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

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

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.

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.

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

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.

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

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

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

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

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.

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

Volumes were derived from metered outflow data from water treatment plants.

The flow meter data are continually monitored and recorded using IICATS. The data are stored within a complex data management system. Adjustments are made to the data (if necessary) to correct any interruptions, errors, and so on.

As data on inflow to each water treatment plant are not available, metered outflow is assumed to be equal to the surface water taken. The volume taken from surface water can be higher than the outflow volume due to losses associated with pipe systems and the filtration process.

This line item applies to Sydney Water Corporation only for its water diversions from the Hawkesbury River to North Richmond Water Treatment Plant. All the other supplies to Sydney Water Corporation are made by the Sydney Catchment Authority.

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

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

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.

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.