Lake Teganuma is a lake in northern Chiba Prefecture that stretches across Kashiwa, Abiko, Shiroi, and Inzai. It belongs to the Tone River water system and is designated as a regulated lake under Japan’s Special Measures Law Concerning Conservation of Lake and Marsh Water Quality.
Surrounded by parks, walking paths, wetlands, and urban areas, Lake Teganuma is an important place for recreation and relaxation. Its convenient location also makes it a popular destination for day trips from the Tokyo metropolitan area.
Lake Teganuma was once a much larger body of water with a shape resembling the Japanese character “つ”. Large-scale land reclamation projects reduced the original water area by approximately 80 percent, leaving the lake divided into northern and southern sections.
The northern section is known as Uwanuma, while the southern section is called Shimonuma. The two are connected by the Tegagawa River.
The urban area of Abiko City lies along the northern side of the lake, while the Tone River and Kokaigawa River flow nearby. To the southeast, the extensive Chiba New Town area has developed, giving the region good transportation connections.
The JR East Joban Line and Narita Line run close to the northern shore of Lake Teganuma, making the lake relatively easy to reach from central areas of Kashiwa and Abiko.
Its combination of accessible transportation and natural surroundings makes Lake Teganuma a convenient place to enjoy a relaxing day away from the center of Tokyo.
Lake Teganuma continues to serve as a source of agricultural water, while fishing and freshwater fisheries have traditionally played an important role in the local economy.
Carp and crucian carp were once caught in large quantities. In 2023, the total reported catch was approximately 3,000 kilograms, with crucian carp accounting for much of the catch.
The lake and its surroundings are also part of the Inba-Tega Prefectural Natural Park. The waterfront is an important recreational area where local residents and visitors can enjoy nature, walking, and outdoor activities.
Several parks around Lake Teganuma provide opportunities to enjoy the lakeside scenery. Kashiwa-Kitakashiwa Furusato Park and Teganuma Park are popular places for walking and relaxing in a natural setting.
At Teganuma Park, visitors can also enjoy swan-shaped pedal boats, making it a popular destination for families.
Teganuma Waterfront Plaza and Mizu-no-Yakata provide opportunities to learn about the lake, its water environment, and the surrounding natural ecosystem.
The Museum of Birds in Abiko is another attraction in the area. It offers visitors an opportunity to learn about birds and their relationship with wetlands and other natural environments.
Walking paths extend around the lake, providing pleasant routes for leisurely strolls and nature observation.
The surrounding biotopes are particularly interesting for visitors who enjoy observing plants, insects, and birds. With many species living around the water, Lake Teganuma is also a popular location for birdwatching.
Every August, the Teganuma Fireworks Festival brings large crowds to the lakeshore. Approximately 13,500 fireworks are launched over the water, creating a spectacular summer night scene reflected across the lake.
In October, the Teganuma Eco Marathon attracts more than 8,000 runners. The course around the lake allows participants to enjoy the natural scenery while taking part in a major local sporting event.
Every November, the Japan Bird Festival brings together birdwatchers, researchers, photographers, and other people interested in birds and nature.
It is one of the largest bird-related events in Japan and reflects Lake Teganuma’s importance as a habitat and observation area for waterbirds.
Lake Teganuma is part of the Shimousa Plateau, which was formed through geological changes beginning approximately 70,000 years ago. The area eventually developed as a lagoon-like remnant of the sea before becoming the lake seen today.
During the Edo period, major changes to the Tone River system altered the surrounding waterways. Land reclamation was attempted both to reduce flooding and to increase agricultural land, but repeated floods prevented the early projects from succeeding.
Despite the difficulties with land reclamation, Lake Teganuma developed as an important fishing and waterfowl-hunting area.
During the Edo period, fish such as carp and eel were especially valued and became well-known local specialties. The lake therefore played an important role not only in agriculture but also in the food culture and economy of the surrounding communities.
After World War II, a large-scale land reclamation project resumed in 1946. The project dramatically reduced the size of Lake Teganuma and contributed to the lake’s present-day configuration.
During Japan’s period of rapid economic growth, increasing amounts of household wastewater and industrial wastewater flowed into the lake.
As a result, Lake Teganuma became known as one of the most heavily polluted lakes in Japan. Between 1974 and 2001, it was recorded as having the worst water quality among Japan’s lakes for many consecutive years.
Water quality has since improved through measures including the North Chiba Water Conveyance System and other environmental initiatives. However, the lake has not yet fully reached the applicable environmental standards.
Lake Teganuma supports a diverse ecosystem, although its biodiversity has been significantly affected by water pollution, land reclamation, and shoreline construction.
Even so, many species continue to live in and around the lake, including fish, aquatic plants, waterbirds, and amphibians.
Lake Teganuma is home to birds such as the common coot and mute swan, making it a well-known destination for birdwatching.
Visitors may also encounter carp, crucian carp, giant freshwater prawns, and amphibians such as the American bullfrog.
The lake is also known for its lotus plants. In 1965, lotus colonies covered only about 1.5 hectares, but by 2017 they had expanded to approximately 23.6 hectares. In some areas, management and removal efforts have been carried out to control their expansion.
Lake Teganuma has lost much of the clear-water environment it once had as a result of historical land reclamation and urbanization. Nevertheless, various programs continue to improve and protect the lake’s environment.
These measures include the removal of water hyacinth and algal blooms, protection and management of aquatic plants, and water-quality improvement through the North Chiba Water Conveyance System.
However, further work is still needed. Important challenges include continued water-quality improvement and the management of invasive species.
Lake Teganuma is more than a scenic body of water. Its history reflects the changing relationship between people, rivers, agriculture, fishing, and the natural environment of northern Chiba.
Today, visitors can enjoy the lake in many ways, from walking and birdwatching to visiting museums, parks, and seasonal events. The area also provides an opportunity to learn about the challenges involved in protecting an urban lake ecosystem.
For travelers looking for a relaxing nature experience within easy reach of the Tokyo metropolitan area, Lake Teganuma offers a combination of waterfront scenery, wildlife, local history, and outdoor recreation.