21-672: Benmore Dam is the largest dam within the Waitaki power scheme , located in the Canterbury Region of New Zealand's South Island . There are eight other power stations in the Waitaki Power Scheme. The dam is the largest earth-fill (zoned embankment dam) water-retaining structure in New Zealand. Its core is low permeability clay material, supported by two massive shoulders of river gravel. Lake Benmore has
42-583: A cost of $ 67 million. This enabled a 6% reduction in water use for the same generation capacity, increasing annual generation by 70 GWh (250 TJ). New switchboards and an upgrade to the switchyard were also undertaken. Benmore is the South Island terminus of the HVDC Inter-Island link between the North and South Islands of New Zealand. The HVDC converter stations are on the west side of
63-598: A major contributing factor. A more modest successor scheme, the North Bank tunnel looked likely to proceed, with water rights being granted in 2009, but land access negotiations were suspended in January 2013 due to flat demand for electricity forecast for the next five years. Lake Benmore Lake Benmore is New Zealand 's largest artificial lake . Located in the South Island of New Zealand and part of
84-508: A proposal for a new series of canals and dams was made by Meridian Energy for irrigation and electricity generation on the river. This scheme, known as Project Aqua , planned to divert up to 77 percent of the lower river's flow to create a hydroelectric scheme, but these plans were dropped in March 2004. Lack of commercial viability was given as the major reason for the scheme's shelving, although strenuous public protest may also have been
105-630: A traditional political boundary between Canterbury and Otago . The term "south of the Waitaki" is often used to refer to the Otago and Southland regions as one common area (the two regions share historical and ethnic relationships which make them distinct from the regions to the north of them). The river is popular for recreational fishing and jetboating . Waitaki translates from southern Māori as "weeping waters" ( wai = "water", taki = "to weep, mourn"). The equivalent in standard (northern) Māori
126-401: A volume of 1.25 billion cubic metres, about 1.5 times as much water as Wellington Harbour . The dam's spillway can cope with over 6,000 cubic metres of water per second, about 20 times the mean river flow. With a generating capacity of 540 megawatts (720,000 hp), Benmore Power Station is the second largest hydro station in New Zealand behind Manapouri , and the largest dam in
147-498: Is Waitangi. The river is the site of many hydroelectricity projects. The Waitaki Hydro Scheme , which includes several large dams, is one of the largest hydroelectric projects in the nation. The Waitaki dam was built first, between 1928 and 1934, and without earth-moving machinery, followed by the development of the Aviemore Dam which created Lake Aviemore , and then Benmore Dam which created Lake Benmore . Lake Pukaki
168-581: Is about 8 kilometres (5.0 mi) up the valley from the township. Benmore is a major switching point in the New Zealand national grid and one of two major switching stations in the Waitaki Valley (the other being Twizel sub-station). The importance is largely due to the location at Benmore of the southern terminal station of the HVDC Inter-Island link. The main AC switching station is on
189-736: The Ahuriri River and the Hakataramea River . It passes Kurow and Glenavy before entering the Pacific Ocean. The River lends its name the Waitaki District on the south side of the river bank. The river's flow is normally low in winter, with flows increasing in spring when the snow cloaking the Southern Alps begins to melt, with flows throughout the summer being rainfall dependent and then declining in
210-666: The Waitaki River , it was created in the 1960s by construction of Benmore Dam . The lake has an area of about 75 km² and a maximum depth of 90 meters. The lake consists of two arms: the Haldon arm, fed mainly by the Tekapo , Pukaki and Twizel rivers, and the Ōhau Canal ; and the Ahuriri Arm, fed mainly by the Ahuriri River . Immediately downstream is Lake Aviemore . As of 2023, Land Air Water Aotearoa described
231-844: The 1960s, work was started on the Upper Waitaki project. This project consisted of taking the discharge from the original Tekapo (A) station through the Tekapo Canal , to Tekapo B station at the edge of Lake Pukaki. The dam at Pukaki was increased in height. Water from Pukaki is then transferred into the Pukaki Canal which meets the Ohau Canal from Lake Ōhau into Ōhau A station and Lake Ruataniwha . The Ohau Canal continues beyond Lake Ruataniwha to Ōhau B midway along, before emptying through Ōhau C into Lake Benmore. The stations are (commissioned/capacity/annual output): In 2001
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#1732802619548252-482: The autumn as the colder weather begins to freeze the smaller streams and streams which feed the catchment. The median flow of the Waitaki River at Kurow is 356 cubic metres per second (12,600 cu ft/s). The first major infrastructure improvements to the river were made between 1881 and 1914 with the construction of road and rail bridges at Kurow and Waitaki Bridge . The middle of the river bed formed
273-489: The country. Construction of the dam and hydroelectric station began in 1958 at a cost of $ 62 million. It was commissioned in 1965, and was officially opened by Prime Minister Sir Keith Holyoake on 15 May that year. It was built for the New Zealand Electricity Department ; since 1999 it has been owned and operated by Meridian Energy . From 2008 to 2010 the six turbines were refurbished at
294-495: The east bank of the tailrace, and electricity generated at Benmore Power Station is injected into the national grid here. Three major 220 kV lines containing five circuits run from the Benmore substation. Clockwise from south, they are: The HVDC converter stations are located on the west side of the tailrace, connected to the AC switching station by lines over the tailrace. The -350 kV thyristor Pole 2 has its valve hall on
315-470: The east coast. It starts at the confluence of the Ōhau and Tekapo rivers, now at the head of the artificial Lake Benmore , these rivers being fed by three large glacial lakes, Pukaki , Tekapo , and Ōhau at the base of the Southern Alps. The Waitaki flows through Lake Benmore, Lake Aviemore and Lake Waitaki , these lakes being contained by hydroelectric dams, Benmore Dam , Aviemore Dam and Waitaki Dam . The Waitaki has several tributaries, notably
336-574: The south side of the site. A new +350 kV thyristor Pole 3 was commissioned in 2013 to replace the ageing Pole 1, and its valve hall is located adjacent to the existing Pole 2 valve hall. Waitaki River The Waitaki River is a large braided river in the South Island of New Zealand . It drains the Mackenzie Basin and runs 209 kilometres (130 mi) south-east to enter the Pacific Ocean between Timaru and Oamaru on
357-717: The tailrace, and convert 220 kV AC power to ±350 kV DC for the 610 km (380 mi) journey to the North Island converter station at the Haywards in Lower Hutt . Otematata is the small town that was created to support workers who constructed the dam, and their families. The town was constructed by the Ministry of Works, which residents called "Uncle Mow" or "Big Mow" as it provides every feature, including social activities and clubs, and expelled criminals from
378-503: The town. After the dam was constructed, much of the village was dismantled. Many of the houses, which had been trucked in from Roxburgh , were trucked away again and moved to the next site in Twizel . Today Otematata supports the dam, although with advances in technology the staffing needed to maintain the dam is drastically smaller. Due to this the town is now a small holiday community, with only around 200 permanent residents. The dam
399-473: The water quality as "very good", with a trophic level index of 1.8. It also described the quality of ecological conditions as "high", with a lake submerged plant indicators score of 72.0%. The lake is split between the Mackenzie , Waimate , and Waitaki districts , within the southern portion of the Canterbury Region . The lake is the reservoir of Benmore Dam , New Zealand's largest earth dam, which
420-618: Was created as part of the Waitaki hydroelectricity power scheme. Construction of Benmore Dam was approved in 1957 and the lake was filled in December 1964. After the lake was created the incidence of seismic shocks increased by a factor of three to six times. Besides being a reservoir for Benmore Dam, the lake is a fishing spot; in 2009 it was the second most- fished lake in New Zealand , with fish such as brown trout , rainbow trout , chinook salmon , and sockeye salmon . Fish in
441-454: Was initially dammed at this stage to provide storage and flow control. A small station was also installed on Lake Tekapo , with water taken through a 1.6 km (1 mi) tunnel to a power station below the level of the lake. The original Waitaki power stations discharge water back into the Waitaki River which then forms a storage lake for the next station in the chain. The three power stations are (commissioned/capacity/annual output): In
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