Sydney
1.5 Inter–region claim on water

Supporting information

This line item (13,612 ML) represents the Sydney regions entitlement on the Fish River Water Supply Scheme that was 2,723ML as of 30 June 2012. Sydney Catchment Authority, Lithgow City Council and Delta Electricity all had an inter–basin claim on the Fish River Water Supply Scheme during the 2011–2012 year.

Each agency has an annual maximum allocation entitlement from the Fish River Water Supply Scheme to supply water to their storages. This entitlement is subject to a number of operating rules and restrictions depending on levels in the supply storages (Oberon Dam and Duckmaloi Weir). There is also the ability to carryover a portion of the entitlement into the following year. No restrictions were in place over the entire 2011–12 year.

Maximum allocation limits and carryover volumes for the 2011–12 year are detailed in the following table.

Maximum allocation limits and carryover for the Fish River Water Supply Scheme during the 2011–12 year

Organisation

Maximum allocation entitlement (ML)

Carryover as at 30 June 2011 (ML)

Carryover as at 30 June 2012 (ML)

Delta Electricity

8,184

216

1,637

Lithgow City Council1

1,778

36

356

Sydney Catchment Authority

3,650

119

730

Total

13,612

371

2,723

1 Lithgow City Councils entitlement includes diversions to storages that are outside the Sydney region boundaries.


The allocation remaining is calculated as shown in the following table.


Volume of inter–region claim on surface water remaining at the start and end of the 2011–12 year

 

Account

Volume

(ML)

 

Opening balance (as at 30 June 2011)

 371

add

9.15 Increase of inter–region surface water claim on water

13,612

less

9.11 Delivery of water under inter–region agreement to surface water

 4,183

less

17.17 Decrease of inter–region claim on water

 7,077

 

Closing balance (as at 30 June 2012)

2,723

 

Quantification approach

Delta Electricity

Data source

Fish River Water Supply Scheme Weekly Use Report 2011–12.

Provided by

New South Wales Office of Water.

Method

The metered supply volume is based on flow measurements provided by the New South Wales State Water Corporation using ABB magflow meters.

Assumptions, limitations, caveats and approximations

Nil.

Uncertainty information

The volume is based on measured data. Estimated uncertainty based on meter accuracy is +/–2%.

Lithgow City Council

Data source

Lithgow City Council, spreadsheets; New South Wales Office of Water Fish River Water Supply Scheme Weekly Use Report 2011–12.

Provided by

Lithgow City Council and New South Wales Office of Water.

Method

The metered supply volume is based on flow measurements by New South Wales State Water Corporation using ABB magflow meters.

Assumptions, limitations, caveats and approximations

Nil.

Uncertainty information

The volume is based on measured data. Estimated uncertainty based on meter accuracy is +/–2%.

Sydney Catchment Authority

Data source

Databases.

Provided by

Sydney Catchment Authority.

Method

Carry-over volume available at the beginning of a year from the Fish River Water Supply Scheme is calculated from the entitlement holder's allocation and metered supply volume for the previous two years (carry-over volume is a two-year rolling average computed every six months; the carry-over volume is capped at 50% of the maximum annual quantity). The metered supply volume to the Sydney Catchment Authority is based on flow measurements using a turbine helix-type flow meter. 

Assumptions, limitations, caveats and approximations

Nil.

Uncertainty information

Carryover volume is based on measured data. Estimated uncertainty based on meter accuracy is +/– 2%.

Comparative year

In the 2010–11 year, 1.5 Inter-region claim on water only reported on Sydney Catchment Authority's entitlement on the Fish River Water Supply Scheme. In the 2011–12 year, this line item now also recognises Delta Electricity and Lithgow City Council entitlements on the Fish River Water Supply Scheme which was previously reported in 3.4 Urban inter–region claim on water. Therefore,line item 3.4 is no longer required in the Sydney account. Consequently, the volume is been restated from 119 ML to 371 ML.