The Tongariro Power Scheme provides an object lesson in harnessing the power of water with minimal impact on the environment. Its two powerhouses produce around seven percent of the country’s electricity, while the outflows that feed into Lake Taupo add flexibility to the much older chain of eight hydroelectric dams along the Waikato River. Some argue it is unacceptable to tamper with such a fine piece of wilderness, but, while there have been some minor environmental impacts, it is surely better than a nuclear power station.
In fact, if it weren’t for the scale models in visitor centres and the ugly bulk of the Tokaanu power station, only astute observers would be aware of the complex system of tunnels, aqueducts, canals and weirs unobtrusively going about their business of diverting the waters of the Tongariro River and myriad streams running off the mountain slopes, back and forth around the perimeter of the national park, using modified natural lakes for storage. Mount Ruapehu poses its own unique problems: the threat of lahars is ever-present and, after the 1995 eruption, abrasive volcanic ash found its way into the turbines of the Rangipo underground powerhouse, causing an unscheduled seven-month shutdown.