Overview
Iō Dam is a dam built on the Morishita River, part of the Ono River system, in Kanazawa, Ishikawa Prefecture. Standing 58.8 meters tall, it is a rockfill dam managed by Ishikawa Prefecture. Its primary purpose is flood control for the Morishita River and the Ono River into which it flows. Set among lush wooded hills, its embankment and reservoir spread across a valley, offering a place to feel the scale of a dam within nature close to the city.
Highlights
- ●The structural beauty of a 58.8-meter rockfill dam
- ●Its role as a flood-control linchpin for the Morishita and Ono rivers
- ●A quiet, as-yet-unnamed reservoir spread through the valley
- ●The scale of a dam experienced in nature near the city
History
Construction advanced from 1977, and the dam was built as a subsidized flood-control dam with support from the national treasury. Beyond flood regulation, it was designed to maintain the normal river flow of the Morishita River, a form of non-specific water use. Built as a rockfill dam by piling up earth and rock, it presents a massive form that blends into the landscape, unlike a concrete dam. Curiously, the reservoir created by the dam has yet to be given an official name.
Access
The dam is located in Kanazawa, Ishikawa Prefecture, at roughly 36.56 degrees north and 136.78 degrees east, in the mountainous area upstream along the Morishita River from central Kanazawa. Public transport is limited, so access by car is the norm. Some sections of road are narrow, so it is best to check road conditions and whether visits are permitted through official sources before setting out.
Best season
The fresh green of early summer, when the surrounding mountains come into leaf, and the coloring foliage of autumn are especially beautiful, with the hillsides reflected on the reservoir’s surface a fine sight. After snowmelt or rain you may witness the force of a release, but in poor weather or high water, please prioritize safety over pushing ahead.
Map
36.5611, 136.7783 · Wikidata
Suggested itinerary
- 1Drive upstream along the Morishita River from central Kanazawa
- 2View the embankment of Iō Dam and observe the rockfill structure
- 3Enjoy the mountain scenery and still water at the reservoir’s edge
- 4Return to the city while taking in the surrounding satoyama nature
Did you know?
💡 At 58.8 meters, this rockfill dam is defined not by a concrete wall but by a slope of piled rock, and seeing it up close reveals the sheer heft of the technique. The fact that its reservoir still has no name is a small talking point unique to Iō Dam.
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