The dam creates a reservoir known as 'Kusaki-ko' which has a total water storage capacity of approximately 60.5 million cubic meters.
Construction required the relocation of the historic village of Kusaki, which was submerged upon the reservoir's completion.
The project was initiated specifically to mitigate flooding in the Watarase River basin and to supplement the water supply for the Gunma and Saitama prefectures.
The dam is classified as a multi-purpose dam, serving electricity generation alongside water management.
Kusaki Dam is a concrete gravity dam completed in 1977 on the Watarase River to provide flood control and water supply for the Kanto region. The structure stands 140 meters high and creates the Kusaki Reservoir, which serves as a significant water source for the Tokyo metropolitan area. Visitors can access two designated observation decks that offer views of the dam face and the surrounding forested mountains. The facility includes a local information center detailing the engineering and construction history of the reservoir. The site serves as a central hub for viewing the changing foliage of the Ashio Mountains throughout the seasons.
The secondary observation deck providing a direct profile view of the concrete dam wall.
Visit during mid-autumn to see the reservoir surrounded by vibrant fall colors.
Bring binoculars for better views of the expansive reservoir surface from the upper observation points.
Check local weather reports before visiting, as mountain conditions near the reservoir can change rapidly.
Do not attempt to access restricted maintenance or staff-only zones near the dam spillways.
