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. Although the term specifically excludes seawater and brackish water, it does incl ...

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...

in Japan, located entirely within

Shiga Prefecture is a prefecture of Japan located in the Kansai region of Honshu. Shiga Prefecture has a population of 1,412,916 (1 October 2015) and has a geographic area of . Shiga Prefecture borders Fukui Prefecture to the north, Gifu Prefecture to the north ...

(west-central

Honshu , historically called , is the largest and most populous island of Japan. It is located south of Hokkaidō across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyūshū across the Kanmon Straits. The island s ...

), northeast of the former capital city of

Kyoto Kyoto (; Japanese: , ''Kyōto'' ), officially , is the capital city of Kyoto Prefecture in Japan. Located in the Kansai region on the island of Honshu, Kyoto forms a part of the Keihanshin metropolitan area along with Osaka and Kobe. , the c ...

. Lake Biwa is an

ancient lake An ancient lake is a lake that has consistently carried water for more than one million years. Many have existed for more than 2.6 million years, the full Quaternary period. Ancient lakes continue to persist due to plate tectonics in an active ...

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

, 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 or is the period between 1603 and 1867 in the history of Japan, when Japan was under the rule of the Tokugawa shogunate and the country's 300 regional '' daimyo''. Emerging from the chaos of the Sengoku period, the Edo period was character ...

. 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 duri ...

''. 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 Mahayan ...

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

Pure land A pure land is the celestial realm of a buddha or bodhisattva in Mahayana Buddhism. The term "pure land" is particular to East Asian Buddhism () and related traditions; in Sanskrit the equivalent concept is called a buddha-field (Sanskrit ). The ...

of the goddess

Benzaiten Benzaiten (''shinjitai'': 弁才天 or 弁財天; ''kyūjitai'': 辯才天, 辨才天, or 辨財天, lit. "goddess of eloquence"), also simply known as Benten (''shinjitai'': 弁天; ''kyūjitai'': 辯天 / 辨天), is a Japanese Buddhist god ...

because she lives on

Chikubu Island is a small island in the northern part of Lake Biwa in Shiga Prefecture, in the Kansai region of Japan. It has been known since ancient times for the beauty of its scenery and for its small Shinto shrine and Buddhist temples. Administrativel ...

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 province of Japan, which today comprises Shiga Prefecture. It was one of the provinces that made up the Tōsandō circuit. Its nickname is . Under the '' Engishiki'' classification system, Ōmi was ranked as one of the 13 "great countr ...

. The lake is also called in literature.

Area and use

The area of this lake is about 670 km² (258.69 sq mi). 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 Prefec ...

, 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 Honshū, Shikoku, and Kyūshū, 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 ...

at Osaka Bay. 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 153458 households and a population density of 740 persons per km². The total area of the city is . Geography Ōtsu ...

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 metropoli ...

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

trout Trout are species of freshwater fish belonging to the genera '' Oncorhynchus'', '' Salmo'' and '' Salvelinus'', all of the subfamily Salmoninae of the family Salmonidae. The word ''trout'' is also used as part of the name of some non-salm ...

, and for the pearl culture industry. The

Lake Biwa Canal is a historic waterway in Japan connecting Lake Biwa to the nearby City of Kyoto. Constructed during the Meiji Period the canal was originally designed for the transportation of lake water for drinking, irrigation and industrial purposes, but a ...

, 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, for example,

Shiga is a prefecture of Japan located in the Kansai region of Honshu. Shiga Prefecture has a population of 1,412,916 (1 October 2015) and has a geographic area of . Shiga Prefecture borders Fukui Prefecture to the north, Gifu Prefecture to the northe ...

Beach and Omi-Maiko. The Mizunomori Water Botanical Garden and The Lake Biwa Museum in Kusatsu are also of interest. The Lake Biwa Marathon takes place in Ōtsu, the city at the southern end of the lake, annually since 1962.

Natural history

Lake Biwa is of

tectonic Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents ...

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) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...

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

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics ( morphology), but that can successfully interbreed. Not all specie ...

in the lake, including about 60

endemics Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

. 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 ('' Carassius cuvieri'', '' Gnathopogon caerulescens'', '' Ischikauia steenackeri'', '' Opsariichthys uncirostris'' and '' Sarcocheilichthys biwaensis''), a

true loach Cobitidae, also known as the True loaches, is a family of Old World freshwater fish. They occur throughout Eurasia and in Morocco, and inhabit riverine ecosystems. Today, most "loaches" are placed in other families (see below). The family in ...

('' Cobitis magnostriata''), two gobies ('' 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 The goldfish (''Carassius auratus'') is a freshwater fish in the family Cyprinidae of order Cypriniformes. It is commonly kept as a pet in indoor aquariums, and is one of the most popular aquarium fish. Goldfish released into the wild have beco ...

'', '' Cobitis minamorii'', '' Sarcocheilichthys variegatus'' and '' Squalidus (chankaensis) biwae''. Lake Biwa is also the home of a large number of molluscs, including 38

freshwater snail Freshwater snails are gastropod mollusks which 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 ...

s (19 endemic) and 16

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of marine and freshwater Mollusca, molluscs that have laterally compressed bodies enclosed by a shell consisting of two hing ...

s (9 endemic). Recently the

biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic ('' genetic variability''), species ('' species diversity''), and ecosystem ('' ecosystem diversity'') ...

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 "copper nose" as is common in Texas, is a species of North American freshwater fish, native to and commonly found in streams, rivers, lakes, ponds an ...

. Bluegill were presented to the

Emperor An emperor (from la, imperator, via fro, empereor) is a monarch, and usually the sovereign ruler of an empire or another type of imperial realm. Empress, the female equivalent, may indicate an emperor's wife ( empress consort), mother ( ...

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 salmoides'') is a carnivorous freshwater gamefish in the Centrarchidae ( sunfish) family, a species of black bass native to the eastern and central United States, southeastern Canada and northern Mexico, ...

weighing 10.12 kg (22 pounds, 4 ounces) 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 ball h ...

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 organization ...

held solely by George Perry for 77 years.

Archaeology

The Awazu site, a submerged Shell midden, 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 historic or contemporary), and which has been, or may be, investigated using the discipline of archaeology an ...

of the

Jōmon period The is the time in Japanese history, traditionally dated between 6,000–300 BCE, during which Japan was inhabited by a diverse hunter-gatherer and early agriculturalist population united through a common Jōmon culture, which reached a c ...

. 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 is the generic name of several peoples who lived in the Japanese archipelago during the Jōmon period (). The Jōmon people may have consisted of multiple groups, which arrived and merged at different times in the Japanese archipelago, using mul ...

. 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 ( pKa around 6) is due to the numerous phenol groups in the structure. The chemical formula for commercial tannic acid is often given as C76H52O46, which corresp ...

, 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.Kira, T., Ide, S., Fukada, F., Nakamura, M. (2005
Lake Biwa: Experience and Lessons Learned Brief.
International Lake Environment Committee Foundation, Shiga, Japan. Legislation to prevent

eutrophication Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as "nutrient-induced increase in phyt ...

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 the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

and

phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ea ...

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 cleansing properties when in dilute solutions. There are a large variety of detergents, a common family being the alkylbenzene sulfonates, which are soap-like compounds that are m ...

s which contain phosphorus.

Wetlands protection

The lake was designated as a

UNESCO The United Nations Educational, Scientific and Cultural Organization is a List of specialized agencies of the United Nations, specialized agency of the United Nations (UN) aimed at promoting world peace and security through international coope ...

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 sites (wetlands). It is also known as the Convention on Wetlands. It ...

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

wetlands A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The p ...

. The Kushiro marsh ( 釧路湿原, Kushiro Shitsugen) in Japan is under this treaty now.

Conservation of Reed Vegetation Zones

Reed colonies on the shore form 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,

File:Biwa Lake.jpg, Sunrise over Lake Biwa File:Port_of_imazu01s3200.jpg, Imazu Port, Takashima File:Nagahama_port01s3872.jpg, Nagahama Port File:Biwa lake.jpg, Lake Biwa (Biwa-ko) File:Kusatsu Reisho Tokaido.jpg, Hiroshige 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 duri ...

Landforms of Shiga Prefecture Jōmon period Ōmihachiman, Shiga