Canberra
9.9 Discharge from urban water system

The volume reported in the water accounting statements is 31,702 ML that represents the total volume of water discharged from the urban water system to surface water within the Canberra region during the 2012–13 year.

This line item is made up of several components. When capacity is available, treated water is transferred from Mount Stromlo Water Treatment Plant (WTP) into Googong Reservoir via the ACTEW Water water reticulation network. In addition to this there are three sewage treatment plants (STPs) within the Canberra region that discharge treated water into the Molonglo River: the Lower Molonglo Water Quality Control Centre (LMWQCC) upstream from the confluence with the Murrumbidgee, Uriarra STP, and the Queanbeyan STP.

The table below contains a breakdown of the volume of water discharge to surface water at each sewage treatment plant and the volume of water transferred to the Googong reservoir.

The table above provides a breakdown of the volume of wastewater discharge to surface water from STPs in the Canberra region for the 2012–13 reporting period. ACTEW Water STPs (LMWQCC and Uriarra) and the QCC STP discharged treated wastewater to the surface water system.

Under the urban water utility water access entitlement, ACTEW abstracts water from the regulated storages of Bendora and Cotter reservoirs, and the unregulated system of the Murrumbidgee River and transfers this water to Mount Stromlo WTP. If capacity is available, it is also possible to transfer treated water from Mount Stromlo WTP into Googong Reservoir via the water reticulation network.

The volume 28,998 ML is the total wastewater discharge from LMWQCC measured at the discharge point plus the volume of effluent discharged from Uriarra STP.  The volume discharged is measured using level sensing and flow measuring equipment.

Nil.

Derived from measured data. Estimated uncertainty is +/– 5%.

ACTEW Water's flow meter measures the release from the water distribution system to Googong Reservoir. The metered volume of this release for 2012-13 was 66 ML.

Nil.

Derived from measured data. Estimated uncertainty is +/– 5%.

The volume of treated wastewater discharged to the surface water system 2,638 ML was derived from the daily measured values of wastewater discharged to surface water at the Queanbeyan STP.  The Queanbeyan STP is the only QCC STP that discharges treated wastewater to the surface water system.

Nil.

Derived from measured data. Estimated uncertainty is +/– 5%.