Hydro stations

How hydro energy works

Most of Meridian's electricity is made from the energy of falling water. Our hydro stations generate enough electricity to power around 1.4 million homes each year.

  • The water, falling through a pipe called a ‘penstock’, is used to spin a turbine.
  • These turbines look like large wheels with wide spokes. The water hits the blades and pushes them to make the turbine spin.
  • The spinning turbine spins the generator, which generates the electricity.
  • This spinning therefore ‘changes’ the force of falling water into electricity.

It's not possible to store large amounts of electricity. But it is possible to store water in dams.

The Waitaki hydro scheme

The Waitaki hydro scheme is a series of interconnected lakes and canals used to generate electricity. It's made up of eight hydro stations on the Waitaki River in the South Island. Tekapo A and B, owned by Genesis Energy, are the first two hydro stations that make up the Waitaki hydro scheme. Meridian owns and operates the remaining six hydro stations located from Lake Pūkaki to Waitaki. The six hydro stations from Lake Pūkaki to Waitaki generate enough electricity each year for about 832,000 average New Zealand homes.

Building the Waitaki hydro scheme

The New Zealand government recognised the electricity generation potential of the Waitaki Valley as early as 1904. However, work on the large-scale project only began in the 1920s. The Waitaki dam was the first station to be built on the Waitaki River, as a ‘make work’ project during the Depression of the 1920s and 30s.

In 1958, the Mid-Waitaki hydro scheme began with the construction of Benmore dam and the DC link. This was the start of a unified power transmission system for the whole of New Zealand. The scheme was completed in 1968 with the commissioning of Aviemore power station.

The Upper Waitaki hydro scheme began in 1968 in response to New Zealand’s increased need for power. Work continued until 1985 when the last station, Ōhau C, was commissioned.

During that time four hydro stations were constructed, along with two dams and six canals (totalling 56 kilometres).


Key dates

  • 1928 
    Work starts on the Waitaki dam, as a ‘make work’ project during the Depression of the 1930s
  • 1968
    Work starts on the Upper Waitaki hydro scheme
  • 1999
    Meridian Energy forms and is assigned ownership of the Waitaki Scheme
  • 2011
    Tekapo A and B hydro stations are sold to Genesis Energy

Dry river bed safety

Meridian's hydro assets are located in some of the most scenic places in New Zealand, making them popular spots to visit.

At times, we’ll release water from our hydro assets. We’ll always update signage near our assets to let you know when we’re going to do this. If you’re camping or fishing in a dry river bed, you must remain vigilant and follow all instructions. If you see water appear, the most important thing to do is get out of the water and stay out.

If you want more information on our planned flow releases, you can call the Meridian Control Centre on 03 4350 928.