The Edgar Dam is an earthfill

embankment Embankment may refer to: Geology and geography * A levee, an artificial bank raised above the immediately surrounding land to redirect or prevent flooding by a river, lake or sea * Embankment (earthworks), a raised bank to carry a road, railwa ...

saddle The saddle is a supportive structure for a rider of an animal, fastened to an animal's back by a girth. The most common type is equestrian. However, specialized saddles have been created for oxen, camels and other animals. It is not kno ...

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, a ...

without a

spillway A spillway is a structure used to provide the controlled release of water downstream from a dam or levee, typically into the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure tha ...

, located offstream in the

South West The points of the compass are a set of horizontal, radially arrayed compass directions (or azimuths) used in navigation and cartography. A compass rose is primarily composed of four cardinal directions—north, east, south, and west—each sepa ...

region of

Tasmania ) , nickname = , image_map = Tasmania in Australia.svg , map_caption = Location of Tasmania in AustraliaCoordinates: , subdivision_type = Country , subdi ...

, Australia. The impounded

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 ...

, also formed with the

Scotts Peak Dam The Scotts Peak Dam is a rockfill embankment dam without a spillway across the Huon River, located in the South West region of Tasmania, Australia. The impounded reservoir, also formed with the Edgar Dam and the Serpentine Dam, is called Lak ...

and the Serpentine Dam, is called

Lake Pedder Lake Pedder, once a glacial outwash lake, is a man-made impoundment and diversion lake located in the southwest of Tasmania, Australia. In addition to its natural catchment from the Frankland Range, the lake is formed by the 1972 damming of the ...

which flooded Lake Edgar, a naturally forming

fault scarp A fault scarp is a small step or offset on the ground surface where one side of a fault has moved vertically with respect to the other. It is the topographic expression of faulting attributed to the displacement of the land surface by movement al ...

pond. The dam was constructed in 1973 by the Hydro Electric Corporation (TAS) as part of the Gordon River Power Development Scheme for the purpose of generating

hydro-electric power Hydroelectricity, or hydroelectric power, is Electricity generation, electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other Renewabl ...

via the

Gordon Power Station The Gordon Power Station is the largest Hydroelectricity#Conventional (dams), conventional hydroelectric power station in Tasmania, Australia; located in the South West Tasmania, South West region of the state. The power station is situated on ...

. Water from Lake Pedder is diverted to

Lake Gordon Lake Gordon is a man-made reservoir created by the Gordon Dam, located on the upper reaches of the Gordon River in the south-west region of Tasmania, Australia. Features The reservoir was formed in the early 1970s as a result of the dam constr ...

(formed by the

Gordon Dam The Gordon Dam, also known as the Gordon River Dam, is a major gated double curvature concrete arch dam with a controlled spillway across the Gordon River, located in South West Tasmania, Australia. The impounded reservoir is called Lake Gordon. ...

) via the McPartlan Pass Canal.

Location and features

The Edgar Dam, together with the Scotts Peak Dam and the Serpentine Dam, are three major dams that form the headwaters for the Gordon River Power Development Scheme. The dam is located near Lake Pedder's most easterly point in the upper reaches of the

Huon River The Huon River is a perennial river located in the south-west and south-east regions of Tasmania, Australia. At in length, the Huon River is the fifth-longest in the state, with its course flowing east through the fertile Huon Valley and empt ...

where the river descends from the Marsden Range and descends into what is now known as the Huon Basin. Also at the southern end of the Lake Pedder, the Scotts Peak Dam impounds the Huon River. At the northwestern end of the lake is impounded by the Serpentine Dam across the Serpentine River. The water in Lake Pedder provides around 40% of the water used in the Gordon Power Station. The water flows to Lake Gordon via McPartlan Canal. Water from Lake Gordon then exits through the Gordon Dam. The Edgar Dam wall, constructed with of earth core, is high and long. At 100% capacity the dam wall holds back of water. The surface area of Lake Pedder is and the catchment area is . The dam wall does not have a spillway. The dam draws its name from the flooded Lake Edgar.

Lake Edgar Fault

The Lake Edgar Fault is a long north–south trending scarp that occurs within the boundary of the

Southwest National Park Southwest National Park is an Australian national park located in the south-west of Tasmania, bounded by the Franklin-Gordon Wild Rivers National Park to the north and the Hartz Mountains National Park to the east. It is a part of a chain of ...

. The scarp traverses the button grass of the Huon Plains and is notable because faulting resulted in the defeat of westerly flowing drainage and the consequent formation of the fault-bound sag pond of Lake Edgar. In spite of a tremor measuring 3.2 on the

Richter magnitude scale The Richter scale —also called the Richter magnitude scale, Richter's magnitude scale, and the Gutenberg–Richter scale—is a measure of the strength of earthquakes, developed by Charles Francis Richter and presented in his landmark 1935 ...

in January 2001 near the Lake Edgar fault, which runs adjacent to the Edgar Dam, the ability of the dam to cope with stresses associated with seismic activity. . Hydro Tasmania is confident that the eventuality of the Edgar Dam being destroyed by an earthquake is an extremely remote possibility.

Location and features

Lake Edgar Fault

See also

References

Further reading