Ord

The volume recognised in the water accounting statements (17,415 ML) represents the volume of water abstracted during 2009–10 from:

• the Ord River above Lake Argyle
• unregulated tributaries of the Ord River, including the Dunham River and Packsaddle Creek
• Moochalabra Dam, for the purpose of water supply to Wyndham
• Lake Argyle, for the purpose of water supply to the Lake Argyle village.

The breakdown of the abstraction according to the stated license entitlement purpose is provided in the table below.

Data source

Western Australian Department of Water: Water Resource Licensing (WRL) database and Water Information (WIN) database.

Data provider

Western Australian Department of Water.

Method

The volume presented for this line item is a combination of metered data and estimates.

Where metered data are available, the abstraction is calculated as the actual abstraction for the reporting period. Where metered data are not available, the volume of abstraction is estimated to be the full annual entitlement, divided by the number of days that each licence was active during the reporting period. The number of days the licences were active is calculated using the annual renewal date of each individual licence:

• for licences that expired during the reporting year, the volume of abstraction is estimated to be the full entitlement, divided by the number of days from 1 July 2009 until its expiry date
• for new licences that were created during the reporting year, the volume of abstraction is estimated to be the full entitlement, divided by the number of days from the licence start date until 30 June 2010.

Some licences are issued in perpetuity and do not have an annual renewal date. In these cases, the volume of abstraction is estimated to be the amount of one full year’s allocation for licences in force during the reporting year.

Uncertainty

Derived from estimated data. Ungraded.
Derived from measured data. Uncertainty range +/–5%.

Assumptions, approximations and caveats/limitations

• There is not sufficient information relating to actual abstraction to provide more accurate estimates of abstraction for all licences. The pro-rata estimates of abstraction assume that the full annual entitlement is abstracted each year and that the rate of abstraction is uniform throughout the year. It is unlikely on both counts that this will be the case for
  all licences.
• For licences that are metered, the licencee is required to install a cumulative water meter of a type approved under the Rights in Water and Irrigation (Approved Meters) Order 2009 for each water draw point under the licence. The licencee must ensure the installed meter(s) accuracy is maintained to within +/–5% of the volume metered, in field conditions.
• Meters must be installed in accordance with the provisions of the Guidelines for Water Meter Installation (Western Australian Department of Water 2009).