Private entrepreneur Fukuzawa Momosuke founded the Tenryūgawa Electric Power (天竜川電力, Tenryūgawa Denroku), which later became Yasaku Hydroelectric (矢作水力電気, Yasaku Suiroku Denki) 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.)

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.

The new company, in part through foreign aid loans from the United Nations, began work on a new dam in 1952, based on plans which had begun as early as 1921.

Construction was facilitated by the steep V-shaped walls of the site, and its proximity to the Iida Line train (several stations of which had to be relocated once the reservoir began to fill.

The official opening ceremonies on October 28, 1957 were attended by Emperor Hirohito and Empress Kojun and was the occasion for the issuance of a commemorative postage stamp.

The Sakuma Dam Reservoir is a popular attraction for canoeing and camping, due to its proximity to downtown Hamamatsu and ease of access.

On the 50 Hz side, two 275/54 kV transformers, in separate tanks, feed the valves, again with one in delta and the other in star connection of the low-voltage windings.