The ACT collects and stores water from rivers arising in the Brindabella mountain range to the west of Canberra and has paramount rights to water in the Molonglo and Queanbeyan rivers – giving it an interest in a number of catchments that straddle the ACT border. Its current water supply system should be adequate until 2017. Supply is augmented from some water that is treated
and distributed, and domestic greywater.

Rainfall in the region is variable and, to ensure water security for urban use, dams have been built to capture and store water as security against dry years (e.g. during 2006, flow into the ACT catchments was reduced by 85% and dam levels dropped as stored water was used). Following severe damage to the catchments in the 2003 bushfires and low inflows due to the continuing drought from 2001, the ACT Government has been re-examining its water security options. Security to 2023 will be achieved by:

• enabling transfer of water from the Murrumbidgee and from dams in the ACT into the Googong Reservoir in NSW
• enlargement of the Cotter Dam to 20 times its current capacity
• water from Tantangara Dam bought from irrigators and allowed to flow down the Murrumbidgee River into the ACT
• water efficiency measures and stormwater re-use projects and possibly
• use of a water purification plant.

Until 2003, supply catchments to the west of Canberra were fairly pristine needing little treatment before distribution. More extensive treatment of this water has been needed since the 2003 bushfires. Catchments to the east of Canberra flowing into the Googong Reservoir are mainly rural and water from this source also needs treatment so that it meets Australian Drinking Water Guidelines (NHMRC 2004). Land management practices in the Googong catchment are monitored.

The water supply catchments target will protect and rehabilitate catchments that are used for potable water supply. Recovery of the catchments following the 2003 bushfires and efforts to improve groundcover to reduce sediment run-off from erosion are continuing to ensure that relevant water quality standards are met. Wherever possible, use will be made of natural processes. This work will complement efforts to increase biodiversity in these catchments. Measurement of targets will use holistic systems to assess the condition of the entire catchment not just water quality.