What Is the Inari River Fourth Sabo Dam?
The Inari River Fourth Sabo Dam (稲荷川第四砂防堰堤, Inarigawa Daiyon Sabō Entei) is a concrete gravity erosion-control dam built in 1921 on the Inari River in the 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 3.6 meters high and is owned by the national government (Ministry of Land, Infrastructure, Transport and Tourism).
The dam lies 323 meters upstream of the Sixth Dam and 110 meters downstream of the Second, making it the second of the seven registered Inari River Sabo Dams counting from the bottom of the valley. At 3.6 meters it is also the lowest of the seven. The Nikko Sabo Office gives the same completion date as the Third Dam upstream, 1 July 1921.
A Vertical Upstream Face and a Batter of 0.4
The Agency for Cultural Affairs is unusually specific about the cross-section of the Inari River Fourth Sabo Dam. The upstream face is vertical; the downstream face has a batter described in Japanese as yon-bu, meaning that it leans back 0.4 units horizontally for every unit of height. Seen from below, the face rises with a slight backward tilt.
With a height of only 3.6 meters, this is not a dam meant to store large volumes of sediment. Its job is to hold the riverbed across the full width of the valley with a long, low wall of 69 meters, so that gravel collecting behind it evens out the bed and slows the current. The face is laid in diagonal Tanizumi masonry with mortared Nerizumi joints, like its neighbors.
On the right bank, on the downstream side, a stone plaque recording the dam's date and other details is set into the structure. According to the Japan Society of Civil Engineers, the downstream Sub-dam (sub-dam) was rebuilt in 1967.
Why the Inari River Fourth Sabo Dam Was Registered
The Inari River Fourth Sabo Dam has registration number 09-0055 and was registered for contributing to the historic landscape of the nation. The Agency for Cultural Affairs points to the view from this dam, framed by bedrock and greenery, up the valley to the Second and Third Dams, and calls it a picture of a historic modern river. What earned the registration is less any single structure than the valley with its sequence of low steps.
What to Look for at the Inari River Fourth Sabo Dam
The Inari River Fourth Sabo Dam is an outdoor facility with no admission fee, viewed from the riverside path. You may not climb onto the dam.
Start by looking for the stone plaque on the downstream right bank, the one on-site clue to the dam's age. Then walk a little way downstream and look back up the valley: behind the low wall of the Fourth Dam the Second rises, and behind that the Third, which is exactly the stepped view the agency describes. Because the dam is so low, on days of high water the flow over the notch tends to spread across the full width of the crest. 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 Fourth Sabo Dam
- [ Nikko Toshogu Shrine & Kegon Falls Day Trip ]
Q&A
- When was the Inari River Fourth Sabo Dam built?
- In 1921. The Nikko Sabo Office gives a completion date of 1 July 1921.
- How big is the Inari River Fourth Sabo Dam?
- It is 69 meters long and 3.6 meters high, the lowest of the seven registered Inari River Sabo Dams.
- What does the batter of 0.4 on the Inari River Fourth Sabo Dam mean?
- It describes the slope of the downstream face, which sets back 0.4 units horizontally for each unit of height. The upstream face is vertical.
- Where is the best place to view the Inari River Fourth Sabo Dam?
- A little downstream, looking up the valley. From there the Second and Third Dams appear stacked behind the Fourth, the landscape the Agency for Cultural Affairs highlighted. Also look for the stone plaque on the downstream right bank.
- Can I visit the Inari River Fourth Sabo Dam, and is there a fee?
- Yes, you can view it from the riverside path free of charge. It is a working erosion-control dam, so climbing on it is not allowed.
Basic Information
| Name | Inari River Fourth Sabo Dam (稲荷川第四砂防堰堤) |
|---|---|
| Location | Aza 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, 3.6 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 Fourth Sabo Dam
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00002881
- Cultural Heritage Online: Inari River Fourth Sabo Dam
- https://online.bunka.go.jp/heritages/detail/140151
- 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 Fourth 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%9B%9B%E7%A0%82%E9%98%B2%E5%A0%B0%E5%A0%A4%E3%80%91/
Last verified: 2026.10.01
