Lake Biwa: The Largest Lake In Japan

Lake Biwa is the largest freshwater lake in Japan, located northeast from the former capital city of Kyoto, in Shiga Prefecture.

Lake Biwa Stats

Lake NameLake Biwa
Surface area673.480
Maximum depth104.0
Average depth41.6
Lake typeNatural, dammed
Catchment area3672.10
Inflows118 rivers
OutflowsSeta River
Islands3 islands
Shore length234.68
Age2 - 20 million years
Mixing typeMonomictic
SettlementsHikone, Otsu, Nagahama, Takashima
Residence time2897.4
FrozenNever freezes
Trophic stateMesotrophic
Average discharge111.850
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Hydrology and Geography

Lake Biwa occupies a structural depression and is fed by more than 460 small streams coming from the surrounding mountains. Its main outlet is the Seta River, which later transforms into the Uji River, and after meeting Katsura and Kizu, it becomes the Yodo River which flows into the Seto Inland Sea at Osaka Bay. The lake’s surface rises 10 meters during spring, a result of melting snow and spring rains. In the autumn water levels are also higher thanks to typhoon rains.

Lake Biwa serves as an important reservoir for Kyoto and the city of Otsu, and is a valuable resource for the nearby textile industries. It also provides drinking water for more than 15 million people in the Kansai region.


In early Japanese times the lake served as the main avenue of movement between the Sea of Japan and the Inland Sea, which later contributed to the economic development of the Hanshin Industrial Region. The rice produced in the regions facing the Sea of Japan were carried by ship through the lake towards Kyoto and Osaka. In the Edo Period between 1603 and 1868 transportation of rice mostly switched to marine routes, but various merchandise from Northern Japan was still brought to Kyoto and Osaka through Lake Biwa. The Lake Biwa Canal was constructed in the 1890’s and expanded during the Taisho period (1912-1926). It had a significant role in reviving Kyoto’s industrial life.

A significant freshwater pearl cultivation began in the 1890’s and for a brief time the Biwa pearl was world-renown. Unfortunately today this industry has faced a decline.

Geology and Economy

The lake is of tectonic origin and is one of the World’s 20 oldest lakes, which has formed more than 4 million years ago. Because of its long, uninterrupted age it has an extremely diverse ecosystem, giving home to more than 1100 species of which 58 are endemic. Around 50 species and subspecies, such as the pearl mussel, can only be found at Lake Biwa and nowhere else in the World. The bottom of the lake has been and continues to subside due to diastrophism, making it impossible to fill up with the sediments that are brought in by the numerous inflows.

Lake Biwa is an important place for waterbirds, since more than 5000 of them visit it yearly. Out of the 46 native fish species 12 are considered endemic species and 5 are endemic subspecies. 5 types of cyprinids, 2 true loaches, 2 gobies, 2 silurid catfish and one cottid make up the list of endemic fish species.

A large number of mollusks can also be encountered at Lake Biwa, including 38 freshwater snails, of which 19 are endemic, and 16 bivalves of which 9 are endemic species. Local rich biodiversity has unfortunately suffered due to the invasion of foreign fish such as the black bass and the bluegill. The black bass was introduced as a sport fish, whilst the bluegill was presented to the Emperor and was later let into the lake for other fish to feed on it. These two species have been dominating the local fish community since the 1980s.

Conservation Efforts

Due to the introduction of invasive fish species, threats coming from recreational use, overfishing and eutrophication, a few conservation efforts have been made through environmental legislation.

A legislation aiming on preventing eutrophication was enacted in 1981 and enforced on the 1st of July 1982. It establishes standards for the nitrogen and phosphorous levels that can be let into the lake through agricultural, industrial and household water sources. Dumping of synthetic detergents containing phosphorous have been banned from Lake Biwa.

The reed colonies located along the coast of the lake have a characteristic importance in purifying the water and providing habitat for numerous fish and bird species. The Shiga Ordinance for Conservation of Reed Vegetation aims to protect, grow and utilize reed beds and has been doing so since 1992.

Since 1993 Lake Biwa is part of the Ramsar Wetlands, which protects wetlands around the World.

Origin of Its Name

There has been a lot of debate regarding the origins of the lake’s name. Many proclaim that the name “Biwa” was established in the Edo Period and it refers to a stringed musical instrument to which the lake’s shape resembles. The lake was previously known as the “Awaumi”, meaning freshwater sea, or “Chikatsu Awaumi”, meaning freshwater sea near the capital. This later changed into the modern Ömi, referring to the Ömi Province. The lake was also called „Nio No Umi” at once, meaning Little Grebe Lake.  

Tourism and Recreation

The numerous cities located along the lake’s coast offer varied sightseeing opportunities. Hikone is an old castle town located between Kyoto and Nagoya, while Nagahama, although small, has plenty of historic attractions. Otsu is the capital of the Shiga prefecture and Sakamoto forms serves as the gateway to hiking in Mount Hiei.

The area can easily be reached by train. One can get from one town to another through numerous boat cruises offering a variety of services. Some of the favorite outdoor activities practiced at Lake Biwa are fishing, boating, kayaking, sailing and waterskiing. Cycling is also a beloved activity, since on the lake’s shores one can find one of the greatest cycling routes in Japan, of 220 kilometers and stunning views over the lake and the surrounding mountains.

For a relaxing day spend your time at Ominamaiko beach, one of the best beaches on the lakeshore. Numerous hot springs and hiking paths can be found in the area, and the southwestern shores are also home to lush green parks.

Lake Biwa Museum is a must-see for every history enthusiast, showcasing the relationship between the lake and the people living around it, and the impact they had on Lake Biwa. The Museum houses one of the largest freshwater aquariums in Japan with plenty of endemic species on display.

Lake Biwa Map