Lake Biwa (琵琶湖)

Lake Biwa is a lake in Shiga Prefecture. It is the largest lake in Japan. The lake is designated under the Law Concerning Special Measures for Conservation of Lake Water Quality. The wetlands are registered under the Ramsar Convention.
In the River Act, Lake Biwa is a class A river belonging to the first-class rivers of 'the Yodo-gawa River system,' and is officially described as 'Lake Biwa, a class A river (一級河川琵琶湖).'

Geography
Lake Biwa occupies one-sixth of Shiga Prefecture's land area, and the water flowing from the lake flows into Osaka Bay in the Seto Inland Sea through the Seta-gawa River, whose name changes to the Uji-gawa River and later the Yodo-gawa River. Lake Biwa Canal runs to Kyoto, supplying lake water for drinking to Kyoto City and the areas along the Yodo-gawa River. The part of the lake to the north of the Biwako Ohashi Bridge, which was built at the narrowest point, is called the Northern Lake or 'Taiko,' while the part to the south is called the Southern Lake; accordingly, the water quality and water flow differ between them.

The municipalities surrounding Lake Biwa are roughly classified as Konan (south of the lake), Koto (east of the lake), Kohoku (north of the lake) and Kosai (west of the lake)(and sometimes Koka too, as seen separately from Konan). See 'Districts in Shiga Prefecture' for the details regarding this classification.

The water of Lake Biwa originates from the surrounding mountains, so the lake functions as a water reservoir for the Kyoto-Osaka-Kobe area. Moreover, the lake has been used for water transport since ancient times, and until the railroad opened in the Meiji period it had been used to carry goods from Kyoto City and Osaka City to Tosando and the Hokuriku region.

The Japanese proverb 'isogaba maware (more haste, less speed)' originated from a waka that was written about a ferry called the 'Yahashi no Watashi' connecting the present-day Kusatsu City and Otsu City.

The Biwako Basic Surface Water Level (BSL) is set at T.P. (Tokyo Peil) +84.371 m and O.P. (Osaka Peil) +85.614 m, and 'the water level of Lake Biwa' is relative to the B.S.L., being either above or below the B.S.L. (0 m). The B.S.L. was set at the observation point of the Torii-gawa River in 1874, in the assumption that 'the water level was the lowest possible' at that time; however, later the water levels of Lake Biwa often went below the B.S.L., partly due to the improvement of the Seta-gawa River, which caused more water to flow out of the lake. Today, the water level is adjusted in order to maintain the B.S.L. at the approximate high-water level.

History

Lake Biwa originated as a tectonic lake (Lake Oyamada); it formed approximately four to six million years ago around the present-day Hirata in Iga City, Mie Prefecture, as the result of tectonic movement. Lake Biwa gradually moved northward until it reached its current position, being blocked by the Hira Mountains. Before Lake Oyamada was formed, there had been mountains (古琵琶湖山脈) in the current location of Lake Biwa; the Suzuka Mountains had not yet risen, and the rivers in the southeast of the present-day Lake Biwa flowed out to Ise Bay. This is evidenced by the fact that the Suzuka Mountains consist mainly of a layer of conglomerate. Additionally, the Yasu-gawa River, as the largest river in the southeast to flow into Lake Biwa, is known to have flowed eastward, not westward, at that time.

Lake Biwa is regarded as the third-oldest ancient lake in the world after Lake Baikal and Lake Tanganyika.

The lake had been used for water transport since the Jomon and Yayoi periods, and items such as dugouts have been found. In ancient times the lake was called Chikatsu-awa-umi (or simply Awaumi) as the body of freshwater nearest to the capital.
It was described in the Kojiki as 'Afumi-no-umi.'
Lake Hamana was called Totsu-awa-umi as a freshwater sea far away from the capital compared to Lake Biwa, and the names of 'Omi Province (the present-day Shiga Prefecture)' and Totoumi Province (the west of present-day Shizuoka Prefecture) originated from those old lake names. Nionoumi, another name for Lake Biwa, is an utamakura, a word or phrase used in waka specifically in the context of a certain theme, which in this case is Omi Province.

There was a time when the Emperor Tenchi had established Otsu-kyo on the western shore of Lake Biwa. After the middle of the Edo period, when land-surveying techniques were developed and the shape of the lake turned out to look like a Japanese lute, the name of the lake became widely known as Lake Biwa.

The lake was used for the water transport of annual tributes from Wakasa Bay, and records show that ships were attacked by pirates on the lake. Various transport routes were constructed to the west of the lake, such as the Nishi-omi-ji Road and the Wakasa Kaido Road stretching from Otsu to Wakasa Province, and the Hokkoku Kaido Road linking Kyoto and, via Lake Biwa, Imajo-cho, where the road connected to the Hokurikudo Road. Water transport via Lake Biwa was also used to carry goods, and places such as Otsu and Katata developed as key ports.

In the Azuchi Momoyama period, Hideyoshi TOYOTOMI set up Otsu-hyakuso-sen (a hundred ships in Otsu) for funamochi (owners of boats) in Otsu, put them under the control of the ship superintendent at Kannon-ji Temple and protected them with special privileges. In the early modern era, Otsu was opposed to other ports such as Matsubara and Maibara City; but during the Edo period Matsubara, Maibara and Nagahama City as `Hikone-han-san-minato' (three ports in Hikone-han) were protected by the Ii clan.

Goods unloaded at the ports in Wakasa Bay were transported via Lake Biwa to Kyoto and Osaka from the point where the river from Lake Biwa running to Osaka Bay became the Yodo-gawa River during those periods when Kyoto was the capital. Water transport via the lake declined due to the development of road transport, but the plan to build canals from Lake Biwa to the Sea of Japan, the Pacific Ocean and the Seto Inland Sea were conceived during a period of high economic growth. Initially, the governor of Fukui Prefecture, Eizo KITA, accommodated the plan 'Framework on Hanko Canal' (阪敦運河構想) to connect the Sea of Japan and the Seto Inland Sea via Lake Biwa, but because Sukenori HIRATA, who was then the mayor of Yokkaichi City, was keen on the plan, the alliance for the construction of the canal to connect Wakasa Bay and Ise Bay via Lake Biwa (at a total cost of 250 to 350 billion yen) was formed with Banboku ONO, the Vice President of the Liberal Democratic Party, as chairman, among Fukui Prefecture, Shiga Prefecture, Gifu Prefecture, Aichi Prefecture, Mie Prefecture, Nagoya City, Tsuruga City and Yokkaichi City. However, in 1970 the headquarters of Chubu Area Development and Improvement (中部圏開発整備本部) announced the termination of the survey after the loss of key members of the alliance: ONO, the vice-president of the Liberal Democratic Party, and HIRATA, the mayor of Yokkaichi City, had both passed away, while KITA, the governor of Fukui Prefecture, and the mayor of Tsuruga City, HATAMORI (畑守), continually lost in the elections.

1890: The Lake Biwa Canal to supply water to Kyoto City opened.

1950: Lake Biwa and the surrounding area were designated as Lake Biwa Quasi-National Park.

September 28, 1964: The Biwako Ohashi Bridge opened.

September 26, 1974: The Omi Ohashi Tollway opened.

1980: The Lake Biwa Ordinance (the Ordinance for the Prevention of Eutrophication of Lake Biwa) was enacted.

1985: The lake was among those included in the Law Concerning Special Measures for the Conservation of Lake Water Quality.

1993: The lake was registered as a wetland under the Ramsar Convention.

2003: The Ordinance Related to the Appropriate Leisure Usage of Lake Biwa was enacted.

Biophysical aspects

Lake Biwa has great biological diversity and is home to more than 1,000 species of animals and plants. Among them, there are many species indigenous to Lake Biwa because the area has been independent for such a long time. The species are large in scale, and a unique fishery has developed.

On the other hand, the catches of many species have been significantly reduced by the disturbance of native species, caused by the invasion of introduced fish such as the largemouth bass and bluegill, the amendment of the Ordinance on Control of Water Level (琵琶湖水位操作規則の改訂) in 1992, the loss of lagoons and the disconnection of the lake from the network of paddy fields. Although various actions--including the removal of introduced species, environmentally friendly operation of water-level control and restoration of lagoons--have been taken to resolve those issues, sufficient results have not been achieved. At the same time, the larvae of ayu hatched in Lake Biwa are released into the local rivers in Japan, and therefore Lake Biwa can be a source of introduced species.

Fish and shellfish

Endemic species (fish): Lake Biwa catfish (Siluridae), Biwa rock catfish (Siluridae), willow shiner (Cyprinidae), Biwa oily gudgeon (Cyprinidae), minnow (Cyprinidae)

Endemic subspecies (fish): Biwa salmon (Salmonidae)

Endemic species (Shellfish): Gastropod, Seta clam (Corbiculidae), Biwamelania (Biwamelania, Pleuroceridae), Ohmigai (Lymnaeidae), Kadohiramakigai (Planorbidae), Hirokuchimakigai (Planorbidae)

Introduced species (fish): largemouth bass, smallmouth bass, bluegill, northern snakehead (channidae), silver carp and bighead carp

Water plants

Endemic species: Sannenmo (Potamogetonaceae), Negiremo (Hydrocharitaceae)

Other species

Endemic species (plankton): Biwakunshomo, Biwatsubokamuri

Major rivers flowing into Lake Biwa
(The names of municipalities in the main basin are shown.)

Yasu-gawa River (Koka City, Konan City, Yasu City, Moriyama City)
Hino-gawa River (Shiga Prefecture; Gamo-gun, Omihachiman City)
Echi-gawa River (Echi-gun, Higashiomi City)
Ado-gawa River (Takashima City)
Kamo-gawa River (Takashima City)
Uso-gawa River (Echi-gun, Hikone City)
Inukami-gawa River (Inukami-gun, Hikone City)
Seri-gawa River (Shiga Prefecture) (Inukami-gun, Hikone City)
Ane-gawa River (Higashi-Azai-gun, Nagahama City)
Yogo-gawa River (Ika-gun, Higashi-Azai-gun)
Mano-gawa River (Shiga Prefecture) (Otsu City)
Ports

Otsu Port (Shiga Prefecture)
Nagahama Port (Shiga Prefecture)
Hikone Port
Chikubushima Port
Imazu Port
Okishima Fishing Port
Ogoto Onsen Port
Kusatsu Karasuma Hanto Port (草津烏丸半島港)
Biwako Ohashi Port

Islands in the lake
The lake is home to various islands: Chikubushima (area: 0.14 sq. km), Oki (area: 1.5 sq. km), Takeshima, Oki no Shiraishi (沖の白石) and Yabasekihanto. Yabasekihanto Island is an artificial island built on landfill for sewage plants.

Biwako-Hakkei (eight places of scenic beauty around Lake Biwa)
These were chosen from among the public in June 1945.

Gyomu: Kaizuosaki no Gansho (Takashima City)
Ryofu: Omatsuzaki no Hakutei (Otsu City)
En-u: Hiei no Jurin (Otsu City)
Sekiyo, Seta, Ishiyama no Seiryu (Otsu City)
Shinsetsu: Shizugadake no Taikan (Kinomoto-cho)
Shinryoku: Chikubushima no Chin-ei (Nagahama City)
Getsumei: Hikone no Kojo (Hikone City)
Shunshoku: Azuchihachiman no Suigo (Omihachiman City, Azuchi-cho)

Environmental conservation in Lake Biwa
As the economy grew rapidly, the lake's water quality degraded and it became increasingly eutrophic. Consequently, Shiga Prefecture independently enacted the so-called Lake Biwa Ordinance (Ordinance for Prevention of the Eutrophication of Lake Biwa) in order to regulate factory and household effluents. There are more ordinances enacted with regard to Lake Biwa: for example, the Ordinance Related to the Appropriate Leisure Usage of Lake Biwa, the Ordinance of Reed-Community Conservation, and the Ordinance for Protecting and Creating Beautiful Landscapes in the Shiga Homeland.

Because factories around Lake Biwa pumped the water out of the ground, and many of them dumped effluents deliberately until the Water Pollution Control Law was amended to prevent them from discharging effluents into the ground, the contamination of underground water in the factory area near the lake has worsened, and some people have strongly urged quick action in order to protect the water in what is the world's most enclosed watershed area.

Municipalities along the shore
The following are the municipalities on the shore of Lake Biwa (clockwise from the north):

Nishi-Azai-cho
Takatsuki-cho
Kinomoto-cho
Kohoku-cho
Nagahama City
Maibara City
Hikone City
Higashiomi City
Omihachiman City
Yasu City
Moriyama City
Kusatsu City
Otsu City
Takashima City

Establishment of borders
The municipal borders of Lake Biwa had never been established, but at a joint conference held by the municipalities on the shore of the lake, their delegates reached an agreement to establish the borders of Lake Biwa on May 8, 2007; a document was submitted to the Ministry of Internal Affairs and Communications after the approval of each municipality's assembly, and finally the establishment of borders was officially announced in the official gazette on September 28.

The main purpose in establishing the borders was that each municipality could receive more of the state subsidies destined for municipalities. Still, the announcement has been made that half of the increased subsidies would be allocated to the conservation of Lake Biwa.

Others
Notation
Since the kanji for 'bi' and 'wa' are not in common use and have not been designated as kanji for daily use, Lake Biwa (or Biwako) is often written in Shiga Prefecture either completely in hiragana (びわこ) or with the first two characters written in hiragana and the last one in kanji (びわ湖). There once was a municipality described as 'Biwa-cho' (Biwa in hiragana and cho in kanji).

Examples of 'びわこ' (Biwako):
Biwako Bank (びわこ銀行), Biwako Kyotei (びわこ競艇場), Otsu Biwako Keirin (大津びわこ競輪場), MIO Biwako Kusatsu (MIOびわこ草津), Biwako Seikei Sports College (びわこ成蹊スポーツ大学), JA Higashi Biwako (東びわこ農業協同組合), and others
Examples of 'びわ湖' (Biwa-ko):
Biwako Broadcasting Co., Ltd., Minami Biwako Station (tentative name, formerly Biwako Ritto Station), etc.