What Is the Inari River Sixth Sabo Dam?
The Inari River Sixth Sabo Dam (稲荷川第六砂防堰堤, Inarigawa Dairoku Sabō Entei) is a concrete gravity erosion-control dam built in 1922 on the Inari River in the Tenguzawa and Nakasuzu area of Nikko City, Tochigi Prefecture, and registered in 2002 as a Registered Tangible Cultural Property (Structure) of Japan, with effect from 21 August. It is 69 meters long and 7.3 meters high and is owned by the national government (Ministry of Land, Infrastructure, Transport and Tourism).
The Inari River joins the Daiya River about 300 meters below the Shinkyo Bridge of Futarasan Shrine. The Sixth Dam stands about 2.8 kilometers above that confluence, the farthest downstream of the seven registered Inari River Sabo Dams, with the Fourth Dam 323 meters upstream. Its registration number, 09-0054, is the first in the series of seven.
From a 9.9 Percent Slope to 5.4 Percent
The Agency for Cultural Affairs states the purpose of the Inari River Sixth Sabo Dam in figures. The river here falls at a gradient of 9.9 percent, and the dam was built to ease that to 5.4 percent, stabilizing the channel and the ground and allowing vegetation to return to the banks.
A 9.9 percent gradient means the riverbed drops nearly 10 meters for every 100 meters of distance. Once gravel piles up behind a dam, the surface of that deposit becomes the new bed, and it slopes more gently than the old one. Slower water scours less from the bed and the banks, and plants get a chance to take root on slopes that had been collapsing. The Sixth Dam is a wall that stops sediment, but it is equally a device for reshaping the tilt of the valley.
The dam rests on andesite bedrock and was built as a low gravity dam of mortared Nerizumi masonry, faced with diagonal Tanizumi stonework like the others. The Nikko Sabo Office has published a photograph of the dam under construction on 9 April 1922.
Why the Inari River Sixth Sabo Dam Was Registered
The Inari River Sixth Sabo Dam was registered for contributing to the historic landscape of the nation. A century after it was finished, it still does what it was built to do, keeping the gradient down and the valley stable, and it has settled into its setting of rock and forest.
What to Look for at the Inari River Sixth Sabo Dam
The Inari River Sixth Sabo Dam is an outdoor facility with no admission fee, viewed from the riverside path. Climbing onto the dam is not allowed.
Walking up the valley from below, this is the first registered dam you reach. Watch how the river changes character across it: below the dam the stream is steep and strewn with stones, while above it the bed flattens into a gentler spread of gravel. It is a place to see the change of gradient the agency describes with your own eyes. Where the water drops at the foot of the dam, look too for the bedrock on which it was founded. Directions to the dams are on the Inari River Sabo Dams page.
- 📍 Plan Your Visit to Tochigi
- Find tours, activities & transport passes near Inari River Sixth Sabo Dam
- [ Nikko Toshogu Shrine & Kegon Falls Day Trip ]
Q&A
- When was the Inari River Sixth Sabo Dam built?
- In 1922. The Nikko Sabo Office has published a photograph of it under construction on 9 April 1922.
- Where is the Inari River Sixth Sabo Dam?
- On the Inari River in Nikko, about 2.8 kilometers above its confluence with the Daiya River. It is the farthest downstream of the seven registered Inari River Sabo Dams.
- What was the Inari River Sixth Sabo Dam built to do?
- To reduce the river's gradient from 9.9 percent to 5.4 percent, steadying the channel and the ground and helping vegetation recover along the banks. The figures come from the Agency for Cultural Affairs.
- How big is the Inari River Sixth Sabo Dam?
- It is 69 meters long and 7.3 meters high, a low gravity dam of mortared masonry founded on andesite bedrock.
- Can I visit the Inari River Sixth Sabo Dam, and is there a fee?
- Yes, you can view it from the riverside path free of charge. It is a working dam, so you cannot climb onto it, and the stream can rise quickly after rain.
Basic Information
| Name | Inari River Sixth Sabo Dam (稲荷川第六砂防堰堤) |
|---|---|
| Location | Aza Tenguzawa and Nakasuzu, Oaza Nikko, Nikko City, Tochigi Prefecture |
| Designation | Registered Tangible Cultural Property (Structure) |
| Year Designated | Registered in 2002 |
| Quantity | 1 structure |
| Dimensions | 69 meters long, 7.3 meters high (concrete gravity dam) |
| Owner | Government of Japan (Ministry of Land, Infrastructure, Transport and Tourism) |
| Public Access | Outdoor erosion-control facility; exterior viewable from the riverside path (no fee) |
References
- Agency for Cultural Affairs, Database of National Cultural Properties: Inari River Sixth Sabo Dam
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00002880
- Cultural Heritage Online: Inari River Sixth Sabo Dam
- https://online.bunka.go.jp/heritages/detail/187610
- MLIT Kanto Regional Development Bureau, Nikko Sabo Office: History of the Registered Sabo Dams (Japanese)
- https://www.ktr.mlit.go.jp/nikko/nikko00038.html
- Japan Society of Civil Engineers, Kanto Branch: Sabo Dams of the Inari River Basin, Nikko (Japanese)
- https://www.jsce.or.jp/branch/kanto/04_isan/h26/h26_3.html
- Tochigi Prefecture Cultural Properties: Inari River Sixth Sabo Dam (Japanese)
- https://bunkazai.pref.tochigi.lg.jp/cultural/%E3%80%90%E7%A8%B2%E8%8D%B7%E5%B7%9D%E7%AC%AC%E5%85%AD%E7%A0%82%E9%98%B2%E5%A0%B0%E5%A0%A4%E3%80%91/
Last verified: 2026.10.01
