The Trevallyn Dam is a dam on the South Esk River

South Esk River

The South Esk River is the longest river in Tasmania. It starts in the mountains near Fingal flowing through Avoca, Evandale, Longford, Hadspen and finally Launceston. The river is dammed at Trevallyn Dam near Launceston and used for the city's Hydro Electricity scheme...

 in Launceston

Launceston, Tasmania

Launceston is a city in the north of the state of Tasmania, Australia at the junction of the North Esk and South Esk rivers where they become the Tamar River. Launceston is the second largest city in Tasmania after the state capital Hobart...

, Tasmania, Australia and is used to provide water for hydroelectricity

Hydroelectricity

Hydroelectricity is the term referring to electricity generated by hydropower; the production of electrical power through the use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy...

. The spillway height is 26.8 metres and the dam wall is 177 metres long. The lake has a surface area of 1.48 km² and storage capacity of 12.33 million m³. ANCOLD

ANCOLD

ANCOLD is the Australian National Committee on Large Dams. It is an association that sets national standards in relation to large dams and their environs...

 says that this is a Dam and lists the dam wall height as 33 metres and the completion date as 1955. The total volume of the wall is 61,000 cubic metres.

The dam diverts water to the Trevallyn Power Station through a 3.2km tunnel.