What Is Bannai River No. 4 Sabo Dam?
Bannai River No. 4 Sabo Dam (万内川四号堰堤, Bannaigawa Yongō Entei) is a stone-and-concrete 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 placed across a mountain stream to hold back sediment and slow debris flows. Bannai River No. 4 Sabo Dam is a gravity dam of stone and concrete, 26 meters long at the crest and 4.0 meters high, the shortest of the registered dams on the Bannai. A secondary dam stands in front of it, and stone revetments line both banks downstream.
Its upstream face has a batter of 1:0.1 and its downstream face 1:0.2, so both faces are close to vertical.
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, although small, Bannai River No. 4 Sabo Dam has helped steady the banks and bed of the stream and has encouraged vegetation to return around it.
The Taisho-era photographs on the prefecture's explorer map show a raw, almost treeless riverbed. Compare them with the green slopes around Bannai River No. 4 Sabo Dam today and the agency's point about revegetation becomes easy to see.
What to Look For
The prefecture's explorer map calls Bannai River No. 4 Sabo Dam a two-step dam. The main dam and the secondary dam in front of it form two tiers, and the floor between them, the apron that takes the falling water, is paved with stone. Water pours off the main dam, runs across the stone apron, and drops again over the secondary dam. Watch the two falls from the front.
On the right bank, facing downstream, the stone revetment linking the two dams does not run straight but curves, turning the current gently so that it does not scour the bank. The curve is easiest to read from a little way downstream.
At 26 meters, the crest is only a little more than half the length of No. 1's 43 meters. A short main dam is combined with a secondary dam, a stone apron and a curved revetment, so that the force of the falling water is broken in stages within a small space.
How to Visit
Bannai River No. 4 Sabo Dam lies further up the path beyond No. 3. It is the uppermost dam on the prefecture's explorer map of dams No. 1 to No. 4, so if you walk up from No. 1, this is where the map's route ends.
Bannai River No. 4 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. 4 Sabo Dam
- [ Sado Island & Echigo-Yuzawa Ski Resort Tours ]
Q&A
- When was Bannai River No. 4 Sabo Dam built?
- Around 1922, as part of the sabo project Niigata Prefecture began on the Bannai River in 1921.
- Why is Bannai River No. 4 Sabo Dam a Registered Tangible Cultural Property?
- It was registered on March 18, 2003, as a structure contributing to the historic landscape. Despite its small size, it has stabilized the stream's banks and bed and encouraged the valley to green over.
- What does it mean that Bannai River No. 4 Sabo Dam is a two-step dam?
- A secondary dam stands in front of the main dam, and the two are joined by a stone-paved apron, so the water falls in two stages. On the right bank, a curved stone revetment links them.
- Can I visit Bannai River No. 4 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. 4 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. 4 Sabo Dam (万内川四号堰堤) |
|---|---|
| Location | Nishinoya, Myoko City, Niigata Prefecture |
| Designation | Registered Tangible Cultural Property (Structure), Registration No. 15-0147 |
| Year Designated | Registered 2003/3/18 (Heisei 15) |
| Quantity | 1 structure |
| Dimensions | Crest length 26 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: 万内川四号堰堤
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00003214
- 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
