Lake Ruataniwha
Encyclopedia
Lake Ruataniwha is located in the Mackenzie Basin
in New Zealand
's South Island
. An artificial lake, it was formed as part 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.
It is named after Ruataniwha Station, a large sheep station in the area, part of which was purchased by the NZ Electricity Department as the site for the township of Twizel. Ruataniwha was a Maori chief who was drowned when the canoe Arai-te-uru
sank near Moeraki
in the 12th century.
It was formed by the New Zealand Ministry of Works as part of the Upper Waitaki Power Project between 1977 and 1981 in a gorge created by the Ohau River
. The gorge was blocked by the building of the Ruataniwha Dam whose crest carries State Highway 8 between Twizel and Omarama
.
Lake Ruataniwha is fed by the output from the Ohau A
power station and also by an overflow discharge from Lake Ohau
down the normally dry bed of the Ohau River.
Ruataniwha discharges through a natural gap in the dam into a canal which feeds the Ohau B
power station. Immediately downstream is a connection to Wairepo Arm, a small lake. Connected to the Wairepo Arm by way of a culvert under State Highway 8 is Kellands Pond, whose 22 hectare area occupies further gravel pits.
There is a spillway (Gate 22) built into the dam which contains 3 gates with a total discharge capacity of 4,900 cubic metres per second which flows into the normally dry bed of the Ohau River.
The lake functions as a surge reservoir for the power scheme. If, during excessive inflows into Lake Ohau which Ohau A is unable to pass or, when there has been a failure of the Ohau canal, Lake Ohau can overflow a weir into the normally dry bed of the upper reaches of the Ohau River and thus into Lake Ruataniwha. Also, if water cannot pass down the canal to Ohau B then the excess inflows into the lake can be diverted by the spillway down the bed of the lower reaches of the Ohau River to Lake Benmore
. While limited the storage capacity of the lake also ensures that the flows through Ohau A do not have to be exactly matched to those through Ohau B and Ohau C
.
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.
venues.
This was not planned as part of the hydroelectric project but instead came about as facilities were constructed as a public service on the instructions of Max Smith, the locally based Project Engineer of the Upper Waitaki Power Project. The rowing course was surveyed, landscaping undertaken and anchors put down for lane markers before the lake was filled. He reached agreement with the Rowing Association that it would fund the building of the regatta control building at an estimated cost of NZ$75,000. When pressure to complete the building before the official opening of the lake raised the cost to approximately NZ$130,000 he used project funds to temporarily bridge the gap until the Rowing Association made full payment. Senior officials in the headquarters of the Ministry of Works alleged this was a misuse of funds. Despite overwhelming support from the local community he took early retirement rather than face charges under the State Services Act. At the time Smith was voicing disagreement with the government’s proposals to reduce the Ministry of Works' experienced construction workforce and to disestablish Twizel
, all of which may have influenced the official displeasure. The principal access road to the lake was named Max Smith Drive by the local community in his honour while the South Island Rowing Association made him its first life member.
The lake’s facilities can accommodate 600 rowing boats and 2000 competitors. The rowing course has eight lanes. The regatta control building contains a first aid room, drug testing area, administration rooms, storage rooms and on the upper floor, facilities for judges and the timekeepers, as well as a commentary room. The lake typically hosts an average of 5 major rowing events a year. The New Zealand national rowing championships are held there every second year, alternating with the national secondary school rowing championships. (During these the Maadi Cup
is contested.)
The lake is also used for swimming, yachting, canoeing and windsurfing.
Mackenzie Basin
The Mackenzie Basin , is an elliptical intermontane basin, located in the Mackenzie and Waitaki Districts, near the centre of the South Island of New Zealand. It is the largest such basin in New Zealand...
in New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
's South Island
South Island
The South Island is the larger of the two major islands of New Zealand, the other being the more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman Sea, to the south and east by the Pacific Ocean...
. An artificial lake, it was formed as part of the Waitaki
Waitaki River
The Waitaki River is a large river in the South Island of New Zealand, some 110 km long. It is the major river of the Mackenzie Basin.It is a braided river which flows through Lake Benmore, Lake Aviemore and Lake Waitaki. These are ultimately fed by three large glacial lakes, Pukaki, Tekapo,...
hydroelectric
Hydroelectricity
Hydroelectricity is the term referring to electricity generated by hydropower; the production of electrical power through the use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy...
project.
It lies on the traditional boundary of the Canterbury
Canterbury, New Zealand
The New Zealand region of Canterbury is mainly composed of the Canterbury Plains and the surrounding mountains. Its main city, Christchurch, hosts the main office of the Christchurch City Council, the Canterbury Regional Council - called Environment Canterbury - and the University of Canterbury.-...
and Otago
Otago
Otago is a region of New Zealand in the south of the South Island. The region covers an area of approximately making it the country's second largest region. The population of Otago is...
provinces with the town of Twizel
Twizel
TwizelUrban AreaPopulation:1,000Extent:Territorial AuthorityName:Mackenzie District CouncilPopulation:Mayor:Website:Extent:Regional councilName:Environment Canterbury...
two kilometres to the north.
It is named after Ruataniwha Station, a large sheep station in the area, part of which was purchased by the NZ Electricity Department as the site for the township of Twizel. Ruataniwha was a Maori chief who was drowned when the canoe Arai-te-uru
Araiteuru
In Māori mythology, Āraiteuru is the canoe in which brought the ancestors the Ngāi Tahu people of the South Island. The canoe was conveyed to New Zealand by the north-east wind, carrying the chiefs Kirikiri-ka-tata, Aroarokaehe, Mangaatua, Aoraki, Kakeroa, Te Horokoatu, Ritua, Ngamautaurua,...
sank near Moeraki
Moeraki
Moeraki is a small fishing village on the east coast of the South Island of New Zealand. It was once the location of a whaling station. In the 1870s, local interests believed it could become the main port for the north Otago area and a railway line, the Moeraki Branch, was built to the settlement...
in the 12th century.
Features
The lake is approximately 4.5 km in length and covers 3.4 square km.It was formed by the New Zealand Ministry of Works as part of the Upper Waitaki Power Project between 1977 and 1981 in a gorge created by the Ohau River
Ohau River
Ohau River may refer to two watercourses in New Zealand:*Ohau River, Canterbury*Ohau River, Wellington...
. The gorge was blocked by the building of the Ruataniwha Dam whose crest carries State Highway 8 between Twizel and Omarama
Omarama
Omarama is a small township at the junction of State Highways 8 and 83, near the southern end of the Mackenzie Basin, in the South Island of New Zealand. Omarama is in the Waitaki District, in the historic Province of Otago...
.
Lake Ruataniwha is fed by the output from the Ohau A
Ohau A
Ohau A is a power station operated by Meridian Energy in the South Island of New Zealand.It is located on the artificial Ohau canal. The dam is fed by water from Lake Ohau and Lake Pukaki and spills into the artificial Lake Ruataniwha....
power station and also by an overflow discharge from Lake Ohau
Lake Ohau
Lake Ohau is a glacial lake in the Mackenzie Basin of New Zealand's South Island. It is fed by the Hopkins and Dobson rivers, which have their headwaters in the Southern Alps, and has its outflow in the Ohau River, which itself feeds into the Waitaki River hydroelectric project.Ohau is the smallest...
down the normally dry bed of the Ohau River.
Ruataniwha discharges through a natural gap in the dam into a canal which feeds the Ohau B
Ohau B
Ohau B is a power station operated by Meridian Energy in the South Island of New Zealand.It is a twin station with Ohau C and is part of the Waitaki hydro scheme which consists of eight power stations operated from a control centre near Twizel...
power station. Immediately downstream is a connection to Wairepo Arm, a small lake. Connected to the Wairepo Arm by way of a culvert under State Highway 8 is Kellands Pond, whose 22 hectare area occupies further gravel pits.
There is a spillway (Gate 22) built into the dam which contains 3 gates with a total discharge capacity of 4,900 cubic metres per second which flows into the normally dry bed of the Ohau River.
The lake functions as a surge reservoir for the power scheme. If, during excessive inflows into Lake Ohau which Ohau A is unable to pass or, when there has been a failure of the Ohau canal, Lake Ohau can overflow a weir into the normally dry bed of the upper reaches of the Ohau River and thus into Lake Ruataniwha. Also, if water cannot pass down the canal to Ohau B then the excess inflows into the lake can be diverted by the spillway down the bed of the lower reaches of the Ohau River to Lake Benmore
Lake Benmore
Lake Benmore is a lake located in the South Island of New Zealand. It was artificially created in the 1960s by construction of Benmore Dam. The lake covers an area of approximately 75 km²...
. While limited the storage capacity of the lake also ensures that the flows through Ohau A do not have to be exactly matched to those through Ohau B and Ohau C
Ohau C
Ohau C is a power station operated by Meridian Energy in the South Island of New Zealand.It is a twin station with Ohau B and is part of the Waitaki hydro scheme which consists of eight power stations operated from a control centre near Twizel...
.
Construction
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 100,000 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.
Recreation
The lake has been developed by the Ministry of Works into a major recreational resource for the area with a large number of trees and a holiday park on the lakeside. Ruataniwha is also one of New Zealand's main rowingSport rowing
Rowing is a sport in which athletes race against each other on rivers, on lakes or on the ocean, depending upon the type of race and the discipline. The boats are propelled by the reaction forces on the oar blades as they are pushed against the water...
venues.
This was not planned as part of the hydroelectric project but instead came about as facilities were constructed as a public service on the instructions of Max Smith, the locally based Project Engineer of the Upper Waitaki Power Project. The rowing course was surveyed, landscaping undertaken and anchors put down for lane markers before the lake was filled. He reached agreement with the Rowing Association that it would fund the building of the regatta control building at an estimated cost of NZ$75,000. When pressure to complete the building before the official opening of the lake raised the cost to approximately NZ$130,000 he used project funds to temporarily bridge the gap until the Rowing Association made full payment. Senior officials in the headquarters of the Ministry of Works alleged this was a misuse of funds. Despite overwhelming support from the local community he took early retirement rather than face charges under the State Services Act. At the time Smith was voicing disagreement with the government’s proposals to reduce the Ministry of Works' experienced construction workforce and to disestablish Twizel
Twizel
TwizelUrban AreaPopulation:1,000Extent:Territorial AuthorityName:Mackenzie District CouncilPopulation:Mayor:Website:Extent:Regional councilName:Environment Canterbury...
, all of which may have influenced the official displeasure. The principal access road to the lake was named Max Smith Drive by the local community in his honour while the South Island Rowing Association made him its first life member.
The lake’s facilities can accommodate 600 rowing boats and 2000 competitors. The rowing course has eight lanes. The regatta control building contains a first aid room, drug testing area, administration rooms, storage rooms and on the upper floor, facilities for judges and the timekeepers, as well as a commentary room. The lake typically hosts an average of 5 major rowing events a year. The New Zealand national rowing championships are held there every second year, alternating with the national secondary school rowing championships. (During these the Maadi Cup
Maadi Cup
The Maadi Cup is the prize for the New Zealand Secondary Schools Boys' Under 18 Rowing Eights. More colloquially, it is the name given to the New Zealand Secondary Schools Rowing Regatta, at which the Maadi Cup is raced...
is contested.)
The lake is also used for swimming, yachting, canoeing and windsurfing.