The scheme takes water from tributaries of the Rangitikei, Whangaehu, Whanganui, and Tongariro rivers, which drain a area covering Ruapehu, Ngauruhoe, Tongariro and the western Kaimanawa Ranges. The water is then sent through a large canal and tunnel system to generate electricity at three hydro power stations, located at Rangipo (120 MW), Tokaanu (240 MW) and Mangaio (2MW). The water is then drained into Lake Taupo where it is stored for further use in the succession of Waikato River power stations.