Mercury has begun a four-year refurbishment project at its Maraetai II Hydro Station on New Zealand’s Waikato River.
The NZ$29.6m project will involve refurbishing the turbines, generators and water intake gates for each of the station’s five generation units.
Mercury Chief Operating Officer – Generation, Kevin Taylor, said the work is aimed at improving reliability and extending the plant’s operating life: “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 programme is being led by ANDRITZ, which previously completed the three-year rehabilitation of Mercury’s Karāpiro Hydro Station in 2025.
ANDRITZ New Zealand General Manager Tony Mulholland said the company welcomed the opportunity to work with Mercury again: “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.”
According to Taylor, the work forms part of Mercury’s broader programme to upgrade all 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 electricity since 1970 and operates alongside the neighbouring Maraetai I station. Each station has five generation units and together they produce an average annual output of about 880GWh.
Mercury said the refurbishment began in January 2026 and will be completed in stages through to 2029, with each unit expected to take around six months to overhaul.
Taylor said the company plans to follow the project with further upgrades across the hydro system.
“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.”
