What the Kamakurazawa River No. 2 Sabo Dam Is
The Kamakurazawa River No. 2 Sabo Dam is a stone gravity check dam on the Kamakurazawa River in Yoshizato, Minamiuonuma City, Niigata Prefecture, completed in 1928 and entered on the national register as a Registered Tangible Cultural Property structure on 4 August 2015.
It measures 32 meters across and 2.7 meters high and stands about 30 meters above the No. 1 Sabo Dam. A plaque incised with the characters 堰堤２ sits on the upper right wing, matching the number in its name.
What distinguishes this dam is how it was built. The Agency for Cultural Affairs points to its scale and, alongside that, to a method in which carefully laid andesite facing stones enclose a core filled with cyclopean concrete. What the eye sees is masonry; behind it lies concrete, still a young material in Japan at the time. The Kamakurazawa River No. 2 Sabo Dam belongs to the moment when the two techniques overlapped.
Stone Outside, Concrete Within
The dam was registered under the criterion of contributing to the historic landscape of the country, recommended on 13 March 2015 and entered on 4 August that year as registration number 15-0413.
Its completion date of 1928 falls in the middle of the shift in Japanese sabo engineering from stone to concrete. The face is andesite set by hand on the diagonal; the interior is rubble concrete mixed on site. A structure that uses different technologies front and back can only appear before one of them wins out, which is what the national database means when it calls the workmanship characteristic of its period.
Cyclopean concrete is concrete poured around large pieces of broken stone. It reduces the amount of cement required, which mattered a great deal on mountain sites where every sack had to be carried up the valley. The choice of method records the conditions under which the work was done.
Andesite at Close Range
The facing stones are andesite, laid in the diagonal bond called tanizumi. The database describes the work as finely laid, and it shows: the faces align closely and the joints hold an even width the whole way across. Set beside unworked masonry such as Nozurazumi, the amount of splitting and fitting that went into this face becomes obvious.
At 2.7 meters, this is the lowest of the six registered dams, which happens to make it the easiest to study. You can get close enough to see how the joints were packed and how the corners were turned. For anyone interested in stonework rather than hydraulics, the Kamakurazawa River No. 2 Sabo Dam repays a longer look than any of the other seven structures.
The No. 1 Sabo Dam just downstream is 13 meters longer and 0.9 meters taller. Seeing two dams built a year apart in quick succession shows how the dimensions were adjusted to the shape of the valley at each point.
Visiting the Kamakurazawa River No. 2 Sabo Dam
This is a working outdoor structure with no interior. Viewing is from the bank, free of charge, with no reception and no restriction on photography.
If the masonry is what you have come for, stand near the front of the dam body and choose a time when the light strikes the stone at an angle. Overhead light flattens the joints and the raking lines of the diagonal bond become hard to follow. The plaque is on the right wing, so look from the right bank facing downstream.
Stay out of the streambed; it is dangerous when the water rises, and snow closes the valley in winter. Roughly May to November is the practical season. Directions and the parking situation are covered on the Kamakurazawa River Sabo Facilities page.
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Q&A
- Can the Kamakurazawa River No. 2 Sabo Dam be visited, and is there a charge?
- It can be seen from the bank at any time, free of charge. No car park or footpath has been provided, and the streambed should not be entered.
- How was the Kamakurazawa River No. 2 Sabo Dam built?
- Andesite facing stones laid on the diagonal enclose a core of cyclopean concrete. The combination of masonry and concrete is characteristic of Japanese sabo work in the late 1920s, and the national database singles it out.
- What is the cyclopean concrete inside the Kamakurazawa River No. 2 Sabo Dam?
- Concrete poured around large fragments of broken stone. Using stone in bulk cut the amount of cement needed, an advantage on mountain sites where materials had to be hauled a long way.
- What size is the Kamakurazawa River No. 2 Sabo Dam and when was it built?
- 32 meters long and 2.7 meters high, completed in 1928. It was registered as a Registered Tangible Cultural Property (structure) on 4 August 2015, under registration number 15-0413.
- Where is the plaque on the Kamakurazawa River No. 2 Sabo Dam?
- Cut into the upper right wing, reading 堰堤２. Two other structures on the stream carry plaques of the same kind, the No. 1 Sabo Dam and the No. 23 Ground Sill.
Basic Information
| Name | Kamakurazawa River No. 2 Sabo Dam (鎌倉沢川第二号堰堤) |
|---|---|
| Location | Yoshizato, Minamiuonuma City, Niigata Prefecture |
| Designation | Registered Tangible Cultural Property (Structure) |
| Year Designated | Registered 2015/8/4 (Heisei 27) |
| Quantity | 1 site |
| Dimensions | 32 meters long, 2.7 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. 2 Sabo Dam (Agency for Cultural Affairs)
- https://kunishitei.bunka.go.jp/heritage/detail/101/00010578
- 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
