The construction of Yasaka Dam started in 1973 and was completed in March 1991.

Before its completion, the dam basin was damaged due to flooding from the Ose River, as well as Typhoon Ruth, and occasional droughts.

Yasaka Dam was built to prevent this type of damage from floods and droughts and also to harness water resources. It took 20 years and a total construction cost of 110 billion yen from its initial research to final completion.

This dam, 120 meters high and 540 meters long, with a basin area of 301 square meters can store 112 million cubic meters of water.

Yasaka Dam has not only controled damage from floods and droughts, but also has played a major role to supply water to areas which traditionally had problems with water shortages, including Yanagii city in the east of Yamaguchi Prefecture and Oshima county.Miwa se trouve