What the Kamakurazawa River No. 1 Sabo Dam Is
The Kamakurazawa River No. 1 Sabo Dam is a stone gravity check dam on the Kamakurazawa River in Yoshizato, Minamiuonuma City, Niigata Prefecture, completed in 1927 and entered on the national register as a Registered Tangible Cultural Property structure on 4 August 2015.
It runs 45 meters across and stands 3.6 meters high, making it the longest of the eight registered structures on the stream. A gravity dam resists the push of water and sediment through its own weight alone, without reinforcement inside the body. The unusual ratio of length to height comes from the site: the valley opens out here, and the dam had to reach the whole way across it.
The Agency for Cultural Affairs places the dam just below the point where the Komochizawa, a tributary entering from the left, joins the main stream. It therefore catches sediment from two sources at once, the main channel and a side valley prone to landsliding, and the database describes the Kamakurazawa River No. 1 Sabo Dam as the key structure of the whole scheme. A plaque reading 堰堤１ is cut into the upper right wing.
The Key Structure of the Scheme
Registration was made under the criterion of contributing to the historic landscape of the country, recommended by the Council for Cultural Affairs on 13 March 2015 and entered on 4 August that year as registration number 15-0412.
One thing sets this dam apart from its neighbours. The No. 2 through No. 9 dams all sit in a line along the main channel; this one also has to take whatever the Komochizawa brings down from the side. Just below a confluence the flow becomes unruly and the sediment load rises, and it is at exactly that widened point in the valley that the longest of the eight bodies was laid.
The completion date supports the same reading. Built in the opening year of the project alongside the No. 1 Ground Sill, the Kamakurazawa River No. 1 Sabo Dam became the hinge from which nine years of construction spread both up and down the valley.
The Plaque and the 45-Meter Body
Look for the plaque on the upper right wing. The three characters 堰堤１ cut into the stone are the serial number the project gave this dam, left on site by the men who built it. The incision is shallow and can be hard to pick out; raking light makes it easier.
The figure of 45 meters registers properly only on the ground. With a height of just 3.6 meters, the dam reads as width rather than mass, and taking in both wings at once means standing well back from it.
Look upstream as well. The thin channel coming in from the left is the Komochizawa, and its water and sediment can be watched joining the main stream over the crest of the Kamakurazawa River No. 1 Sabo Dam. What the dam was built to intercept is written into the shape of the ground in front of it.
Visiting the Kamakurazawa River No. 1 Sabo Dam
This is a working outdoor structure with no interior. Visiting means viewing the exterior from the bank, at no charge, with no reception desk and no restriction on photography.
Given the length of the body, an oblique view from downstream shows more than a square-on one. The plaque sits on the right wing, so look for it from the right bank facing downstream. The No. 1 Ground Sill lies about 50 meters below and the No. 2 Sabo Dam about 30 meters above, which puts a sill and two dams of different size within a very short walk.
Do not enter the streambed; water gathers fast below a confluence. Snow closes the valley in winter, so plan for roughly May to November. Directions and the parking situation are set out on the Kamakurazawa River Sabo Facilities page.
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Q&A
- Can the Kamakurazawa River No. 1 Sabo Dam be visited freely?
- Yes, from the bank, at any time and without charge. There is no visitor car park or footpath, and going down into the streambed is dangerous.
- How large is the Kamakurazawa River No. 1 Sabo Dam?
- 45 meters long and 3.6 meters high. That length is the greatest among the eight registered structures, and the height is second only to the No. 8 Sabo Dam.
- Where is the plaque on the Kamakurazawa River No. 1 Sabo Dam?
- On the upper right wing, facing downstream. The characters are shallowly incised, so a time of day when the light falls across the stone at an angle makes them much easier to read.
- Why is the Kamakurazawa River No. 1 Sabo Dam called the key structure of the scheme?
- Because it stands immediately below the mouth of the Komochizawa and takes sediment both from the main stream and from a side valley where landslides are frequent. The national database describes it in those terms.
- When was the Kamakurazawa River No. 1 Sabo Dam registered?
- As a Registered Tangible Cultural Property (structure) on 4 August 2015, under registration number 15-0412. All eight structures on the stream were registered that day, the first structures in Minamiuonuma City to receive the status.
Basic Information
| Name | Kamakurazawa River No. 1 Sabo Dam (鎌倉沢川第一号堰堤) |
|---|---|
| Location | Yoshizato, Minamiuonuma City, Niigata Prefecture |
| Designation | Registered Tangible Cultural Property (Structure) |
| Year Designated | Registered 2015/8/4 (Heisei 27) |
| Quantity | 1 site |
| Dimensions | 45 meters long, 3.6 meters high |
| Owner | Niigata Prefecture |
| Public Access | Working outdoor structure; exterior visible from the bank at any time, no interior access |
References
- National Cultural Properties Database: Kamakurazawa River No. 1 Sabo Dam (Agency for Cultural Affairs)
- https://kunishitei.bunka.go.jp/heritage/detail/101/00010577
- Sabo Facilities on the Kamakurazawa River Entered on the National Register (Niigata Prefecture, Minamiuonuma Regional Promotion Bureau)
- https://www.pref.niigata.lg.jp/sec/minamiuonuma_seibi/1356827806289.html
- Registered Cultural Properties of Minamiuonuma City (Minamiuonuma City Board of Education)
- https://www.city.minamiuonuma.niigata.jp/docs/890.html
Last verified: 2026.09.12
