Melbourne
11.18 Increase of urban claim on surface water

The volume presented (425,527 ML) represents the volume of water effectively allocated under the bulk entitlements held by Melbourne's retail water authorities. 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 2011–12 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 gross inflow	336,495
			Rainfall on all reservoirs in Yarra basin	36,463
Subtotal Yarra River				372,958
City West Water South East Water Yarra Valley Water	Tarago and Bunyip rivers	Tarago River	Share of gross inflow	32,199
			Rainfall on all reservoirs in Tarago basin	2,552
		Bunyip River	increase = delivery	2,196
Subtotal Tarago and Bunyip rivers				36,947
Western Water	Melbourne Headworks system	Melbourne Headworks system	increase = delivery	5,108
Subtotal Melbourne Headworks system				5,108
Western Water	Maribyrnong catchment	Gisborne—Baringo Creek	share of inflow	3
		Lancefield	share of inflow	171
		Macedon and Mount Macedon	share of inflow	723
		Maribyrnong—Rosslynne Reservoir	share of inflow	3,819
		Riddells Creek	share of inflow	10
		Romsey	share of inflow	326
Subtotal Maribyrnong catchment				5,052
Western Water	Werribee Catchment	Myrniong—Pykes Creek Reservoir	increase = delivery	39
		Werribee system—Merrimu and Djerriwarrh reservoirs	share of inflow	5,423
Subtotal Werribee catchment				5,462
Total				425,527

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.

In the 2011 Account, it was reported that  bulk entitlements held by Melbourne's retail water authorities did not have formal allocation announcements. Consequently, the volume of water effectively allocated was equivalent to the volume of water diverted from surface water storages in the Melbourne region. This does not accurately reflect the nature of the bulk entitlements operating in the Melbourne region.

In the 2012 Account, increases to these bulk entitlements have been reported as the sum of the following two components:

• 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 for those bulk entitlements which do not include a share of storage.

This represents a significant change compared to the 2011 Account, but provides improved and more accurate information for users of the Account and ensures consistency in the approach used to report on other claims to water (refer to line item 9.15 Increase of inter–region surface water claim on water); however, data on inflows to these storages were not available at the time of publication.

Consequently, the comparative year volume was restated as 937,686 ML and comprised of:

• the delivery volume (355,241 ML) for all bulk entitlements for the 2010–11 year
• an adjustment (582,445 ML) equivalent to the closing balance for line item 3.7 Urban claim on surface water for the 2010–11 year.