天竜川
The potential of the Tenryū River valley for hydroelectric power development was realized by the Taishō period Japanese government in the early 20th century. The Tenryū River was characterized by a high volume of flow and a fast current. Its mountainous upper reaches and tributaries were areas of steep valleys and abundant rainfall, and were sparsely populated, and the Tenryū River’s propensity for flooding made flood control a priority. By the late 1960s, numerous dams had been constructed on the river’s upper and middle reaches and on several of its tributaries.