The Kazunogawa Dam (葛野川ダム) uses water from the Sagami River system to power an 800 MW pumped storage hydroelectric scheme. It is located 18 km (11 mi) east of Kōshū in Yamanashi Prefecture, Japan.

When energy demand is high, water from the upper reservoir is released down to the underground power station via a single 3.3 km (2 mi) long headrace tunnel which splits into two 1.8 km (1 mi) tunnels before each separate into two 620 m (2,034 ft) long penstocks. Each penstock feeds a single reversible 400 MW Francis turbine-generator with water before it is released into a 3.3 km (2 mi) long tailrace tunnel which discharges into the lower reservoir, created by the Kazunogawa Dam. When energy demand is low and therefore inexpensive, the turbines reverse into pumps and send water from the lower reservoir back to the upper reservoir. The process is repeated when necessary to help balance electricity loads. The difference in elevation between the upper and lower reservoirs affords an effective hydraulic head of 714 m (2,343 ft) and maximum of 779 m (2,556 ft).

There are currently two expansion projects that are taking place including listed separately as Kazunogawa (No.3) Pump Expansion and Kazunogawa (No.4) Pump Expansion.




Open-loop Pumped Hydro Storage