Kamaguchi Floodgate

The Kamaguchi Floodgate is a sluice near Okaya that diverts water from Lake Suwa into the Tenryu River. The structure manages flows from multiple tributaries into one river system, maintaining water control across the region.

The sluice was built in 1936 to prevent repeated flooding around Lake Suwa. The structure underwent several improvements and reinforcements through 1988.

The sluice gate serves as an educational site where students learn about regional hydrology and its connection to surrounding Suwa municipalities.

The gate is accessible during day and night hours, with parking available on both sides of the structure. Visitors can walk the grounds freely and view the water control mechanisms up close.

This location marks where the Tenryu River officially begins before flowing south through Nagano Prefecture. The water travels many kilometers downstream until it reaches the Pacific Ocean.

Location: Okaya

Inception: 1936

GPS coordinates: 36.05342,138.05303

Latest update: December 10, 2025 16:27