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Mangorei Power Station

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Mangorei Hydroelectric Power Station first supplied power to New Plymouth in 1906. The present 25 metre (m) high earth dam across the Mangamahoe Stream was completed in 1931 and enables the Station’s average annual output of 20.9 GWh. Recent efficiency projects include upgrading the Scheme’s water supply tunnels and turbines; while environmental measures include a fish pass and a trap and transfer programme for eels.

At a Glance


Commissioned 1931

Max Capacity 4.5 MW

Annual output 20.9 GWh

The original Mangorei Station was constructed in 1904 and used water from the Waiwakaiho River, supplying power for New Plymouth street lighting and 41 customers. Increased demand led to the Mangamahoe Stream dam. On completion in 1931, this was the highest earth dam in Australasia. It supplies water via two tunnels to three 1.3 MW and one 700 kW generator. 

In recent years, we have put real focus on improving the scheme’s efficiency. There’s been extensive work on the supply tunnel linings to reduce friction. An upgrade of the turbines is due in the near future too. 

Environment and recreation 

As part of our environmental commitment, we have installed a fish pass at the intake weir on the Waiwhakaiho River. We also run a successful trap and transfer programme during migration season. Since the programme began, Trustpower has transferred over 400,000 migrating elver as part of the upstream trap and transfer programme.

Trustpower maintains a minimum downstream flow for the Waiwhakaho River at all times, regardless of generation requirements.

We gained new Resource Consents for the scheme in 1996. Consents will again be due for renewal in 2021.

Mangorei power station

Mangorei power station

Mangorei Penstock Manifold
Mangorei Penstock Manifold

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