Improvement of river environment through dam reconstruction (Hita City, Oita Prefecture, 2000s-2020s)

Improvement of river environment through dam reconstruction (Hita City, Oita Prefecture, 2000s-2020s)

In the Oyama River in Hita City, Oita Prefecture, the river environment deteriorated due to a drastic decrease in water volume caused by the delivery of dam water to a power plant in 1973. In the 2010s, local residents and companies actively worked to protect the environment through river cleanups, vegetation restoration projects, and the introduction of new water quality measurement technology. In the 2020s, measures utilizing scientific data were promoted, with reports of improved feeding conditions for juvenile ayu and reduced flooding damage during heavy rainfall. These efforts have resulted in sustainable improvement of the river environment and increased safety in the region, and are attracting attention as a national model case.