is a dam built on the Yoshino River in Agawa District, Kōchi Prefecture of Japan. This concrete dam 73.5m high. It is a hydroelectric dam of the Shikoku Electric Power Company. It supplies water to the company's hydroelectric plant, Ōhashi Power Station, which can produce up to 5,500kW. It is the lower reservoir for a pumped-storage hydroelectric plant. The upper reservoir being Inamura Dam. Water flowing between these two can produce up to 615MW. It is a public works which The Japan Society of Civil Engineers has recommended as a site of Public Works Heritage. Construction The Yoshino River flows through Shikoku with an abundant volume. In the upper reaches there are swift currents so it was a suitable place for hydroelectric power generation. In Ehime Prefecture the Sumitomo Group have many factories and the Besshi copper mine. Tosa City-Yoshino River Hydroelectric Company (currently Sumitomo Joint Electric Power Company) was founded to promote the construction of the hydroelectric power station, on the Yoshino River, in 1919, (Taishō period 8). The Takayabu Power Station, (14.3MW), was built at the Okuyoshino torrents of the upper reach of River Yoshino, and it commenced operation in 1930 (Shōwa period 5). This company conceived of further developing the upper reaches of the river. Diverting the water flow of Yoshino River, separating the watershed, to the south flowing Edagawagawa River of the drainage system, and planned to perform hydroelectric power generation utilising that volume of water and the topography. However, in this plan, the diversion of water did not avoid the decrease in the volume of water flowing downstream. Because of this, a plan was made to regulate the quantity water flowing in the river by forming a large-scale artificial lake and building the Ōhashi Dam between Takayabu Power Station and the upstream inflow. In 1934 (Showa 9), the Tosa-Yoshino River Hydroelectric Company was renamed the Central Shikoku Electric Power Company, and from 1937 (Showa 12) work started on the Ōhashi Dam. Engineers who took part in the Pujon River Dam on the Korean Peninsula and the construction of the Senzu Dam of the Ōi River drainage system in Shizuoka Prefecture were invited to the construction to study the concrete mix. The results of the geological survey were to confirm that rock suitable for concrete aggregate could not be collected from around the dam's construction site. Therefore, an overhead freight-carrying cable was built to in the