MERCURY NEWS

5 March 2026

Mercury begins four‑year refurbishment of Maraetai II Hydro Station 

Mercury has started working on improvements to its Maraetai II Hydro Station on the Waikato River.

Mercury’s Chief Operating Officer – Generation, Kevin Taylor, said the project will involve refurbishing the turbines, generators, and water intake gates for each of the station’s five generation units.

“We’re investing $29.6m in the four-year project, which will improve the hydro station’s operational reliability and extend its life by 20 years.”

The refurbishment project is being led by hydro specialists ANDRITZ, which completed the three-year rehabilitation programme of Mercury’s Karāpiro Hydro Station in 2025.
 

The rotor being lifted out of the generator unit 10 at Maraetai II.

ANDRITZ New Zealand General Manager Tony Mulholland said ANDRITZ was pleased to again partner with Mercury on a new project.

“We’re excited about having this opportunity to use our expert skills and experience to extend the life of the generation units at Maraetai II.”

Mr Taylor said the project was part of Mercury’s hydro rehabilitation programme, which involves upgrading each of the nine hydro stations in the Waikato Hydro System.

“Taking care of our generation assets is part of our Kaitiakitanga strategy; we want to make sure our hydro stations are operating in harmony with the natural environment they were built in, many years ago.

“This ensures we are protecting the mauri of the awa, the lifeforce of the river, while improving the longevity of hydro stations so they can keep generating   clean renewable energy for many years to come.

“Our success as a good kaitiaki will help us embrace our Kōtuitanga strategy; building trust with the iwi and communities where we operate our hydro assets.”
Maraetai II has been generating energy for New Zealand since 1970 and continues to play a critical role within the hydro system.

It was constructed in the same valley as Maraetai I and the two are operated as one hydro station.

The powerhouse's 10-tonne crane was used to move the rotor to the loading bay.

Each station has five generation units and combined, the average annual output is 880GWh, that’s enough to power the equivalent of 110,000 average homes every year.

Mr Taylor said the goal was to complete the Maraetai II project by 2029 and have it fully operational before heading into the next stage of the hydro rehabilitation programme.

“We are planning a major upgrade project of our Maraetai I, Ātiamuri and Ōhākurī hydro stations under one, multi-year programme.

“We expect to make an announcement on that project in March 2026.”

 For more information about the  Maraetai II Refurbishment Project click here.