Nagaragawa Estuary Barrage, estuary barrage in Kuwana, Mie Prefecture, Japan

The Nagaragawa Estuary Barrage is a water control structure spanning 661 meters with ten adjustable gates that manage river flow and prevent saltwater intrusion. Fish ladders on both banks allow species such as sweetfish and crabs to move between upstream and downstream sections.

Planned from 1968 as an industrial water reservoir, the project stalled for over thirty years as heavy industry's demand fell, and its stated purpose shifted to flood control. Work on the barrage itself began in March 1988 and the structure was finished in 1994, with full operation starting in July 1995. It stands in Kuwana, Mie Prefecture, 5.4 km from the river mouth, and drew fierce opposition from fishing cooperatives, conservation groups and canoeists.

The Aqua Plaza Nagara visitor center offers exhibits about the river's history and how the barrage operates through interactive displays. Visitors can learn about the relationship between this infrastructure and the local environment.

The barrage lies in Kuwana, Mie Prefecture, about 5.4 km upstream from the mouth of the Nagara River, at the end of Nagashima-cho. It is a working weir, not a walkway, so viewing is from the banks and the visitor facilities rather than across the 661 m crest. Allow time to reach the riverside on foot or by car.

The barrage was first planned to store industrial water, but heavy industry's demand fell during more than 30 years of revisions, so flood control became the stated purpose. Its 1995 start of full operation followed a dispute that widened beyond development versus environment to who counts as a party in publicly funded river works.