The Thomson Dam is a major Clay core and rockfill embankment

dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use ...

with a Uncontrolled, Ogee-shaped overflow weir and chute spillway across the Thomson River, located about east of

Melbourne Melbourne ( ; Boonwurrung/Woiwurrung: ''Narrm'' or ''Naarm'') is the capital and most populous city of the Australian state of Victoria, and the second-most populous city in both Australia and Oceania. Its name generally refers to a met ...

in the

West Gippsland West Gippsland, a region of Gippsland in Victoria, Australia, extends from the southeastern limits of metropolitan Melbourne and Western Port Bay in the west to the Latrobe Valley in the east, and is bounded by the Strzelecki Ranges to the south ...

region of the Australian state of

Victoria Victoria most commonly refers to: * Victoria (Australia), a state of the Commonwealth of Australia * Victoria, British Columbia, provincial capital of British Columbia, Canada * Victoria (mythology), Roman goddess of Victory * Victoria, Seychelle ...

. The

reservoir A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including contro ...

(or storage basin) created by the dam is officially called Thomson Reservoir, sometimes called Lake Thomson.

Location and features

The dam is located near the former township of Beardmore and the

Baw Baw National Park The Baw Baw National Park is a national park located on the boundary between the Victorian Alps and Gippsland regions of Victoria, Australia. The national park is situated approximately east of Melbourne and north of the Latrobe Valley. ...

. Despite opposition from conservationists and farmers, plans for the dam were originally approved in late December 1975 to provide Melbourne with

water security Water security is the focused goal of water policy and water management. A society with a high level of water security makes the most of water's benefits for humans and ecosystems and limits the risk of destructive impacts associated with water. T ...

. 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. Early work in the early 1970s saw construction of a tunnel through the Thomson Yarra divide to allow water from the Thomson River to flow into the

Upper Yarra Reservoir The Upper Yarra Reservoir is located east of Melbourne, Victoria, Australia, beyond Warburton within the locality of Reefton. Water from Upper Yarra Reservoir supplies towns in the upper Yarra Valley, and Silvan Reservoir, which transfers water t ...

. 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 to

Silvan Reservoir The Silvan Reservoir is located in Silvan about east of Melbourne, Victoria, Australia. It has a capacity of . The reservoir is operated by Melbourne Water. Operations Silvan is an off-stream storage reservoir, meaning that most of the water ...

for distribution as drinking water in Melbourne.

Hydroelectricity generation

Downstream releases from Thomson Reservoir pass through a 7.4 MW hydro power plant, at the base of the dam which generates electricity and feeds it into the state power grid.

Water supply levels

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. Heavy rainfall in 2010 and 2011 increased Melbourne's water storages to levels not seen for ten years. The Thomson Dam entered winter 2011 at 39% full and by the end of 2011 had reached 54.4% full. On 28 October 2022, the dam reached 100% capacity and began spilling for the first time since the spring of 1996. The Thomson Dam is managed by

Melbourne Water Melbourne Water is a Victorian Government-owned statutory authority that controls and manages much of the water bodies and supplies in metropolitan Melbourne, Victoria, Australia, including the reservoirs, lakes, wetlands, canals and urban cree ...

.Melbourne Water
/ref>

References

External links

The Age ''The Age'' is a daily newspaper in Melbourne, Australia, that has been published since 1854. Owned and published by Nine Entertainment, ''The Age'' primarily serves Victoria, but copies also sell in Tasmania, the Australian Capital Territory ...

, 5 June 2003
Crunch time today for Thomson Dam
-

, 13 December 2006
'Drought-proof' dam hits record low level
{{Melbourne dams Dams completed in 1983 Gippsland Embankment dams Dams in Victoria (Australia) Environment of Victoria (Australia) 1983 establishments in Australia