Arapuni Power Station is a hydroelectric power station on the Waikato River, in the North Island of New Zealand. It is owned and operated by Mercury Energy, and is the seventh and penultimate hydroelectric power station on the Waikato River. It is also the oldest currently generating, the first government-built, and the largest capacity single hydroelectric power station on the Waikato River. The two power houses that make up the Maraetai Power Station have a larger combined capacity however.