Cotter River

Cotter River
The Cotter Dam in December 2005, surrounding country still showing the effects of the 2003 bushfires.
Origin	Scabby Range
Mouth	confluence with Murrumbidgee River
Basin countries	south-east Australia
Length	74 km
Source elevation	1781 m
Mouth elevation	460 m
Avg. discharge	2.21 m³/s immediately downstream Corin Dam
Basin area	482 km²

The Cotter River is a fresh water river in the Australian Capital Territory. It is a tributary of the Murrumbidgee River and part of Murray-Darling Basin. The Cotter River is one of two rivers—the Queanbeyan River is the other—that meet the water supply needs of the Canberra and Queanbeyan region. The river is named after a colonial convict Garrett Cotter who first settled and had a very long and continued association with the Cotter River region in the mid 19th century.

When the Government surveyor, Charles Scrivener, recommended Canberra as the best site for Australia's national capital, water catchment was a significant consideration. Of the total 910 square miles (2,400 km²) of the Australian Capital Territory, 170 square miles (440 km²) were reserved as the catchment area of the Cotter River.^[1] The catchment area was calculated to support a planned population of 100,000.^[2]

Dams

There are three reservoirs on the river, the Corin, Bendora and Cotter Dams which supply water to Canberra. Most of the Cotter catchment is in the Namadgi National Park.

• Cotter Dam is a concrete gravity dam built in 1912 when the city of Canberra was established. The height of the dam wall was raised in 1951 to increase capacity. The top water level of the dam is 500.69m above sea level. The dam has a capacity of 3,856 million litres; a review in October 2006 using more accurate mapping methods resulted in capacity being re-estimated downwards from the previous estimate of 4,700 million litres. Water was pumped from the dam to Mount Stromlo and from there the water flowed by gravity to fill the city's reservoirs. The dam water quality had deteriorated compared with Bendora and Corin dams and the dam was only used when water is in short supply. However, in December 2004, ActewAGL brought the dam back on line in response to the ongoing drought.^[3]
• Bendora Dam, a double curvature concrete arch dam completed in 1961. It has a capacity of 11,540 million litres.
• Corin Dam, an earth and rockfill embankment dam with a capacity of 70,900 million litres. This dam which was completed in 1967 is situated upstream of the Bendora Dam and controls the release of water into Bendora Dam.

Corin Dam from west

As part of a suite of potential options for increasing water storage capacity in the ACT, a plan has been proposed to increase capacity of the Cotter Dam through the construction of a new 76m high dam wall downstream of the existing Cotter Dam, which would inundate the existing 26m dam wall. This would increase storage capacity of the Cotter Dam from the current 4.7GL to 78GL.

Recreation

Cotter River picnic area

Although waters of the Cotter Dam itself, or other dams in the Cotter Catchment, are not able to be utilised for recreation, just below the dam on the Cotter River are a number of popular picnic areas on the river bank. These areas are generally equipped with limited barbecue facilities and tables. There are a number of areas that are suitable for swimming when there is sufficient water flowing in the river. There is also a short term camping site which can accommodate a very limited number of caravans and tents.

The Cotter Road, ACT tourist route 5, begins as a side road off Adelaide Avenue in the suburb of Deakin. The scenic drive stretches 17.6 km from the centre of Canberra past the suburbs of Curtin, Holder and Duffy, in between Stromlo Forest and Narrabundah Hill Pine Plantation, and past Casuarina Sands into the Cotter Avenue river area. "The Cotter" and the adjoining 7.1 km winding Brindabella Road (the beginning of "The Loop") are well known to motorcyclists, many of whom ride there in the evening after work or on weekends. The Cotter Hotel, which stood near the children's swings alongside the river, was burned down in the 2003 bushfires. It was a well known location for motorcyclists to meet on weekend mornings.

References

External links

• Media related to Cotter River at Wikimedia Commons
• ACTEW Corporation. Future Water Options
• Ecological effects of serial impoundment on the Cotter River, Australia
• High-resolution total stream power estimates for the Cotter River, Namadgi National Park, Australian Capital Territory
• State of the Environment Report 2003 Australian Capital Territory Indicator: water use

Coordinates: 35°19′S 148°57′E / 35.317°S 148.95°E / -35.317; 148.95