What Is Bannai River No. 11 Sabo Dam?
Bannai River No. 11 Sabo Dam (万内川十一号堰堤, Bannaigawa Jūichigō Entei) is a stone-and-concrete sabo dam built around 1926 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 traps sediment in a mountain stream. Bannai River No. 11 Sabo Dam is a gravity dam of stone and concrete, 33 meters long at the crest and 4.0 meters high, with revetments on both banks downstream and a secondary dam in front. It was remodeled around 1933.
It stands in a gorge where the middle reach of the valley pinches in. The downstream face has a batter of 1:0.2 and the upstream face 1:0.05.
Why It Was Registered
The dam was registered as a structure contributing to the historic landscape of the country. The Agency for Cultural Affairs notes that the spillway notch of Bannai River No. 11 Sabo Dam sits in the center of the dam, giving it an almost symmetrical form, and that its revetments, apron and secondary dam all survive in good condition.
Above all, the agency credits its defenses against scour. Scour is the gouging of the streambed at the foot of a dam by falling water; left unchecked, it can tilt or undermine the dam itself. Here the apron is solidly paved with stone and the notch is made wide, spreading the falling water.
Where a valley narrows, flow concentrates and the risk of scour grows. That the foot of a dam in exactly such a spot was protected with such care says a good deal about how the builders matched design to site.
What to Look For
From the front, the dam is neat and balanced, its two halves mirroring each other around the central notch. Compare it with No. 3 downstream, which runs longer toward the right bank, and you can see that the Bannai dams were not all shaped by the same rule.
The stone-paved apron below the main wall is the part of Bannai River No. 11 Sabo Dam most worth studying. Its stones are laid flush to armor the floor that takes the full force of the falling water. Together with the secondary dam beyond and the revetments on both banks, it lets you trace at a glance how the water is caught and passed downstream.
Glance up at the slopes pressing in on both sides, too. Standing between them, you can feel how narrow the gorge is here.
How to Visit
Bannai River No. 11 Sabo Dam lies just upstream of No. 10. 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. 11 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. 11 Sabo Dam
- [ Sado Island & Echigo-Yuzawa Ski Resort Tours ]
Q&A
- When was Bannai River No. 11 Sabo Dam built?
- Around 1926, with remodeling around 1933, as part of the sabo project Niigata Prefecture began on the Bannai River in 1921.
- Why is Bannai River No. 11 Sabo Dam a Registered Tangible Cultural Property?
- It was registered on March 18, 2003, as a structure contributing to the historic landscape. Its near-symmetrical form, its well-preserved revetments, apron and secondary dam, and its measures against scour are all cited.
- How does Bannai River No. 11 Sabo Dam guard against scour?
- Its apron is solidly paved with stone, and the notch is made wide so the falling water is spread out, protecting the foot of a dam that stands in a narrow gorge.
- Can I visit Bannai River No. 11 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. 11 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. 11 Sabo Dam (万内川十一号堰堤) |
|---|---|
| Location | Nishinoya, Myoko City, Niigata Prefecture |
| Designation | Registered Tangible Cultural Property (Structure), Registration No. 15-0151 |
| Year Designated | Registered 2003/3/18 (Heisei 15) |
| Quantity | 1 structure |
| Dimensions | Crest length 33 meters, height 4.0 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: 万内川十一号堰堤
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00003218
- 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
