Gassan Dam is located in the city of Tsuruoka, Yamagata, 34km downstream from Yamagata Prefectural Nature Museum Gardens. It collects precipitation and snowmelt from Mt. Gassan at Asahi Gassan Lake through the Bonji, Tamugi and Yudono rivers; and manages the quantity of water to the lower reaches of the Akagawa River. It was built in 2001 as a multipurpose dam, for not only flood control, but also to generate electricity.
The Akagawa River, which runs south to north across the Shonai Plain, has the alias, “violent river”. As the name suggests, local residents used to suffer from frequent floods. According to the record, the river often flooded and damaged residential areas. “For Shonai, which accumulates a substantial amount of meltwater underground, water can be a benefit but also a threat. Before the government began its construction, local flood fighters devoted themselves to dealing with many disasters,” explained Mr. Yoshinobu Chonan, from Gassan Dam Management Place.
Even now we can trace how intense all the battles with floods were at every corner of Shonai. Denden Ohashi, meaning “a long bridge between rice fields,” was built to secure a safe school route. This is one of the achievements of lobbying between the residents and the prefectural government. Before it was built, they had had only one bridge, called Moguribashi, meaning “easily sunk in freshets.” There were cases of students trespassing beyond a traffic barrier and going to school in danger anyway. Along the Akagawa River, we see crescent-shaped rice fields, which are vestiges of floods. Also, flood control basins in various places were designed and used as a measure in order to avoid water destroying farms and fields. Minakami Hachiman Shrine in Tsuruoka is a place where people’s prayer concentrated to calm the water. The inner shrine was built to assuage the water god in the Muromachi period. It represents that people had been fearing and dealing with the threat of water for at least six hundred years.
