Perth

This line item refers to the total forfeiture of water allocations for the major reservoirs within the Perth region that supply water to the urban system.

All but one of the 14 surface water resources are used for public water supply within the Perth region. The other (Helena River), primarily supplies water to the Kalgoorlie Goldfields, located outside the Perth region boundary.

Data source

Western Australian Department of Water: Water Resource Licensing database.

Data provider

Western Australian Department of Water.

Method

The portion of a regulated entitlement that has not been abstracted at the end of the reporting period is forfeited. That is, there is no carryover of entitlements into the next reporting period.

For all but one of the 14 surface water Urban Supply licences within the Perth region, the licensed water management year is from 1 July to 30 June. For these licences, the forfeiture that occurs at the end of the reporting period (30 June 2010) is calculated as the total annual allocation for these surface water resources minus the total allocation diversion, as shown in the table below.

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

Total forfeiture for all surface water resources within the Perth region is calculated in the table below.

Uncertainty

Ungraded.

Approximations, assumptions, caveats/limitations

Nil.