Bureau Home » Water Information » National Water Account » 2020 Account » Melbourne » Supporting information » Supporting information

Melbourne: Supporting information

  • Above-average rainfall contributed to high runoff and storage inflows across the region.
  • Total storage at 30 June 2020 was 66% full, the highest end of year storage since 2015.
  • 37% of the allocated water was taken in 2019–20, primarily for residential use.

Schematic representation of the Melbourne region. In 2019–20, runoff was 25% more than average. Storage volumes at 30 June 2020 were 66% full, higher than the previous year. 38% of the total surface water allocation (926 GL) was taken. 28% of the total groundwater allocation (67 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

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

 

  • Total water asset volumes in the region at 30 June 2020 were 1,884 GL, about two thirds of which is water held in storages.
  • Around 30% of the water assets are 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.

 

Bar graph of annual storage volume in the Melbourne 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 66% full, higher than the previous four years. Since 2010, the highest end-of-year storage volume was in 2014 when storages were 75% full, the lowest was in 2010 when storages were 36% full.
Figure S1 Total storage volume in the region at 30 June 2020 compared with the previous 10 years

 

  • Storage volumes increased from 53% full at 30 June 2019 to 66% full at 30 June 2020.
  • The end-of-year storage volume at 30 June 2020 was the highest since 2015.

 

Map of Melbourne 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. Tarago, Silvan, Sugarloaf, Yan Yean, Maroondah, Greenvale, and Pykes Creek storages were over 80% full. Cardinia and Melton storages were over 60% full. O'Shannassy, Merrimu, and Rosslynne 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. Melbourne storages at 30 June 2020 were 66% full, higher than last year.
Figure S2 Percentage-full volume on 30 June 2020 for each storage and total daily storage volume from 2013–2020 (inset)

 

  • Storage volumes peaked in late-November 2019 following rainfall during the winter months.
  • Above-average rainfall during the early part of 2020 kept storage levels above 60% for the remainder of the 2019–20 year.
  • More detailed information on the individual storages within the region is available on the Bureau of Meteorology's Water Storage website.

 

Water liabilities

Werribee river shoreline (Bureau of Meteorology © Brett Anderson)

 

  • Water liabilities in the Melbourne 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)Transfer: inter-region
 Opening balance at 1 July 20195,958441,9410
add Allocation16,787904,1945,225
less Allocated diversion8,651337,9154,263
less Adjustment and forfeiture2,865472,418962
 Closing balance at 30 June 202011,229535,8020

 

Table S2 Volume of groundwater allocation remaining at 30 June 2020
DescriptionIndividual users (ML)Urban system (ML)
 Opening balance at 1 July 201900
add Allocation65,0511,499
less Allocated extraction18,27872
less Adjustment and forfeiture46,7731,427
 Closing balance at 30 June 202000

 

  • 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 in the Melbourne region is given in the Water use section below.

 

Water flows

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

 

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 2,007 GL. The key item contributing to surface water inflows was runoff, which made up more than 80% of the total surface water inflows.
  • Runoff was above average (based on modelled data from 1971–2020) and the highest since 2011–12 due to the above-average rainfall across the region, particularly during the first half of 2020.
  • A key item contributing to surface water outflows from the region's storages was river outflow, which made up more than half of the total surface water outflows. River outflow was above average due to the wet conditions and high runoff across the region.
  • Water taken from surface water and groundwater resources for consumptive use was 380 GL, around 15% of the total outflow (see the Water use section below).

 

Water use

City of Melbourne, aerial view (istock © BluesandViews)

 

Doughnut graphs of water supplied to different users in 2019–20. Surface water taken in the Melbourne region was 361 GL, mostly for the urban system. Groundwater taken was 18 GL, mostly for individual users.
Figure S4 Water taken for consumptive use in the Melbourne region in 2019–20

 

  • Total surface water diverted in the region was 361,152 ML.
  • 94% of the total surface water diverted was for urban system supply, mostly by the Melbourne Water Corporation; 5% was for individual users (comprising allocated and non-allocated diversions) while 1% was for inter-region supply.
  • Total groundwater extracted in the region was 18,350 ML.
  • More than 99% of the total groundwater extracted was for individual users; less than 1% was for the urban water system.

 

Bar graph of annual surface water allocation and diversion for different users in the Melbourne region from 2012–13 to 2019–20. Most of the surface water allocations are associated with the urban system. Allocations for the urban system were much higher than the previous few years. In 2019–20, 37% of the allocation for the urban system was taken, lower than the previous year. 52% of the allocation for individual users was taken. 82% of the allocation for inter-region supply was taken. Non-allocated surface water is also taken for individual users.
Figure S5 Surface water allocations and diversions in the Melbourne region for the years ending 30 June, from 2013–2020

 

  • In 2019–20, total surface water allocation was 926 GL, mostly for urban system supply. 38% of the allocated surface water was taken.
  • Allocations for the urban system increased by almost 50% from the previous year.
  • Actual diversions to the urban system were much lower than previous years. The lower surface water supply was influenced by the Melbourne Water Corporation opting to reduce pressure on its surface water resources and increase its reliance on desalinated water to meet urban demand (see Urban system supply section below).
  • Total diversions to individual users (allocated and non-allocated) were similar to last year.

 

Bar graph of annual groundwater allocation and extraction for different users in the Melbourne region from 2012–13 to 2019–20. Most of the groundwater allocations are associated with individual users. The allocation in 2019–20 was similar to the previous few years. In 2019–20, 28% of the allocation for individual users was taken, similar to the previous few years. 5% of the allocation for the urban system was taken.
Figure S6 Groundwater allocations and extractions in the Melbourne region for the years ending 30 June, from 2013–2020

 

  • Total groundwater allocation was 67 GL, mostly for agricultural purposes. 28% of the allocated groundwater was taken.
  • Allocated extractions for both individual users and the urban water system were similar to last year. Urban supply in particular has changed little over the last few years.

 

Urban system supply

Stacked bar graph showing the annual water sourced for Melbourne region's urban supply system during the period from 2010–11 to 2019–20. Each bar in the stack progressively represents surface water, groundwater, and desalinated water. Between 2010–11 and 2016–17 there was a general increasing trend in total water sourced for the urban system. Since 2016–17, there have been three consecutive decreases in total annual water sourced. Surface water is the predominant water source for the urban system. Desalinated water has been a source of water for the urban system for the last 4 years. Key aspects of the graph are described in the text below the figure.
Figure S7 Water sources used in the Melbourne region's urban supply system during the 2019–20 year compared with the previous nine years

 

  • Total inflows to the water supply system was 456 GL, similar to last year.
  • 74% of the total urban supply was from surface water storages. Desalinated water made up 26% of urban supply while less than 1% was from groundwater extractions.
  • The contribution of desalinated water to urban supply was the highest it's ever been. The Melbourne Water Corporation opted to increase its reliance on desalinated water in 2019–20 following the very dry conditions in the previous year.

 

Water market activity

Werribee South coastline (istock © Greg Brave)

 

Table S3 Water trade in the Melbourne region during the 2019–20 year
Transaction typeNumber of transactionsVolume (ML)
Surface water transactions  
Entitlement trades231,425
Allocation trades251,765
Permanent trade of take-and-use licences19402
Temporary trade of take-and-use licences31972
Groundwater transactions  
Permanent trade of take-and-use licences*221,714
Temporary trade of take-and-use licences*32998

* Excludes any trade within unincorporated areas

 

  • Entitlement and allocation trades and lease (term transfers) of water shares, and temporary and permanent trade of take-and-use licences are allowed in the Melbourne region.
  • More information about water trading in the Melbourne region is available from the Bureau's Water Market Dashboard and the Victorian Water Register.

 

Cultural and environmental water

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

 

Cultural benefits

  • In general, water regimes required to support cultural values are not quantitatively defined in water allocation plans; however, the cultural values are considered within the environmental water provisions.
  • More information on cultural water requirements are provided in the Cultural water management section in the 'Region description'.

 

Environmental benefit

Environmental water management scenarios

  • In the Melbourne region, environmental water is provided according to the scenarios: held environmental water, planned and partly regulated surface water, and planned and unregulated surface water.

 

Environmental entitlements: held environmental water

  • The Victorian Environmental Water Holder holds three environmental water entitlements: Consolidated Yarra Environmental Entitlement 2006 (revised in July 2014), Tarago and Bunyip Rivers Environmental Entitlement 2009 (revised in June 2014), and Werribee River Environmental Entitlement 2011.
  • These entitlements prescribe environmental flow regimes in respective rivers including the characteristics of recommended environmental flows for the river reaches.
  • In 2019–20, 4,870 ML of water was released by Melbourne Water to meet the region's ecological objectives in the Yarra, Tarago, Maribyrnong and Werribee rivers (see figure below).

 

Map of environmental releases in the 4 major river systems. 830 ML of water was released to the environment from Werribee River, in the southwest of the region. 0 ML was released from the Maribyrnong River in the region's northwest. 4,000 ML was released from the Yarra River in the region's northeast. 40 ML was released from Tarago River in the region's southeast.
Figure S8 Delivery of held environmental water in each river system within the Melbourne region

 

Bulk entitlements

  • Bulk entitlements with the provisions for planned partly regulated surface water are: Southern Rural Water's bulk entitlement to the Maribyrnong River, Western Water's bulk entitlement to the Maribyrnong River, and Melbourne Water's bulk entitlement to the Maribyrnong, Bunyip and Tarago rivers.
  • Bulk entitlements with the provisions for planned unregulated surface water are: Southern Rural Water's bulk entitlement to the Werribee system for irrigation, Melbourne Water's bulk entitlement to the Yarra River, and Western Water's bulk entitlements to various sources in the Maribyrnong catchment and in the Werribee system.
  • Details of compliance with the conditions specified for the entitlement during the year, in particular the passing flows, are available in a report submitted by relevant bulk entitlement holders to the Victorian Minister for Water (this information is also typically contained in the responsible holder's annual report).

 

Streamflow management plans: planned unregulated surface water

  • In accordance with Section 32C of the Water Act, Melbourne Water, which administers streamflow management plans, must submit to the Victorian Minister for Water a report detailing its compliance with the plan during the year.
  • For more information, these reports can be found on the Melbourne Water website.