This satellite image shows Lake Gordon to the north and east of Strathgordon, the village located near the Gordon dam and hydro-electric power station.
The Huon-Serpentine Impoundment (officially known as "Lake Pedder", colloquially known as "the new Lake Pedder") lies to the south and east of Strathgordon and has a surface area of 242 sq. km. For a discussion of nomenclature, see the topic A Controversial and Contested Name in the Lake Pedder article in Wikipedia.
Lake Pedder (surface area 10 sq. km.) lies beneath 12 metres of water west-north-west of the largest island in the Huon-Serpentine Impoundment.
The devegetated zone visible at the waterline in Lake Gordon indicates that the reservoir is not full. The Huon-Serpentine impoundment does not function as a reservoir; its water level is fixed and there is no devegetated zone.
The impoundment traps the water of the Serpentine River (whose source was the original Lake Pedder) flowing to the north west and the Huon River flowing to the south east. These waters are lifted by the impoundment to a height from which their current combined volume of flow drains by gravity into Lake Gordon through the McPartlan Pass Canal.
The large volume of water stored in the impoundment serves no purpose other than to lift the current flows of the Serpentine and Huon Rivers to a height from which they can flow into Lake Gordon.
The most common fallacy and piece of misinformation in understanding and debating the Lake Pedder issue is the belief that the Huon-Serpentine Impoundment is a valuable, even indispensable water storage. For example, former Premier Robin Gray speaking as Minister for Energy,(circa 1994):
"Conservationists must be aware that Lake Pedder is a crucial storage for the Tasmanian hydro-electric system...
the lake is a source of stored energy that Tasmania cannot afford to lose...
the bulk of the long term storage capacity is held in just three lakes, Pedder, Gordon and Great Lake...
storages have fallen...without the storage in Lake Pedder the situation would be worse"
– for more, see Tasmanian Government view, circa 1994.
These statements are fallacious. Lake Pedder is NOT a water storage – it is a mechanism to raise and divert the current flows of the Serpentine and Huon Rivers into Lake Gordon. It holds a large volume of water but that water is never used to generate electricity.
This image shows in more detail the devegetated zone at the waterline in Lake Gordon (top centre of image) and the absence of a similar zone in the Huon-Serpentine impoundment (bottom left of image). The image is offered as visual proof that the impoundment does NOT function as a reservoir.
As the impoundment is not a reservoir, the power scheme can therefore be re-engineered to restore Lake Pedder and transfer the water that passes through the impoundment to Lake Gordon without any loss in storage capacity.