Thomson Dam

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title: "Thomson Dam" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["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"] description: "Dam in West Gippsland, Victoria" topic_path: "geography/australia" source: "https://en.wikipedia.org/wiki/Thomson_Dam" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Dam in West Gippsland, Victoria ::

::data[format=table title="Infobox dam"]

Field	Value
name	Thomson Dam
image	Thomson_Reservoir.jpg
image_size	250px
location_map	Victoria
location_map_caption	Location of the Thomson Dam in Victoria
coordinates
country	Australia
location	West Gippsland, Victoria
purpose	Water supply, irrigation
status	O
construction_began	1976
opening
owner	Melbourne Water
dam_type	E
dam_crosses	Thomson River
dam_length	590 m
dam_height_foundation	166 m
dam_volume	1.417 e6m3
spillway_count	1
spillway_type	Uncontrolled Ogee-shaped overflow weir and chute
spillway_capacity	1040 m3/s
res_name	Thomson Reservoir (official); called Lake Thomson
res_capacity_total	1.12309 e6ML
res_catchment	487 km2
res_surface	22.3 km2
res_elevation	494 m
website	Thomson Reservoir at Melbourne Water
::

| country = Australia | location = West Gippsland, Victoria | purpose = Water supply, irrigation | status = O | construction_began = 1976 | opening = | demolished = | cost = | owner = Melbourne Water | dam_type = E | dam_crosses = Thomson River | dam_length = 590 m | dam_height_foundation = 166 m | dam_height_thalweg = | dam_elevation_crest = | dam_width_crest = | dam_width_base = | dam_volume = 1.417 e6m3 | spillway_count = 1 | spillway_type = Uncontrolled Ogee-shaped overflow weir and chute | spillway_capacity = 1040 m3/s | res_name = Thomson Reservoir (official); called Lake Thomson | res_capacity_total = 1.12309 e6ML | res_capacity_active = | res_capacity_inactive = | res_catchment = 487 km2 | res_surface = 22.3 km2 | res_max_length = | res_max_width = | res_max_depth = | res_elevation = 494 m | res_tidal_range = | plant_name = | plant_coordinates = | plant_operator = | plant_commission = | plant_decommission = | plant_type = | plant_turbines = | plant_capacity = | plant_annual_gen = | website = Thomson Reservoir at Melbourne Water | extra = The Thomson Dam is a major Clay core and rockfill embankment dam with a Uncontrolled, Ogee-shaped overflow weir and chute spillway across the Thomson River, located about 130 km east of Melbourne in the West Gippsland region of the Australian state of Victoria. The reservoir (or storage basin) created by the dam is officially called Thomson Reservoir, sometimes called Lake Thomson.

Location and features

::figure[src="https://upload.wikimedia.org/wikipedia/commons/7/73/Thomson_Reservoir_2009-12-02_01.jpg" caption="December 2009 during drought."] ::

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 19 km 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.

References

References

1. Pigram, John J.. (2007). "Australia's Water Resources: From use to management". CSIRO Publishing.
2. "Dam powerful".
3. [http://www.melbournewater.com.au/content/water_storages/water_report/weekly_water_report_archives.asp Melbourne Water: Water Storage Levels Archive ]
4. "Melbourne Water : Water Storages : Water Report : Weekly Water Report Archives".
5. "Archived copy".
6. "Archived copy".
7. (28 October 2022). "The Age : Thomson Dam spills over for first time in 26 years as rain drenches Victoria".
8. [http://www.melbournewater.com.au Melbourne Water]

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::