17.11 Surface water allocation diversion
The volume diverted from the North Para and Little Para rivers under the surface water liability in the 2010–11 year was 1,234 ML. The volume reported increased marginally compared to the previous reporting period (1,067 ML). This increase suggests that demand on the surface water resources within the Barossa Prescribed Water Resources Area (PWRA) did not change significantly, despite increased precipitation for the reporting period.
Metered watercourse diversions were obtained from the WILMA licensing database for the Barossa PWRA. The source description field in WILMA licensing database was used to determine if an on-channel storage was present. Diversions that do not list an on-channel storage were assumed to be diverted directly from the watercourse.
Some diversions were unmetered in the Barossa PWRA. The volume of metered diversions in the Barossa was increased based on the assumption that 20% of the total extraction was unmetered.
|Direct watercourse extraction||323|
|From on-channel storage||664|
|Correction for unmetered extraction||247|
Assumptions, Limitations, Caveats and Approximations
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. In the 2010 Account, surface water diversions from the Barossa PWRA were reported at line item 14.6 Entitled diversion of unregulated surface water flows. 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 1,067 ML.