Melbourne

1.1 Storages – entitlement system

Supporting information

The volume recognised in the water accounting statements (381,507 ML) represents the volume of water held in surface water storages that are used to supply water for licensed entitlements. The volume reported for this line item includes the volume of dead storage.

The volume provided is the sum of the volume held in all the reservoirs in the Melbourne region. Specific details of individual storages are provided in the table below.

Volume of water held in entitlement system storages in the Melbourne region
Storage manager	Storage name	Total capacity [ML]	Dead storage [ML]	Volume (ML) 01 Jul 2009	Volume (ML) 30 Jun 2010
Melbourne Water	O'Shannassy	3,123	unknown	1,978	3,155
	Yan Yean	33,125	2,859	5,721	11,197
	Greenvale	27,501	662	20,022	16,999
	Maroondah	28,233	6,054	6,344	10,772
	Silvan	40,581	136	34,971	35,931
	Cardinia	288,964	2,053	109,642	101,279
	Upper Yarra	204,985	4,406	82,074	113,718
	Sugarloaf	99,222	2,969	14,914	58,402
	Tarago	37,580	unknown	22,025	21,784
Southern Rural Water	Melton	14,360	140	532	2,879
	Merrimu	32,215	335	3,135	3,046
	Pykes Creek	22,119	1,770	540	1,196
	Rosslynne	25,400	150	798	1,149
Total		857,408	21,534	302,696	381,507

Note: Melbourne Water typically quote live storage volumes for reservoirs they manage. Live storage is the difference between total capacity and dead storage.

Quantification approach

Data source

Bureau of Meteorology: water storages, Australian Water Resources Information System.

Data provider

Bureau of Meteorology.

Method

Storage volume was measured at the start and end of 2009–10 by using gauged water level height(s) (metres, Australian Height Datum) for individual storages. The height measurement was converted to a volume using the storage rating table(s) provided by the managing authority.

The storage volume of individual storages was aggregated to present the total volume for the line item.

Uncertainty

The volume is estimated from measured data. The accuracy is ungraded.

Approximations, assumptions, caveats/limitations

Storage-volume curves represent specifically surveyed parts of the water storage, and may not reflect the storage-volume relationship across the entire storage.
Water storages are subject to sedimentation and other physical changes over time, which in turn affects the accuracy of the storage rating table.
Southern Rural Water use different figures for the management of their resources. These differences reflect uncertainty in the true value of these quantities. They use 14,364 ML for the volume of Melton Reservoir at capacity (compared to 14,360 ML) and they use 141 ML for dead storage (compared to 140 ML). Southern Rural Water use dead storage of Pykes Creek Reservoir of 1,923 ML (compared to 1,770 ML) and Merrimu at capacity of 32,516ML (compared to 32,215 ML).