We are currently working on a ~$90million upgrade to the Karāpiro Hydro Power Station.

We have already replaced the first unit and we are now starting the work on the second. This is the first time since the station was commissioned in 1948 that the three turbines have been replaced.


Photo: Head gate lift for the first unit at Karāpiro Hydro Power Station, April 2023.

This is a project that is expected to continue until 2025.

The upgrade will extend the power stations life span by another 50 years and make it more efficient in generating more renewable electricity for New Zealand. 


This is a major works project, and we will be continuing with station upgrades with the removal and replacement of the second unit and headgate. This will mean the road across the dam will need to close again from Monday 11 September 2023 through to August 2024.
Access over the Dam has been part of the landscape for 75 years and we appreciate that not having access during our refurbishment of the power station may be inconvenient for some locals and other road users. We thank everyone for their patience as we continue to undertake this important work on the station. 

The road will open over the summer holidays from 6:00pm Friday 22 December 2023 and close again for works to resume at 7:00am on Monday 8 January 2024.


Work on the third unit will occur over a similar time frame in the following year. We will be able to confirm actual dates closer to the time.


Are you allowed to close the road?
While the public are allowed to use the road that crosses the dam, it is privately-owned by Mercury. Under the rules of the easement that Mercury has with Waipa District Council, Mercury is allowed to restrict public access when we need to maintain the dam.

Will there be access for pedestrians and cyclists when the road is closed to traffic?
Unfortunately, we will not be able to provide safe crossing for pedestrians or cyclists during this second phase.
During this phase, there is additional work being undertaken and large equipment needed on the dam. This equipment will be left on the dam for extended periods of time. It will not be possible to safely secure the site over night or on weekends and therefore access across the road would be very unsafe for members of the public at any time.

Why is Mercury doing this?
It’s vital that we maintain and, where possible, improve upon our generation assets to make sure they continue to provide as much renewable energy to New Zealanders as possible.
We have nine dam structures on the Waikato hydro system aged 60 to 97 years. About $350 million is being spent on the upgrading these dams over the next 15 years.
Construction of Karāpiro Hydro Power Station was completed in 1947 and it was commissioned in 1948. This is the first time since the station was commissioned that the turbines have been replaced.
This project will extend the asset’s life by 50 years and make the power station more efficient.

How much more efficient will it be?
When the upgrade is complete the station will generate an additional 16.5MW, taking output from 96MW to 112.5MW and increasing the average energy production by 32GWh to 537GWh each year.
This means that Karāpiro power station will generate, enough new renewable power for approximately 19,000 New Zealand homes. That’s 17% more than its current output.