Canberra: Physical information
General description
Area: 4,202 km²
Population: Approximately 426,000 (Australian Bureau of Statistics [ABS] 2011)
The Canberra region is located in the southeast of Australia (Figure C1) and within the Murray–Darling Basin (Figure C2).
The region is characterised by forested mountains in the south and west, and plains in the north. The Canberra region boundary (Figure C3) encompasses the Australian Capital Territory (ACT) and extends into New South Wales (NSW). The boundary of the Canberra region captures the whole of the water supply system in the ACT. The ACT and NSW governments administer the part of the region that is within their respective jurisdictions.
Figure C1 The Canberra region within Australia
Figure C2 The Canberra region in the context of the Murray–Darling Basin region
Figure C3 Contextual map of the Canberra region
The geographic boundaries of the Canberra region include the following catchments:
- Upper Murrumbidgee River catchment downstream of Michelago to downstream of the Ginninderra Creek confluence (just upstream of Halls Crossing gauge)
- Cotter River
- Gudgenby River
- Molonglo River
- Queanbeyan River.
The headwaters of the upper Murrumbidgee catchment are not included in this region as the majority of the runoff from this section of the catchment is diverted to the Snowy Mountains Scheme in NSW.
For the 2015 Account, the Canberra region includes the following water assets:
- surface water and groundwater administered under ACT and NSW water legislation
- urban water system.
The following elements are not considered water assets of the Canberra region:
- water in farm dams because these constitute water that is already abstracted and no longer available for sharing
- water stored in the landscape, such as soil moisture
- stormwater harvesting for park watering.
As a consequence of differences in spatial coverage, volumetric information provided in the Canberra region for some attributes can differ from volumetric information provided for the ACT water resource plan area in the Murray–Darling Basin region. The Canberra region water account incorporates the whole of the ACT water resource plan area and a part of the NSW Murrumbidgee water resource plan area. Information for these two planning areas is provided separately in the Murray–Darling Basin region water account.
Land use
The major urban centres in the region are:
- Canberra metropolitan area: population 381,700
- Queanbeyan: population 40,000.
Population data for significant urban areas were sourced from the Census QuickStats website (ABS 2011).
In addition to urban land use, major land uses in the Canberra region include conservation and natural environment areas, and grazing. Conservation and natural environment areas are extensive throughout the region and are particularly dominant through the forested mountains in the south and west of the region. Grazing occurs across much of the plains within the region. The relative area and location of each major land use in the Canberra region is shown in Figure C4 (Australian Bureau of Agricultural and Resource Economics and Sciences 2014). A more detailed break down of land use type and area for the Canberra region is provided in this table.
Figure C4 Land use in the Canberra region
Significant aquatic ecosystems
The Canberra region contains the Ginini Flats Wetland Complex, which is a Ramsar-listed wetland, in the Namadgi National Park. It consists of a series of interconnected flats known as the Ginini Flats and the Cheyenne Flats.
Figure C5 shows that the Canberra region also contains 14 nationally important wetlands that are listed in A Directory of Important Wetlands in Australia (Environment Australia 2001). Most these wetlands are located upstream of any water abstraction or storage and so are unaffected by water resource management activities.
Figure C5 Significant wetlands in the Canberra region
Water resources
The Canberra region relies mainly on surface water. Prior to the last four years, prolonged low streamflow conditions led to an increase in groundwater use; however, it is still low in comparison to surface water use. Recycled wastewater is also used in the region.
The Water Resources Determination 2007 of the ACT Water Resources Act 2007 sets an allowable surface water and groundwater abstraction limit for the ACT (see Table C4 in 'Administration'). The current level of abstraction in the ACT is well under the allowable limit and below the Murray–Darling Basin cap (refer to Water rights). This will be replaced by the sustainable diversion limit set under the Murray–Darling Basin Plan (Basin Plan) by 2019.
The water resource in the NSW portion of the Canberra region has already been incorporated under the current long-term cap for the Murray–Darling Basin (refer to Water rights).
Surface water
The Murrumbidgee is the largest river that flows through the Canberra region. All rivers and creeks drain into this river. The Molonglo, Cotter, and Queanbeyan rivers are three main rivers which begin in the Canberra region and flow into the Murrumbidgee River.
Figure C6 shows mean monthly flow in these rivers and flow volumes at the gauging stations of Molonglo River at Burbong (410705), Cotter River at Gingera (410730) and Queanbeyan River upstream of Googong Dam (410781). Figure C7 provides the location of the key flow gauging stations along the main rivers within the region. While there is little seasonality in the rainfall of the region, streamflow does vary seasonally, with flows being lowest in autumn and highest in winter and spring. Potential evaporation increases in summer causing the catchments to dry out. In autumn and winter, the catchments typically become partially saturated, leading to higher runoff in spring.
Figure C6 Mean monthly flows along the Molonglo, Cotter, and Queanbeyan rivers and mean monthly rainfall for the Canberra region
Figure C7 Key flow gauging stations on the Cotter, Molonglo, Queanbeyan, and Murrumbidgee rivers within the Canberra region
Major storages
The Canberra region contains a number of major storages used for urban water supply, and other storages that are used for water pollution control and recreational purposes. These storages are shown in Figure C8 and listed in tables C1 and C2.
Figure C8 Surface water storages within the Canberra region
| Major storage | Total storage capacity ML | Dead storage capacity ML |
| Bendora Reservoir | 11,543 | 97 |
| Corin Reservoir | 70,897 | 110 |
| Cotter Reservoir | 79,374 | 3,178 |
| Googong Reservoir | 121,084 | 1,675 |
| Total | 282,898 | 5,060 |
| Major storage | Total storage capacity ML | Purpose |
| Lake Ginninderra | 3,700 | pollution control, landscape, and recreation |
| Lake Tuggeranong | 1,800 | pollution control, landscape, and recreation |
| Lake Burley Griffin | 33,723 | landscape and recreation |
| Total | 39,223 |
Groundwater
The Canberra region falls within the Lachlan Fold Belt geologic province. The region encompasses low-yield fractured volcanic aquifers overlain in places by minor, high-yield aquifers in superficial, unconsolidated alluvium and colluvium. The alluvial aquifers can be a locally significant source of water, but groundwater is a minor component of total water use in the Canberra region.
Within the ACT, groundwater is managed as a combined resource with surface water as part of the water management areas. In NSW, groundwater is managed separately from surface water. There are three groundwater management areas (GMAs) in the Canberra region: the ACT GMA, the Lachlan Fold Belt GMA, and the Yass Catchment GMA. The Lachlan Fold Belt and Yass Catchment GMAs extend beyond the region's boundaries; however for clarity, their extents are only shown within the Canberra region in Figure C9.
Figure C9 Groundwater management areas in the Canberra region
Other water resources and systems
Urban water system
Icon Water (formerly ACTEW Water) is a statutory body of the ACT government. It owns and manages most of the Canberra region's water supply system including:
- managing surface water diversions
- operating water treatment plants
- maintaining ACT's reticulation system
- delivering bulk water to Queanbeyan City Council.
Icon Water does not manage Queanbeyan City Council’s reticulation system.
Icon Water also manages ACT’s wastewater systems including:
- the wastewater network
- commercial wastewater
- wastewater treatment
- returning treated water back to the environment.
Queanbeyan City Council receives the bulk water from Icon Water and supplies potable water through its reticulation system to the customers. Also, Queanbeyan City Council collects and treats wastewater for its own local government area. Most treated water is discharged to the Molonglo River with the balance recycled for on-site use.
Figure C10 shows the key components of the Canberra and Queanbeyan urban water supply systems. It consists of four water storages, two water treatment plants, and three main wastewater treatment plants. Water is sourced from three catchments: the Cotter, Murrumbidgee, and Queanbeyan river catchments.
Figure C10 Key infrastructure of the urban water system in the Canberra region
The Mount Stromlo water treatment plant receives water from the Corin, Bendora, and Cotter reservoirs, all located on the Cotter River, and water from the Murrumbidgee River at the Cotter pump station. Water diverted from Googong Reservoir receives treatment at the Googong water treatment plant. Excess treated water from the Mount Stromlo plant can be transferred to the Googong Reservoir for storage.
Two main projects were completed in order to secure water resources for the future of the Canberra region. The more significant is the increase in the total storage capacity of the Cotter Reservoir from 3,865 ML to 79,374 ML. Construction of the new dam wall was completed in 2013. As Cotter Reservoir continued to fill during the 2014–15 year, its water storage increased from 57% to 84% of capacity.
The second project was the construction of a 12 km underground pipeline, completed in August 2012. This pipeline can transfer up to 100 ML/day from the Murrumbidgee River at Angle Crossing to Burra Creek, from where it flows into the Googong Reservoir.
For more details on these projects, please refer to the Icon Water website.
Further, the Tantangara Transfer Option agreements, which help to improve water security in the event of future drought conditions, were executed during the 2013–14 year.
The Lower Molonglo Water Quality Control Centre (LMWQCC) shown in Figure C10 is the largest sewage treatment plant in Canberra. The plant receives about 90 ML/day of wastewater. Most treated water is discharged to the Molonglo River with the balance recycled for internal use at the treatment plant and irrigation to nearby a vineyard and golf course.
The Fyshwick sewage treatment plant collects and treats industrial and domestic sewage from Fyshwick and surrounding suburbs. Treated wastewater from this plant is then discharged back into the sewer or delivered to the North Canberra Water Reuse Facility where it undergoes secondary treatment before it is used for irrigation purposes.
A sewer mining facility at Southwell Park can supply recycled wastewater for irrigation purposes but is not operational.
Outward Bound uses recycled water for the irrigation of sports fields.
Wastewater treated at the Queanbeyan sewage treatment plant is discharged to the Molonglo River with only a small fraction used for on-site irrigation purposes.
Recycled water
Three wastewater reuse schemes (Table C3) operate in the ACT.
| Scheme | Volume supplied 2014–15 ML | Purpose |
| LMWQCC Effluent Reuse | 4,365 | Irrigation and for LMWQCC operations |
| Fyshwick | 0 | Irrigation of sports fields |
| Outward Bound | 2 | Irrigation of sports fields |
The majority of the water recycled at the LMWQCC is recirculated within the treatment process.
Farm dams
Farm dams refer to landscape catchment storages used to harvest runoff, floodwater, or collected rainwater. They are an important water resource in the region; however, water held in farm dams is considered to be taken from the shared pool of water resources and, as such, is not included as part of the region's water assets (see General description).
Farm dams hold approximately 7,000 ML or 3% of the total surface water storage capacity in the Canberra region. The majority of the region's farm dams are filled by rainfall–runoff capture; a smaller portion of farm dams are filled by groundwater extractions, surface water diversions, or recycled water transfers. Runoff harvesting by farm dams is calculated to reduce streamflow in the Canberra region by approximately 2%.
The water held in farm dams is primarily used for stock and domestic, and agricultural purposes.