Flooding in the Niigata area continued following the construction of the Ōkōzu Channel.
As a result, another channel, which was originally planned in the Edo period (1700s–1800s), was built on the western outskirts of Niigata City to further mitigate the risk of flooding and to help prevent saltwater intrusion into the Shinano estuary.
The Sekiya Diversion Channel was originally to be funded by the Niigata Prefecture; however the 1964 Niigata earthquake resulted in the funds no longer being available so it was adopted as a national project.

Construction of the Sekiya Diversion Channel commenced in 1968 and concluded in 1973 with a channel 1.8 kilometres (1.1 mi) long and 240–280 metres (790–920 ft) wide.
The channel provides another alternate path for sediment to be directed straight out to sea and away from the Niigata port.
The channel is crossed by the Echigo Line and the National Route 402 (excavated materials from the channel were used in the construction of Route 402).
Flooding in the Niigata area continued following the construction of the Ōkōzu Channel. As a result, another channel, which was originally planned in the Edo period (1700s–1800s), was built on the western outskirts of Niigata City to further mitigate the risk of flooding and to help prevent saltwater intrusion into the Shinano estuary. The Sekiya Diversion Channel was originally to be funded by the Niigata Prefecture; however the 1964 Niigata earthquake resulted in the funds no longer being available so it was adopted as a national project.
Construction of the Sekiya Diversion Channel commenced in 1968 and concluded in 1973 with a channel 1.8 kilometres (1.1 mi) long and 240–280 metres (790–920 ft) wide. The channel provides another alternate path for sediment to be directed straight out to sea and away from the Niigata port. The channel is crossed by the Echigo Line and the National Route 402 (excavated materials from the channel were used in the construction of Route 402).
Shinano River