13.1 Adjustment and forfeiture of surface water allocation

Supporting Information

Information on rollover allocations was not available at the time this report was compiled. For water accounting purposes, where the volume of carryover is not available, the volume of unused allocated water is considered to be forfeited. Therefore, the volume reported (1,525 ML) was the unused portion of the surface water allocation volume in the 2010–11 year.

Although data were unavailable, the Barossa Prescribed Water Resources Area (PWRA) water allocation plan does indicate that licensees may carryover the unused portion of their allocation up to a maximum of 30% of the annual allocation. At a maximum this would mean that approximately 800 ML would be allowed to be carried over. This represents a significant proportion of the water available for diversion and almost 50% of the water forfeited. Overall, the omission of this information is very relevant to users of the National Water Account.

For more information on this surface water liability see line item 5.1 Surface water allocation remaining.

Quantification Approach

Data Source

Bureau of Meteorology.

Provided by

Bureau of Meteorology.


The volume of water forfeited at the end of the 2010–11 year was calculated by subtracting the volume of water abstracted under the surface water liability in the Barossa PWRA from the volume of water available for abstraction (allocation) under the water liability. This calculation is summarised in the following table. 

Calculation of forfeiture on the surface water liability in the Adelaide region for the 2010–11 year


Line item

Volume (ML)

Volume available for abstraction (carryover) at the start of the year

5.1 Surface water allocation remaining (opening balance)

add  – volume of water made available for abstraction during the year (announcement)

21.1 Surface water allocation announcement


less – volume of water diverted

17.11 Surface water allocation diversion


less – volume of water permitted to be carried over to the proceeding year

5.1 Surface water allocation remaining (closing balance)



13.1 Adjustment and forfeiture of surface water allocation


Assumptions, Limitations, Caveats and Approximations

This approach assumes that all unused allocated water is forfeited.

Uncertainty Information

The uncertainty estimate was not quantified.

Comparative year

In the 2010 Account surface water liabilities were not recognised in the Adelaide region, therefore there was no corresponding line item reported. In 2011, due to an improved understanding of the nature of surface water rights in the Adelaide region, water licences for surface water diversions in the Barossa PWRA were recognised as surface water liabilities. Restatement of the value published in the 2010 Account was made as the change was material, and increased the accuracy and comparability of the information provided to the users of the National Water Account. The restated comparative year volume is 1,692 ML. Similar to the volume reported in the 2011 Account, the restated volume assumed the unused portion of the allocated water was forfeited.