Sydney
Water accounting policies

The information presented in the Sydney region is based on agreements between the Bureau of Meteorology (the Bureau) and reporting partners, including:

• New South Wales Office of Water
• Sydney Catchment Authority
• Sydney Water Corporation
• Shoalhaven City Council
• Wingecarribee Shire Council
• Goulburn Mulwaree Council
• Lithgow City Council.

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 litres presented as megalitres (ML).

Only water that is held or managed by the State licensing authority or the urban utilities and is part of the entitlement system is defined as a water asset. 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 size of the storage or its connection to the system). This is because the attendant water right has already been exercised.

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 or the Statement of Water Flows.

Precipitation and evaporation are recognised only in relation to the surfaces of open storage volumes and unregulated river channels (9.1 Precipitation on surface water and 17.1 Evaporation from surface water) for which volumes have been provided They do not represent all precipitation, evaporation and evapotranspiration within the region (notably, these processes occurring from the landscape are not captured).

The portion of runoff that flows into the surface water store (storages and rivers) is quantified and recognised on the Statement of Changes in Water Assets and Water Liabilities or the Statement of Water Flows. This runoff includes precipitation captured in the catchment less evaporation and infiltration and is recorded as line item 9.4 Runoff to surface water.

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

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

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

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

1.3 Regulated river

1.4 Lakes and wetlands

2.1 Water table aquifer

3.1 Urban water supply system

3.2 Wastewater system

3.3 Recycled water system

The volumes of several changes to water assets and water liabilities identified in the Sydney region were not reported 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.

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

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

10.1 Groundwater inflow from outside region

10.2 Groundwater inflow from outside region at coast

10.3 Recharge from landscape

18.1 Groundwater outflow to outside region

18.2 Groundwater outflow to outside region at coast

18.3 Discharge to landscape

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:

• change in the presentation of the water accounting statements, in which line items have been generally simplified since the 2011 Account
• change in scope, e.g. 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 led to an automatic restatement of the values in the water accounting statements. Changes of methodologies and data availability, although not required by the Standards, led to a restatement of the volumes 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 detail on all the restatements made.