What Aoshita No. 2 Dam Is
Aoshita No. 2 Dam (青下第２ダム) is a water-supply barrage on the Aoshita River at Kumagane, Aoba Ward, Sendai City, Miyagi Prefecture, completed in 1934 and listed as a Registered Tangible Cultural Property (Structures) on 7 June 1999. It occupies the middle step of three dams staggered up the valley, passing water from the reservoir above to the one below.
The main barrage stands 14.4 m high and 39.2 m long, the shortest span of the three. A subsidiary weir 2.4 m high and 23.6 m long sits downstream, and a maintenance bridge 1.5 m wide crosses the crest on the right-bank side. The construction is concrete faced with river cobbles, the same finish used at Aoshita No. 1 Dam further down.
What defines Aoshita No. 2 Dam is the difference in level between reservoirs. Full water level here sits roughly 10 m above the first reservoir. That step lets water fall from one pool to the next without pumps, using only the slope of the valley. Stacking three dams in sequence was a way of turning topography into machinery. Together the three reservoirs hold about 590,000 cubic metres.
Three Dams, One Instrument
Taken alone, Aoshita No. 2 Dam looks modest. But Sendai's first waterworks expansion did not need one large structure; it needed three reliable ones. When work began in 1931, the problem was how to capture a limited flow without losing any of it. Divide the valley into three steps and each reservoir can stay small while the total remains sufficient. Lower barrages also meant a build that the budget and the engineering of the day could carry comfortably.
The listing criterion is contribution to the historic landscape of the nation. For this barrage the case rests less on its own form than on the sequence it belongs to. Walk upstream and the water surface rises step by step while the same detailing reappears at each stage. That repetition is what makes the Aoshita valley read as a designed landscape rather than a set of separate works.
The subsidiary weir does the same job here as it does downstream: it absorbs the drop so falling water cannot scour the bed and undercut the barrage. Its height, 2.4 m, is identical at all three dams, a small sign that one design mind ran through the whole scheme.
What to Look For
There is nowhere to stand and face this barrage head-on. Of the routes the Sendai City Waterworks Bureau publishes, only the longer forest walk reaches it, about 900 m there and back and roughly 16 minutes. Push to the far end and the structure enters the view, but always at an angle. Never quite seeing it square is part of the experience.
The cobbled face appearing through a gap in the trees is the same surface you can touch at the first dam. Here you meet it at a distance instead. Individual stones that read as objects up close merge into a single grain when seen from across the water.
The path itself deserves attention. It was deliberately left unpaved so that walkers feel soil and leaf litter underfoot. Horsetail shoots come up in spring; chestnuts drop in autumn. A clearing partway along frames the hillside and the reservoir in one view, which keeps the approach to Aoshita No. 2 Dam from feeling like a corridor.
Visiting Aoshita No. 2 Dam
The barrage lies inside the Aoshita water source grounds and can be seen from the far end of the longer forest route. The grounds open from 9:30 a.m. to 4 p.m. and there is no admission charge. The crest and the maintenance bridge are closed to visitors, and no special opening is offered.
Start at the Aoshita Dam Former Management Office. The forest route runs in the opposite direction to the hiking trail and stays level, so it suits families with children. Allow about 900 m for the round trip. Partway along, a branch leads to the lawn in front of the Sendai City Waterworks Memorial Hall. An attendant-operated electric wheelchair is kept at the hall, though it can only be used on the flat sections.
No notice restricts photography. Shooting from the paths is fine. For tripod work or commercial photography, check with the Memorial Hall on 022-393-2188 beforehand.
By bus, take the Sendai City service for Jōgi from Sendai Station, alight at Ōtemon-iriguchi and walk 8 minutes. From Kumagane Station on the JR Senzan Line it is 20 minutes on foot. Driving takes about 40 minutes from Sendai Station or about 30 minutes from the Sendai-Miyagi interchange. The Memorial Hall closes from 1 December to 31 March.
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Q&A
- Can I get close to Aoshita No. 2 Dam?
- Not directly. The longer forest walk, about 900 m round trip, brings you to a point where the barrage is visible at an angle. The crest itself is closed to visitors.
- How large is Aoshita No. 2 Dam?
- The main barrage measures 14.4 m high and 39.2 m long, with a subsidiary weir 2.4 m high and 23.6 m long below it. A maintenance bridge 1.5 m wide crosses the crest.
- Why was Aoshita No. 2 Dam built as one of three dams?
- Splitting the valley into three steps kept each barrage low while securing about 590,000 cubic metres in total. The full water level here stands roughly 10 m above the first reservoir, so water descends by gravity alone.
- How do I reach Aoshita No. 2 Dam?
- Take the Sendai City bus for Jōgi, alight at Ōtemon-iriguchi and walk 8 minutes to the water source grounds, or walk 20 minutes from Kumagane Station. Inside, follow the forest route from the Aoshita Dam Former Management Office.
- When was Aoshita No. 2 Dam registered as a cultural property?
- On 7 June 1999. The criterion applied to this barrage is contribution to the historic landscape of the nation, and eight structures in the Aoshita water source area were listed on the same date.
Basic Information
| Name | Aoshita No. 2 Dam (青下第２ダム, Aoshita Dai-ni Damu) |
|---|---|
| Location | 27-2 Oharamichi, Kumagane, Aoba Ward, Sendai City, Miyagi Prefecture |
| Designation | Registered Tangible Cultural Property (Structures) |
| Year Designated | Registered on 7 June 1999 |
| Quantity | 1 unit |
| Dimensions | Main barrage 14.4 m high, 39.2 m long; subsidiary weir 2.4 m high, 23.6 m long; maintenance bridge 23.6 m long, 1.5 m wide |
| Owner | Sendai City Water Supply Business Manager |
| Public Access | Distant view from the walking paths only, 9:30 a.m. to 4 p.m., free of charge. Crest closed |
References
- Agency for Cultural Affairs, National Cultural Properties Database: Aoshita No. 2 Dam
- https://kunishitei.bunka.go.jp/heritage/detail/101/00001089
- Sendai City Waterworks Bureau: Aoshita Water Source Walking Map
- https://www.suidou.city.sendai.jp/soshiki/somu-eigyo/koho/7/405.html
- Sendai City Waterworks Bureau: Visitor Information for the Aoshita Water Source Area and Memorial Hall
- https://www.suidou.city.sendai.jp/soshiki/somu-eigyo/koho/7/403.html
- Sendai City Waterworks Bureau: Dams Serving as Water Sources
- https://www.suidou.city.sendai.jp/jigyo/suigen-shisetsu-suishistsu/syuyoshisetsu/625.html
Last verified: 2026.09.08