The dam is 82 metres tall, the fourth highest in New Zealand. It was the first dam constructed using tertiary sandstone and siltstone as fill materials. The dam impounds Lake Rotorangi, which is the longest man-made lake in New Zealand (46km). With three 10,000 kW vertical Francis turbine generator sets and a 700 kW auxiliary generator, the scheme has a total capacity of 30,700 kW and an average annual output of 118 GWh.