Oirase Steam
Interesting facts
- Omachi Keigetsu's 1908 travel essay so impressed Crown Prince Yoshihito, the future Emperor Taishō, that he asked Aomori's governor whether he could visit Lake Towada.
- For about a decade, officials who wanted the lake's water for hydropower and irrigation fought conservationists, and the 1936 national park emerged as a compromise between them.
- Much of the water leaving Lake Towada bypasses the stream entirely, running through a tunnel in the mountains to a power station downstream that has operated since 1943.
- Because the lake has no large river feeding it, water from the stream's side tributaries is periodically sent back through the tunnel to top up the lake level.
- A forest road along the stream was completed as early as 1903, at the urging of the local village head Ogasawara Koichi.
- The stream's protection was raised to the top category of Special Place of Scenic Beauty in 1952.
- The nature trail along the whole stream took fourteen years to build, from 1961 to 1975.
- With little sunlight on the valley floor, many trees grow thick trunks and wrap their roots around boulders to anchor themselves in the unstable soil.
- Takamura Kōtarō's bronze Maidens statue, unveiled on the lakeshore in 1953, honours on its pedestal the three men who campaigned for the national park.
- More than two dozen individual waterfalls, rapids and rocks along the stream carry their own names, such as the Shiraito Falls and Tengu Rock.
Why it is worth it
For about 14 kilometres, the Oirase River runs out of Lake Towada through a narrow, forested valley so green and damp that moss covers almost everything – fallen trunks, boulders, stone walls and even the railings of footbridges. Waterfalls drop from the valley sides one after another, and the river breaks into rapids, pools and braided channels around wooded islets. The stream lies in Towada-Hachimantai National Park in Aomori Prefecture, in the north of Honshu, and is protected nationally as both a Special Place of Scenic Beauty and a Natural Monument.
The valley is a product of volcanism. Lake Towada fills a double caldera formed by eruptions of the Towada volcano, which built up thick deposits of pumice and ash that hardened into welded tuff. When the caldera rim gave way at Nenokuchi, where the lake now drains, the resulting flood cut a deep U-shaped valley through this plateau, leaving sheer rock walls and the falls seen today. The upper section near the lake is sometimes called the "waterfall road" for the density of its cascades: Choshi Otaki, about 7 m high and 20 m wide, is said to stop fish from swimming up into the lake, and Kudan-no-taki falls about 15 m in nine steps. Downstream come named stretches such as the Ashura current and Kumoi falls, with beech and horse-chestnut forest spreading over the wider lower valley.
Because the valley floor gets limited sunlight, its trees – mostly katsura, Japanese horse-chestnut and wingnut, with beech and oak on drier ground – grow tall and straight. The variety of mosses is such that in 2013 the Bryological Society of Japan listed the Oirase valley among the country's notable moss forests. The area became known nationally after the travel writer Omachi Keigetsu described it in 1908, and his campaign with local officials helped bring about national protection in 1928 and the national park in 1936. A walking path runs the length of the stream alongside the road, and the valley draws large crowds in the fresh green of spring and the autumn colours.
Getting there
National Route 102 follows the stream between Yakeyama and Nenokuchi on the shore of Lake Towada. The nearest city is Towada, about 23 km away in a straight line. The nearest airport is Aomori Airport (AOJ), about 33 km away.
On these lists
40.52528, 140.97450per Wikidata