Hitokura Dam and Lake Chimyo are located in Kawanishi, Hyogo Prefecture, where a reservoir surrounded by wooded hills provides a peaceful escape from the nearby urban areas. Hitokura Dam was built across the Hitokura-Oroji River, part of the Yodo River system, and is managed by the Japan Water Agency. This multipurpose concrete gravity dam stands 75 meters high and plays an important role in flood control and the supply of drinking water.
The artificial lake created by the dam is known as Lake Chimyo. It is an important water resource for Kawanishi and neighboring communities, as well as a popular destination for outdoor recreation. Its combination of tranquil waters, forested scenery, and nearby parks makes it an appealing place for walking, fishing, camping, and enjoying the changing seasons.
Hitokura Dam was constructed to help control flooding along the Hitokura-Oroji River and downstream waterways, including the Inagawa and Kanzaki rivers. It also supplies drinking water to Kawanishi, Amagasaki, and other municipalities in the surrounding region.
Lake Chimyo has been selected for the 100 Best Dam Lakes of Japan, a recognition established by the Dam Water Source Area Environment Improvement Center. The lake serves both practical and recreational purposes, supporting local water supplies while providing a scenic setting for residents and visitors.
The Inagawa River flows through a densely populated part of the Kansai region, including Amagasaki, Toyonaka, Kawanishi, Ikeda, and Itami. The river basin has long required careful flood management because of its urban development and the concentration of industry in the Hanshin Industrial Zone.
In 1938, engineer Nagae Monobe proposed a comprehensive river management plan that helped encourage flood-control projects throughout Japan. The plan also highlighted the need for better management of the Inagawa River. However, as the Pacific War intensified, the project was suspended, and dam development remained on hold in the years immediately after the war.
A major flood caused by Typhoon No. 13 in 1953 renewed concern about flood risks throughout the Inagawa River basin. At the same time, residential development around Kawanishi accelerated, raising concerns that forest clearing would reduce the land’s ability to absorb rainfall. Growing industrial activity also increased demand for water.
In response to these challenges, the Water Resources Development Public Corporation, now the Japan Water Agency, advanced plans for Hitokura Dam in 1968. The project became part of the wider water-resource development program for the Yodo River system.
Because residential areas were already expanding along the main Inagawa River, constructing a large dam there would have been difficult. The project was therefore located farther upstream on the Hitokura-Oroji River, in the Hitokura area of Kawanishi.
The dam has a total reservoir capacity of approximately 33.3 million cubic meters. Its main functions are flood control for the Inagawa and Kanzaki river systems, maintaining water for general river use, and supplying drinking water to nearby municipalities.
Land acquisition and compensation negotiations proved challenging, partly because of rising property values in the surrounding residential areas. In 1974, Hitokura Dam was selected as the first dam designated under Japan’s Special Measures Act for Water Source Area Development. This designation provided a framework for support and compensation measures for communities affected by the project.
Construction proceeded, and the dam was completed in 1983. It continues to support flood management and water supply in the region. An odor problem later arose in the Hitokura-Oroji River due to algae growth. The use of controlled flushing releases, known as flash releases, helped address the problem.
Lake Chimyo was formed when Hitokura Dam was completed. Its name comes from nearby Mount Chimyo. The mountain’s name is believed to have evolved from the older name Mount Kimyo, and the surrounding area once had mines that produced silver and copper.
In 2005, Lake Chimyo was included in the 100 Best Dam Lakes of Japan. The reservoir is valued not only for its role in water management but also for the way it blends with the surrounding natural landscape.
The lake and its surroundings lie within Inagawa Valley Prefectural Natural Park. The area is also a popular destination for hiking along the Kinki Nature Trail. Nearby outdoor attractions include Hyogo Prefectural Hitokura Park, Kunisaki Seseragi Plaza, and Lake Chimyo Campground. National Route 173 runs along the western side of the lake, making the area relatively easy to reach by road.
Lake Chimyo is known as a fishing destination for largemouth bass and crucian carp, including herabuna, a popular variety of crucian carp in Japan. Its convenient location near residential developments makes it accessible to anglers from the surrounding urban areas.
Several spots along the shore have relatively easy footing, making them suitable for beginners. The lake is also known among fishing enthusiasts for the possibility of catching large bass. Where streams flow into the reservoir, visitors may also find opportunities for stream fishing, depending on local conditions and regulations.
The Kawanishi Hitokura Dam Circuit Marathon is held around the lakeshore each year on November 23. The event attracts more than 2,000 participants and brings runners and spectators to the area.
Autumn is another appealing time to visit, when the wooded hills around Lake Chimyo turn shades of red, orange, and gold. The lake’s calm surface and surrounding foliage create attractive scenery for a leisurely walk or a relaxing break in nature.
Visitors can explore the surrounding parks and riverside areas, enjoy the forested landscape, or spend time outdoors at designated recreational facilities. Lake Chimyo Campground and nearby green spaces offer opportunities to experience the natural environment beyond the lakeshore.
One notable destination in the wider area is Mount Myoken, affectionately known as Nose no Myoken-san. This mountain has a long association with religious devotion and is an important site for Nichiren Buddhism. Its natural surroundings and spiritual heritage complement a visit to Lake Chimyo.
The surrounding region combines wooded hills, historic religious sites, and modern residential communities, making it a place where visitors can explore both nature and local culture.
Residential developments such as Maruyamadai and Miyamadai have grown around the Hitokura Dam area. The Nose Electric Railway serves the wider region, connecting it with the Osaka metropolitan area and making the surrounding communities convenient for commuters traveling toward Osaka and Kobe.
This blend of accessible transport, residential neighborhoods, and nearby natural scenery gives the area a distinctive character. Lake Chimyo offers residents an easy escape into the outdoors without requiring a long journey from the city.
Hitokura Dam was the first dam completed in the Inagawa and Kanzaki river basins and helped establish the foundation for later river development projects in the region.
In the Inagawa basin, plans for Aigawa Dam in Osaka Prefecture began in 1976. Designed as a rockfill dam with a central earth-core cutoff wall, it was later built on a reduced scale following reviews of public works projects in the 1990s. Minoo River Dam, a 47-meter-high flood-control dam of a similar type, was also completed in the wider region.
By contrast, the Yono River Dam project, originally planned as a 74-meter-high concrete gravity dam, was discontinued in 2005. These projects reflect the changing approach to water management and public infrastructure in the Inagawa River basin, where Hitokura Dam remains an important part of the region’s flood-control and water-supply system.
Hitokura Dam and Lake Chimyo offer more than an impressive example of water infrastructure. The reservoir’s tranquil scenery, surrounding hiking routes, fishing opportunities, and nearby outdoor facilities make it a rewarding destination for nature lovers. Whether visiting for autumn foliage, a lakeside walk, a fishing trip, or a local sporting event, travelers can enjoy a peaceful side of Hyogo Prefecture within reach of the Osaka and Kobe metropolitan areas.