Oshio Dam

Oshio Dam is an earth-fill dam in Tomioka that spans over 250 meters in length and rises about 32 meters high. The structure uses compacted soil layers to hold back water while maintaining stability across the landscape.

The dam was completed in 1965 as part of regional water management projects in Gunma Prefecture. Its construction marked the start of improved water supply and flood control for surrounding communities.

The dam represents Japanese engineering practices through its earth-fill construction method, which demonstrates the integration of infrastructure within the natural environment.

The dam is accessible by public transportation from town and has several observation points overlooking the structure. Daytime visits offer the best views of the reservoir and surrounding landscape.

The interior consists of carefully compacted soil layers that form a waterproof barrier and prevent seepage. This traditional method differs from modern concrete designs and demonstrates a time-tested construction approach.

Location: Tomioka

Inception: 1965

Height: 31.9 m

Length: 250.6 m

GPS coordinates: 36.22556,138.87750

Latest update: December 14, 2025 13:05