A Brick Arch Hidden in the Forest
Walk a few hundred metres north of Yunohora-Onsenguchi Station in Mino, Gifu, follow the Nagaragawa Railway tracks upstream, and the trees give way to something unexpected: a stout brick arch viaduct spanning a small ravine, water running silently along its top deck. This is the Shimosuharadani Aqueduct Bridge, one of nine Meiji-period structures registered as Tangible Cultural Properties under the umbrella designation of the Nagaragawa Power Plant complex.
Despite its workaday function — carrying part of the 4.9-kilometre headrace channel that feeds Japan's longest continually operating hydroelectric station — the bridge has the dignity of a small Roman aqueduct dropped into the Japanese mountains. Red brick laid in English bond, granite springers cut from the surrounding hills, and a low parapet that still channels Nagara River water toward the turbines completed in 1910.
The Power Plant That Lit Nagoya
To understand the bridge, one needs to understand the project it serves. The Nagaragawa Power Plant was first imagined in 1898 by Kobayashi Shigemasa, a former samurai of the Iwamura domain who had been inspired by the Keage Power Plant on the Lake Biwa Canal in Kyoto. His proposal stalled in the post-Sino-Japanese-War recession, and the plan was eventually taken over by Nagoya Electric Light Company, which spent fifteen years bringing it to completion.
Ground was broken in 1908. Generators arrived at Gifu Station by rail, were transferred to ox carts for a week-long haul to the opposite bank of the Nagara, then floated to the construction site on great rafts assembled on the river. On 15 March 1910, the plant began producing 4,200 kilowatts. The very next day, that electricity travelled 52 kilometres south to illuminate the Tenth Kansai Prefectural Joint Industrial Exhibition at Tsuruma Park in Nagoya — one of the first large-scale demonstrations of hydroelectric lighting in central Japan.
Because Mino's section of the Nagara has a gentle gradient, the engineers chose a run-of-river design. Rather than damming the river, they carved a near-level channel along the valley wall, so that by the time the water reached the power station it had built up enough head to drive the turbines. That long, near-level channel had to cross every side valley along its route. Each crossing required a bridge, and Shimosuharadani is one of them.
Why It Matters
The headrace water bridges of the Nagaragawa system were registered as Tangible Cultural Properties on 28 August 2001, alongside the plant's main hall (registered earlier in December 2000), main gate, perimeter wall, and intake structures. Together, these nine items document a specific moment in Japanese engineering history.
Around 1910, Japanese builders were still learning Western masonry from European instructors. The Nagaragawa plant relied heavily on German expertise — Siemens generators, Voith turbines, design consultation from Noguchi Jun, who had been on Siemens's Japan staff. Yet the masonry was executed by Japanese craftsmen, drawing on a tradition that had already produced railway tunnel portals, fortress walls, and the brickwork of Yokohama's bonded warehouses. The viaducts at Nagaragawa are where that hybrid tradition is most visible. The brick is laid in English bond, the favoured pattern for civil-engineering structures in late-Meiji Japan; the abutments rise from local granite; the arch profile is a flattened segmental curve, chosen for its low rise and high lateral stiffness.
The Shimosuharadani bridge has survived for more than a century without any change in its function. Water still flows across it every day. Its sister bridges — the Yunohoradani Aqueduct (62 metres, five segmental arches) and the Hidani Aqueduct (54 metres, five arches on a curve in plan) — are slightly better documented, but together the three form a continuous demonstration of how a single engineering vocabulary adapted to different valley widths and curves.
Visiting
The bridge itself sits on private property owned by Chubu Electric Power and is part of an active power-generation system. Direct access to the deck or the channel is not permitted, and the surrounding paths are mostly maintenance roads. Visitors generally view the structure from public lanes that thread along the headrace route, or from the riverside path between Yunohora-Onsenguchi and the next station upstream.
The best approach is to take the Nagaragawa Railway — itself a charming single-car local line winding through the Nagara gorge — to Yunohora-Onsenguchi. From there it is a short walk to the power-plant frontage along the river, where the main hall's red-brick façade is clearly visible from the public road. The Yunohoradani Aqueduct, with its photogenic five-arch profile, is the easiest of the three water bridges to see; reaching Shimosuharadani requires more legwork and some local map-reading, since it lies a little further toward the intake. Sturdy footwear is sensible: the lanes are narrow, sometimes overgrown, and snake-aware caution is wise in the summer months.
The plant occasionally opens its grounds for guided tours, organised by Chubu Electric Power and the city of Mino — most often during the Nagaragawa Onpaku cultural-tourism season. These tours allow visitors inside the main hall to see the German turbines and original archive photographs. Tour dates are announced only a few weeks in advance, so checking the Mino City tourism page before travel is worthwhile.
Around the Site
Mino is best known for washi, the handmade paper that has been produced here for more than 1,300 years and that is itself a UNESCO-listed intangible heritage element. The Udatsu-no-Agaru Townscape Preservation District, a thirty-minute drive south of the power plant, is a remarkably intact Edo-period merchant streetscape, its rooflines punctuated by the fire-break parapets (udatsu) that gave the area its name. Mino Washi Museum (Mino Washi no Sato Kaikan) offers paper-making workshops and a small but well-curated collection.
For travellers interested in industrial heritage, the Nagaragawa Power Plant pairs naturally with Yaotsu's hydroelectric stations on the nearby Kiso River system — a different river, but the same generation of early-twentieth-century engineering. The Nagaragawa Railway continues north into the Itadori and Gujō valleys, with Gujō Hachiman, the well-preserved castle town famous for its summer Odori dance festival, accessible in about an hour.
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Q&A
- Can I walk across the bridge?
- No. The bridge is operational infrastructure carrying water to the power plant, and it sits on Chubu Electric Power's property. Viewing is restricted to public roads and footpaths near the alignment.
- What does the name "Shimosuharadani" mean?
- It is a place name: Shimo (lower) + Suhara (the local district, written 須原) + dani (valley). The bridge takes its name from the small valley it crosses on the western, upstream side of the headrace route.
- Why is the brick pattern called "English bond"?
- English bond alternates a course of headers (short faces of brick) with a course of stretchers (long faces). It produces a strong, almost rope-like vertical interlock and was the standard pattern for railway bridges, fortifications, and aqueducts in late-Meiji Japan. The earlier Flemish bond, seen at the Tomioka Silk Mill, fell out of fashion by the 1890s because Japanese engineers considered English bond structurally more secure.
- Is the power plant still in operation?
- Yes. The Nagaragawa Power Plant has been running continuously since 1910 and is one of the oldest operating hydroelectric stations in Japan. Its current maximum output is 4,800 kilowatts, supplying electricity to the Mino and Gujō areas.
- Are photographs allowed?
- From public roads and footpaths, yes. Drone use over the plant grounds and headrace channels is not permitted, and visitors should respect any "No Entry" signage along the maintenance paths.
Basic Information
| Name | Nagaragawa Power Plant Shimosuharadani Aqueduct Bridge (長良川発電所下須原谷水路橋) |
|---|---|
| Designation | Registered Tangible Cultural Property (Structures) — registered 28 August 2001 |
| Period | Meiji, c. 1910 (contemporaneous with the rest of the Nagaragawa Power Plant complex) |
| Type | Civil-engineering structure (aqueduct bridge, headrace channel) |
| Location | Aza Kobora, Ōaza Suhara, Mino City, Gifu Prefecture |
| Owner | Chubu Electric Power Co., Inc. |
| Access | Approx. walking distance from Yunohora-Onsenguchi Station, Nagaragawa Railway |
| Public access | Exterior viewing only from public lanes; bridge deck and channel are not open to visitors |
| Part of | Nagaragawa Power Plant complex — nine Registered Tangible Cultural Properties (Main Hall, Main Gate, Perimeter Wall, Intake Structures, Yosuiro Crossing Bridge, Hidani Aqueduct, Yunohoradani Aqueduct, Shimosuharadani Aqueduct, and Substation-related structures) |
References
- National Database of Registered Tangible Cultural Properties — Nagaragawa Power Plant Shimosuharadani Aqueduct Bridge
- https://sitereports.nabunken.go.jp/ja/cultural-property/486963
- Mino City — Nagaragawa Power Plant Main Hall and Eight Other Structures
- https://www.city.mino.gifu.jp/docs/1174.html
- Cultural Heritage Online — Nagaragawa Power Plant Main Hall
- https://bunka.nii.ac.jp/heritages/detail/193039
- Cultural Heritage Online — Nagaragawa Power Plant Yunohoradani Aqueduct Bridge
- https://bunka.nii.ac.jp/heritages/detail/178466
- Cultural Heritage Online — Nagaragawa Power Plant Hidani Aqueduct Bridge
- https://bunka.nii.ac.jp/heritages/detail/148855
- Wikipedia (Japanese) — Nagaragawa Power Plant
- https://ja.wikipedia.org/wiki/長良川発電所
Last verified: 2026.05.15