14.2 Adjustment and forfeiture of groundwater allocation – urban water system

Supporting information

This line item volume (13,150 ML) represents the total forfeiture of groundwater allocations for the urban water system in the Perth region during the 2011–12 year.

Quantification approach

Data source

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

Provided by

Department of Water and Water Corporation.


The portion of groundwater allocation that has not been abstracted at the end of the 2011–12 year is forfeited, i.e. there is no carry-over of entitlements into next year's account.

For all the groundwater licences within the Perth region that supply water to the urban water system, the licensed water management year is 1 July to 30 June. The forfeiture that occurs at the end of the 2011–12 year is calculated as the total annual allocation for these groundwater resources less the total allocation diversion.

Total forfeiture also includes the volume of allocation remaining after a licence has been terminated or cancelled. During the 2011–12 year, the groundwater licences for the Gingin bore field were terminated. The allocation remaining for these licences at the termination date were forfeited.

Total forfeiture is calculated as shown in the following table.

Total forfeiture of groundwater allocation for the urban water system during the 2011–12 year



Volume (ML)


22.2 Groundwater allocation announcement



18.12 Allocated groundwater extraction






Forfeiture from terminated licences



Total forfeiture on 30 June 2012


Assumptions, limitations, caveats and approximations


Uncertainty information

The uncertainty estimate was not quantified.