HEC Derwent Scheme

Construction of the Derwent hydropower scheme began in 1934 and the last power station was commissioned in 1968.

There are two sections in the Derwent hydropower scheme – the upper and lower. This is because of the difference in how the water is stored in the sections. Visually the scheme resembles a Y shape.

The upper section of the scheme uses larger, deeper lakes for water storage than the lower section. The four main power stations in the upper section release water when it is needed to generate electricity. The upper section is formed from the Nive River system in the east and the Derwent River system in the west, making up the top of the Y.

The lower section is called run-of-river, which means water flows to power stations directly from a river, and cascades through a series of power stations. This means the same water is used to generate energy multiple times. There are six power stations in the lower section and they use water from the Derwent River multiple times. The lower section forms the ‘tail’ of the Y.

No 2 Canal

While No 1 Canal has a fairly straightforward journey from Lake King William to Tarraleah, No 2 Canal has nothing of the sort.  Firstly it goes through Nieterana Power Station and then is raised up the hill through an underground pipe / siphon.  It exits this pipe into Canal No 2 and flows at roughly a parallel course to Canal No 1 until it hits the Mossy Marsh Tunnel at approximately -42.277214, 146.337375.  From there the water travels underground to the Mossy Marsh Canal at -42.275950, 146.366638.  At -42.279872, 146.374323 this canal simply exits into Mossy Marsh the water is allowed to run its natural course which runs into Mossy Marsh Pond.  From Mossy Marsh Pond the water runs through a short canal to Pump Pond (Sometimes called Tarraleah Pond #2) and then onto Tarraleah Pond #1 to join No 1 Canal.  The point where the cache is a short canal between Pump Pond and the Tarraleah Pond #1

Hints