What Aoshita No. 1 Dam Is
Aoshita No. 1 Dam (青下第１ダム) is a water-supply dam on the Aoshita River in Kumagane, Aoba Ward, Sendai City, Miyagi Prefecture, completed in 1934 and entered on the national register as a Registered Tangible Cultural Property (Structures) on 7 June 1999. The Aoshita is a tributary of the Hirose River, and three dams stand in its narrow valley. Aoshita No. 1 Dam sits furthest downstream and catches what the two upper dams release.
Piped water reached Sendai households in 1923. Demand outgrew supply within a decade, and the city launched its first waterworks expansion in 1931. The Aoshita valley was chosen as the new source, and the city built the three dams itself rather than buying water from elsewhere. Together the reservoirs hold roughly 590,000 cubic metres. Ninety years on, the system still works, sending raw water to the Nakahara Purification Plant.
The register describes the structure as a concrete barrage faced with cobblestones, with a subsidiary weir and the Aoshita Bridge attached. The main barrage stands 13.4 m high and 41.8 m long. The subsidiary weir downstream measures 2.4 m by 25.7 m, and the bridge across the crest runs 43.6 m long and 1.8 m wide.
Why the Cobblestone Facing Matters
What gives Aoshita No. 1 Dam its face is the layer of river cobbles pressed into the downstream side of the concrete. Water spilling over the crest never meets a flat wall. It splits and slides across hundreds of rounded bulges, so on a bright afternoon the sheet breaks into pale threads that follow the lines of the stones.
The registration criterion applied here is contribution to the historic landscape of the nation. Read that alongside the date and the meaning becomes clearer: a provincial city in the early Shōwa era assembled its own water source with its own engineers, and the result survived. The dam is an overflow gravity type, which means the water is meant to pass over the top rather than through gates or outlet pipes. Few moving parts, few things to fail.
The subsidiary weir below exists to stop falling water from scouring the riverbed and undermining the main structure. At 2.4 m it is barely more than a step, but the pool it creates absorbs the energy of the drop. Look into that pool and you can watch the current lose its momentum before gathering itself again for the run downstream.
What to Look For
The best vantage point is the Aoshita Bridge along the crest, a slim girder span 43.6 m long and only 1.8 m wide. Standing on it puts the overflow directly beneath your feet. The sound rises rather than travels, and on high-water days spray reaches the handrail. The bridge was built for maintenance access and now forms part of the walking route.
Partway across, a cylindrical intake tower rises out of the reservoir. It carries its own listing as Aoshita No. 1 Dam Intake Tower, and the combination of barrage, tower and footbridge in one continuous line is what makes this site read as a single piece of engineering rather than a collection of parts.
Move to where you can see the face obliquely from below and the cobbles begin to look like masonry. The stones are roughly the size of a pickling weight and vary in colour. In low-water months the boundary between the wet and dry zones is sharp enough to read the recent flow like a tide mark.
Aoshita No. 1 Dam was chosen in 1985 for the national selection of one hundred modern waterworks. The Sendai City Waterworks Memorial Hall next to it hands out a dam card for the site to anyone who asks at the office counter.
Visiting Aoshita No. 1 Dam
The dam stands inside the Aoshita water source grounds and can be viewed from the walking paths without booking. The grounds are open from 9:30 a.m. to 4 p.m. The interior of the structure and the working installations are closed, but crossing the bridge and looking straight down at the spillway is entirely possible.
The shortest approach is the history route that begins at the Aoshita Dam Former Management Office: 500 m there and back, about 10 minutes. The dam appears at the bottom of the slope. Paths are deliberately unpaved, so expect leaf litter and bare earth underfoot. Visitors who find that difficult can borrow an attendant-operated electric wheelchair kept at the Memorial Hall, usable on the level sections. There is one unit, and reservations take priority, so call ahead.
No published notice restricts photography. Shooting from the outdoor paths is fine; if you plan to set up a tripod or shoot commercially, contact the Sendai City Waterworks Memorial Hall on 022-393-2188 first.
By public transport, take a Sendai City bus bound for Jōgi from the Sendai Station front, get off at Ōtemon-iriguchi and walk 8 minutes. From Kumagane Station on the JR Senzan Line it is a 20-minute walk. By car, allow 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, so plan around that window.
- 📍 Plan Your Visit to Miyagi
- Find tours, activities & transport passes near Aoshita No. 1 Dam
- [ Matsushima Bay Cruise & Sendai Food Tours ]
Q&A
- Can you visit Aoshita No. 1 Dam, and what are the hours and fees?
- Yes. The dam is visible from the walking paths of the Aoshita water source grounds, open from 9:30 a.m. to 4 p.m. There is no charge, and the adjacent Sendai City Waterworks Memorial Hall is also free.
- How do I get to Aoshita No. 1 Dam from Sendai?
- Take a Sendai City bus for Jōgi from Sendai Station, alight at Ōtemon-iriguchi and walk 8 minutes. Alternatively walk 20 minutes from Kumagane Station on the JR Senzan Line. Driving takes about 40 minutes from Sendai Station.
- When was Aoshita No. 1 Dam registered as a cultural property?
- On 7 June 1999. The criterion applied to this dam is contribution to the historic landscape of the nation. Eight structures in the Aoshita water source area were listed on the same date.
- Is Aoshita No. 1 Dam still in use?
- It is. Water drawn here travels through a conduit tunnel to the Nakahara Purification Plant and supplies part of central Sendai, which makes the dam a working piece of infrastructure rather than a preserved relic.
- Where can I get the Aoshita No. 1 Dam card?
- At the Sendai City Waterworks Memorial Hall on the same grounds. Ask at the office counter. Note that the hall is shut from 1 December to 31 March.
Basic Information
| Name | Aoshita No. 1 Dam (青下第１ダム, Aoshita Dai-ichi Damu) |
|---|---|
| Location | 17-2 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 13.4 m high, 41.8 m long; subsidiary weir 2.4 m high, 25.7 m long; Aoshita Bridge 43.6 m long, 1.8 m wide |
| Owner | Sendai City Water Supply Business Manager |
| Public Access | Viewable from the walking paths of the Aoshita water source grounds, 9:30 a.m. to 4 p.m., free of charge. Interior closed |
References
- Agency for Cultural Affairs, National Cultural Properties Database: Aoshita No. 1 Dam
- https://kunishitei.bunka.go.jp/heritage/detail/101/00001086
- Sendai City Waterworks Bureau: Introducing the Aoshita Water Source Area
- https://www.suidou.city.sendai.jp/soshiki/somu-eigyo/koho/7/404.html
- 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