Lake Inba

{{Short description|Lake in Chiba Prefecture, Japan}} {{Infobox body of water | name = Lake Inba | native_name = {{native name|ja|印旛沼}} | image = File:Lake Inba.JPG | alt = | caption = | image_bathymetry = | alt_bathymetry = | caption_bathymetry =  | location = Chiba Prefecture, Japan{{Location map |Japan Chiba Prefecture#Japan Kanto#Japan |width=200 |relief=1 |float=center |caption=Location of Lake Inba within Chiba Prefecture##Location of Lake Inba within Kanto region##Location of Lake Inba within Japan |coordinates={{coord|35|46|37.5|N|140|13|55.2|E}} }} | group = | coordinates = {{coord|35|46|37.5|N|140|13|55.2|E|type:waterbody_region:JP|display=inline,title}} | type = Polder | etymology = | part_of = | inflow = | rivers = {{ubl|Nagato River|Kashima River|Moroto River|Takasaki River|Teguri River|Kanzaki River|Kannō River|Shin River}} | outflow = | catchment = {{convert|494|km2}} | basin_countries = Japan | agency = | designation = | date-built =  | engineer = | date-flooded =  | length =  | width =  | area =  | depth =  | max-depth = {{ubl|{{convert|4.8|m}} (north)|{{convert|2.9|m}} (west)}} | volume = {{convert|19700000|m3}} | residence_time = | salinity = | shore =  | elevation =  | temperature_high =  | temperature_low =  | frozen = | islands = 0 | sections = {{ubl|{{nihongo|North Lake Inba|北印旛沼|Kita Inba-numa}}|{{nihongo|West Lake Inba|西印旛沼|Nishi Inba-numa}}|{{nihongo|Inba Cutoff Canal|印旛捷水路|Inba Shōsuiro}}}} | trenches = | benches = | cities = {{ubl|Inzai|Narita|Sakae|Sakura|Yachiyo}}  | mapframe = yes | mapframe-custom = {{Maplink2 |zoom=10 |frame=yes |plain=no |frame-align=right |frame-width=250 |frame-height=250 |type=shape |fill=#87cefa |stroke-color=#0000ff |stroke-width=2 |id=Q63860206 |title='''Lake Inba, northern section''' |type2=shape |fill2=#87cefa |stroke-color2=#0000ff |stroke-width2=2 |id2=Q63860210 |title2='''Lake Inba, western section''' }}  | website = | reference = <ref name="lake survey 2019"/><ref name="inbanuma overview"/> }} {{nihongo|'''Lake Inba'''|印旛沼|Inba-numa}} is a man-made polder lake consisting of northern and western sections connected by a canal and located in Inba Tega Prefectural Natural Park in the Tone River basin in Chiba Prefecture, Japan. It is the largest lake in the prefecture. It was formed from remnants of the Katori Sea after the Tone River was diverted.

It is a popular location for outdoor activities, including fishing, bicycling, and birding, and is home to numerous species of plants, birds, and other wildlife. The National Museum of Japanese History is located on the grounds of the ruins of Sakura Castle, southwest of the lake. It is easily accessible through a number of train and bus services.

The lake is also variously known as '''Lake Imba''', '''Lake Imbanuma''', '''Inbanuma''', and '''Imbanuma'''.

==Geography and history== Lake Inba is located in Inba Tega Prefectural Natural Park, and is the largest lake in Chiba Prefecture, with an original surface area of {{convert|25.8|km2|mi2}}.<ref name="inbanuma overview"/><ref name="jt navitime"/> It is a man-made lake created by the natural damming of a small valley, and it is the largest lake in Chiba Prefecture. The lake is within the Shimōsa Plateau, which covers most of northern part of the prefecture. After multiple land reclamation projects, similar to those carried out on Lake Teganuma, its surface area was significantly reduced to about {{convert|13.1|km2|mi2}},<ref name="encyclopedia of japan"/> before being further reduced to {{convert|9.43|km2|mi2}}.

About 1000 years ago, the Tone River flowed into what is now Tokyo Bay, and the area where Lake Inba is now located was part of the inland Katori Sea and was called {{nihongo|Inbaura|印旛浦|}}.<ref name="inbanuma overview"/> As part of a large project to control flooding in the Tokyo area during the Edo Period, the river's course was diverted to flow into the Pacific Ocean, with its mouth now at Chōshi.<ref name="inbanuma overview"/> The Katori Sea was slowly filled in and the remaining water and land desalinated, and a large swampy area that eventually drained into Tokyo Bay was created.<ref name="inbanuma overview"/>

Lake Inba was a large, swampy area containing a W-shaped lake of about {{convert|25.8|km2|mi2}} until the 1930s.<ref name="inbanuma overview"/> A project completed in 1949 reduced the surface area of the lake almost in half, and split the lake into northern and western sections connected by the {{nihongo|Inba Cutoff Canal|印旛捷水路|Inba Shōsuiro}}.<ref name="inbanuma overview"/><ref name="jt navitime"/> The Inba Cutoff Canal is listed as one of the top 100 canals in Japan.<ref name="top 100 canals"/> The northern section reaches depths of {{convert|4.8|m}}, while the western section is shallower at about {{convert|2.9|m}} maximum depth.<ref name="lake survey 2019"/> A reclamation project completed from 1963 to 1969 developed additional water resources, improved area rice fields, and better managed flooding.<ref name="wldb detail"/> The lake contains no islands.

Due to population increases in the area during the 1970s, nutrient runoff into the lake began causing blue-green algae blooms, an increase in water chestnut growth, and municipal water odors. Various education programs and better handling of wastewater have reduced these issues.<ref name="wldb detail"/>

The lake spans multiple municipalities, including the cities of Inzai, Narita, Sakura, and Yachiyo, and the town of Sakae.<ref name="inbanuma overview"/><ref name="national area survey 2014"/> The drainage basin, which spans {{convert|494|km2}}, includes these municipalities as well as the cities of Chiba, Funabashi, Kamagaya, Yotsukaidō, Yachimata, Shiroi, and Tomisato, and the town of Shisui.<ref name="inbanuma overview"/> The population found within the lake's basin is about 794,000 {{as of|lc=yes|2020}}.<ref name="inbanuma overview"/>

There are numerous rivers that empty into Lake Inba. These include the Nagato River, Kashima River, Moroto River, Takasaki River, Teguri River, Kanzaki River, Kannō River, and Shin River. The lake holds a water volume of about {{convert|19700000|m3}}, and each year supplies about {{convert|34831000|m3|cuyd}} of potable water, {{convert|47368000|m3|cuyd}} of water for industrial uses, and {{convert|76876000|m3|cuyd}} for agricultural uses.<ref name="inbanuma overview"/>

==Flora and fauna== Lake Inba supports a variety of plants and animals in the lake and its surrounding environs. Major plants found there include the hornwort, common reed, Japanese reed, the water snowflake, various eelgrasses, the fringed water lily, Carolina fanwort, Manchurian wild rice, water chestnut, pondweeds such as potamogeton wrightii and potamogeton lucens, western waterweed, the lesser bullrush, spiny water nymph, trapa incisa, various members of the water caltrop genus, hydrocharis dubia, and the lotus.<ref name="wldb detail"/><ref name="japan nature guides"/> A number of species of phytoplankton are also found in the lake, including microcystis, cyclotella, and chlamydomonas.<ref name="wldb detail"/>

Fish found in the lake include the common carp, the Japanese bitterling, tamoroko, pond loach, pond smelt, Japanese halfbeak, icefish, Japanese eel, kawahigai, hasu, oikawa, mugitsuku, Chinese false grudgeon, and various types of Crucian carps and gobies.<ref name="wldb detail"/>

Inba Lake is a popular birding destination due to many birds frequenting the lake and the surrounding wetlands. Birds found there include yellow, Eurasian, and Schrenk's bitterns (though the latter is very rare), Oriental reed warblers, ducks such as the falcated and Baikal teals and the smew, Japanese green pheasants, Siberian meadow buntings, Japanese buzzards, kestrels, sparrowhawks, and eastern marsh harriers.<ref name="japan nature guides"/> A single great white pelican has been living at the lake since the early 2000s.<ref name="japan nature guides"/>

==Recreation and access== The lake features relatively-flat bicycle paths along most of the shoreline, including the main canal, and bicycles can be rented.<ref name="chiba tourism"/><ref name="live japan inba"/> The cycling path continues for a few kilometers along the Shin River off the western section, and along the western shore of the northern section up to the Sakano Water Gate on the Nagato River. It is also a popular fishing and birding destination.<ref name="jt navitime"/><ref name="chiba tourism"/><ref name="live japan inba"/>

The National Museum of Japanese History is located on the grounds of the ruins of Sakura Castle, southeast of the western section of the lake in Sakura. The castle ruins are 20th on Japan's Top 100 Castles list by the Japan Castle Foundation.<ref name="top 100 castles"/> A Dutch windmill and fields of tulips are located next to the lake.<ref name="live japan inba"/>

There are no toilet facilities at the lake.<ref name="japan nature guides"/>

===Transportation=== Narita International Airport is located about {{convert|11.3|km|mi}} southeast of Lake Inba. The Higashi-Kantō Expressway, a limited-access toll road, runs east-west and then northeast several kilometers south (and then east) of the lake. The lake is accessible from the Tomisato, Narita, Shisui, and Sakura Interchanges.

The following railway stations are within about {{convert|6|km|mi}} of Lake Inba (listed by line, then by distance): *Keisei Narita Airport Line<ref name="visit chiba inbanuma"/> **Keisei-Usui (Sakura) – {{convert|1.3|km|mi}} **Sōgosandō (Shisui) – {{convert|2.5|km|mi}} **Kōzunomori (Narita) – {{convert|3.1|km|mi}}, has buses that go to the lake<ref name="live japan inba"/> **Keisei Sakura (Sakura) – {{convert|3.3|km|mi}}, has buses that go to the lake<ref name="live japan inba"/> **Yūkarigaoka Station (Sakura) – {{convert|3.4|km|mi}} **Ōsakura (Sakura) – {{convert|3.8|km|mi}} **Shizu (Sakura) – {{convert|4.5|km|mi}} **Keisei Shisui (Shisui) – {{convert|4.7|km|mi}} **Keisei Narita (Narita) – {{convert|4.8|km|mi}}

*Narita Line<ref name="japan nature guides"/> **Shimōsa-Manzaki (Narita) – {{convert|1.3|km|mi}}<ref name="japan nature guides"/> **Sakura (Sakura) – {{convert|2.6|km|mi}} (also on the Sōbu Main Line) **Ajiki (Sakae – {{convert|3|km|mi}}<ref name="japan nature guides"/> **Shisui (Shisui) – {{convert|4.4|km|mi}} **Kobayashi (Inzai) – {{convert|4.8|km|mi}} **Narita (Narita) – {{convert|5.3|km|mi}} **Monoi (Yotsukaidō) – {{convert|5.75|km|mi}}

*Hokusō Line **Imba Nihon-idai (Inzai) – {{convert|3.6|km|mi}}<ref name="jt navitime"/><ref name="japan nature guides"/><ref name="inzai parque 20250603"/> **Inzai-Makinohara (Inzai) – {{convert|5|km|mi}}<ref name="inbanuma park guide"/>

All stations on the looping Yamaman Yūkarigaoka Line are near the west end of the west section of the lake.<ref name="CEC 201107 pp20-23"/>

===Surrounding area=== * Chiba New Town * {{jct|country=JPN|Route|16}} * {{jct|country=JPN|Route|51}} * {{jct|country=JPN|Route|296}} * {{jct|country=JPN|Route|356}} * {{jct|country=JPN|Route|464}} * Ryūkaku-ji, located on a plateau near the lake

==See also== *List of lakes in japan

==References== {{reflist|30em|refs=

<ref name="CEC 201107 pp20-23">{{cite web |url=https://www.jcca.or.jp/kaishi/252/252_toku4.pdf |script-title=ja:都市計画の視点から見た中量軌道システム「山万ユーカリが丘線」 |trans-title=Medium-Capacity Rail System from an Urban Planning Perspective: "Yamaman Yukarigaoka Line" |author=林新二郎 (Hayashi Shinjirō) |language=ja |date=July 2011 |publisher=Civil Engineering Consultant |access-date=21 October 2025 |archive-date=14 April 2023 |archive-url=https://web.archive.org/web/20230414061309/https://www.jcca.or.jp/kaishi/252/252_toku4.pdf |url-status=live }}</ref>

<ref name="chiba tourism">{{cite web |url=https://www.visitchiba.jp/spot/lake-inbanuma/ |title=Lake Inbanuma |publisher=Chiba Prefectural Tourism & Local Products Association |access-date=19 September 2025 |archive-date=19 September 2025 |archive-url=https://archive.today/20250919214817/https://www.visitchiba.jp/spot/lake-inbanuma/ |url-status=live }}</ref>

<ref name="encyclopedia of japan">{{cite encyclopedia |encyclopedia=Encyclopedia of Japan |title=Inbanuma |url=http://rekishi.jkn21.com/ |access-date=21 July 2012 |year=2012 |publisher=Shogakukan |location=Tokyo |oclc=56431036 |archive-url=https://web.archive.org/web/20070825113418/http://rekishi.jkn21.com/ |archive-date=25 August 2007 |url-status=dead }}</ref>

<ref name="inbanuma overview">{{cite web |url=https://www.insuikyo.jp/environment/gaiyou/ |script-title=ja:印旛沼の概要 |trans-title=Inba-numa Overview |language=ja |date=2020 |publisher=印旛沼水質保全協議会 |access-date=19 September 2025 |archive-date=19 September 2025 |archive-url=https://archive.today/20250919225736/https://www.insuikyo.jp/environment/gaiyou/ |url-status=live }}</ref>

<ref name="inbanuma park guide">{{cite web |url=https://www.pref.chiba.lg.jp/kouen/toshikouen/guidemap/documents/parkguide-inba.pdf |script-title=ja:印旛沼公園 |trans-title=Inbanuma Park |language=ja |publisher=印旛土木事務所 (Inba Civil Engineering Office) |access-date=21 October 2025 |archive-date=23 April 2025 |archive-url=https://web.archive.org/web/20250423073550/https://www.pref.chiba.lg.jp/kouen/toshikouen/guidemap/documents/parkguide-inba.pdf |url-status=live }}</ref>

<ref name="inzai parque 20250603">{{cite web |url=https://inzaiparque.com/inzai-intro-nichiidai/ |script-title=ja:印旛日医大地区の紹介 |trans-title=Introduction to the Greater Inba Area |language=ja |publisher=千葉ほくそうパルケ |date=3 June 2025 |access-date=21 October 2025 |archive-date=21 October 2025 |archive-url=https://web.archive.org/web/20251021200453/https://inzaiparque.com/inzai-intro-nichiidai/ |url-status=live }}</ref>

<ref name="japan nature guides">{{cite web |url=https://www.japannatureguides.com/chiba-prefecture/ |title=Chiba Prefecture |first1=Mark |last1=Brazil |first2=Chris |last2=Cook |publisher=Japan Nature Guides |date=5 June 2021 |access-date=21 October 2025 |archive-date=14 June 2025 |archive-url=https://web.archive.org/web/20250614194407/https://www.japannatureguides.com/chiba-prefecture/ |url-status=live }}</ref>

<ref name="jt navitime">{{cite web |url=https://japantravel.navitime.com/en/area/jp/spot/02301-12800398/ |title=Lake Imbanuma |publisher=Japan Travel by Navitime |access-date=21 October 2025 |url-status=live }}</ref>

<ref name="lake survey 2019">{{cite web |url=https://www.gsi.go.jp/kankyochiri/koshouchousa-list.html |script-title=ja:調査実施湖沼一覧 |trans-title=List of Surveyed Lakes |language=ja |date=2019 |publisher=Geospatial Information Authority of Japan |access-date=19 September 2025 |archive-date=19 September 2025 |archive-url=https://archive.today/20250919211725/https://www.gsi.go.jp/kankyochiri/koshouchousa-list.html |url-status=live }}</ref>

<ref name="live japan inba">{{cite web |url=https://livejapan.com/en/in-tokyo/in-pref-chiba/in-narita/spot-lj0000725/ |title=Lake Inba |publisher=Live Japan |access-date=21 October 2025 |archive-date=19 July 2025 |archive-url=https://web.archive.org/web/20250719122206/https://livejapan.com/en/in-tokyo/in-pref-chiba/in-narita/spot-lj0000725/ |url-status=live }}</ref>

<ref name="national area survey 2014">{{cite web |url=https://www.gsi.go.jp/KOKUJYOHO/MENCHO/backnumber/GSI-menseki20141001.pdf |script-title=ja:平成26年全国都道府県市区町村別面積調 |trans-title=2014 National Area Survey by Prefecture, City, Ward, and Municipality |language=ja |date= 2014 |page=97 |publisher=Geospatial Information Authority of Japan |access-date=19 September 2025 |archive-date=24 August 2025 |archive-url=https://web.archive.org/web/20250824110255/https://www.gsi.go.jp/KOKUJYOHO/MENCHO/backnumber/GSI-menseki20141001.pdf |url-status=live }}</ref>

<ref name="top 100 canals">{{cite web |url= https://www.inakajin.or.jp/works/pr/sosui/search |script-title=ja: 疏水百選 |trans-title= Top 100 Canals |language=ja |publisher= 全国土地改良事業団体連合会 (National Federation of Land Improvement Associations) |access-date=19 September 2025 |archive-date=19 September 2025 |archive-url=https://archive.today/20250919202955/https://www.inakajin.or.jp/works/pr/sosui/search |url-status=live }}</ref>

<ref name="top 100 castles">{{cite web |url=https://jokaku.jp/business/great-castles/ |script-title=ja:日本１００名城 |trans-title=Japan 100 Famous Castles |language=ja |publisher=Japan Castle Foundation |access-date=23 September 2025 |archive-date=23 September 2025 |archive-url=https://archive.today/20250923171505/https://jokaku.jp/business/great-castles/ |url-status=live }}</ref>

<ref name="visit chiba inbanuma">{{cite web |url=https://www.visitchiba.jp/spot/lake-inbanuma/ |title=Lake Inbanuma |publisher=Chiba Prefectural Tourism & Local Products Association |date=17 March 2025 |access-date=21 October 2025 |archive-date=16 July 2025 |archive-url=https://web.archive.org/web/20250716201220/https://www.visitchiba.jp/spot/lake-inbanuma/ |url-status=live }}</ref>

<ref name="wldb detail">{{cite web |url=https://wldb.ilec.or.jp/Display/html/3546 |title=Inba-Numa (Lake Inba) |publisher=International Lake Environment Committee Foundation |access-date=19 September 2025 |archive-date=19 September 2025 |archive-url=https://archive.today/20250919215602/https://wldb.ilec.or.jp/Display/html/3546 |url-status=live }}</ref>

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== External links == *Maps: **GSI interactive: [https://maps.gsi.go.jp/#15/35.802531/140.251205/&base=std&ls=std%7Clakedata&blend=0&disp=11&vs=c1g1j0h0k0l0u0t0z0r0s0m0f0&d=m North Inba-numa], [https://maps.gsi.go.jp/#15/35.755347/140.194657/&base=std&ls=std&disp=1&vs=c1g1j0h0k0l0u0t0z0r0s0m0f0&d=m West Inba-numa] **PDF: [https://www1.gsi.go.jp/geowww/lake/download/kita-inbanuma/kita-inbanuma-2019_A3.pdf North Inba-numa], [https://www1.gsi.go.jp/geowww/lake/download/nishi-inbanuma/nishi-inbanuma-2019_A3.pdf West Inba-numa]

{{DEFAULTSORT:Inba, Lake}} Category:Inzai Category:Lakes of Chiba Prefecture Category:Narita, Chiba Category:Polders Category:Sakae, Chiba Category:Sakura, Chiba Category:Yachiyo, Chiba Category:Artificial lakes of Japan