Koai Tamei

Koai Tamei is a water management facility in Katsushika-ku and Misato featuring channels and basins that direct flow across eastern Saitama Prefecture. The system connects multiple waterways and adjusts their movement depending on seasonal conditions.

Izawa Yasobee started building this facility in 1729 to reduce flooding in the Nakagawa Basin. The project was an early solution for water control in an already densely settled region.

The place shows how water could be managed in areas where many people live close together. Local residents see it as a connection between their daily lives and the landscape they depend on.

The facility is reachable from Tokyo using local trains and buses, with several spots where you can look out and see the water system. These observation areas let you understand how the channels work together.

This facility works as a dual system, holding water during dry times and catching overflow during heavy rains. This two-part function in one structure shows the thoughtful design from the Edo period.

Location: Katsushika-ku

Location: Misato

Inception: 1729

Founders: Izawa Yasobee

GPS coordinates: 35.78806,139.87107

Latest update: December 10, 2025 16:24