The Kannagawa Hydropower Plant (神流川発電所) is an under construction pumped-storage hydroelectric power plant near Minamiaiki in Nagano Prefecture and Ueno in Gunma Prefecture, Japan.

[3] When completed, the plant will have the third-largest (after Fengning Pumped Storage Power Station and Bath County Pumped Storage Station) pumped-storage power capacity in the world.

[4][5] In July 1993, the Kannagawa Hydropower Field Survey Office was initiated and in July 1995, the power plant was approved by the Electric Power Development Coordination Council.

In May 1997, construction on the project began and by October 2003, the area behind the Ueno Dam was being inundated with water and the next year, the Minamiaiki Dam's reservoir began to fill as well.

The water tunnel connecting the two reservoirs is 3.8 miles (6.1 km) long.