Arapuni

Arapuni is a small village just over 10 kilometres west of Putāruru. From the village visitors can access fishing from the Arapuni Dam Bridge, recreational activities like water-skiing, boating and fishing from Jones' Landing and many a tramping and cycling experience from the Waikato River Trails.

Arapuni Power Station and Dam
Built between 1924 and 1929, the Arapuni Power Station and Dam was the first government-built high dam constructed on the Waikato River. It pioneered the development of the Waikato Valley Hydro Electric Power Programme, which was carried out between 1929 and 1966.

In 1923, worldwide tenders were ca1. A4 Info Sheetlled for the building of Arapuni and access to the site from Putāruru was commenced. A contract was placed with the British firm of Armstrong Whitworth in September 1924.

The diversion tunnel was completed in July 1926, and the site dewatered soon after. Good progress was made with the head works, but at the power house site there was disagreement between the contractor and the Public Works Department (PWD) over the suitability of the foundations. The impasse was broken when the PWD took over the works in December 1927.

The works progressed in the face of extensive difficulties, not the least of which was severe flooding. However the first 15 megawatt (MW) unit was put into service in June 1929 and by June 1930, three generators were in service, with work well advanced towards the fourth.

The completion of the power station and dam was an important first step in harnessing the Waikato River for hydro electricity production. This became an important issue in the mid-20th century. A 1947 film, Power from the River, highlights the limitations of the North Island's electricity supply at that time, especially during peak evening hours, and promoted the construction of Waikato River power stations to supplement the supply from Arapuni. Six other stations were constructed as part of the scheme, including Maraetai, the only one with larger capacity than Arapuni.

The dam is 64 metres (m) high from its foundations to the roadway running along its crest, and raised the water 42.7 m above its old level. The water then flows about 1.2 kilometres (km) in an open headrace, and then through penstocks to the powerhouse at the base of the gorge. The powerhouse is a reinforced concrete structure 136 m long, 22.8 m wide, and 22 m from tailrace water level to roof.

Eight steel-lined penstocks, each 3.6 m diameter, feed the water from the forebay to the turbines. The eight vertical Francis type turbines have a total capacity of 164 MW. From the main busbars at the outdoor station, power at 110 kilovolts is supplied to the North Island system.

This item of New Zealand’s engineering heritage was recognised as part of the IPENZ “Engineering to 1990” project, which the Institution organised to help celebrate the country’s sesquicentenary in 1990. A plaque was unveiled to mark the significance of this power station as part of the development of the nation.

Source: https://www.engineeringnz.org/our-work/heritage/heritage-records/arapuni-power-station-and-dam/