What Is Bannai River No. 3 Sabo Dam?
Bannai River No. 3 Sabo Dam (万内川三号堰堤, Bannaigawa Sangō Entei) is a stone sabo dam built around 1922 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 before it can reach homes and fields downstream. Bannai River No. 3 Sabo Dam is a low gravity dam of stone, 35 meters long at the crest and just 2.0 meters high, and it is the next registered dam upstream from No. 1.
It was first laid as dry stone (Karazumi), with no mortar in the joints. In the early Showa era it was strengthened with mortared masonry. The Agency for Cultural Affairs names this reinforcement, and the extra length of the crest on the right bank, as the dam's defining features.
Why It Was Registered
In its description of Bannai River No. 3 Sabo Dam, the Agency for Cultural Affairs opens with the project itself: the Bannai works were the first sabo project carried out in Niigata, launched to hold back the sediment that kept coming down after the 1902 collapse, and run by the prefecture with national subsidies. The dam was registered as a structure contributing to the historic landscape of the country.
The switch from dry stone to mortared masonry shows a project that did not stop in the Taisho era but kept being repaired and strengthened into the Showa years. At only 2.0 meters high, the dam is small, yet it records both the technique the Bannai works began with and how that work was later reinforced.
What to Look For
The prefecture's explorer map picks out Bannai River No. 3 Sabo Dam as the one dam that still looks, from the outside, like it is built of the original local Nishinoya stone, and calls it especially valuable among the surviving Bannai dams. The prefecture also records that stonemasons split the stones on the riverbed, so it is worth looking closely at the varied shapes and sizes in the face.
Then look at the plan. Facing downstream, the dam runs further toward the right bank than the left, so the two sides are not symmetrical. Compare it later with No. 11 or No. 13 upstream, where the notch sits in the middle and the two halves match, and you can see how the early Taisho dams were shaped to fit the ground.
The joints between the stones are worth a look as well. Knowing that the wall began as dry stone and was later mortared, you can read about a century of maintenance in the masonry.
How to Visit
Bannai River No. 3 Sabo Dam lies a short walk up the riverside path from No. 1. It is covered by the prefecture's explorer map of dams No. 1 to No. 4, so the easiest plan is to take the map and walk the four in order.
Bannai River No. 3 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. 3 Sabo Dam
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Q&A
- When was Bannai River No. 3 Sabo Dam built?
- Around 1922, as part of the sabo project Niigata Prefecture began on the Bannai River in 1921, the first such project in the prefecture.
- Why is Bannai River No. 3 Sabo Dam a Registered Tangible Cultural Property?
- It was registered on March 18, 2003, as a structure contributing to the historic landscape. Its dry-stone wall reinforced with mortar in the early Showa era, and its longer right-bank crest, are cited as its key features.
- What is the difference between dry stone and mortared masonry?
- Dry stone is stacked without any binding material, while mortared masonry sets the stones in mortar. Bannai River No. 3 Sabo Dam began as dry stone and was later strengthened with mortar.
- Can I visit Bannai River No. 3 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. 3 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. 3 Sabo Dam (万内川三号堰堤) |
|---|---|
| Location | Nishinoya, Myoko City, Niigata Prefecture |
| Designation | Registered Tangible Cultural Property (Structure), Registration No. 15-0146 |
| Year Designated | Registered 2003/3/18 (Heisei 15) |
| Quantity | 1 structure |
| Dimensions | Crest length 35 meters, height 2.0 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: 万内川三号堰堤
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00003213
- Niigata Prefecture: Bannai River stone sabo dams (Registered Tangible Cultural Properties)
- https://www.pref.niigata.lg.jp/sec/jouetsu_sabou/bunkazai-bannai.html
- Niigata Prefecture: Explorer map of registered dams No. 1 to No. 4 (PDF)
- https://www.pref.niigata.lg.jp/uploaded/attachment/48362.pdf
- 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
