Twin Falls (Newfoundland and Labrador)
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The Twin Falls are a pair of waterfalls, 175 ft (53 m) high, that are located on the Unknown River, a tributary of the Churchill River that drains the central Labrador basin and flows into Lake Melville and the Atlantic Ocean. Hydroelectric power development rights on the river were acquired by the British Newfoundland Development Corporation (Brinco) in the 1950s. In partnership with Wabush Mines Limited and the Iron Ore Company of Canada, the two mining corporations operating in Western Labrador, Brinco created the Twin Falls Power Corporation to deliver power 115 miles (185 km) west to the two mining operations being developed near the Labrador-Quebec border.
Construction of the Twin Falls power station began in 1960 and was located at the base of a 300 ft (91 m) high dry river canyon adjacent to the Unknown River. The river was dammed at Twin Falls to form a reservoir (Ossokmanuan Reservoir), raising the water to the height of the old channel's escarpment. When finished in 1963, the station had a total capacity of 225 MW with two 115-mile (185 km) long transmission lines at 230,000 volts (or 230 kV), with remote switching at the far end from the station. It was a masterpiece of hydroengineering constructed at a cost of $47.5 million (1963).
Twin Falls power was essential to the later power development at Churchill Falls. It helped open up the area and supplied the power required during the construction phase of the project. In the planning stage, however, it became apparent that greater efficiency in the production of electricity could be achieved by diverting the flow of water from the Ossokmanuan Reservoir into the Smallwood Reservoir. Utilizing this water at the Churchill Falls plant enabled approximately three times as much electricity to be produced from the same volume of water. In July 1974 the Twin Falls plant was closed and the water diverted into the Smallwood Reservoir under an agreement with Churchill Falls Labrador Corporation Limited (CFLCo).