Yamaguchi Reservoir

Yamaguchi Reservoir is an artificial lake in the towns of Tokorozawa and Iruma in Saitama Prefecture. The water comes from the Higashikawa and Yanasegawa rivers, which flow down from the wooded Sayama Hills and feed the basin.

The construction started in 1927 to supply water to the growing settlements near Tokyo. The project aimed to secure supply during a period of rapid urban expansion.

The artificial lake sits within a wooded area of the Sayama Hills and serves as a nearby escape for residents from both towns. Walkers and birdwatchers use the shoreline paths, especially on weekends.

The site is accessible through several entrances spread along the shoreline. Parking areas and information points help with orientation around the water.

The water treatment system supplies households in several towns through a network of underground pipes. The facility has been upgraded repeatedly to keep pace with technical standards.

Location: Tokorozawa

Location: Iruma

Inception: 1927

GPS coordinates: 35.77806,139.40861

Latest update: December 5, 2025 22:26