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ActewAGL: Cotter River, Bendora Dam

ActewAGL: Cotter River, Bendora Dam

Bottle number: 6

About the water

Colour photo of Amanda Brown collecting a water sample at the Cotter River collection site.
Amanda Brown, Water Quality Officer, ActewAGL at Cotter River, Bendora Dam ACT. Photo: Ron Chesham, ActewAGL.

Collected at: Bendora Dam, ACT

Cotter River environmental flows, 400m downstream of Bendora Dam, ACT.

View location on Google map


Collected by: ActewAGL

ActewAGL provides drinking water services to Canberra and bulk treated water to Queanbeyan as an agent of ACTEW Corporation (originally ACT Electricity & Water), including source water protection, water quality and ecological monitoring and reporting.

Bendora Reservoir is the one of three water supply reservoirs located within the Cotter River catchment.


Water quality:

Turbidity: 1.1NTU median);
(min. 0.65; max. 2.2)
pH: 7.0 (median);
(min. 6.0; max. 7.4)
Nitrates: 0.0075mg/L NOX (median);
(min. 0.002; max. 0.034)
Salinity: 16.08 mg/L (median, calculated);
(min. 12.06; max. 19.43)
Phosphates: 0.003mg/L P (median, calculated);
(min. 0.002; max. 0.005)
Dissolved oxygen: 9.0mg/L (median);
(min. 4.9; max. 12.3)

The above water quality figures have been obtained from water quality monitoring conducted fortnightly (approximately) between 24 November and 2 November 2008 at Bendora Dam, 400m upstream from sample collection site.

ACT Waterwatch says:

ActewAGL partners with Waterwatch in the region to ensure the highest possible standards for drinking and environmental water. As you can see, their level of monitoring is VERY high, and the quality of the water is about as good as it can get.

Cotter River 400m downstream from Bendora Dam, ACT.
Cotter River 400m downstream from Bendora Dam, ACT.
Photo: Ron Chesham, ActewAGL.

About the site

Bendora Dam is the one of three water supply reservoirs located within the Cotter River catchment. Cotter River flows directly into the Murrumbidgee River, approximately 20km downstream of this sample point. The Cotter River Catchment is the main source for drinking water for the ACT and Queanbeyan. The majority of the Cotter catchment lies within Namadgi National Park with much of the upper catchment being classified as wilderness. A significant amount of scientific study has been undertaken in the catchment for monitoring environmental flows out of the reservoirs. Of particular importance is the Macquarie perch, a nationally threatened species and declared endangered in the ACT, which has been recorded as breeding successfully with the catchment.

Grazing is excluded and human activity carefully controlled within the Park, resulting in natural landscapes and high vegetation cover. Recreation is also excluded in the reservoirs. Consequently the water from Bendora is of very high quality and requires minimal treatment for use as potable water.

The Cotter Catchment, and in particular Bendora and Cotter Reservoirs, suffered major disturbances following the devastating fires in 2003. Water quality in Bendora Dam suffered shortly after the fires as a consequence of sediment load entering the streams. Natural regeneration since the fires has allowed the water quality in Bendora to return to its original quality.

What's going on:

The site is currently used for monitoring environmental flows as discharged from the Bendora Reservoir. The environmental flows are monitored for fish and ecological health as well as water quality. Since the 2003 fires, erosion stabilisation has been undertaken in the area as well as allowing natural regeneration to occur. Controlled recreation is also allowed in the area, but not in Bendora Reservoir.

ActewAGL is involved in management of environmental flows and monitoring of ecological health and water quality, as well as conducting programs to ensure the protection of the source water for drinking water purposes.