Government and hydroelectricity
Central government regarded water as a public resource. In the 1890s, when entrepreneur Josiah Firth proposed to use the Huka Falls on the Waikato River for hydroelectric generation, the government moved to prevent this happening.
In 1896 Premier Richard Seddon introduced legislation to prevent the development of electrical power generation without government permission. The state gained monopoly control over water for hydro development. This served the country’s energy needs well, as it encouraged the creation of a national system, centralising planning, and aiding extension of electricity into rural areas.
In 1904 the government commissioned a survey of hydro resources. It constructed a large power station at Lake Coleridge to supply the city of Christchurch. The station began generating power in 1914.
Hydroelectricity in the North Island
During the First World War the government investigated large schemes in the North Island, with the intention of creating an island-wide system. Stations were planned at Arapuni on the Waikato River, Tuai, Piripāua, and Kaitawa on Lake Waikaremoana and Mangahao in the Tararua Range.
Small but useful
Many very small hydro plants were vital for isolated areas not yet reached by power lines. The 1934 Dawson Falls hydro station on Mt Taranaki is one of the oldest still operating unchanged.
This plan became the foundation of the country’s 20th century integrated electricity system, based on hydro power. The goal was to achieve economies of scale, with large generating plants at power sources feeding a network of high voltage transmission lines carrying electricity to centres of use.
Mangahao, in Horowhenua, was completed in 1924. The station was on the small side with an erratic water supply. Construction was difficult at the wet and inaccessible site, and frequent flooding hindered progress on the works.
Arapuni, finished in 1929, was plagued by serious engineering problems because of the geology of the area. The Lake Waikaremoana stations were built in 1929 (Tuai), 1943 (Piripāua) and 1948 (Kaitawa). In 1934 Mangahao, Arapuni and Tuai stations were interconnected into a single North Island system.
The state employed large workforces to build stations. They lived in temporary ‘hydro towns’ during the construction phase, then moved on to other hydro works.
Demand for electricity
In the second half of the 1920s increased availability of both electricity and electrical appliances led to spiralling demand. Existing electricity supply was no longer sufficient.
Government attention shifted to the South Island. Southland, with central government’s agreement, built the Monowai station in 1925, and reticulated the region, erecting power poles and lines. The government made plans for the centrally located Waitaki River, and a large station was built there by 1934. New Zealand had a fledgling national electricity generation system based on hydro power.