Perth
5.1 Surface water allocation remaining

Supporting Information

This line item refers to all surface water supply in the Perth region not related to urban water systems or irrigation schemes. It includes water supply to individual users in the mining, industrial and agricultural sectors.

The volume recognised in the Statement of water assets and water liabilities (28,763 ML) represents the volume of surface water allocation remaining for these licence entitlements at the end of the 2010–11 year.

Quantification Approach

Data Source

Department of Water: Water Resource Licensing database.

Provided by

Department of Water.

Method

The allocation remaining was calculated as shown in the following table.


Volume of surface water allocation remaining at the start and end of the 2010–11 year

 

Account

Volume (ML)

 

Opening balance (as at 30 June 2010)

28,830

add

21.1 Surface water allocation announcements

42,876

less

17.11 Surface water allocation diversion

42,640

less

13.1 Adjustment and forfeiture of surface water allocation

303

 

Closing balance (as at 30 June 2011)

28,763


 

The total allocation remaining on 30 June 2011 for private user entitlements is relatively large compared to that for urban water or irrigation scheme supply (see line items 5.2 and 5.3, respectively). This is because there are many private user entitlements within the Perth region that do not have an anniversary date occurring at 30 June (in general, the water management year commences when the licence is issued).


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 5.1

2011 Account line item

2010 Account line item

2011 Account volume at 30 June 2010 (ML)

2010 Account volume at 30 June 2010 (ML)

Change from the 2010 Account to the 2011 Account

5.1 Surface water allocation remaining

8.1.9.7 Allocation on regulated flows remaining–other lumped holders

28,830

24,422

Prior period error: incorrect dates used when calculating the allocation remaining

Change in line item name and number