Murray–Darling Basin
Water accounting policies

a. Introduction

The information presented in the Murray–Darling Basin region water accounting report is based on agreements between the Murray–Darling Basin Authority and the Bureau of Meteorology (the Bureau).

The report has been prepared using an accrual basis of water accounting, with the exception of the water flow information. The water attribute being quantified is volume and the unit of account is megalitres (ML).

b. Recognition of water assets and water liabilities

Only water that is held or managed by the jurisdictional licensing authority, and from which future benefit can be derived by stakeholders of the region, is identified as a water asset. Water liabilities are constituted by present commitments to supply water, the discharge of which is expected to result in a decrease of the region's water assets or an increase in another water commitment to supply water.

A water asset is recognised in the Statement of Water Assets and Water Liabilities providing:

  • its volume can be quantified in a way that is complete, neutral and free from material error

  • the derived benefit is probable.

A water liability is recognised in the Statement of Water Assets and Water Liabilities providing:

  • its volume can be quantified in a way that is complete, neutral and free from material error

  • the decrease of the region's water assets to supply water is probable.

Water held in off-channel water 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 volume of line item 2.5 Other groundwater assets  included in the water accounting statements has been recognised as the long-term estimates of volumes for extraction (including New South Wales supplementary access licences for the specific year)  plus basic landowner right of groundwater, representing the extractable portion that is required under the Australian Water Accounting Standard 1 (Water Accounting Standard Board 2012). The relationship (i.e. depth/distance) between the water table and the environmentally sustainable limit changes during the year and on a year-to-year basis. As such, in any one year the actual depth of the water table or piezometric surface may be very different to the long-term average level. Due to the fact that information about the actual groundwater levels is not available, the long-term average information has been considered an appropriate quantification method for the groundwater asset.

c. Recognition of changes in water assets and water liabilities

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

Precipitation (line item 9.1 Precipitation on surface water) and evaporation (line item 17.1 Evaporation from surface water) are recognised only in relation to the storage surfaces (includes storages, lakes, weirs and locks in the regulated river). It does not represent all precipitation, evaporation and evapotranspiration within the region (notably, these processes occurring from the landscape are not captured).

That portion of runoff that flows into the surface water store is quantified and recognised. This runoff includes precipitation captured in the catchment less estimated evaporation and seepage and recorded as line item 9.4 Runoff to surface water.

The volume of water that returns after urban use (line item 9.9 Discharge from urban water system) meets the identification criteria as an increase to water assets; wherever it could be quantified accurately it is recognised in the Statement of Changes in Water Assets and Water Liabilities and Statement of Water Flows, and information is provided in the Notes.

Line item 10.13 Other groundwater increases and line item 18.18 Other groundwater decreases do not represent any physical groundwater flow. The volumes provided for these line items represent the change of the long-term estimates of volumes for extraction between the reporting year and the previous year. These changes were as a result of implementation of new water sharing plans, abolition of existing plans or changes made to New South Wales supplementary access licences. Both the Statement of Changes in Water Assets and Water Liabilities and Statement of Water Flows include line items 10.13 and 18.18, and information is provided in the Notes.

d. Water assets and water liabilities that fail the recognition criteria

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

  • they could not be quantified in a way that is complete, neutral and free from material error
  • in the case of water assets, they were unlikely to provide a future benefit to the region or the region's stakeholders
  • in the case of water liabilities, they were unlikely to result in a decrease in the region's water assets or an increase in another water liability when the obligation is discharged.

While water within line item 1.2 Unregulated river is a vital water asset for the conveyance of water within the region, it cannot be quantified accurately due to a lack of reliable information.

Details of volumes of water stored in lakes and wetlands are available in line item 1.4 Lakes and wetlands. The line item includes information only for nine lakes. Volume of water stored in other lakes and wetlands are not available.

The description of other water assets and water liabilities that failed the recognition criteria is given in line items 2.1 Water table aquifer and 2.2 Underlying aquifers.

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

The volumes of changes to several water assets and water liabilities identified in the Murray–Darling Basin region were not recognised in the water accounting statements but replaced by dashes ('–') because they could not be quantified in a way that is complete, neutral and free from material error.

The description of those changes to water assets and water liabilities that failed the recognition criteria is given in the following line item notes:

These line items that could not be quantified form part of:

f. Restatement of comparative year information

Several comparative year volumes in the water accounting statements were restated from the 2011 Account in order to provide more useful information to the users. Restatements may be due to either of the following causes:

  • line item name changes
  • error in the 2011 Account, referred-to as 'prior period error'
  • change in the presentation of the water accounting statements, where line items were generally simplified since the 2011 Account
  • change in scope, for instance to include more of the region's area in the definition of a line item in order to present more complete information
  • improvement in quantification methodology
  • increase in the data available to quantify a line item.

In accordance with the Standard, changes of presentation and scope of the line items require restatement of the comparative values in the water accounting statements. Changes of methodologies and data availability, although not required by the Standard, were restated in the water accounting statements if the change was considered material. In particular, any change affecting the allocation accounts was restated.

The notes attached to the line items of the water accounting statements give the details of all the restatements made.

g. Level of reporting in case of bulk entitlements in Victoria

When water is managed under a bulk entitlement in Victoria (see Water management plans  and Water entitlements under 'Contextual information') the National Water Account 2012 reports at the level of the collective retail water access entitlements issued under the bulk entitlements. This means that the water liabilities identified against the region are the allocations announced on these retail entitlements and for bulk entitlements held for the benefit of the environment. Where a bulk entitlement holder has a claim over water located outside the region, that claim will likewise be identified as a water asset of the region.

h. Treatment of water trade

It is assumed that all water traded (allocation trade) within the Murray–Darling Basin region has been provided to an account holder within the region, even though delivery may be provided via the distribution network to a location outside of the region.

Water trades are not reported in the water accounting statements; however, some water trades result in the conversion of the category and purpose of use, which will affect their classification. It is believed these effects are reflected in relevant line items for allocation remaining, allocation announcements, allocation diversion, and forfeiture and adjustments in the water accounting statements.

Information about inter-state, inter-valley and intra-valley trade is included in the Water market activity note.

i. Treatment of external transfers

Transfers of water that occur across the boundaries of the Murray–Darling Basin region and impact on the water assets and water liabilities of the region are reported in the water accounting statements. Information about these transfers is also provided in the line item notes.

The following external transfers are reported in the water accounting statements:

  • Import from the Glenelg River (appears as an inter-basin transfer, see line items 9.11, and 9.15)
  • Import from the Snowy Mountains scheme (appears as an inter-basin transfer, see line items 1.5, 9.11, 9.15 and 17.7).

The following transfers form part of allocation diversion volumes, and are not reported separately in the water accounting statements:

  • Export to Sydney region from the Fish River system in the Macquarie River system (allocation diversion from the Fish River, see line item 17.7).
  • Export to Metropolitan Adelaide and associated country areas (allocation diversion made under the River Murray entitlements held by South Australia, see line items 21.2 and 17.12).
  • Export to Melbourne (diversion made under commercial agreement from the Goulburn–Broken River system, see line item 17.12).
  • Water transfers from the Goulburn–Broken River system to Ballarat (in the Barwon River system) via 'Goldfields superpipe' (see line item 17.12).
  • Water transfers from the Goulburn–Broken River system (from Silver and Wallaby creeks, which are tributaries of the Goulburn River) to the Melbourne urban supply system, see line item 17.8).

Import from South East Queensland region (see note of line item 9.11) is not reported in the water accounting statements as it is a direct import by the Toowoomba Council distribution system, which is not considered part of the region.