【Sasagamine Dam (Lake Otomi)】
Sasagamine Dam is a rock-filled earthen dam between Lake Otomi and the Seki River. It is 48.6 meters high and 318 meters long.
Lake Otomi was formed over thirty-thousand years ago, when the crest of Mt. Kurohime (2,053 m) collapsed and caused an enormous landslide that obstructed the Seki River. Since being dammed, the lake’s volume has increased to 900,000 tons of water, which feeds several hydroelectric power stations and irrigates 7,200 hectares of fields 50 kilometers downstream.
Twelve hydropower stations were built along the river between 1906 and 1939 to take advantage of the steep drops in elevation. The power produced by these generators was intended to encourage local development by lowering the cost of electricity. In 1929, two electric power companies dammed the confluence of two Seki River tributaries to build a reservoir and hydropower station. In 1951, it was renamed Sasagamine Dam. The present dam was constructed in the same location between 1970 and 1979. Looking from north to south (right to left), the peaks opposite the dam are Mt. Myōkō, Mt. Hiuchi, Mt. Yake, Mt. Kana, Mt. Tenguhara, and Mt. Jizō. At the other end of the dam, a staircase leads up to the Yumemidaira Hiking Trail. Beside the staircase is a tunnel that was used during the dam’s construction and leads to a maintenance building at the side of the dam.