Mangahao Hydro-Electric Power Scheme

Project summary

To renew the consents for the existing Mangahao Hydro-Electric Power Scheme.

The scheme, which draws from the Mangahao River, generates up to a maximum 39.9 megawatts (MW) of electricity with an average annual output of 131 gigawatt-hours (GWh) which is enough to power approximately 20,000 homes.

The activities associated with this generation of renewable energy include the: 

• damming and diversion of water, involving the damming of the Mangahao River at No.1 and No.2 Dam sites and the Tokomaru River at No.3 Dam site, and the diversion of Mangaore Stream for erosion control and water between reservoirs

• discharge of water to water associated with all 3 reservoirs and from Mangahao Power Station to the Mangaore and Mangatangi streams

• discharge of contaminants to water associated with drain valves associated with turbines, cooling water from Mangatangi Stream, stormwater runoff from the Power Station area, and sediment flushing

• use of structures in the bed of a stream or river including the existing dams and associated infrastructure in the Mangahao and Tokomaru Rivers.

Project location

The Mangahao River at the northern section of the Tararua Ranges approximately 28 kilometres southwest of Palmerston North and 10 kilometres, at the farthest point, east of Shannon.

Project referral

The Minister for Infrastructure referred the project to the Fast-track on 6 November 2025. The application was lodged on 24 July 2025.

Notice of decisions on application for referral of the Mangahao Hydro-Electric Scheme Project (PDF, 222KB)