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. Sekiya Diversion Channel 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 long and 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). Major dams There are a number of major dams in the Shinano River system, but not on the main river itself, rather its tributaries are extensively dammed and used for electricity generation as well as water for irrigation. The major dams in the system are listed below: The Takase Dam, on the Takase River, a tributary of the Sai River, holds and is the tallest of its size in Japan. It is also the second tallest dam in Japan, after the Kurobe Dam. The Nanakura Dam, which is part of the Takase Dam system, holds . The Ōmachi Dam is further downstream from the Nanakura Dam and holds . The Nagawado Dam is on the Azusa River, another tributary of the Sai, holds and is followed downstream by a number of smaller dams including the Midono Dam and Inekoki Dam. The Sagurigawa Dam sits on the Sankuni River which is a tributary of the Uono River. It holds and is used for a range of purposes including storage for power generation, flood control and water for irrigation. Watershed The basin of the