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National Water Account 2015

Ord: Water accounting policies

Lake Argyle Dam, Western Australia (iStock © czardases)

Introduction

The information presented in the Ord region water accounting report is based on collaboration between the Bureau of Meteorology and the:

  • Western Australian Department of Water (Department of Water)
  • Water Corporation of Western Australia (the Water Corporation).

The report has been prepared using an accrual basis of water accounting, with the exception of the physical water flow information. The water attribute being quantified is volume, and the unit of account is megalitres (ML). Where a reported volume is negative, it is shown in brackets. The applicable reporting period is from 1 July 2014 to 30 June 2015.

 

Recognition of water assets and water liabilities

Only water that is held or managed by the State or Territory licensing authority or the urban utilities and from which a future probable benefit can be derived by the region's stakeholders is defined as a water asset.

Water liabilities are constituted by present commitments to supply water, the discharge of which is expected to result in a probable decrease of the region's water assets or a probable increase in another water commitment to supply water.

Provided its volume can be quantified in a way that is complete, neutral, and free from material error, the volume of the water asset or water liability is recognised in the Statement of Water Assets and Water Liabilities.

Water held in storages that has already been abstracted from the entitlement system is deemed not to be part of the region (regardless of the storage's size or connection to the system). This is because the attendant water right has already been exercised.

The regulated channel of the lower Ord River is recognised as a water asset when the electrical conductivity is below 1,500 μS/cm. Water in the regulated channel above this salinity level is not deemed fit for use and as such does not provide a future benefit to the Ord region.

 

Recognition of changes in water assets and water liabilities

The increases and decreases to the reported water assets and water liabilities consist of changes that can be quantified in a way that is complete, neutral, and free from material error. These volumes are presented in the Statement of Changes in Water Assets and Water Liabilities and the Statement of Water Flows.

Precipitation and evaporation are recognised only in relation to the surfaces of open storage volumes. They do not represent all precipitation and evaporation within the region (notably, these processes occurring from the landscape are not captured).

That portion of runoff that flows into the surface water store (storages and rivers) is quantified and recognised in the Statement of Changes in Water Assets and Water Liabilities. This runoff includes precipitation captured in the catchment less evaporation and infiltration and is recorded as Runoff to surface water.

Allocation announcements on regulated entitlements have been recognised as an increase in water liabilities. Note that the definitions of regulated or unregulated entitlements for the purpose of the National Water Account may be different to the meaning applied by the jurisdiction (refer to 'Glossary'). Please refer to the Water rights, entitlements, allocations and restrictions note for more information on allocations.

 

Water assets and water liabilities that fail the recognition criteria

The volumes of several water assets identified in the Ord region were not reported in the water accounting statements but replaced by dashes ('–') as they 'failed the recognition criteria' specified in the Australian Water Accounting Standard 1, because:

  • they could not be quantified in a way that is complete, neutral and free from material error; and/or
  • they were unlikely to provide a future benefit to the region or the region's stakeholders.

Water assets that failed the recognition criteria include unregulated rivers, lakes and wetlands (see Surface water note) and groundwater aquifers (see Groundwater note).

 

Changes to water assets and water liabilities that fail the recognition criteria

The volumes of several changes to water assets identified in the Ord region were not reported in the water accounting statements but replaced by dashes ('–') as they 'failed the recognition criteria' specified in the Australian Water Accounting Standard 1, because:

  • they could not be quantified in a way that is complete, neutral and free from material error; and/or
  • they were unlikely to provide a future benefit to the region or the region's stakeholders.

Items that failed the recognition criteria include inter-region groundwater flows and groundwater discharge to landscape (see Groundwater note).

 

Restatement of comparative year information

In accordance with the Australian Water Accounting Standard 1, comparative year volumes must be restated in the statements if there is a prior period error or a change in item presentation. Comparative year volumes are not required to be restated if there is a change in scope or methodology, or subsequent data availability for the quantification of an item.

There were no comparative year volumes in the water accounting statements restated from the 2014 Account.

 

Transactions within the region

Transactions between water assets and water liabilities within the region (e.g., between the surface water store and the groundwater store) are not reported in the water accounting statements because they do not affect the region's total water assets and water liabilities.

This information is reported in the Water resources and systems note, which includes water accounting statements for each water store. These contain internal transactions that were excluded from the consolidated water accounting statements. This ensures that transactions between water assets and water liabilities within the region are still reported.