page_title: Tenryū River
section_title: Hydroelectric development
hierarchical_section_title: Tenryū River / Hydroelectric development
caption_attribution_description: English: Tenryu River, at the Komami Bridge 日本語: 駒見大橋から見た天竜川
context_page_description: The Tenryū River is a river in central Honshū, Japan. With a length of 213 km, it is Japan's ninth longest river.
  Its source is Lake Suwa in the Kiso Mountains, near Okaya in Nagano Prefecture. It passes Aichi Prefecture, and flows through western Shizuoka Prefecture
context_section_description: The potential of the Tenryū River valley for hydroelectric power development was realized by the Meiji government at the start of the 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. However, the bulk of investment in hydroelectric power generation in the region was centered on the Ōi River, and it was not until the Taishō period that development began on the Tenryū River.
  Private entrepreneur Fukuzawa Momosuke founded the Tenryūgawa Electric Power (天竜川電力 Tenryūgawa Denroku), which later became Yahagi Hydroelectric (矢作水力 Yahagi Suiroku) before it was nationalized into the pre-war government monopoly Japan Electric Generation and Transmission Company (日本発送電株式会社 Nippon Hassoden K.K.) in 1938. The first dam on the main stream of the Tenryu River, the Yasuoka Dam was completed in 1935. This was followed by the Iwakura Dam in 1938. The Hiraoka Dam was started in 1938, but completed until 1951 due to the start of World War II. 
  After the end of World War II, the American occupation authorities ordered the dissolution of Nippon Hassoden, which was divided into regional power companies. Central Japan came under Chubu Electric Power, which inherited the various dams and projects on the Tenryū River, all of which were located in Nagano Prefecture. For develop of the hydroelectric potential of the river in Shizuoka Prefecture, the government turned to the Electric Power Development Company. The new company, in part through foreign aid loans from the United Nations, and with the use of new dam technologies completed the huge Sakuma Dam in the 1956, at the time the 10th largest in the world. Further dams were completed in the 1960s and 1970s until the completion of the Funagira Dam in 1976 brought development of the Tenryū River to a close.
caption: Tenryū river, upper reaches
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