Perth
14.2 Adjustment and forfeiture of groundwater allocation - urban water system

Supporting Information

This line item refers to the total forfeiture of groundwater allocations for the bore fields that supply water to the urban water system.

Quantification Approach

Data Source

Department of Water: Water Resource Licensing database, Water Corporation: Operational Data Storage System database.

Provided by

Department of Water.

Method

The portion of groundwater allocation that has not been abstracted at the end of the 2010–11 year is forfeited. That is, there is no carryover of entitlements into next year's account.

For all but one of the 10 bore fields within the Perth region that supply water to the urban water system, the licensed water management year is from 1 July to 30 June. For these licences, the forfeiture that occurs at the end of the 2010–11 year is calculated as the total annual allocation for these groundwater resources minus the total allocation diversion, as shown in the following table.

The water supply licences for Gingin have a water management year that ends on 30 September. Therefore, the forfeiture reported for Gingin is calculated as the total annual allocation minus the total allocation diversion between 1 October 2009 and 30 September 2010.

Total forfeiture for all groundwater resources within the Perth region is calculated in the following table.


Total forfeiture of groundwater allocation for the urban water system during the 2010–11 year

 

 

Volume (ML)

 

Licences with a water management year from 1 July to 30 June

 

 

Allocation announcement (refer to 22.2)

174,105

less

Allocation diversion (refer to 18.12)

165,141

 

Subtotal forfeiture

8,964

plus

Forfeiture for Gingin (reported on 30 Sept 2010)

105

 

Total forfeiture on 30 June 2011

9,069

 

Assumptions, Limitations, Caveats and Approximations

Nil.

Uncertainty Information

The uncertainty estimate was not quantified.

Comparative year

The following table presents substantive changes in the line item reported in this 2011 Account with the corresponding line item in the 2010 Account.

 

Comparative year information for line item 14.2

2011 Account line item

2010 Account line item

2011 Account volume for the 2009–10 year (ML)

2010 Account volume for the 2009–10 year (ML)

Change from the 2010 Account to the 2011 Account

14.2 Adjustment and forfeiture of groundwater allocation - urban water system

28.1.3.4 Adjustment and forfeiture of groundwater allocation–urban holder

1,405

1,522

Volume restated due to subsequent availability of actual meter readings (see line item 18.12)

Change in line item name and number