About the Akatan Sabo Obira Mizuya Upper Dam
The Akatan Sabo Obira Mizuya Upper Dam (アカタン砂防大平ミズヤ上堰堤, Akatan Sabō Ōbira Mizuya Kami Entei) is a dry-stone check dam on the Akatani River in Furuki, Minamiechizen, Fukui Prefecture, built between 1897 and 1906 and registered as a Registered Tangible Cultural Property on July 23, 2004.
The Obira Mizuya Upper Dam is the highest of the nine Akatan Sabo Dams, and its registration number, 18-0027, puts it at the head of the series. The Akatani is a side stream of the Takura River, which flows into the Hino, and this dam sits in its upper reach, directly below a mass of debris that had slid off the slopes and piled up in the channel.
It measures 20 meters along the crest and 7.5 meters high. The stones are stacked without mortar in dry-stone fashion and bedded on exposed rock. About 10 meters downstream stands its partner, the Obira Mizuya Lower Dam.
Why It Was Registered
Along with the other eight, the Akatan Sabo Obira Mizuya Upper Dam was registered in 2004 as a structure that contributes to the historic landscape of the country. The Agency for Cultural Affairs singles it out as a key piece of the sabo plan because of where it stands: right below the debris mass. If that material had broken loose in one surge, it would have swept through every dam and field downstream. This single dam was placed to hold it at the source.
The details reward a close look. The face is built to a batter of 0.85 horizontal to 1 vertical, and a lower step on the downstream side is set at 0.7. The crest is laid in a shallow sag toward the middle, a profile Japanese builders call nawa-darumi, "slack rope."
What to Look For
Start with the line of the crest. Like a rope held at both ends, it dips slightly at the center, so that when the stream rises the water gathers there and drops clear of the valley walls instead of gnawing at them. It is a simple shape that keeps the banks from being cut away.
Then look at the foot of the downstream face, where the batter changes and a separate step takes the impact of falling water. For a dam holding back a debris mass, it is not especially tall, but the stone packs the full width of the gorge and the weight shows.
Seen together with the Mizuya Lower Dam just below, the two form a pair of stairs cut into the stream's gradient.
Visiting
The Akatan Sabo Obira Mizuya Upper Dam marks the far end of the walking trail. Fukui Prefecture estimates the round trip from Retreat Takura at about 2 hours, with steps and steep pitches along the way, so allow time and wear proper footwear. Stay on the trail and view the dam from safe ground; do not climb onto the crest or the stone faces.
The trail is open to visitors from April through November and closed in winter. Parking, directions and guided walks are covered on the Akatan Sabo Dams page.
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Q&A
- Where is the Akatan Sabo Obira Mizuya Upper Dam, and how long is the walk?
- It is the highest of the Akatan Sabo Dams, on the upper Akatani River in Furuki, Minamiechizen, Fukui Prefecture. Fukui Prefecture puts the round trip on foot from Retreat Takura at about 2 hours.
- How big is the Akatan Sabo Obira Mizuya Upper Dam?
- It is a dry-stone dam 20 meters long at the crest and 7.5 meters high, set on exposed bedrock, with a batter of 0.85 to 1, a lower downstream step at 0.7, and a sagging nawa-darumi crest.
- Why is the Akatan Sabo Obira Mizuya Upper Dam a Registered Tangible Cultural Property?
- It was registered in 2004 as a structure from 1897 to 1906 that contributes to Japan's historic landscape. The Agency for Cultural Affairs calls it a key element of the sabo plan because it stands directly below a debris mass.
- What is the nawa-darumi crest on the Akatan Sabo Obira Mizuya Upper Dam?
- The crest sags gently toward the center, like slack rope. In a flood the water collects in the middle and falls away from the valley sides, which protects the banks from erosion.
- When can I visit the Akatan Sabo Obira Mizuya Upper Dam?
- From April through November. The trail is closed to visitors in winter, and the dam is viewed from the walking trail.
Basic Information
| Name | Akatan Sabo Obira Mizuya Upper Dam |
|---|---|
| Location | Furuki, Minamiechizen, Nanjo District, Fukui Prefecture |
| Designation | Registered Tangible Cultural Property (Structure) |
| Year Designated | Registered 2004/7/23 (Heisei 16) |
| Quantity | 1 dam |
| Dimensions | Crest length 20 meters, height 7.5 meters |
| Owner | Fukui Prefecture |
| Public Access | Exterior only, from the walking trail; closed in winter |
References
- Agency for Cultural Affairs, Database of National Cultural Properties: Akatan Sabo Obira Mizuya Upper Dam
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00004230
- Fukui Prefecture, Sabo Division: Akatan Sabo Dams
- https://www.pref.fukui.lg.jp/doc/sabo/akatan.html
- Fukui Prefecture: Akatan Sabo Dams leaflet (PDF)
- https://www.pref.fukui.lg.jp/doc/sabo/akatan_d/fil/akatan.pdf
Last verified: 2026.09.26
