Arapuni

The Arapuni Power Station and Dam, constructed between 1924 and 1929, holds the distinction of being the first government-built high dam on the Waikato River. It played a pioneering role in the development of the Waikato Valley Hydro Electric Power Programme, which spanned from 1929 to 1966.

In 1923, worldwide tenders were solicited for the construction of Arapuni, and access to the site from Putāruru began. The contract was awarded to the British firm Armstrong Whitworth in September 1924.

The completion of the diversion tunnel in July 1926 allowed for the dewatering of the site. While progress on the head works was favorable, there was a disagreement between the contractor and the Public Works Department (PWD) regarding the suitability of the foundations at the power house site. In December 1927, the impasse was resolved when the PWD took over the works.

Despite numerous challenges, including severe flooding, the project continued to make headway. In June 1929, the first 15-megawatt (MW) unit was put into service, and by June 1930, three generators were operational, with progress underway on the fourth.

The completion of the power station and dam marked a significant milestone in utilizing the Waikato River for hydroelectricity generation—an issue of great importance in the mid-20th century. A 1947 film titled "Power from the River" highlighted the constraints of electricity supply in the North Island, particularly during peak evening hours, and advocated for the construction of Waikato River power stations to augment the supply from Arapuni. As part of the scheme, six additional stations were built, including Maraetai, the only one with a larger capacity than Arapuni.

The dam stands 64 meters high from its foundations to the roadway along its crest, raising the water level 42.7 meters above its previous mark. The water then travels approximately 1.2 kilometers in an open headrace before passing through penstocks to reach the powerhouse located at the base of the gorge. The powerhouse is a reinforced concrete structure measuring 136 meters in length, 22.8 meters in width, and 22 meters from the tailrace water level to the roof.

The eight penstocks, each with a diameter of 3.6 meters, transport water from the forebay to the turbines. The vertical Francis-type turbines have a combined capacity of 164 MW. Power is supplied to the North Island system at 110 kilovolts from the main busbars at the outdoor station.

Recognized as part of the IPENZ "Engineering to 1990" project, which aimed to commemorate New Zealand's sesquicentenary in 1990, the Arapuni Power Station and Dam exemplify the nation's engineering heritage. A plaque was unveiled to commemorate the significance of this power station in the country's development.

The Arapuni Suspension Bridge, situated downstream from the Arapuni Power Station on the Waikato River in New Zealand's South Waikato District, was built in the mid-1920s. Its purpose was to provide access for workers from the village of Arapuni to the power station construction site in the bush-lined gorge.

Spanning the Arapuni gorge near the Arapuni Dam, the suspension bridge was a simple structure associated with New Zealand's largest civil engineering project at the time. Construction commenced in May 1925 and was completed within three months after April 1926, without any formal opening ceremony.

The bridge linked "top camp," which eventually became the Arapuni township, with the western side of the gorge, accommodating workers involved in constructing the spillway, powerhouse, and penstock.

Designated as a Category II historic place by the Historic Places Trust on April 21, 1994, the bridge attracts many tourists. Access to the site is available via a walkway that begins on Arapuni Road, opposite Rabone Street.

Visitors crossing the bridge are treated to breathtaking views of the scenic gorge, with visible geological features. The cliffs on the true right of the landing were formed by volcanic ignimbrite blocks, exhibiting vertical fissures resulting from cooling stresses.

Occasionally referred to as the Arapuni Swing Bridge, the bridge is colloquially known as a swing bridge in New Zealand, denoting a suspension bridge exclusively used for pedestrians.

As part of the ongoing development of the Waikato River Trails, a section of the New Zealand Cycle Trail, the trail will pass the bridge on the true right side of the Waikato River.

The presence of the Waikato River Trails has led to an increase in visitors to the village, attracting hikers, walkers, and cyclists who tackle portions of the 100km trail during weekends.