The information presented in the Sydney region is based on agreements between the Bureau of Meteorology (the Bureau) and reporting partners, including:
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).
Only water that is held or managed by the state licensing authority or the urban utility and which is part of the entitlement system is defined as a water asset. Provided its volume can be quantified with representational faithfulness (WASB 2009, p. 4), the asset is recognised in the Statement of Water Assets and Water Liabilities. Where a water asset or water liability does not meet the recognition criteria, it is reported in the Statement of Water Assets and Water Liabilities with a dash (–). Water held in storages that has already been abstracted from the entitlement system is deemed not to be part of the water report entity (regardless of its size or connection to the system). This is because the attendant water right has already been exercised.
Line item 1.2 Unregulated channel is recognised as a water asset for the channel reaches for which reliable data are available to quantify the volume with representational faithfulness. For the other channel reaches, water in the unregulated channel connected surface water is not recognised in the water accounting statements.
Although water within Line item 1.3 Regulated channel is a vital water asset for the conveyance of water within the water report entity, it cannot be quantified with representational faithfulness because reliable data are not available.
The volume of water within Line item 1.4 Lakes and wetlands - connected cannot be quantified with representational faithfulness because reliable data are not available. The volume of water held in lakes and wetland is relatively small in size and its omission does not have a material impact on the total water resource available. It is recognised that water within Line item 1.4 makes a significant contribution to environment benefits in the water report entity.
Line item 2 Groundwater store assets within the Sydney region cannot be quantified with representational faithfulness because reliable data are not available. Information in relation to groundwater is recorded in the contextual statement, at the end of this note (Water assets and liabilities that fail the recognition criteria) and in the note Water rights, entitlements, allocations and trade.
The water within Line item 5 Water distribution system store cannot be quantified with representational faithfulness because reliable data are not available and, as such, it is not recognised in the Statement of Water Assets and Water Liabilities. It is considered that the pipes are always full and may hold a large volume of water, but the omission of the volume from the Statement of Water Assets and Water Liabilities is not considered material because the volume is nearly the same throughout the year.
The increases and decreases to the water assets and water liabilities reported consist only of changes that can be quantified with representational faithfulness (WASB 2009, p. 4). Where a change to a water asset or water liability does not meet the recognition criteria, it is reported in the Statement of Changes in Water Assets and Water Liabilities and the Statement of Physical Water Flows with a dash (–). These increases and decreases form part of Line item 30 Unaccounted-for difference and are explained in the notes.
Precipitation and evaporation (Line item 13.1 Precipitation on connected surface water and Line item 14.1 Evaporation from connected surface water) are only recognised in relation to storage surfaces and unregulated river channels for which volumes are provided in the water accounting statements. It does not represent all precipitation and evaporation within the physical region of the water report entity. Notably, these processes occurring from the landscape are not captured.
The portion of run-off that flows into the storages is quantified and recognised. This run-off includes precipitation captured in the catchment less landscape evaporation and seepage to groundwater and is recorded as Line item 13.4.1 Run-off to connected surface water.
Line item 13.4.2 Diffuse return of irrigation water to connected surface water refers to seepage into river channel of water used for irrigation that does not enter the river at a gauged entry point. This item is considered material even though it is small in volume. The volume cannot be quantified with representational faithfulness because reliable data are not available.
Volume of water stored in aquifers, and groundwater flows and extractions could not be quantified with representational faithfulness (WASB 2009 , p. 4), so are not recognised in the water accounting statements. Other information in relation to groundwater is recorded in the contextual statement and in the notes (‘Water rights, entitlements, allocations and trade’).
Sydney’s desalination plant at Kurnell provides desalinated water to Sydney Water Corporation’s (SWC) distribution system (see ‘Other water resources’ in the contextual statement for more details on desalinated water supply). The following table details the Sydney desalination plant production for 2009–10.
Sydney desalination plant 2009–10 production volumes
| Annual plant production capacity (ML) | 2009–10 sea-water intake (ML) | 2009–10 desalinated water produced (ML) | 2009–10 return to sea (ML) |
|---|---|---|---|
| 91,250* | 67,061 | 19,952 | 47,109 |
* Annual plant capacity was not available for production for the whole of 2009–10 because the plant commenced its operation on 28 January 2010.
Source: Sydney Water Corporation (2010c)
Sydney Water Corporation has a contract agreement with the plant operator to provide water. This agreement does not specify carry-over volumes resulting from unused water in the previous year. Therefore, there is no claim remaining at the beginning of the year for carry-over volumes.
Although there was a maximum daily supply rate, there was no binding volume contracted in 2009–10. Therefore, for 2009–10, there are no contracted volumes for desalinated water transfer or adjustment or forfeitures.
The following table shows the volume of recycled water supplied by water authorities to a variety of users in the Sydney Region during 2009–10.
Recycled water supplied in 2009–10
| Water authority | Volume supplied for industrial, commercial, agricultural and municipal purposes (ML) | Volume supplied for residential use (ML) | Volume supplied for environmental purposes (ML) | Total volume supplied (ML) |
|---|---|---|---|---|
| Sydney Water Corporation | 13,180 | 2,209 | 1,980 | 17,369* |
| Shoalhaven City Council | 763 | 0 | 0 | 763 |
| Wingecarribee Shire Council | 60 | 0 | 0 | 60 |
| Total | 14,003 | 2,209 | 1,980 | 18,192 |
* 16,314 ML recycled water used at the wastewater and recycling water plants is not included
Water accounting statements and notes for the National Water Account 2010 include information on recycled water supplied (line items 13.7.3 and 20.5.1, and organisation-specific notes for Sydney Water Corporation, Shoalhaven City Council and Wingecarribee Shire Council). Although some of those supplies were covered by contracts, no information is available regarding any volumes committed to be supplied under those contracts. Therefore, volumetric commitment to provide recycled water by water authorities is not recognised in the water accounting statements.
The water distribution store is comprised of an:
Water stored in components such as pipes, tanks and channels in these systems could not be quantified with representational faithfulness, so are not recognised in the water accounting statements.
Details of unregulated river sections for which the volume of stored water was estimated are available in Line item 1.2 Unregulated channel. Volume of water stored in the unregulated river channel has not been estimated for the following rivers because reliable data are not available;
This list accounts approximately 70% of the total unregulated river length in the Sydney Region.
Data on leakage from the water distribution system to the landscape for the Shoalhaven City Council, the Sydney Water Corporation and the Wingecarribee Shire Council are recognised at Line item 20.2.1. Reliable data were not available for the following urban water utilities:
National Water Account 2010
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