Rawan River
Overview
The Rawan River is the only river flowing out of Lake Onneto. It carries the blue waters of the lake out of the national park toward the town of Ashoro, connecting with the Ashoro River before finally joining the Tokachi River and continuing on to the Pacific Ocean. The upper section of the Rawan River is surrounded by a primeval forest zone, where fish such as gobies can be seen on the riverbed. The river is known for its Rawan-buki (Petasites japonicus), a giant variety of Japanese butterbur that flourishes in the river basin. In the clear waters of the Rawan River, they can reach astonishing heights of two to three meters and have been designated a “Hokkaido Heritage.” The best time to see Rawan-buki is between June and July, in the farmland surrounding Akan-Mashu National Park.
The Rawan-buki
The reason Rawan-buki grow so high here remains unknown. An edible plant, they were heavily harvested in the past. The number of wild Rawan-buki colonies found within the river basin has decreased significantly, so they are also cultivated on farms and exported as a specialty of Ashoro Town.