The Shimizu River
The Shimizu, a 300-meter-long tributary of the Azusa River, splits from the Azusa just upstream of the iconic Kappa Bridge. The waters of the Shimizu come from underground springs fed by rainwater that falls on Mt. Roppyaku and filters through the rock. The water temperature remains relatively constant, ranging from 4°C to 8°C year-round.
The water at the source is pure enough to be drunk directly. Hot-spring resorts and hotels in Kamikochi draw their drinking water from the Shimizu, and campers along the riverbanks often use the river’s cool waters to chill drinks and watermelon. During the summer months, the brilliant white flowers of the Japanese water buttercup (baikamo), which grows only in the cleanest water, fill the shallow river.