Mangahao Power Station is a hydroelectric power station near the town of Shannon, New Zealand. After being delayed by war, access road construction and foundation testing was started by late 1919 and the station opened in November 1924. It makes use of the Mangahao River, through a series of tunnels and pipelines totalling 4.8 kilometers in the Tararua Ranges. It is jointly owned and operated by Todd Energy and King Country Energy.