Sydney
11.12 Entitled diversion of allocated surface water to urban water system

Supporting information

a. Urban water supply system overview

The urban water supply system is one of three subcomponents of Sydney's urban water system. The three subcomponents are the:

  • urban water supply system
  • wastewater system
  • recycled water system.

In the 2012–13 year, all water supplied to the urban water supply system was sourced from surface water (11.12 Allocation diversion of surface water to urban water system) with a small volume of 596 ML sourced from the Fish River Water Supply Scheme by Lithgow City Council (11.9 Delivery of water to urban water system under inter-region agreement). Sydney Water Corporation in the past has also sourced water from desalinated water (11.6 Delivery of desalinated water to urban water system); however, no desalinated water was reported this year.

Potable and nonpotable urban water consumption (part of 19.4 Delivery to urban water system users) was 472,541 ML during the 2012–13 year, representing 88% of all urban water supply system outflows.The remaining outflows are reported as being lost through leakage (19.3 Leakage to groundwater) as well as other operational losses (19.20 Other urban water decreases), and a small volume was exported outside the region (19.11 Transfer of water outside of region).

The following figure shows all the inflows and outflows associated with the urban water supply system.

For more detail on a particular flow associated with the urban water supply system, refer to the line item notes.


Schematic diagram of water inflows and outflows during the 2012–13 year for Sydney's urban water supply system; line item numbers are provided in brackets
Schematic diagram of water inflows and outflows during the 2012–13 year for Sydney's urban water supply system; line item numbers are provided in brackets

Supporting information

The following tables provide a summary and breakdown of the allocation diversion of surface water by urban water utilities in the Sydney region.


Volume of entitled water diverted during the 2012–13 year: summary

Description of the diversion

Water diverted

(ML)

Sydney Catchment Authority supplies to urban holders

536,948

diversion by other urban entitlement holders

5,767

Total

542,715

 

Volume of water diverted by the Sydney Catchment Authority to supply to urban holders during the 2012–13 year
Urban holder Water treatment plant Volume diverted by Sydney Catchment Authority for urban holders (ML)
Goulburn Mulwaree Council   53
Sydney Water Corporation Cascades 4,958
Illawarra 28,220
Macarthur 26,542
Nepean 4,297
North Richmond 6,395
Orchard Hills 20,295
Prospect 408,145
Warragamba 1,169
Woronora 17,999
Shoalhaven City Council Kangaroo Valley 96
Bamarang and Flat Rock 14,824
Wingecarribee Shire Council Wingecarribee 3,775
Raw water to other retail customer Not applicable 76
Unfiltered water to other retail customers Not applicable 104
Total 536,948


The previous table is based on supply records of the bulk supplier, Sydney Catchment Authority; however, the water utilities, in the form of Goulburn Mulwaree Council, Shoalhaven City Council, Sydney Water Corporation, and Wingecarribee Shire Council, record differences in received volumes. The differences are attributed to different metering locations and metering accuracies and other unaccounted losses. In order to maintain consistency in calculations, the previous table, as well as the accounting statements, show the volumes recorded by the bulk supplier.


Volume of water diverted by other surface water entitlement holders during the 2012–13 year

Urban holder

Water source

Water treatment plant

Water diverted (ML)

Goulburn Mulwaree Council

Wollondilly River

Marulan

105

Goulburn Mulwaree Council

 

Goulburn

2,664

Lithgow City Council

 

Oakey Park

1,226
Palerang Council Shoalhaven River Braidwood 155

Wingecarribee Shire Council

 

 

Bundanoon

793

 

Medway

824

Total

 

 

5,767

Quantification approach

Goulburn Mulwaree Council

Data source

Data spreadsheets.

Provided by

Goulburn Mulwaree Council.

Method

Diversions to the water treatment plants were measured at the plants. At the Goulburn Water Treatment Plant, inflow from the plant was measured using a flow meter.

Assumptions, limitations, caveats and approximations

Nil.

Uncertainty information

The volume is based on metered data. Estimated accuracy based on meter accuracy and professional judgement is +/– 20%.

Lithgow City Council

Data source

Data spreadsheets.

Provided by

Lithgow City Council.

Method

The flow diverted from Farmers Creek No. 2 Reservoir to Oakey Park water treatment plant was measured by the height of the water over the weir in the channel at the inlet works at the plant. There is a direct pipeline connection between the storage and the plant. The outflow from the water treatment plant was measured by an ABB Magflow meter.

Assumptions, limitations, caveats and approximations

Nil.

Uncertainty information

The volume is based on measured data. Estimated uncertainty based on meter accuracy is +/– 2%. Meters are calibrated annually by their supplier, ABB.

Palerang Council

Data source

Database maintained as spreadsheets.

Provided by

New South Wales Office of Water.

Method

An ABB Magmaster-type induction meter was used to measure flow data. 

Assumptions, limitations, caveats and approximations

Nil.

Uncertainty information

The volume is based on metered data. Estimated accuracy based on meter accuracy is +/– 2%. Meters are calibrated annually by ABB (meter supplier).

Sydney Catchment Authority

Data source

Invoices, DRS database, IICATS meter readings.

Provided by

Sydney Catchment Authority.

Method

Full-bore magnetic flow meters and ultrasonic flow meters were used to measure water diversions to urban utilities.

Assumptions, limitations, caveats and approximations

There are minor differences in the supplied volumes recorded by the Sydney Catchment Authority and its recipients. In order to maintain consistency, the values provided by the Sydney Catchment Authority have been used for this line item.

Uncertainty information

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

Sydney Water Corporation

Data source

Hydraulic Systems Services.

Provided by

Sydney Water Corporation.

Method

The volumes stated for this line item are derived from data measured at the water filtration plants.

Assumptions, limitations, caveats and approximations

Nil.

Uncertainty information

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

Wingecarribee Shire Council

Data source

ABB Magflow meters based at raw-water pump stations, Supervisory Control and Data Acquisition (SCADA) system and data spreadsheets.

Provided by

Wingecarribee Shire Council.

Method

Volumes were derived from ABB Magflow meter data received through the SCADA system and transferred into spreadsheets.

Assumptions, limitations, caveats and approximations

The quantification method used in this note only applies to the council's water diversions from Medway and Bundanoon storages to their respective water treatment plants. Supplies to the council's Wingecarribee Water Treatment Plant are made by the Sydney Catchment Authority.

Uncertainty information

The volume is based on measured data. Estimated accuracy based on meter accuracy is +/– 7%. External flow verification audits for the flow meters are conducted annually by Hydrometric Consulting Services.