21.2 Surface water allocation announcements – urban water system

Supporting information

The volume presented (368,435 ML) represents the volume of water effectively allocated under the bulk entitlements held by Melbourne's retail water authorities.

Quantification approach

Data source

Melbourne Water: Internal Records; Western Water: Westen Water annual report 2012–13.

Provided by

Melbourne Water; Western Water.


The volume includes:
  • increases to this share of storage through inflows such as rainfall and runoff for those bulk entitlements which include a share of storage
  • increases in the entitlement equivalent to the delivery volume reported at line item 11.12 Entitled diversion of allocated surface water to urban water system for those bulk entitlements which do not include a share of storage.
The following table shows the breakdown of increases to the urban claim on surface water itemised by bulk entitlement and source.

Increase of urban claim on surface water for the Melbourne region during the 2012–13 year
Entitlement holder Source–bulk entitlement Component1 Volume (ML)
City West Water
South East Water
Yarra Valley Water
Yarra River Yarra River reservoirs share of net inflow* 312,311
Subtotal Yarra River 312,311
City West Water
South East Water
Yarra Valley Water
Tarago and Bunyip rivers Tarago River share of gross inflow 26,378
rainfall on Tarago reservoir 2,290
environmental internal spill to retailers account 2,077
Bunyip River increase = delivery 2,190
Subtotal Tarago and Bunyip rivers 32,935
Western Water Melbourne Headworks system Melbourne Headworks system increase = delivery 10,824
Subtotal Melbourne Headworks system 10,824
Western Water Maribyrnong catchment Gisborne–Baringo creek share of inflow 0
Lancefield share of inflow 2,123
Macedon and Mount Macedon share of inflow 650
Maribyrnong–Rosslynne Reservoir share of inflow 5,864
Riddells Creek share of inflow 101
Romsey share of inflow 340
Subtotal Maribyrnong catchment 9,078
Western Water Werribee Catchment Myrniong–Pykes Creek Reservoir increase = delivery 39
Werribee system–Merrimu and Djerriwarrh reservoirs share of inflow 3,248
Subtotal Werribee catchment 3,287
Total 368,435

1 Precipitation data provided by Melbourne Water (not precipitation data reported at line item 9.1) was used to calculate increases to the urban claim on surface water.

* Net inflow has been used in calculation, because evaporation volumes at Cardinia and Silvan reservoirs are unavailable for the full reporting year.

Assumptions, limitations, caveats and approximations


Uncertainty information

There is no uncertainty associated with this value.