Kiyotsu River

The Kiyotsu River flows from Mt. Shirasuna through Mitsumata and into the Shinano River, carrying snowmelt and spring water cold enough to support two indicator species: Arctic char, a salmonid with cream and red spots on a dark body, and baikamo, an aquatic plant with white five-petaled flowers that blooms from early summer to early autumn. Baikamo needs fast-flowing water under 25 degrees Celsius and sandy soil, conditions that are increasingly rare across Japan. Where it grows, the water is genuinely clean. Streams in Yuzawa still support both species, making this river a practical measure of the region's environmental health.