Hydro Generation.

Hydro Generation.

We harness the power of water through our nine hydro plants along the Waikato River to produce about 10% of New Zealand’s electricity. The great thing about hydro generation is that it can be increased or decreased quickly to meet peak demand for electricity. Our hydro system is the largest peaker in the North Island – and located close to the country’s largest city Auckland.


Hydro Stations.

Nine stations on the Waikato River. Flexible and rain fed, hydro output can be increased or decreased quickly and efficiently.


Since 1947 
188km downstream of Lake Taupō, the Karāpiro Lake is the home of NZ Rowing.


Since 1929 
Protected under the Historic Places Trust Arapuni has the largest capacity of any station in the Waikato hydro system.


Since 1961
The smallest power station on the Waikato River and is used to supplement other stations.

Maraetai I and II 

Since 1952 and 1970
Combined they offer the largest output from any lake on the Waikato River.


Since 1956 
The main switching station for upper Waikato generation and supplies the transmission system that leads north.  


Since 1958
Originally designed for three generators, a fourth was later added and commissioned in 1962.


Since 1961 
Lake Ōhakuri covers 12 sq km and is the largest lake on the Waikato River.


Since 1964
13km downstream from Taupō, Aratiatia is the smallest hydro reservoir in the Waikato Hydro System.

Upgrading our vital hydro assets.

Upgrading our vital hydro assets.

We’re upgrading our vital hydro plants, some of which have been operating for over 80 years, so they can keep producing clean electricity reliably and efficiently for decades to come.

We’re applying state-of-the-art technology and engineering techniques – along with an approach that respects the heritage and original construction of the plants – to achieve gains in performance and efficiency.  

We have completed upgrades to major generating equipment at Ōhakuri and Arapuni, along with upgrades now in progress at Whakamaru. The upgrade at Whakamaru will increase capacity at this station by 20MW to 120MW, and is due for completion in 2020.

80+ years some of our Hydro stations have been operating

5% This year we expect to increase efficiency by 5%

Whakamaru upgrade.

Watch 8 months' work in 30 seconds. Teams can be seen rehabilitating generator and turbine technology to make Whakamaru station more productive. Wonderful.