Sydney
13.2 Adjustment and forfeiture of surface water allocation – urban water system
Supporting information
The liability decrease to the surface water store from the adjustment of a part of the allocation/claim considered for the urban water system is 597,366 ML.
The volume is the difference between calculated volumetric allocation stated in line item 21.2 (1,035,355 ML) and regulated diversions stated in line item 17.12 (440,989 ML).
Reconciliation of this line item is shown in the following table.
Calculation |
Line item |
Volume (ML) |
|
5.2 Opening balance (as at 30 June 2011) |
0 |
add |
21.2 Surface water allocation announcements – urban water system |
1,038,355 |
less |
440,989 |
|
less |
597,366 |
|
equals |
5.1 Closing balance (as at 30 June 2012) |
0 |
Quantification approach
Data source
Entitlement information was extracted from: Water Sharing Plan for the Greater Metropolitan Unregulated River Water Sources; databases and water management licences for Goulburn Mulwaree Council, Lithgow City Council, Shoalhaven City Council, Palerang City Council and Wingecarribee Shire Council. Line item 17.2 provides data sources for metered diversions from storages.
Provided by
The Bureau calculated adjustment and forfeiture of allocation/claim; entitlement information provided by the New South Wales Office of Water, Goulburn Mulwaree Council, Lithgow City Council, Shoalhaven City Council and Wingecarribee Shire Council: entitlement information. See 'Data provider' in line item 17.2; metered diversions from storages.
Method
Under the Water Sharing Plan, carryover of any unused allocation at the end of the year is allowed for licences not issued under the Major utility category. The maximum volume of carryover allowed is determined by the rules in the Water Sharing Plan and the volume of water diverted under the licence. The carryover volume for the licences reported under this line item have not been quantified. Therefore, for the purposes of the National Water Account, the carryover volume (opening and closing balance as reported in 5.2 Surface water allocation remaining) was assumed to be zero. In order to the balance the account, the liability decrease reported in this line item is equal to any remaining unused allocation.
Calculation methods for the announced allocation and measured diversions are available in:
- line item 21.2 for the volumetric value for the announced allocation
- line item 17.12 for metered diversions from storages.
Assumptions, limitations, caveats and approximations
- Carryover has not been quantified
Uncertainty information
For entitlements: the allocation/claim was derived from the Water Sharing Plan for the Greater Metropolitan Unregulated River Water Sources. Uncertainty was not quantified.
Wingecarribee Shire Council: the volume is based on measured data. Estimated accuracy based on meter accuracy is +/– 7%. External flow verification audits for the flow meters are conducted annually by Hydrometric Consulting Services.
Sydney Catchment Authority: the volume is based on measured data. Estimated accuracy based on meter accuracy is +/– 2%.
Lithgow City Council: the volume is based on measured data. Estimated uncertainty based on meter accuracy is +/– 2%. Meters are calibrated annually by ABB (meter supplier).
Goulburn Mulwaree Council: the volume is based on metered data. Estimated accuracy based on meter accuracy and professional judgment is +/– 20%.
Sydney Water Corporation: the volume is based on measured data. Estimated accuracy based on meter accuracy is +/– 2%.