page_title: Lake Ruataniwha
section_title: Construction
hierarchical_section_title: Lake Ruataniwha / Construction
caption_attribution_description: Flight from Rotorua to Queenstown. Over South Island, New Zealand
context_page_description: Lake Ruataniwha is located in the Mackenzie Basin in New Zealand's South Island. An artificial lake, it formed in 1977–1981 as a result of the Waitaki hydroelectric project. It lies on the traditional boundary of the Canterbury and Otago provinces, with the town of Twizel two kilometres to the north.
  The lake takes its name from the Ruataniwha Station, a large sheep-station in the area, part of which the NZ Electricity Department purchased as the site for the township of Twizel. Ruataniwha was a Māori chief who drowned when the canoe Arai-te-uru sank near Moeraki in the 12th century CE.
  Lake Ruataniwha served as one of the filming locations of the 2009 zombie film Last of the Living.
context_section_description: Before construction of the dam could start the Ohau River was diverted by cutting a channel through a low, rocky extension of the Benmore Range and building three diversion gates there which consumed 200,000 cubic metres of concrete.  The Ohau River was diverted in August 1980 so that water passed through Ohau A and then back down the river bed. Later that year, downstream of Ohau A, the river was again diverted, this time away from its natural channel and through the completed gates.  An earth dam with gravel shoulders was then built on its upstream and downstream sides. The main dam, which blocks the original river channel, is 240 metres long while an adjoining wing dam is 480 metres.
  When the dam was completed the diversion gates were closed which, beginning in March 1982, impounded the water behind the dam up to and over a temporary weir which had been built downstream of Ohau A. In 1984 the lake was temporarily lowered by 3 metres while this weir was removed to improve the performance of the Ohau A power station. The diversion gates now function as spillway gates to allow excess water to pass safely through the dam.
  The lake was officially opened on Saturday 24 April 1982. There was a weekend event which attracted 7000 spectators with the rowing course hosting a regatta attended by 188 crews and representing 80 South Island rowing clubs.
caption: View of the canal that flows via Ohau B station from Lake Ruataniwha (centre distance) to Lake Benmore (foreground)
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