Niyodo River Basin, 22 km to the south and, rock was collected to and brought from there. The Ōhashi Dam was completed in 1939 (Showa 14). In the same year, Ōhashi Power Station, using water from the Ōhashi Dam, started production (at that time 5.3MW). After that, Central Shikoku Electric Power Company, went ahead with the construction of a diversion canal from up stream of the Ōhashi Dam to the Niyodo River. In 1940 (Showa 15) the First Diverted Water Power Station (26.6MW), and in 1941 (Showa 16) the Second Diverted Water Power Station (7.8MW), and Third Diverted Water Power Stations (10.9MW) started operation. However, in the meantime, the Japanese government had an eye on the state control of the electric utilities, and steadily advanced preparations for the establishment of the in 1939. The Central Shikoku Electric Power Company financed many hydroelectric power stations such as starting the Ōhashi Dam and Diverted Water System Power Stations, the Japan Electric Generation and Transmission Company, and the with electric distribution companies established under similar state control. In 1943 (Showa 18) it changed its name to the present Sumitomo Group of electric power companies. Japan Electric Generation and Transmission Company took over the development of the improving Central Shikoku Electric Power Company. In 1949 (Showa 24), upstream of Ōhashi Dam, as well as Nagasawa Dam (5.2MW), in 1950 (Showa 25) at the water diversion's lowest point the Fourth Diverted Water Power Station (8.1MW) was completed. Notes Dams in Kōchi Prefecture Hydroelectric power stations in Japan Dams completed in 1939