What Is Bannai River No. 10 Sabo Dam?
Bannai River No. 10 Sabo Dam (万内川十号堰堤, Bannaigawa Jūgō 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 built across a mountain stream to hold back sediment. Bannai River No. 10 Sabo Dam is a gravity dam of stone and concrete, 42 meters long at the crest and 3.5 meters high, with revetments on both banks downstream and a secondary dam in front. It was remodeled around 1933.
Its downstream face has a batter of 1:0.2 and its upstream face just 1:0.05, so the upstream side rises almost vertically. It is a low dam with nearly upright faces.
Why It Was Registered
The dam was registered as a structure contributing to the historic landscape of the country. According to the Agency for Cultural Affairs, Bannai River No. 10 Sabo Dam stands about 120 meters from the sabo dams on either side of it.
What the agency values is how plainly the dam shows a model plan: a run of low dams placed one after another through a landslide-prone stretch. The frequent slope failures and sediment flows that plagued the valley before construction were, in the agency's account, cut off by that series.
The idea behind a stepped series is simple. Sediment settles behind each low dam, the bed rises a little at a time, and the stream's gradient eases. A higher bed props up the foot of the slopes on either side, so they are less likely to slide. Bannai River No. 10 Sabo Dam shows the whole principle in a single structure.
What to Look For
On paper, 3.5 meters sounds modest; in front of the dam it feels lower still. That lowness is the point. Rather than one tall barrier catching everything, a string of low dams at regular intervals calms the whole reach.
Compare the level of the streambed above and below the dam. How far the sediment trapped upstream has raised the bed shows how the dams have reshaped the river's profile. Downstream, the secondary dam and the revetments take the falling water.
Notice the spacing, too. Lines of masonry spaced about 120 meters apart make it clear on the ground that these are parts of a single, planned system.
How to Visit
Bannai River No. 10 Sabo Dam lies upstream of the No. 7 and No. 8 dams. 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. 10 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.
- 📍 Plan Your Visit to Niigata
- Find tours, activities & transport passes near Bannai River No. 10 Sabo Dam
- [ Sado Island & Echigo-Yuzawa Ski Resort Tours ]
Q&A
- When was Bannai River No. 10 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. 10 Sabo Dam a Registered Tangible Cultural Property?
- It was registered on March 18, 2003, as a structure contributing to the historic landscape. It is valued as a clear example of a model plan: a series of low dams set through a landslide-prone stretch.
- How far apart are Bannai River No. 10 Sabo Dam and its neighbors?
- According to the Agency for Cultural Affairs, it stands about 120 meters from the sabo dams upstream and downstream.
- Can I visit Bannai River No. 10 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. 10 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. 10 Sabo Dam (万内川十号堰堤) |
|---|---|
| Location | Nishinoya, Myoko City, Niigata Prefecture |
| Designation | Registered Tangible Cultural Property (Structure), Registration No. 15-0150 |
| Year Designated | Registered 2003/3/18 (Heisei 15) |
| Quantity | 1 structure |
| Dimensions | Crest length 42 meters, height 3.5 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: 万内川十号堰堤
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00003217
- 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
