A catchment is the area of land surrounding a dam and the river that feeds it. Rain falling in the catchment area that isn't absorbed into the ground runs into the river and dam. The quality of the water is determined by how 'clean' the catchment area is. It is important that we take care of our catchment areas, as good water quality is important for healthy and successful communities.

ACT water supply catchments

The ACT draws its water supply from three separate catchment systems...

Cotter River Catchment

The Cotter River Catchment lies over 482 square kilometres within the ACT and the upper reaches of the Cotter River catchment are in the Namadgi National Park. The river itself starts high up the Brindabella Mountains, fed by rainfall and melting snow. The Cotter River Catchment is protected with no farms or houses and restrictions on recreation activities within the catchment also help to protect the quality of the water.


The quality of the water within the catchment suffered greatly during the January 2003 bushfires. A loss of vegetation immediately following the fires increased the amount of dirt and sediment entering the water meaning that water running off the catchment was more variable with increases in turbidity (cloudiness) as well increases in iron and manganese in the water. Since then, significant remediation works have been undertaken in the lower catchment to minimise these impacts.

There are three dams on the Cotter River: Corin, Bendora and Cotter. Corin Dam is located furthest upstream on the Cotter River. Water stored in Corin Dam is released downstream into the Cotter River and flows down to Bendora Dam. From Bendora Dam a large diameter pipeline carries water by gravity to the treatment plant on Mount Stromlo (to the west of Canberra). The Bendora Gravity Main is 20 kilometres long and has the capacity to carry 310 million litres of water per day. The third dam, Cotter Dam is lower than the Mount Stromlo Water Treatment Plant, water from this reservoir must be pumped from the historic Cotter Pump Station, to the treatment plant.

Queanbeyan River Catchment

Googong Dam is located on the Queanbeyan River to the southeast of Queanbeyan and is part of the Queanbeyan River Catchment. The catchment area covers 873 square kilometres in NSW. The Queanbeyan River Catchment is a rural catchment which includes farmlands and small communities, the water quality from this catchment can be variable and requires extensive treatment in order to meet drinking water quality requirements.

Water from the Googong Dam, once treated at the Googong Treatment Plant, is pumped to Canberra and Queanbeyan.

Murrumbidgee Catchment

The use of water from the Murrumbidgee River commenced in May 2007 from a location near the Cotter Pumping Station to supplement water from the ACT’s then depleted water storages.

The Murrumbidgee River is one of Australia's major rivers and many communities use it as their source of water. For decades, major towns upstream and downstream of Canberra, such as Cooma and Wagga Wagga, have been drawing water from the Murrumbidgee River, treating it and safely using it for drinking water supply.