Canberra
17.12 Surface water allocation diversion - urban water system

This line item refers to the amount of water that was diverted under ACTEW's urban water access entitlement. A breakdown of the amount of water diverted from each reservoir is provided in the following table.

1 Diversions from the Murrumbidgee River have been included in this line item in National Water Account 2011 as diversions are based upon the same licence as extractions from the water storages.

2 This value represents the volume of water transferred to the Googong Reservoir from the Cotter Reservoir or Murrumbidgee River to take advantage of the storage capacity in the Googong Reservoir.

The total volume taken from surface water for urban water supply in the 2010–11 reporting year was calculated as the volume diverted from the Bendora, Corin, Cotter and Googong reservoirs together with the volume diverted from the Murrumbidgee River. These are metered volumes obtained from the ActewAGL production records.

The volume of water reported in this line item captures the total volume diverted from the water storages and the Murrumbidgee River. 4,365 ML of water was diverted from the storages on the Cotter River or the Murrumbidgee River, transported through the urban water supply system and then discharged into the Googong Reservoir at the Mount Stromlo Water Treatment Plant. This occurred to take advantage of the storage capacity of the Googong Reservoir. As this water was actually diverted, it has been included in this line item. The Googong transfer was included as an adjustment in line item 9.9 Discharge from urban water system.

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

This line item corresponds to Line Item 19.8.4 Allocation/claim diversion of regulated flows – urban water access entitlements/arrangements reported in the 2010 Account. The diversions from the Murrumbidgee (1,941 ML) were not included in this line item in the 2010 Account, as the diversions were from a river rather than a water storage. Further investigation into the urban entitlement indicate that the diversions from the Murrumbidgee River actually occur on the same licence as the diversions from water storages. This has resulted in a method change in the 2011 Account, where by diversions from both water storages and the Murrumbidgee River are included in this line item.

These changes are summarised in the following table.