21.6 Other surface water liability increases

Supporting Information

This line item reflects the increase to the banked environmental flow water during the 2010–11 year.

Between 1 June 2005 and 3 March 2008, environmental flow releases into the Hawkesbury–Nepean River required under Sydney Catcment Authority's (SCA) Water Management Licence were halved as directed by the minister responsible for water in New South Wales due to the continuing drought. A condition of halving the flows was that the SCA would maintain a rolling 12-month bank in storage reservoirs and release the banked water as directed by the minister. 

During the 2010–11 year, a total of 3,100 ML was added to the banked environmental flow after a period of construction at Pheasant's Nest Dam that disrupted environmental flows.

The rolling annual volume in the bank is reflected in line item 5.6 Other surface water liability. Reconciliation of this line item is shown in the following table.

Calculation of other surface water liability increases in the 2010–11 year
Line item
Volume (ML)


5.6 Other surface water liability – opening balance



21.6 Other surface water liability increases



17.16 Other delivery of allocated surface water



13.6 Other surface water liability decreases



5.6 Other surface water liability – closing balance (as at 30 June 2011)


Quantification Approach

Data Source

SCA and NSW Office of Water agreement; SCA database of daily requirements and release; SCA compliance reporting to the NSW Office of Water.

Provided by



The volume stated for this line item is based on agreements between the SCA and NSW Office of Water.

Assumptions, Limitations, Caveats and Approximations


Uncertainty Information

The uncertainty was not quantified.

Comparative year

The following table compares the value for the 2009–10 year reported in this account with the corresponding value reported in the 2010 Account.


Comparative information from the 2010 Account for line item 21.6

2011 Account line item

2010 Account line item

Value reported in the 2010 Account (ML)

Value reported in the 2011 Account (ML)

Additional information

21.6 Other surface water liability increases

Not applicable

Not applicable


Line item classification: as there was no increase to the banked environmental flow volume in the Sydney region, this volume was not stated in the 2010 Account. With the increase in the bank for the 2010–11 year, this volume has been placed in this line item.