What Is Bannai River No. 12 Sabo Dam?
Bannai River No. 12 Sabo Dam (万内川十二号堰堤, Bannaigawa Jūnigō Entei) is a stone-and-concrete sabo dam built around 1925 on the Bannai River in Nishinoya, Myoko City, Niigata Prefecture, and was registered as a Registered Tangible Cultural Property on March 18, 2003.
A sabo dam is a check dam that holds back sediment in a mountain stream. Bannai River No. 12 Sabo Dam is a gravity dam of stone and concrete, 38 meters long at the crest and 4.2 meters high, with revetments on both banks downstream. It was remodeled around 1933, and its downstream face has a batter of 1:0.2.
By number it lies above No. 10 and No. 11, yet it was built around 1925, about a year earlier than those two, which date from around 1926. The numbering does not simply follow the order of construction.
Why It Was Registered
The dam was registered as a structure contributing to the historic landscape of the country. The Agency for Cultural Affairs points to three features of Bannai River No. 12 Sabo Dam: the whole body is built in finely worked Tanizumi masonry; the crest outside the spillway notch slopes about 4% toward the center; and a stone nameplate is set into the right-bank side of the dam.
In tanizumi, stones are set on the diagonal so that neighbors lean into one another, and the courses alternate direction, giving the wall a distinctive herringbone-like pattern. The agency values the dam both for steadying the streambed and holding back sediment and for forming the base of the natural scenery around it.
What to Look For
Start with the masonry. The entire face of Bannai River No. 12 Sabo Dam is laid in tanizumi, the angled stones switching direction course by course to form a zigzag. Step back to take in the pattern as a whole, then move close to see how each stone is seated; the fit the agency calls precise is easiest to appreciate that way.
Then follow the crest. Outside the notch it is not level but dips slightly toward the middle. A 4% slope is not obvious at a glance, but run your eye from the end of the crest toward the center and the intention, to steer water to the notch, becomes readable.
On the right-bank side of the dam is a stone nameplate. Among the registered Bannai dams, this is the only one whose nameplate the agency mentions.
How to Visit
Bannai River No. 12 Sabo Dam lies just upstream of No. 11. The upper dams are reached by following the riverside path up from Bannai River Sabo Park. Check the on-site map for how far the maintained path runs, and do not continue onto the riverbed or slopes where it ends.
Bannai River No. 12 Sabo Dam stands in the open and can be viewed freely from the path; neither the prefecture nor the city lists any restriction on photography. It is a working sabo structure, so stay off the crest and the spillway notch, and keep back from the water after heavy rain. Opening season and directions to Bannai River Sabo Park are covered on the Bannai River Sabo Facilities page.
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- Find tours, activities & transport passes near Bannai River No. 12 Sabo Dam
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Q&A
- When was Bannai River No. 12 Sabo Dam built?
- Around 1925, with remodeling around 1933, as part of the sabo project Niigata Prefecture began on the Bannai River in 1921.
- Why is Bannai River No. 12 Sabo Dam a Registered Tangible Cultural Property?
- It was registered on March 18, 2003, as a structure contributing to the historic landscape. Its finely laid tanizumi masonry, a crest that slopes toward the center, and a stone nameplate on the right bank are cited.
- What is the tanizumi masonry on Bannai River No. 12 Sabo Dam?
- It is a way of laying stones on the diagonal so that neighboring stones lean into each other, with the direction alternating course by course. The result is a zigzag pattern across the wall.
- Can I visit Bannai River No. 12 Sabo Dam, and is there a fee?
- Yes. It is outdoors and can be seen freely from the path. Bannai River Sabo Park is open from April to November and there is no charge.
- Where is Bannai River No. 12 Sabo Dam?
- Bannai River No. Directions to Bannai River Sabo Park are on the Bannai River Sabo Facilities page.
Basic Information
| Name | Bannai River No. 12 Sabo Dam (万内川十二号堰堤) |
|---|---|
| Location | Nishinoya, Myoko City, Niigata Prefecture |
| Designation | Registered Tangible Cultural Property (Structure), Registration No. 15-0152 |
| Year Designated | Registered 2003/3/18 (Heisei 15) |
| Quantity | 1 structure |
| Dimensions | Crest length 38 meters, height 4.2 meters |
| Owner | Niigata Prefecture |
| Public Access | Outdoors and freely viewable; Bannai River Sabo Park is open April to November, free of charge |
References
- Agency for Cultural Affairs, Database of National Cultural Properties: 万内川十二号堰堤
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00003219
- Niigata Prefecture: Bannai River stone sabo dams (Registered Tangible Cultural Properties)
- https://www.pref.niigata.lg.jp/sec/jouetsu_sabou/bunkazai-bannai.html
- JSCE Kanto Branch: Bannai River sabo dams and Hikagesawa ground sills
- https://www.jsce.or.jp/branch/kanto/04_isan/h29/h29_8.html
Last verified: 2026.09.24
