Sanbuichi Yusui Kan

The Sanbuichi Yusui Kan museum is dedicated to the Sanbuichi Yusui, a more than 400-year-old mountainside weir. The weir was reputedly dug by Takeda Shingen, the warlord who ruled Kai Province (present-day Yamanashi) from 1540 to 1573. Using a triangle-shaped stone, the weir split the natural spring carrying fresh water from the southern foot of the Yatsugatake Mountains into three separate streams to distribute water equally among the settlements further down the mountain, which had been competing for resources. The name of the weir translates as “three parts from one spring.”

An impressive feat of engineering in the sixteenth century, the weir remains in good condition today and its water is still used for rice farming and other agricultural purposes. An estimated 8,500 tons of water flows through the Sanbuichi Yusui every day and the water is an average of 9 degrees Celsius year-round. The triangular stone is still visible and continues to split the water into the east, middle, and west streams. The surrounding maple trees turn fiery red in autumn, adding a touch of color to the scene.

The Sanbuichi Yusui Kan has a range of information about the history of the Sanbuichi Yusui, the operation of the weir, the quality of spring water in the area, and local agriculture. There is also a souvenir shop, a bakery, and a restaurant serving the famous soba noodles of Kobuchizawa. Both the museum and the weir itself are a vital link to Yamanashi’s vibrant history.