is the largest

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

lake A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...

in Japan. It is located entirely within

Shiga Prefecture is a landlocked prefecture of Japan in the Kansai region of Honshu. Shiga Prefecture has a population of 1,398,972 as of 1 February 2025 and has a geographic area of . Shiga Prefecture borders Fukui Prefecture to the north, Gifu Prefecture to th ...

(west-central

Honshu , historically known as , is the largest of the four main islands of Japan. It lies between the Pacific Ocean (east) and the Sea of Japan (west). It is the list of islands by area, seventh-largest island in the world, and the list of islands by ...

), northeast of the former capital city of

Kyoto Kyoto ( or ; Japanese language, Japanese: , ''Kyōto'' ), officially , is the capital city of Kyoto Prefecture in the Kansai region of Japan's largest and most populous island of Honshu. , the city had a population of 1.46 million, making it t ...

. Lake Biwa is an

ancient lake An ancient lake is a lake that has consistently carried water for more than one million years. Twelve of the 20 ancient lakes have existed for more than 2.6 million years, the full Quaternary period. Ancient lakes continue to persist due to plat ...

, over 4 million years old. It is estimated to be the 13th oldest lake in the world. Because of its proximity to the country's historical capital

, references to Lake Biwa appear frequently in Japanese literature, particularly in poetry and in historical accounts of battles.

Name

The name ''Biwako'' was established in the

Edo period The , also known as the , is the period between 1600 or 1603 and 1868 in the history of Japan, when the country was under the rule of the Tokugawa shogunate and some 300 regional ''daimyo'', or feudal lords. Emerging from the chaos of the Sengok ...

. There are various theories about the origin of the name ''Biwako'', but it is generally believed to be so named because of the resemblance of its shape to that of a stringed instrument called the ''

biwa The is a Japanese short-necked wooden lute traditionally used in narrative storytelling. The is a plucked string instrument that first gained popularity in China before spreading throughout East Asia, eventually reaching Japan sometime durin ...

''. Kōsō, a learned monk of

Enryaku-ji is a Tendai monastery located on Mount Hiei in Ōtsu, overlooking Kyoto. It was first founded in 788 during the early Heian period (794–1185) by Saichō (767–822), also known as Dengyō Daishi, who introduced the Tendai sect of Mahayana ...

in the 14th century, gave a clue to the origin of the name ''Biwako'' in his writing: "The lake is the

Pure land Pure Land is a Mahayana, Mahayana Buddhist concept referring to a transcendent realm emanated by a buddhahood, buddha or bodhisattva which has been purified by their activity and Other power, sustaining power. Pure lands are said to be places ...

of the goddess

Benzaiten is an East Asian Buddhism, East Asian Buddhist Dharmapala, goddess who originated from the Hindu Saraswati, the patroness of speech, the arts, and learning. Worship of Benzaiten arrived in Japan during the sixth through eighth centuries, mai ...

because she lives on Chikubu Island and the shape of the lake is similar to that of the ''biwa'', her favorite instrument." The lake was formerly known as the or the . Later the pronunciation ''Awaumi'' changed to the modern ''Ōmi'' as in the name of

Ōmi Province was a Provinces of Japan, province of Japan, which today comprises Shiga Prefecture. It was one of the provinces that made up the Tōsandō Circuit (subnational entity), circuit. Its nickname is . Under the ''Engishiki'' classification system, ...

. The lake is also called in literature.

Area and use

The area of this lake is about . Small rivers drain from the surrounding mountains into Lake Biwa, and its main outlet is the

Seta River The , also called the Seta River (瀬田川 ''Seta-gawa'') and the Uji River (宇治川 ''Uji-gawa'') at portions of its route, is the principal river in Osaka Prefecture on Honshu, Japan. The source of the river is Lake Biwa in Shiga Prefectur ...

, which later becomes the Uji River, combining with the Katsura and Kizu to become the Yodo River and flows into the

Seto Inland Sea The , sometimes shortened to the Inland Sea, is the body of water separating Honshu, Shikoku, and Kyushu, three of the four main islands of Japan. It serves as a waterway connecting the Pacific Ocean to the Sea of Japan. It connects to Osaka Ba ...

Osaka Bay Osaka Bay (大阪湾 ''Ōsaka-wan'' ) is a bay in western Japan. As an eastern part of the Seto Inland Sea, it is separated from the Pacific Ocean by the Kii Channel and from the neighbor western part of the Inland Sea by the Akashi Strait. I ...

. It serves as a reservoir for the cities of

and

Ōtsu 270px, Ōtsu City Hall is the capital city of Shiga Prefecture, Japan. , the city had an estimated population of 343,991 in 153,458 households and a population density of 740 persons per km2. The total area of the city is . History Ōtsu is ...

and is a valuable resource for nearby textile industries. It provides drinking water for about 15 million people in the

Kansai region The or the lies in the southern-central region of Japan's main island Honshū. The region includes the prefectures of Nara, Wakayama, Kyoto, Osaka, Hyōgo and Shiga, often also Mie, sometimes Fukui, Tokushima and Tottori. The metropol ...

. Lake Biwa is a breeding ground for freshwater fish, including

trout Trout (: trout) is a generic common name for numerous species of carnivorous freshwater ray-finned fishes belonging to the genera '' Oncorhynchus'', ''Salmo'' and ''Salvelinus'', all of which are members of the subfamily Salmoninae in the ...

, and for the pearl culture industry. The Lake Biwa Canal, built in the late 1890s and later expanded during the Taishō period, played a role of great importance in the rekindling of Kyoto's industrial life, after a steep decline following the transfer of the capital to Tokyo. Lake Biwa is home to many popular beaches along the north-western shore, in particular Shiga Beach and Omi-Maiko. The Mizunomori Water Botanical Garden and the Lake Biwa Museum in Kusatsu are also of interest. The

Lake Biwa Marathon The was a marathon race held in Otsu, Shiga, Japan. It was one of the prominent marathons in Japan. It was a male only competition and had IAAF Gold Label status.Nakamura, Ken (2010-03-07)Tsegay takes Lake Biwa crown IAAF. Retrieved on 2010-03-08 ...

took place annually in Ōtsu, the city at the southern end of the lake, from 1962 until 2021.

Natural history

Lake Biwa is of

tectonic Tectonics ( via Latin ) are the processes that result in the structure and properties of the Earth's crust and its evolution through time. The field of ''planetary tectonics'' extends the concept to other planets and moons. These processes ...

origin and is one of the world's oldest lakes, dating to at least 4 million years ago.Tabata, R.; Kakioka, R.; Tominaga, K.; Komiya, T.; Watanabe, K. (2016).
Phylogeny and historical demography of endemic fishes in Lake Biwa: the ancient lake as a promoter of evolution and diversification of freshwater fishes in western Japan.
' Ecology and Evolution 6(8): 2601–2623. This long uninterrupted age has allowed for a notably diverse

ecosystem An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...

to evolve in the lake. Naturalists have documented more than 1000 species and

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

in the lake, including about 60 endemics. Lake Biwa is an important place for water birds. About 5,000 water birds visit Lake Biwa every year. There are 46 native fish species and subspecies in the lake,Kawanabe, H.; Nishino, M.; and Maehata, M., editors (2012). ''Lake Biwa: Interactions between Nature and People.'' pp 119-120. including 11 species and 5 subspecies that are endemic or near-endemic. The endemic species are five

cyprinids Cyprinidae is a family of freshwater fish commonly called the carp or minnow family, including the carps, the true minnows, and their relatives the barbs and barbels, among others. Cyprinidae is the largest and most diverse fish family, and t ...

('' Carassius cuvieri'', '' Gnathopogon caerulescens'', '' Ischikauia steenackeri'', '' Opsariichthys uncirostris'' and '' Sarcocheilichthys biwaensis''), a true loach ('' Cobitis magnostriata''), two

gobies Gobiidae or gobies is a family of bony fish in the order Gobiiformes, one of the largest fish families comprising over 2,000 species in more than 200 genera. Most of gobiid fish are relatively small, typically less than in length, and the fam ...

('' Gymnogobius isaza'' and '' Rhinogobius biwaensis''), two silurid catfish ('' Silurus biwaensis'' and '' S. lithophilus'') and a cottid ('' Cottus reinii''). The Biwa trout is also endemic to the lake, but some maintain that it is a subspecies of the widespread masu salmon rather than a separate species. The remaining endemic fish are subspecies of '' Carassius auratus'', '' Cobitis minamorii'', '' Sarcocheilichthys variegatus'' and '' Squalidus (chankaensis) biwae''. Lake Biwa is also the home of a large number of

molluscs Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

, including 38

freshwater snail Freshwater snails are gastropod mollusks that live in fresh water. There are many different families. They are found throughout the world in various habitats, ranging from ephemeral pools to the largest lakes, and from small seeps and springs t ...

s (19 endemic) and 16

bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

s (9 endemic). Recently the

biodiversity Biodiversity is the variability of life, life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem diversity and Phylogenetics, phylogenetic diversity. Diversity is not distribut ...

of the lake has suffered greatly due to the invasion of foreign fish, the black bass and the

bluegill The bluegill (''Lepomis macrochirus''), sometimes referred to as "bream", "brim", "sunny", or, in Texas, "copper nose", is a species of North American freshwater fish, native to and commonly found in streams, rivers, lakes, ponds and wetlands ea ...

. Bluegill were presented to the

Emperor The word ''emperor'' (from , via ) can mean the male ruler of an empire. ''Empress'', the female equivalent, may indicate an emperor's wife (empress consort), mother/grandmother (empress dowager/grand empress dowager), or a woman who rules ...

and later freed in the lake as a food source for other fish. Black bass were introduced as a sport fish. In July 2009, a

largemouth bass The largemouth bass (''Micropterus nigricans'') is a carnivorous, freshwater fish, freshwater, ray-finned fish in the Centrarchidae (sunfish) family, native to the eastern United States, eastern and central United States, southeastern Canada an ...

weighing 10.12 kg (22 lb 4 oz) was

caught Caught is a method of dismissing a batsman in cricket. A batsman is out caught if the batsman hits the ball, from a legitimate delivery, with the bat, and the ball is caught by the bowler or a fielder before it hits the ground. If the catch ...

from the lake by Manabu Kurita. It has been officially certified by the International Game Fish Association (IGFA) to tie the largemouth bass

world record A world record is usually the best global and most important performance that is ever recorded and officially verified in a specific skill, sport, or other kind of activity. The book ''Guinness World Records'' and other world records organizatio ...

held solely by George Perry for 77 years.

Archaeology

The Awazu site, a submerged

Shell midden A midden is an old landfill, dump for domestic waste. It may consist of animal bone, bones, feces, human excrement, botanical material, mollusc shells, potsherds, Lithic flake, lithics (especially debitage), and other Artifact (archaeology), ...

, is an important

archaeological site An archaeological site is a place (or group of physical sites) in which evidence of past activity is preserved (either prehistoric or recorded history, historic or contemporary), and which has been, or may be, investigated using the discipline ...

of the

Jōmon period In Japanese history, the is the time between , during which Japan was inhabited by the Jōmon people, a diverse hunter-gatherer and early agriculturalist population united by a common culture, which reached a considerable degree of sedentism an ...

. It goes back to the beginning of the Initial Jōmon period (ca. 9300 BP). It lies near the southern end of Lake Biwa, close to Otsu City, at a depth of 2 to 3 meters from the bottom.Francesco Menotti, Aidan O'Sullivan
The Oxford Handbook of Wetland Archaeology.
OUP Oxford, 2013. p.181 The site shows the use of plant and animal food resources by the

Jōmon people The Jōmon (縄文) were a prehistoric hunter-gatherer culture that inhabited the Japanese archipelago approximately between 14,000 BC and 300 BC. Both genetically and culturally, the Jōmon are among the earliest known ancestors of the modern ...

. It also demonstrates the importance of nut consumption in this period. Shell Midden No. 3 is dated to the Middle Jōmon period. An abundance of horse chestnuts were uncovered here (about 40% of their total estimated diet). This indicates that, by this later period, a sophisticated processing technology was mastered in order to remove the harmful

tannic acid Tannic acid is a specific form of tannin, a type of polyphenol. Its weak acidity (Acid dissociation constant, pKa around 6) is due to the numerous phenol groups in the structure. The chemical formula for commercial tannic acid is often given as ...

, and make this food safe for consumption. Ishiyama is another such site of the Early Jōmon period on Lake Biwa.

Environmental legislation

Various environmental laws cover Lake Biwa:

Eutrophication prevention

At the prefectural level, Eutrophication Control Ordinance was enacted in 1979. It was intended to control the use of synthetic detergents by companies and residents alike and followed a successful citizens' campaign known as the Soap Movement, which had emerged from women's consumer groups earlier in the 1970s. Legislation to prevent

eutrophication Eutrophication is a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of organisms that may deplete the oxygen in the water; ie. the process of too many plants growing on the s ...

was enacted in 1981 and first enforced on July 1, 1982; therefore, this day is called "". The legislation established standards for the

nitrogen Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...

and

phosphorus Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...

levels for agricultural, industrial, and household water sources emptying into the lake. They also banned people from using and selling synthetic

detergent A detergent is a surfactant or a mixture of surfactants with Cleanliness, cleansing properties when in Concentration, dilute Solution (chemistry), solutions. There are a large variety of detergents. A common family is the alkylbenzene sulfonate ...

s which contain phosphorus.

Wetlands protection

The lake was designated as a

UNESCO The United Nations Educational, Scientific and Cultural Organization (UNESCO ) is a List of specialized agencies of the United Nations, specialized agency of the United Nations (UN) with the aim of promoting world peace and International secur ...

Ramsar Wetland (1993) in accordance with the

Ramsar Convention The Ramsar Convention on Wetlands of International Importance Especially as Waterfowl Habitat is an international treaty for the conservation and sustainable use of Ramsar site, Ramsar sites (wetlands). It is also known as the Convention on We ...

. The object of this treaty is to protect and sensibly use internationally valuable

wetlands A wetland is a distinct semi-aquatic ecosystem whose groundcovers are flooded or saturated in water, either permanently, for years or decades, or only seasonally. Flooding results in oxygen-poor ( anoxic) processes taking place, especially ...

. The in Japan is under this treaty now.

Conservation of Reed Vegetation Zones

Reed colonies on the shore give Lake Biwa its characteristic scenery. The reeds play an important role in purifying water as well as providing habitat for birds and fish. At one time there were large areas of reeds along the shores of Lake Biwa, which local government surveys recently found to have halved in size due to encroaching development. This Shiga Ordinance for the Conservation of Reed Vegetation Zones to protect, grow, and utilize the reed beds has been in force since 1992.

Gallery

File:Biwako Quasi-National Park Omihachiman06n3200.jpg, Lake Biwa at Chomeiji-cho, Ōmihachiman File:三井寺疎水 - panoramio.jpg, Lake Biwa Canal File:Mangetsuji Otsu Shiga02n4500.jpg, Mangetsu-ji temple, one of the Eight Views of Omi File:Michigan - Lake Biwa, Japan - DSC07330.JPG, A pleasure boat from

Port File:Chikubujima.jpg, Chikubu Island File:Biwa Lake.jpg, Sunrise over Lake Biwa File:Port_of_imazu01s3200.jpg, Imazu Port, Takashima File:Nagahama_port01s3872.jpg, Nagahama Port File:Two Views of Lake Biwa 2022 Jan 2.webm, A snowy Lake Biwa seen from an airplane window and a not snowy Lake Biwa seen from a ferry, 2022 File:Kusatsu Reisho Tokaido.jpg,

Hiroshige or , born Andō Tokutarō (; 1797 – 12 October 1858), was a Japanese ''ukiyo-e'' artist, considered the last great master of that tradition. Hiroshige is best known for his horizontal-format landscape series '' The Fifty-three Stations ...

File:Biwako-from-Kitahira-Toge-Pass-2014-Luka-Peternel.jpg, Lake Biwa from Kitahira-Tōge Pass

Explanatory notes

References

External links

Department of Lake Biwa and Environment, Shiga Prefecture

Lake Biwa Environmental Research Institute

Lake Biwa Museum

Ramsar site database

go.biwako - Travel Guide of Shiga Prefecture, Japan

Lake Biwa (World Wildlife Fund)

Review of Criodrilidae (Annelida: Oligochaeta) including Biwadrilus from Japan

Japan's Secret Garden NOVA / PBSFishing World Records
{{Authority control Ancient lakes

Biwa The is a Japanese short-necked wooden lute traditionally used in narrative storytelling. The is a plucked string instrument that first gained popularity in China before spreading throughout East Asia, eventually reaching Japan sometime durin ...

Jōmon period Ōmihachiman, Shiga