Overview of Nagara Dam
Nagara Dam was constructed on a tributary of the Kuriyama River in Nagara Town. Together with the Boso Water Conveyance System and Togane Dam in Togane City, it functions as a regulating reservoir for water taken from the Tone River and distributed to different parts of Chiba Prefecture.
The water supplied through this system supports not only the Chosei District area but also communities along the eastern side of the Edo River, including Matsudo City, as well as areas along Tokyo Bay, including Chiba City. The dam therefore serves as an important part of the infrastructure supporting both daily life and industry across the region.
Size and Structure
Nagara Dam is managed by the Japan Water Agency and is an earth-fill dam standing approximately 52 meters high.
It is known as one of Japan’s largest earth-fill dams by height and is particularly notable as the tallest dam of this type in the Kanto region. Although its primary purpose is water management, the scale of the structure is also impressive to see when visiting the surrounding area.
The Dam Lake: Lake Shizuko
The reservoir created by Nagara Dam is called Lake Shizuko. The lake lies near the boundary between Nagara Town and the former Shizu district of Ichihara City.
Surrounded by greenery, Lake Shizuko is appreciated by local residents and visitors as a peaceful outdoor destination. The lakeside landscape changes with the seasons, providing opportunities for activities such as walking, fishing, and birdwatching.
Another Nagara Dam in Japan
There is another dam with the same name, Nagara Dam, in Ayagawa Town, Ayauta District, Kagawa Prefecture. It is a different facility from the Nagara Dam in Chiba Prefecture, so visitors should take care not to confuse the two when searching for travel information.
History of Nagara Dam
Nagara Dam was developed as part of the Boso Water Conveyance System, a major project designed to improve the water supply of the Boso Peninsula. Construction and development took place over several decades.
1970 – Water Resources Development Plan
In 1970, the Boso Water Conveyance System was incorporated into Japan’s basic water resources development plan. The project included plans for the construction of Nagara Dam to strengthen the water supply infrastructure of the Boso Peninsula.
1971 – Construction Begins Between Yokoshiba and Nagara Dam
Construction of the section between Yokoshiba and Nagara Dam began in 1971. This section was designed to convey water from the Tone River toward Nagara Dam, and construction of the dam and associated water conveyance facilities progressed thereafter.
1973 – Construction of the Dam Begins
Construction of the main Nagara Dam structure began in 1973. The project formed part of a major regional effort to establish a stable water supply for communities and industries throughout the Kanto region.
1980 – Completion of the Yokoshiba–Nagara Section
In 1980, the Yokoshiba–Nagara Dam section was completed and a provisional water supply began for the Chosei District area. This helped provide residents with a more stable source of water.
1986 – Industrial Water Supply Begins
In 1986, industrial water began to be supplied to the Chiba coastal industrial zone. Nagara Dam consequently became an increasingly important part of the infrastructure supporting the prefecture’s industrial activities.
1991 – Construction of the Southern Boso Water Conveyance System
In 1991, construction began on the section connecting Nagara Dam with Otaki as part of the Southern Boso Water Conveyance System. The project was intended to extend the reach of the regional water supply network.
1994 – Completion of Nagara Dam
Nagara Dam was officially completed in 1994. Following its completion, the dam became an established part of the water supply network serving a wide area of Chiba Prefecture.
1996 – Water Supply to Southern Boso Begins
In 1996, provisional water supply to the Southern Boso area began, further expanding the regional water distribution network across the Boso Peninsula.
1997 – Completion of the Southern Boso Water Conveyance System
In 1997, the Southern Boso Water Conveyance System connecting Nagara Dam and Otaki was completed. This established a broader water supply network serving many parts of Chiba Prefecture.
Things to See and Do Around Nagara Dam
The area around Nagara Dam combines lakeside scenery with the natural attractions of the Boso countryside. Visitors can enjoy a peaceful outdoor experience while exploring nearby attractions in Nagara Town.
Recreation Around Lake Shizuko
Lake Shizuko offers several ways to enjoy the surrounding natural environment. Fishing and birdwatching are popular activities, while walking along the lakeside provides an opportunity to appreciate the changing scenery throughout the year.
The peaceful landscape makes the lake a pleasant place for local residents and visitors to relax and spend time outdoors. In autumn, the surrounding foliage adds another attractive dimension to the scenery.
Nearby Attractions in Nagara Town
Nagara Town is home to a variety of attractions surrounded by forests and rolling hills. One nearby destination is Resol Seimei no Mori, a large resort complex offering sports facilities, hot spring and relaxation facilities, restaurants, and accommodation.
The resort is also home to Tarzania, a forest adventure facility where visitors can enjoy outdoor activities among the trees. It is an appealing option for travelers who want to combine a visit to Nagara Dam with recreation and adventure.
How to Get to Nagara Dam
By Public Transportation
When traveling by public transportation, one convenient option is to start from Honda Station on the JR East Sotobo Line. Buses serving Nagara Town operate from the station and can be used to reach Nagara Dam and nearby attractions.
Because services in the rural area may be less frequent than in urban centers, checking the latest bus timetable before traveling is recommended.
By Car
By car, Nagara Dam is approximately 20 minutes from the Katsura Interchange on the Chiba Sotobo Toll Road, or around 25 minutes from the Mobara-Kita Interchange on the Ken-O Expressway.
Free parking is available around the dam, making it a convenient stop for travelers exploring Nagara Town and the surrounding Boso countryside by car.
A Peaceful Lakeside Destination Supporting Chiba’s Water Supply
Nagara Dam is an important piece of infrastructure that supports the daily lives and industries of many communities throughout Chiba Prefecture. At the same time, its reservoir, Lake Shizuko, provides a peaceful natural landscape where visitors can enjoy fishing, birdwatching, walking, and seasonal scenery.
For travelers exploring central Chiba, a visit to Nagara Dam can be combined with nearby attractions such as Resol Seimei no Mori and Tarzania. The area offers an opportunity to discover both the practical importance of Japan’s water infrastructure and the quiet beauty of the Boso Peninsula’s rural landscape.