Lake Ruataniwha is an artificial lake in the Mackenzie Basin in the South Island of New Zealand. It was formed in 1977-1981 as part of the Waitaki hydroelectric project. It is located on the traditional border between the provinces of Canterbury and Otago, two kilometers north of Twizel. The lake takes its name from Ruataniwha Station, a large sheep farm in the area, part of which the New Zealand Department of Electricity acquired as a site for the Twizel settlement (founded in 1968). Ruataniwha was the Maori chief who sank when the shuttle Arai-te-ura sank Moeraki in the 12th century.
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| Lake Ruataniwha |
Functions
The lake is about 4.5 km long and covers an area of 3.4 square meters. Km. It was formed by the New Zealand Department of Labor as part of the Upper Waitaki project between 1977 and 1981 in the gorge created by the Ohau River. The gorge was blocked by the Ruataniwha dam building whose crest carries the State Highway 8 between Twizel and Omaram.
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| Lake Ruataniwha |
Lake Ruataniwha is powered by generation from the Ohau A power plant, as well as from the spill from Lake Ohau into the normally dry bed of the Ohau River. Ruataniwha exits through a natural break in the dam into a channel that feeds the Ohau B power plant. Just downstream there is a junction with the small Lake Wairepo.
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| Lake Ruataniwha |
The Kellands pond is connected to the Vairepo arm via a culvert under State Highway 8, with an area of 22 hectares occupied by further gravel pits. The dam has a built-in spillway (Gate 22), which contains 3 locks with a total capacity of 4,900 cubic meters per second, which flow into the usually dry bed of the Ohau River. The lake functions as an injection reservoir for the power supply circuit. If during an overflow into Lake Ohau that Ohau A cannot pass, or when the Ohau Canal breaks off, Lake Ohau may overflow through a dam into the normally dry bed of the upstream of the Ohau River and thus into Lake Ruataniwha.
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| Lake Ruataniwha |
In addition, if water cannot pass through the canal to Ohau B, then the excess flow into the lake can be diverted downstream of the lower course of the Ohau River to Benmore Lake. Although the Lake restricted container also ensures that the flows through Ohau A must not be exactly in accord with those through Ohau B and Ohau C.