The Okuyoshino Pumped Storage Power Station (奥吉野発電所) is located 15 kilometres (9.3 mi) north of Totsukawa in Nara Prefecture, Japan. Using the pumped-storage hydroelectric method, the power plant has an installed capacity of 1,206 megawatts (1,617,000 hp). To accomplish power generation, the power station shifts water between two reservoirs, the lower Asahi Reservoir and the upper Seto Reservoir. Construction on both the Asahi and Seto Dams began in 1971 and was complete in 1978. The power station was commissioned in 1980. Due to heavy sediment and turbidity in the Seto Reservoir, caused by logging and landslides upstream, a sediment bypass tunnel was constructed between 1992 and 1998.