage capacity to better deal with water demand during periods of drought (see 2013 Account).

 

Map of Canberra region showing the status of each storage at 30 June 2020. The storages are colour coded into ten categories of volume as a proportion of capacity. Bendora storage was over 80% full. Cotter storage was over 70% full. Googong and Corin storages were less than 50% full. An inset line graph shows the time series of percentage-full storage volume between 1 July 2013–30 June 2020. Canberra storages at 30 June 2020 were 56% full, slightly less than last year.
Figure S2 Percentage-full volume on 30 June 2020 for each storage and total daily storage volume from 2013–2020 (inset)

 

  • In early February 2020, storage levels had dropped to 45% full, the lowest in more than 10 years.
  • Higher rainfall during February–April 2020 resulted in a rise in storage levels across the region, the first significant rise in storage since June 2016.
  • The low storage volume in Googong Reservoir (47% full at 30 June 2020) is significant. The reservoir had remained full, or near full, since the end of the Millennium Drought in 2010; however, from the start of 2017, the storage volume has dropped by more than 50%.
  • More detailed information on the individual storages within the region is available on the Bureau of Meteorology's Water Storage website.

 

Water liabilities

Lake Burley Griffin, Canberra region (Bureau of Meteorology © Malcolm Watson)

 

  • Water liabilities in the Canberra region refer to the volume of allocation remaining on licence entitlements at the end of the 2019–20 year.

 

Table S1 Volume of surface water allocation remaining at 30 June 2020
DescriptionIndividual users (ML)Urban system (ML)
 Opening balance at 1 July 201900
add Allocation8,33871,060
less Allocated diversion2,78455,383
less Adjustment and forfeiture5,55415,677
 Closing balance at 30 June 202000

 

Table S2 Volume of groundwater allocation remaining at 30 June 2020
DescriptionIndividual users (ML)
 Opening balance at 1 July 20190
add Allocated2,448
less Allocation extraction1,064
less Adjustment and forfeiture1,384
 Closing balance at 30 June 20200

 

  • 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.
  • For individual users and the urban licence entitlement 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 in the Canberra region is given in the Water use section below.

 

Water flows

Scrivener Dam, Canberra region (Bureau of Meteorology © Andrew Terracini)

 

Figure S3 Water inflows and outflows for the region's water stores and systems during the 2019–20 year

 

  • Total surface water flows into the region's storages was 279 GL. The key item contributing to surface water inflows was runoff, which made up two thirds of the total surface water inflows.
  • For the third consecutive year, runoff was much lower than average (based on modelled data from 1971–2020) due to relatively poor rainfall across the region.
  • A key item contributing to surface water outflows from the region's storages was river outflow, which made up more than 50% of the total surface water outflows. River outflow was well below average due to the dry conditions and low runoff across the region, particularly during the latter half of 2019.
  • Water taken from surface water and groundwater resources for consumptive use was 60 GL, around 20% of the total outflow (see Water use section below).

 

Water use

Evening cityscape, Canberra region (Bureau of Meteorology © Andrew Terracini)

 

Doughnut graphs of water supplied to different users in 2019–20. Surface water taken in the Canberra region was 59 GL, mostly for the urban system. Groundwater taken was 1 GL, mostly for licenced individual users.
Figure S4 Water taken for consumptive use in the Canberra region in 2019–20

 

  • Total surface water diverted in the region was 58,662 ML.
  • 94% of the total diversion was for the urban system while 6% was supplied to individual users under allocated diversions and statutory rights.
  • Total groundwater extracted in the region was 1,499 ML.
  • All of the groundwater extractions were for individual users; 71% of the total were allocated extractions while 29% was made under a statutory right.

 

Bar graph of annual surface water allocation and diversion for different users in the Canberra region from 2011–12 to 2019–20. Most of the surface water allocations are associated with the urban system. These allocations change little from year to year. In 2019–20, 78% of the allocation for the urban system was taken, slightly higher than the previous year. 33% of the allocation for individual users was taken. Non-allocated surface water is also taken for individual users under a statutory right.
Figure S5 Surface water allocations and diversions in the Canberra region for the years ending 30 June, from 2012–2020

 

  • In 2019–20, total surface water allocation was 79 GL, mostly for urban system supply. 73% of the allocated surface water was taken.
  • Allocated diversion to the urban system was almost 5% higher than last year. The recent trend of increasing urban water supply reflects the dry conditions across the region over the last three years, which has resulted in an increased water demand from customers.

 

Bar graph of annual groundwater allocation and extraction for different users in the Canberra region from 2011–12 to 2019–20. All the groundwater allocations are associated with individual users. The allocation in 2019–20 was similar to the previous five years. In 2019–20, 43% of the allocation for individual users was taken, similar to the previous year. Non-allocated groundwater is also taken for individual users under a statutory right.
Figure S6 Groundwater allocations and extractions in the Canberra region for the years ending 30 June, from 2012–2020

 

  • Total groundwater allocation was 2 GL, all for private and commercial use. 43% of the allocated groundwater was taken.
  • Allocated extractions for individual users were similar to the previous few years.

 

Urban system supply

Bar graph showing the annual water sourced for Canberra region's urban supply system during the period from 2010–11 to 2019–20. Since 2010–11, total water sourced for the urban system has been generally trending upwards. Surface water is the only water source for urban supply. Key aspects of the graph are described in the text below the figure.
Figure S7 Water sources used in Canberra's urban supply system during the 2019–20 year compared with the previous nine years

 

  • Total inflow to the water supply system was 55 GL, almost 5% higher than the previous year.
  • Surface water diversions from the region's storages make up 100% of the urban supply.

 

Water restrictions

 

  • Icon Water introduced permanent water conservation measures for potable water use in November 2010, which govern how water can be used on gardens and lawns and for pool filling, car washing, and cleaning.
  • For more information, refer to the Bureau of Meteorology's Water Restrictions website.

 

Water market activity

Lake Burley Griffin, Canberra region (Bureau of Meteorology © Perry Wiles)

 

  • The volume of water allocation and entitlement traded in the region is small, typically representing less than 1% of the total water allocation.
  • For more information on water markets in the region, see the Water Markets Dashboard.

 

Cultural and environmental water

Sunset on Lake Burley Griffin, Canberra region (Bureau of Meteorology © Andrew Terracini)

 

Cultural benefit

  • Cultural water values within the region are closely aligned with environmental water outcomes. In cases where complementary outcomes can be achieved, environmental water, delivered for environmental purposes, then also meet the cultural water requirements.
  • More information on cultural water requirements are provided in the Cultural water management section in the 'Region description'.

 

Environmental benefit

Environmental water provisions

  • Environmental water provisions are defined for aquatic ecosystem categories and specific river reaches in Chapter 5 of the 2013 Environmental Flow Guidelines.
  • Environmental water requirements for one of these river reaches, on the Cotter River below Corin Dam, are presented below.

 

Example line graph of daily flow in the Cotter River below Corin Dam, station number 410752. The flow is compared with the required environmental water provisions, including minimum baseflow (which is 75% of the 80th percentile of natural monthly inflows, or inflow, whichever is less, all year), riffle maintenance flow (which is flow greater than 150 ML/day for 3 consecutive days every 2 months), and pool maintenance flow (which is flow greater than 550 ML/day for 2 consecutive days between July and October).
Figure S8 Example environmental water provisions for the Cotter River below Corin Dam

 

  • The required environmental flows are maintained through a combination of strategic water releases or spills from storages, as well as by restricting the volume of water that can be diverted from a catchment.
  • The baseflow requirement is specified on a monthly basis, with fortnightly variations in the rate of release preferred compared to constant discharge for the month.
  • Drawdown limits for impoundments, and protection of larger, less frequent 'channel maintenance' flows are also a part of the environmental water provisions, but are not shown on the figure above.

 

Environmental water outcomes

Line graph of daily flow in 2019–20 in the Cotter River below Corin Dam, station number 410752. The flow is compared with the required environmental water provisions, including minimum baseflow, riffle maintenance flow (150 ML/day), and pool maintenance flow (550 ML/day). Key aspects of the daily flow graph are described in the text below the figure.
Figure S9 Flow in the Cotter River compared with the required flow regime during the 2019–20 year

 

  • In 2019–20, streamflow in the Cotter River below Corin Dam generally exceeded the monthly baseflow requirements.
  • Streamflow exceeded the bi-monthly riffle maintenance requirements for most of the year; however, these requirements were not met during the summer months due to the very dry conditions across the region.
  • Streamflow was well below the pool maintenance requirement.