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, aqua ...

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

Melbourne Melbourne ( , ; Boonwurrung language, Boonwurrung/ or ) is the List of Australian capital cities, capital and List of cities in Australia by population, most populous city of the States and territories of Australia, Australian state of Victori ...

in the West Gippsland region of the

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

n state of Victoria. The

reservoir A reservoir (; ) is an enlarged lake behind a dam, usually built to water storage, store fresh water, often doubling for hydroelectric power generation. Reservoirs are created by controlling a watercourse that drains an existing body of wa ...

(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. Despite opposition from conservationists and farmers, plans for the dam were originally approved in late December 1975 to provide Melbourne with water 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. 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. 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 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
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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 (Australia), Victoria, but copies also sell in Tasmania, the Austral ...

, 5 June 2003
Crunch time today for Thomson Dam
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, 13 December 2006
'Drought-proof' dam hits record low level
{{Melbourne dams Dams in Victoria (state) West Gippsland catchment Rivers of Gippsland (region) Dams completed in 1983 Embankment dams Environment of Victoria (state) 1983 establishments in Australia