Whakamaru Dam

Whakamaru Power Station
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Location of Whakamaru Power Station in New Zealand
Country	New Zealand
Location	Lake Whakamaru
Coordinates
Status	Operational
Opening date	1949
Owner(s)	Mighty River Power
Dam and spillways
Impounds	Waikato River
Power station
Turbines	4
Installed capacity	100 MW

Whakamaru Power Station is a hydroelectric power station on the Waikato River, in the North Island of New Zealand. It is the fourth hydroelectric power station on the Waikato River.

Lake Whakamaru is one of the larger hydro reservoirs on the Waikato river. The power station is owned and operated by Mighty River Power. The adjacent Whakamaru switching station is operated by Transpower and is one of eight reference nodes on the New Zealand national grid.

History

Development work started in 1949 with the construction on 10 kilometres (6.2 mi) of road from Mangakino which at the time was the operational centre of the Waikato hydroelectric scheme. Firstly a diversion channel 259 metres (850 ft) long, 31 metres (102 ft) deep and 7 metres (23 ft) wide was built taking 3 years to complete.

The foundation rock turned out to be deeply cracked and filled with clays rendering it partially porous. Shafts were sunk into the rock and this allowed the clay to be cleared and cement grout was later forced into the rock which was then back-filled with concrete.

Transmission

Whakamaru is a major node in the North Island electricity grid. Electricity generated by Whakamaru, as well as the other five Waikato hydroelectric power stations, and from the geothermal power stations in the area converges at the Whakamaru substation on the western side of the dam. Power from Whakamaru is then transmitted via 220 kV lines to the Bay of Plenty, Hawke's Bay, Manawatu and Hamililton. The largest transmission route is to New Zealand's largest city, Auckland, approximately 200 kilometres (120 mi) to the north - three 220 kV circuits connect Whakamaru to Otahuhu in southern Auckland, with an additional circuit serving Otahuhu via Hamilton.

The main control centre for the electricity generation and transmission system for the entire North Island was established at Whakamaru in 1964. The facility continued to operate as the North Island System Control Centre until a replacement facility was established at Hamilton in 1992.

A major new transmission line has been constructed from Whakamaru to Brownhill Road, the Whakamaru to Brownhill Road transmission line. close to the south Auckland urban boundary. This new line re-inforces supply to Auckland and allows for the large amount of new geothermal generation that is expected in the Taupo region over the next 5–7 years. A separate switching station, designated Whakamaru North, has been built approximately 800 metres (2,600 ft) from the current substation as the terminal station for the new line, with short tie-lines connecting to the existing substation.