Harnessing the Waikato River

When early European settlers arrived in the Waikato, they, like the local Maaori, relied on the river to explore the region and transport supplies. In the early years of peace, it remained a vital supply line, connecting Auckland to the isolated settlements further south. During the Waikato War, the militia also used the river to advance their position into the interior.

Since colonisation, the river has undergone drastic changes. One of the most significant was the introduction of hydroelectric dams. The first - Horahora Power Station - was built in 1913 to supply electricity to the goldfields in Waihi. It remained in operation until 1947, when the newly built Karapiro Dam submerged it under Lake Karapiro.

The government-funded Arapuni Dam followed, taking five years to complete between 1924 and 1929. At its opening, it powered half the homes in the North Island. By 1936, the country had emerged from the Great Depression into a period of prosperity. With more disposable income, many households began purchasing electrical appliances. Electric radiators warmed drawing rooms, tools filled home workshops, and refrigerators and washing machines became increasingly common. Domestic power use surged between 1936 and 1939.

During World War II, electricity demand continued to grow, but little was done to improve supply. At one point, Arapuni required a replacement generator, but wartime shortages meant a seven-year delay, as the necessary parts had to come from Britain, which was focused on the war effort.

In the mid-1940s, a two-year drought caused Lake Taupoo’s water levels to drop alarmingly. This prompted the government to explore new sources of renewable energy. The Ministry of Works proposed building a series of dams along the Waikato River to triple the North Island’s electricity supply.

After Arapuni and Karapiro, further dams were constructed: Maraetai, Whakamaru, Aatiamuri, Waipaapa, Oohakuri, and Aratiatia. While the original plan was to build ten, only eight were completed.

The Waikato hydro scheme made a major contribution to the region and the country’s economy. It helped control flooding and supported fisheries, as well as recreational amenities like the international rowing course at Karapiro. However, the dams also came at a cost. They submerged significant cultural and geothermal sites, altered the river’s ecology, changed its temperature, clarity, and quality, and disrupted other recreational use.

These environmental changes have deeply impacted the relationship between the river and local iwi - a relationship that, for many, has been permanently altered.