Perth

This line item refers to bulk deliveries of water from outside the Perth region boundary into major reservoirs within the Perth region.

The volume of water transferred in to the surface water store during 2009-10 for each bulk water delivery is given below.

In terms of the bulk delivery of water from the Harris Reservoir to the Stirling Reservoir, both storages are managed and operated by Water Corporation. Therefore, there are no trade agreements in place for the delivery of water into the Stirling Reservoir. Water is simply provided from Harris Reservoir on a ‘as needs’ basis for internal, operational reasons.

Data source

Water Corporation: Operational Data Storage System database.

Harvey Water: Supervisory Control and Data Acquisition (SCADA) system.

Data provider

Water Corporation and Harvey Water.

Method

There were two bulk deliveries of water from outside the Perth region boundary into major reservoirs within the Perth region during 2009-10.

The total volume of water transferred into Stirling Reservoir from Harris Reservoir is based on measured data observed at the flow meter at Harris Dam. The total volume of water transferred into Harvey Reservoir from the Collie Irrigation District is based on measured data observed at the pump station located at the border of the Collie River and Harvey Water irrigation districts.

Uncertainty

Expected error for water meters is +/- 5%.

The Department of Water requires that all water meters, when tested in situ conditions, must be within 5% accuracy across the full flow rate range (Department of Water 2009).

Approximations, assumptions, caveats/limitations

It is assumed that the volume of water measured at the flow meter at Harris Dam is equal to the inflow at Stirling Dam (i.e. no leaks or transmission losses). This is a reasonable assumption given the transfer occurs via a closed pipe.