| Thomson Dam | |
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  Location of the Thomson Dam inVictoria | |
| Country | Australia |
| Location | West Gippsland,Victoria |
| Coordinates | 37°50′34″S146°23′56″E / 37.84278°S 146.39889°E /-37.84278; 146.39889 |
| Purpose | Water supply,irrigation |
| Status | Operational |
| Construction began | 1976 |
| Opening date | May 1983 (1983-05) |
| Owner(s) | Melbourne Water |
| Dam and spillways | |
| Type of dam | Embankment dam |
| Impounds | Thomson River |
| Height (foundation) | 166 m (545 ft) |
| Length | 590 m (1,940 ft) |
| Dam volume | 1.417 million m3 (50.0 million cu ft) |
| Spillways | 1 |
| Spillway type | Uncontrolled Ogee-shaped overflow weir and chute |
| Spillway capacity | 1,040 m3/s (37,000 cu ft/s) |
| Reservoir | |
| Creates | Thomson Reservoir (official); calledLake Thomson |
| Total capacity | 1.12309 million ML (247.05 billion imp gal; 296.69 billion US gal) |
| Catchment area | 487 km2 (188 sq mi) |
| Surface area | 22.3 km2 (8.6 sq mi) |
| Normal elevation | 494 m (1,621 ft)AHD |
| Website Thomson Reservoir atMelbourne Water | |
TheThomson Dam is a majorClay core and rockfill embankmentdam with aUncontrolled, Ogee-shaped overflow weir and chute spillway across theThomson River, located about 130 kilometres (81 mi) east ofMelbourne in theWest Gippsland region of theAustralian state ofVictoria. Thereservoir (or storage basin) created by the dam is officially calledThomson Reservoir, sometimes calledLake Thomson.
The dam is located near the former township of Beardmore and theBaw Baw National Park.
Despite opposition from conservationists and farmers, plans for the dam were originally approved in late December 1975 to provide Melbourne withwater security. A dam on the Thomson River was preferred because the river had a large flow, high water quality and was elevated high enough to provide water to the upper Yarra system by gravity flow.[1]
Early work in the early 1970s saw construction of a 19-kilometre-long (12 mi) tunnel through the Thomson Yarra divide to allow water from theThomson River to flow into theUpper Yarra Reservoir. Work on the dam itself commenced in 1976 and the completed dam and reservoir were ready to retain water by 1983.
The tunnel, which is located at the northern end of the reservoir, allows water to be transferred west to Upper Yarra Reservoir and then on toSilvan Reservoir for distribution as drinking water in Melbourne.
Downstream releases from Thomson Reservoir pass through a 7.4 MW[2] hydro power plant, at the base of the dam which generates electricity and feeds it into the state power grid.
Between 1997 and 2011, drought depleted much of the reservoir's water. In early January 2006, the Thomson Dam was at 45.4%. While there were minor rises in water levels occasionally, the Thomson Dam reached its all-time low of 16.2% on 3 July 2009.[3]
Heavy rainfall in 2010 and 2011 increased Melbourne's water storages to levels not seen for ten years.[4] The Thomson Dam entered winter 2011 at 39% full[5] and by the end of 2011 had reached 54.4% full.[6]
On 28 October 2022, the dam reached 100% capacity[7] and began spilling for the first time since the spring of 1996.
The Thomson Dam is managed byMelbourne Water.[8]
{{cite web}}: CS1 maint: archived copy as title (link){{cite web}}: CS1 maint: archived copy as title (link)Waterways of the West Gippsland catchment,Victoria, Australia | |
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