[citation needed] It is also the first full-scale hydroelectric dam built in Japan.

The upper portions of the Kiso River have a strong flow in terms of speed and volume, making it an ideal location for hydroelectric dams.

Given the technologies of the time, though, building a dam along the Kiso River was too difficult because floods often occurred.

The introduction of hydroelectric power at Ōi Dam is considered the greatest lifetime achievement of businessman Momosuke Fukuzawa.

Along with the lake created by the Maruyama Dam downstream, the area has been designated the Hida-Kisogawa Quasi-National Park.