Cotter Dam | |
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Cotter Dam, 2013
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Location of the Cotter Dam in the ACT
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Location | Australian Capital Territory, Australia |
Coordinates | 35°19′10″S 148°56′19″E / 35.31955°S 148.93853°ECoordinates: 35°19′10″S 148°56′19″E / 35.31955°S 148.93853°E |
Purpose | Potable water supply |
Status | Operational |
Opening date | 1912 | ; 2013
Owner(s) | ACTEW Corporation |
Dam and spillways | |
Type of dam | Gravity dam |
Impounds | Cotter River |
Height | 87 m (285 ft) |
Length | 330 m (1,080 ft) |
Dam volume | 380×10 3 m3 (13×10 6 cu ft) |
Spillways | 1 |
Spillway type | Uncontrolled |
Spillway capacity | 5,670 m3/s (200,000 cu ft/s) |
Reservoir | |
Creates | Cotter Reservoir |
Total capacity | 78 GL (1.7×1010 imp gal; 2.1×1010 US gal) |
Catchment area | 482 ha (1,190 acres) |
Surface area | 285 ha (700 acres) |
Normal elevation | 551 m (1,808 ft) |
Website Cotter Dam at ACTEW Water |
The Cotter Dam is a concrete gravity and rockfill embankment dam across the Cotter River, located in the Australian Capital Territory, Australia. The impounded reservoir is called the Cotter Reservoir which is a supply source of potable water for the city of Canberra and its environs.
The original concrete gravity Cotter Dam was built in 1912 when the city of Canberra was established. The height of the dam wall was raised to a height of 31 metres (102 ft) in 1951 in order to increase capacity of the reservoir. The 26-thousand-cubic-metre (920×10 3 cu ft) dam wall was 118 metres (387 ft) long and created a reservoir with a surface area of 500 thousand cubic metres (18×10 6 cu ft). The uncontrolled spillway was capable of discharging 850 cubic metres per second (30,000 cu ft/s). At that time, the top water level of the dam was 501 metres (1,644 ft) above sea level and the reservoir had a capacity of 3,856 megalitres (848,000,000 imp gal; 1.019×109 US gal). A subsequent review in October 2006, using more accurate mapping methods, resulted in capacity being re-estimated downwards from the previous estimate of 4,700 megalitres (1.0×109 imp gal; 1.2×109 US gal). Additional galleries and drains were constructed between 1984 and 1986. In order to supply the city with potable water, water from the reservoir was pumped to Mount Stromlo, and from there the water flowed by gravity to fill the city's reservoirs.