Melbourne
17.14 Surface water transfer under inter-region commitment

Supporting Information

The volume presented in the water accounting statements (235 ML) represents water supplied to Gippsland Water under the Tarago River – Gippsland Water Bulk Entitlement.

Gippsland Water received delivery of water from the Tarago Western Port Pipeline at Rokeby to supply the towns Warragul and Drouin. Gippsland Water also received water from the Tarago Reservoir to supply the towns of Neerim South and Noojee.

Quantification Approach

Data Source

Melbourne Water: Waterworks database.

Provided by

Melbourne Water.

Method

Melbourne Water meters the volume of water it provides to Gippsland Water.

Assumptions, Limitations, Caveats and Approximations

Nil.

Uncertainty Information

The uncertainty estimate was not quantified.

Comparative year

This item corresponds to line item 14.9 Diversion of surface water for transfer-out under inter-basin agreement reported in the 2010 Account. Following publication, an error was identified in the values reported in the 2010 Account, which caused the 2009–10 year volume to be restated.

In the 2010 Account, the volume reported included:

  •  potable water supply from Western Water to Woodend
  •  non-potable water supply from Western Water to Woodend from Macedon storage
  •  non-potable water exported from Melbourne Water via the Tarago catchment to Gippsland Water.

An improved understanding of the nature of the inter-region surface water commitment identified that two of these volumes were incorrectly reported here. Non-potable and potable water supplied from Western Water is not transferred under an inter-region commitment, rather this transfer is part of the regular operations of Western Water in providing water to customers within their service area. These volumes are reported elsewhere in the 2011 Account (see line item 19.11). Therefore, only potable water exported from the Tarago catchment (under the Tarago River – Gippsland Water Bulk Entitlement) should be reported here.

Restatement of the value published in the 2010 Account was made as the change was material and increased the accuracy and comparability of the information provided to the users of the National Water Account. The changes and their respective values are detailed in the following table. The restated comparative year volume is 546 ML.

Restated comparative year information for line item 17.14 Surface water transfer under inter-region commitment

2010 Account line item name

Water exported

Volume at 30 June 2010 reported in the 2010 Account (ML)

Value difference to volume reported due to prior period error correction (ML)

Volume at 30 June 2010 reported in 2011 Account (ML)

14.9 Diversion of surface water for transfer-out under inter-basin agreement

Non-potable water exported from Melbourne Water via the Tarago catchment to Gippsland Water

546

 

546

Potable water supply from Western Water to Woodend

58

-58

 

Non-potable water supply from Western Water to Woodend from Macedon storage

77

-77

 

Total

 

681

-135

546