The Ota-gawa River, as the main water source, continued to meet the water demand until around 1970. However, with the natural flow of the Ota-gawa River being increasingly depleted we began using Haji Dam of the Gono-kawa River system and Takase Weir of the Ota-gawa River system.
As of the end of FY 2013, the volume of utilized water is 362,000m3/day from the Ota-gawa River, 7,500m3/day from the river bed water from the Yahata-gawa River, 100,000m3/day from Haji Dam, 100,000m3/day from Takase Weir. In addition, we receive water totaling 104,300m3/day from Hiroshima Prefecture, and have a reserve of 673,800m3/day, so the total water supply capacity is 628,100m3/day.
In order to ensure a stable water supply for the future, we have secured 200,000m3/day from Nukui Dam as a new water source.
Also, in order to protect the beautiful environment of the Ota-gawa River and pass the river's abundant and clear water on to the next generation, we have acquired forests in the river's headwaters area, and are actively working in close connection with local authorities in this region to conserve these woodlands in the river's upper reaches and maintain their funcion as a watershed protection forest.
The Ota-gawa River springs from Mt. Kanmuri, one of the tallest peaks in the Chugoku Mountain Range. It gathers water from 72 tributaries of various sizes before flowing into Hiroshima Bay. This river has been the source of Hiroshima City water since the waterworks were established in 1898.
Effective storage is 1.78 million m3. This multi-purpose weir was constructed in Ochiai Asakita-ku in 1976 by the national government for flood control and city water service.
Effective storage is 41.10 million m3. Part of the Gono-kawa River system (Yachiyo-cho, Akitakata City), this multi-purpose dam, completed in 1974, was a national project. It discharges water through an approximately 19 km water tunnel into Nenotani-gawa River after using it to generate electric power.
The Yahata-gawa River originates near Mount Amida in Yuki-cho, Saeki-ku, and flows through western Hiroshima Prefecture into Hiroshima Bay.
Discharge in observance of reaching maximum water level on Jan. 28, 2001
Effective storage is 79 million m3. The national government completed the construction of this dam in Kake, Aki Ota-cho, Yamagata-gun in March 2002. It was the first multi-purpose dam in the Ota-gawa River system.
With the completion of this dam, we have not had to regulate the water intake even when the yearly amount of rainfall is low.