The foothills of the Yatsugatake Mountains near Bomichi Road are home to the largest group of springs in Japan, with pure waters springing up through cracks in the bedrock at altitudes near 1,000 meters.
While there was abundant water at high altitudes, water supply was limited in the low plateau of the Koarama district due to its impervious clayey bedrock. Thus, there was constant strife over the right to use the spring water.
To put an end to this strife, a measure was taken to distribute water equally among the three areas located downstream. That is, spring water was drawn into a square wooden reservoir and a triangle-shaped “water dividing stone” was placed in the water to split the flow of water into three directions.
In 1985, Sanbuichi Spring was selected among the Ministry of the Environment’s “Selected 100 Exquisite and Well-Conserved Waters” along with other springs as the “Yatsugatake Nanroku Springs.” The spring continues to be managed today by local residents who hold the water use right, and serves an important role in supplying irrigation water.