Himekawa River is a major river that flows from northern Nagano Prefecture through Itoigawa City in Niigata Prefecture before reaching the Sea of Japan. Rising amid the mountains of the Hakuba area, the river is renowned for its exceptionally clear water, dramatic mountain scenery, and deep connections with the history, mythology, and geology of the region.
Himekawa was officially designated as a Class A river on April 1, 1969. Its abundant flow and rich natural environment have long been recognized as important features of the river basin. According to water-quality surveys published by Japan’s Ministry of Land, Infrastructure, Transport and Tourism, Himekawa has ranked first in Japan for river water quality four times since 1999, earning a reputation as one of the country’s exceptionally clean rivers.
The source of Himekawa is a clear spring that rises in Oyomi Wetland in Hakuba Village, Nagano Prefecture. Tributaries such as the Matsukawa and Hirakawa rivers descend from the Hakuba mountain range and have formed broad alluvial fans, helping create the Hakuba Basin.
Beyond the basin, much of the Himekawa watershed consists of rugged mountain terrain with elevations exceeding 2,000 meters. The steep landscape gives the river a distinctly alpine character as it travels north toward the Sea of Japan.
The name Himekawa is traditionally associated with an ancient Japanese myth. In the Kojiki and the Izumo Fudoki, the deity Okuninushi-no-Mikoto, also known as Yachihoko-no-Kami, is said to have traveled to the land of Koshi to propose marriage to Nunakawa-hime, the daughter of a powerful local family.
According to tradition, the river was named after Nunakawa-hime. Another legend tells that their son, Takeminakata-no-Kami, traveled upstream along Himekawa before entering the region of Suwa. These stories connect the river with some of Japan’s oldest surviving mythology.
Himekawa follows the Itoigawa-Shizuoka Tectonic Line, one of Japan’s major geological boundaries. Large quantities of sediment are supplied to the river from the surrounding mountains, including the Northern Alps and the Nishikubiki Mountains.
The widespread presence of serpentinite contributes to the area’s fragile geological conditions. As a result, landslides, debris flows, and flooding have occurred repeatedly throughout the history of the river.
Himekawa has therefore earned a reputation as a “wild river”. Its dramatic scenery is closely connected with the powerful geological forces that continue to shape the mountains and valleys around it.
A legend preserved at Ama-no-Tsu Shrine in Itoigawa tells another story connected with Himekawa. According to local tradition, the name Itoigawa originated from the expression “Itoigawa,” meaning a troublesome or disliked river, referring to its tendency to repeatedly overflow.
The legend also says that Nunakawa-hime herself had difficulty crossing the river. Such stories illustrate how closely the people living along Himekawa have historically understood and respected the power of the river.
The Himekawa basin has been famous since ancient times as a source of jade. Archaeological evidence suggests that jade from this region was used to create ornaments such as large beads and magatama comma-shaped jewels from the Jomon period through the Nara period.
This jade culture spread far beyond the immediate river basin, making the region an important part of the history of ancient Japanese craftsmanship and exchange.
Even today, jade can sometimes be observed among stones along the Himekawa riverbed and on beaches near its mouth. However, many ordinary stones resemble jade, so identifying a genuine specimen requires considerable experience.
Visitors interested in the region’s jade culture can explore it from both archaeological and geological perspectives. The Chojagahara Archaeological Museum in Itoigawa introduces the history of the area’s jade culture, while the Fossa Magna Museum presents the region’s geology and the formation of the Japanese archipelago.
The Fossa Magna Museum is also known for a service through which visitors can bring stones they have found and ask museum curators for help identifying them, making geology an engaging part of the sightseeing experience.
Oyomi Wetland lies at an elevation of approximately 745 meters. Unlike wetlands formed by incoming rivers, it is supplied by underground springs and has no river flowing into it.
The wetland is known as the only native habitat in Nagano Prefecture for Horomui-so. It is also home to a variety of plants, including Adonis flowers, skunk cabbage, rabbit-ear iris, and sawagikyo.
A wooden boardwalk allows visitors to explore the wetland on foot. The circular walking route takes approximately 20 minutes, making it an accessible way to experience the natural environment around the source of Himekawa. In 1980, Oyomi Wetland was designated as a Natural Monument by Hakuba Village.
The clear water emerging from Oyomi Wetland forms the Himekawa Source Spring, which has been selected as one of Japan’s 100 Remarkable Waters.
Fine gravel covers the riverbed, where aquatic plants such as Baikamo and Seikishoumo grow. In spring, visitors can also see flowers such as Adonis and dogtooth violets around the clear waters.
The environment remains rich enough to support Japanese char, which have been observed migrating upstream. The pristine surroundings provide a glimpse of the healthy natural ecosystem at the upper reaches of Himekawa.
Himekawa’s beauty comes with a reminder of the immense power of nature. In 1911, a massive landslide occurred on the northern slope of Mount Hiedayama. The collapse blocked the river and created a natural dam, forming what became known as Lake Nagase.
The resulting flooding caused devastating damage to settlements along the river. The Hiedayama Landslide is remembered as one of Japan’s Three Great Landslides, highlighting the extraordinary scale of the event.
On July 11, 1995, torrential rain caused a major disaster known as the 7.11 Flood Disaster. Himekawa Onsen and Kambara Onsen were among the areas affected, while the JR Oito Line and National Route 148 were closed for an extended period.
The following year, a debris flow occurred during restoration work, resulting in the deaths of 14 workers. These events demonstrate the continuing challenges of living and traveling in a steep mountain valley where heavy rain, landslides, and flooding can rapidly alter the landscape.
The steep terrain and abundant water of the Himekawa watershed have made the river an important source of hydroelectric power. Development of hydropower facilities began during the Taisho period, and numerous operators have since established power stations throughout the basin.
Companies and organizations including Chubu Electric Power, Hokuriku Electric Power, Denka, and Tokyo Electric Power have operated facilities in the watershed. More than a dozen power stations of various sizes can be found along the river and its tributaries.
Major facilities in the watershed include the Himekawa No. 2 and No. 3 Dams, Kitakotani Power Station, Oami Power Station, and Himekawa No. 6 and No. 7 Power Stations.
Power facilities are also located along tributaries such as the Otoko River and Hirakawa River. In addition, numerous erosion-control dams have been constructed throughout the watershed to help reduce the effects of flooding and sediment movement in this rugged mountain environment.
The Himekawa watershed extends across Hakuba Village and Otari Village in Nagano Prefecture and Itoigawa City in Niigata Prefecture.
Many tributaries flow into Himekawa, including the Matsukawa and Hirakawa rivers. The Kotakigawa River, another important tributary, is particularly notable for its jade-bearing geology.
The valley along Himekawa has long served as an important transportation corridor. Historically, the route was part of the Salt Road, or Chikuni Kaido, which connected inland areas with the Sea of Japan.
Today, National Route 148 and the JR Oito Line run alongside the river, continuing its role as an important link between Nagano Prefecture and the Joetsu region of Niigata Prefecture.
The route also passes near Himekawa Onsen, adding hot springs and mountain scenery to the attractions found along this historic corridor.
Himekawa River is a remarkable destination where pristine water, dramatic mountain landscapes, ancient mythology, jade culture, geology, and local history come together.
From the spring-fed wetlands at its source to its journey through the steep valleys of the Northern Alps and onward to the Sea of Japan, the river reveals a different side of the region at every stage.
Visitors can explore the clear waters and alpine plants around its source, follow the history of jade through archaeological and geological museums, or travel along the historic Salt Road through the Himekawa valley. At the same time, the river’s history of floods and landslides offers an important insight into the powerful natural forces that have shaped the landscape and the communities that live here.
For travelers exploring Hakuba, Otari, and Itoigawa, Himekawa is more than a beautiful river—it is a natural and cultural thread connecting the Northern Alps with the Sea of Japan.