The Melbourne region

Overview of the 2012–13 year

The Melbourne region is located in the southeast of mainland Australia, and extends from the coastlines of Port Phillip Bay, Westernport Bay, and Bass Strait to the south; the Yarra ranges in the east; and the Great Dividing Range to the north and west. The region includes the Bunyip River, Yarra River, Maribyrnong River and Werribee River catchments and also an area adjacent to the Werribee river catchment serviced by the Melbourne Water Western Wastewater Treatment Plant.

Rainfall across the Melbourne region was generally below average during the 2012–13 year. The below average rainfall conditions across Melbourne contributed to decreased inflows into surface water storages. Sligthly above average rainfall was observed during the winter and early spring season across the region, which is reflected in slightly above average streamflows for Bunyip and Yarra rivers. Maribyrnong and Werribee rivers recorded below average streamflows during the reporting year except in the winter season months.

During the 2012–13 surface water was the primary source of water supply for the region while groundwater was the secondary source. Recycled water was a minor supply source and, due to the availability of surface water supplies, no desalination water was ordered for the 2012–13 year. The urban water supply was sourced from surface water storages within the region and supplemented by water from the Thomson Reservoir, which is outside the region.

During the 2012–13 year, the volume of surface water diverted for urban supply to users increased by approximately 9% compared to the 2011–12 year.

Closing net water assets in the Melbourne region were 1,445,709 ML, compared to 1,443,482 ML at the end of the 2011–12 year. The storages volume decreased by 103,651 ML, but the inter-region claim on water increased by 101,767 ML. While surface storage volume within the region decreased, the closing net water assets increased by 2,227 ML due to the increase in inter-regional claim on water from the Thomson Reservoir and Lake Eildon in the region. For more information on the region's water assets refer to Water accounting statements.

The key water account information for the Melbourne region during the 2012–13 year is presented in the following table. Information on the uncertainty associated with the volumes presented in the table is provided in the relevant sections of the account.

 

Key water account information for the Melbourne region during the 2012–13 year


Contextual information: Climate overview
Climate Overview 2012–13 2011–12 Long–term average
Rainfall: 726 mm Rainfall: 1,008 mm Rainfall: 868 mm
Evapotranspiration: 689 mm Evapotranspiration: 788 mm Evapotranspiration: 697 mm
For more detail on the Melbourne climate refer to Climate overview.

 

Contextual information: Water overview
Water overview Werribee River Maribyrnong River Yarra River Bunyip River
below average flows below average flows above average flows above average flows
For more detail on streamflow in the Melbourne region refer to Water overview.

 

Water accounting statements
Accounting statements 2012–13 2011–12
Total water assets (as at 30 June) 1,445,709 1,443,482
Total water liabilities (as at 30 June) 0 0
Change in net water assets 2,227 252,584
Closing net water assets 1,445,709 1,443,482
For more detail on water assets and water liabilities refer to Water Accounting statements.

 

Notes: Water resources and systems

 

Surface water storage
Surface water 30 June 2013 30 June 2012
Total capacity Volume % of capacity Volume % of capacity
857,408 ML 582,979 ML 68% 686,630 ML 80%
For more detail on surface water storage in the Melbourne region refer to Surface water.

 

Water abstractions
Groundwater Total water abstracted  
2012–13 2011–12 Recent activity
Surface water: 436,625 ML Surface water: 404,934 ML Water abstraction for urban water supply and private use has increased.
Groundwater: 15,478 ML Groundwater: 13,173 ML
For more detail on water abstraction in the Melbourne region refer to Surface water and Groundwater.

 

Urban water supply
Urban water system Total water supplied  
2012–13 2011–12 Recent activity
408,878 ML 374,198 ML* Urban water supplied has increased.
For more detail on the urban water system in the Melbourne region refer to Urban water system.

*In 2011-12 the reported value of 356,398 ML was for urban water consumption. This has been changed to urban water supply value this year to 374,198 ML.