Due to seasonal high rainfall in the Shinano's watershed the fertile farmlands on the Niigata plain were subjected to flooding every three to four years which destroyed crops, particularly rice, and villages.
Attempts from local residents to secure funding to build a diversion channel began in the mid-early eighteenth century, during the Kyōhō era.
Government support was not secured until the early twentieth century following severe flooding and inundation in 1896.

Construction work on the 10-kilometre-long (6.2 mi) Ōkōzu Channel (大河津分水路, Ōkōzu Bunsuiro) began in 1909 and concluded in 1922.
The success of the channel was short-lived, however, as the floodgate collapsed in 1927 due to erosion of the channel bed and was not fully repaired until 1931.

The construction of the diversion channel has resulted in marsh fields drying on the Niigata plain which allows for greater production.
Likewise, drier land has also allowed for the construction of infrastructure such as expressways and the Shinkansen express-train network, to support a greater population in the area.

A new weir wall was constructed between 1992 and 2000 due to safety concerns with the original wall.
Construction was planned to limit negative affects on scenery and wildlife.
To this end, natural stones were used for the exterior and fishways were included in the design.
Due to seasonal high rainfall in the Shinano's watershed the fertile farmlands on the Niigata plain were subjected to flooding every three to four years which destroyed crops, particularly rice, and villages. Attempts from local residents to secure funding to build a diversion channel began in the mid-early eighteenth century, during the Kyōhō era. Government support was not secured until the early twentieth century following severe flooding and inundation in 1896.
Construction work on the 10-kilometre-long (6.2 mi) Ōkōzu Channel (大河津分水路, Ōkōzu Bunsuiro) began in 1909 and concluded in 1922. The success of the channel was short-lived, however, as the floodgate collapsed in 1927 due to erosion of the channel bed and was not fully repaired until 1931.
The construction of the diversion channel has resulted in marsh fields drying on the Niigata plain which allows for greater production. Likewise, drier land has also allowed for the construction of infrastructure such as expressways and the Shinkansen express-train network, to support a greater population in the area.
A new weir wall was constructed between 1992 and 2000 due to safety concerns with the original wall. Construction was planned to limit negative affects on scenery and wildlife. To this end, natural stones were used for the exterior and fishways were included in the design.
Shinano River