is the second-largest lake in Japan, located 60 km to the north-east of

Tokyo Tokyo (; ja, 東京, , ), officially the Tokyo Metropolis ( ja, 東京都, label=none, ), is the capital and List of cities in Japan, largest city of Japan. Formerly known as Edo, its metropolitan area () is the most populous in the world, ...

In a narrower sense and officially, Lake Kasumigaura refers to a waterbody with an area of 167.63 km². In a wider sense, Lake Kasumigaura can also refer to a group of contiguous

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 lar ...

s, which includes Lake Kasumigaura proper, hereby referred to as Nishiura (西浦), and two smaller lakes, Kitaura (北浦; 35.16 km²) and Sotonasakaura (外浪逆浦; 5.85 km²), and also encompasses the rivers connecting them. In this case the total area is 220 km². About 45% of the land surrounding the lake is natural landscape and 43.5% is agricultural land.

History

Lake Kasumigaura originally was a brackish-water

lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into '' coastal lagoons'' (or ''barrier lagoons' ...

, with indirect connections to the Pacific Ocean via the Hitachigawa and Tone Rivers. In 1963, the construction of a gate near the confluence of these rivers disconnected the lake from its sources of ocean water. As a result, the salinity of Lake Kasumigaura declined, and today the lake contains fresh water. This lake was famous for its traditional fishery during 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 ...

. But today, fishing production has drastically decreased due to

water quality Water quality refers to the chemical, physical, and biological characteristics of water based on the standards of its usage. It is most frequently used by reference to a set of standards against which compliance, generally achieved through ...

deterioration that was partially caused by the closure of the tide gate in 1963 for purposes of desalination.Havens, K.E., P. Xie, T. Iwakuma, R.T. James, N. Takamura, T. Hanazato, and T. Yamamoto (2001). "Nutrient dynamics and the

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 phytopla ...

of shallow lakes Kasumigaura (Japan), Donghu (PR China), and Okeechobee (USA)". ''Environmental Pollution''. 111(2):263–272.

Use

Today, Lake Kasumigaura is used for

fishing Fishing is the activity of trying to catch fish. Fish are often caught as wildlife from the natural environment, but may also be caught from stocked bodies of water such as ponds, canals, park wetlands and reservoirs. Fishing techniques ...

irrigation Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has been dev ...

tourism Tourism is travel for pleasure or business; also the theory and practice of touring, the business of attracting, accommodating, and entertaining tourists, and the business of operating tours. The World Tourism Organization defines tourism ...

recreation Recreation is an activity of leisure, leisure being discretionary time. The "need to do something for recreation" is an essential element of human biology and psychology. Recreational activities are often done for enjoyment, amusement, or ple ...

, and for consumption by the surrounding public and local industry. A variety of fish can be caught from the waters of Lake Kasumigaura, including smelt, Japanese icefish, crucian carp, goby, Japanese eel and river prawn. The most popular catch is cultivated carp, followed by smelt and goby. Another cultivated treasure from Lake Kasumigaura is the beautiful Kasumi freshwater

pearl A pearl is a hard, glistening object produced within the soft tissue (specifically the mantle) of a living shelled mollusk or another animal, such as fossil conulariids. Just like the shell of a mollusk, a pearl is composed of calcium ca ...

s. They were known for their high luster and rosy hues, which is the result of a four-year cultivation period. However, in 2006, cultivation was discontinued as cheap freshwater pearls from China proved too difficult to compete against. The water from Lake Kasumigaura has long been used for the irrigation of

paddy field A paddy field is a flooded field of arable land used for growing semiaquatic crops, most notably rice and taro. It originates from the Neolithic rice-farming cultures of the Yangtze River basin in southern China, associated with pre ...

s in the surrounding

alluvial plain An alluvial plain is a largely flat landform created by the deposition of sediment over a long period of time by one or more rivers coming from highland regions, from which alluvial soil forms. A floodplain is part of the process, being the s ...

and upland fields on diluvial terraces covered by thick deposits of

volcanic ash Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to refer ...

. The primary crops are

rice Rice is the seed of the grass species '' Oryza sativa'' (Asian rice) or less commonly '' Oryza glaberrima'' (African rice). The name wild rice is usually used for species of the genera '' Zizania'' and ''Porteresia'', both wild and domestica ...

and lotus root (a local speciality). Other crops include

tomato The tomato is the edible berry of the plant ''Solanum lycopersicum'', commonly known as the tomato plant. The species originated in western South America, Mexico, and Central America. The Mexican Nahuatl word gave rise to the Spanish word , ...

cucumber Cucumber (''Cucumis sativus'') is a widely-cultivated creeping vine plant in the Cucurbitaceae family that bears usually cylindrical fruits, which are used as culinary vegetables.eggplant,

watermelon Watermelon (''Citrullus lanatus'') is a flowering plant species of the Cucurbitaceae family and the name of its edible fruit. A scrambling and trailing vine-like plant, it is a highly cultivated fruit worldwide, with more than 1,000 var ...

corn Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn ( North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. ...

, edamame,

sweet potato The sweet potato or sweetpotato ('' Ipomoea batatas'') is a dicotyledonous plant that belongs to the bindweed or morning glory family, Convolvulaceae. Its large, starchy, sweet-tasting tuberous roots are used as a root vegetable. The young ...

, kabocha, daikon and

peanut The peanut (''Arachis hypogaea''), also known as the groundnut, goober (US), pindar (US) or monkey nut (UK), is a legume crop grown mainly for its edible Seed, seeds. It is widely grown in the tropics and subtropics, important to both small ...

. Many tourists come to the lake in the summer to view the ''Hobikibune'' (帆引き船)

sail A sail is a tensile structure—which is made from fabric or other membrane materials—that uses wind power to propel sailing craft, including sailing ships, sailboats, windsurfers, ice boats, and even sail-powered land vehicles. Sails ma ...

ed fishing boats which are unique to Lake Kasumigaura. The Suigo aquapark, located in Tsuchiura, is popular during the hottest months. The

windmill A windmill is a structure that converts wind power into rotational energy using vanes called sails or blades, specifically to mill grain (gristmills), but the term is also extended to windpumps, wind turbines, and other applications, in so ...

of Kasumigaura comprehensive park is a popular site along the shores throughout the year and especially in the spring when the

tulip Tulips (''Tulipa'') are a genus of spring-blooming perennial herbaceous bulbiferous geophytes (having bulbs as storage organs). The flowers are usually large, showy and brightly coloured, generally red, pink, yellow, or white (usually in war ...

s are flowering. The lake is a recreation hotspot. Sport fishing enthusiasts and anglers can be found close to shore and around the river mouths surrounding the lake. Recreational boats, such as yachts, power boats, sail boats and personal watercraft, are regularly enjoyed on warm weekends. The wide surrounding

wetland 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 ...

s are wonderful for

birdwatching Birdwatching, or birding, is the observing of birds, either as a recreational activity or as a form of citizen science. A birdwatcher may observe by using their naked eye, by using a visual enhancement device like binoculars or a telescope, b ...

, as large numbers of water fowl can be observed, primarily during the wintering period. Japanese cormorant,

Bewick’s swan The tundra swan (''Cygnus columbianus'') is a small swan of the Holarctic. The two taxa within it are usually regarded as conspecific, but are also sometimes split into two species: Bewick's swan (''Cygnus bewickii'') of the Palaearctic and the w ...

, little egret,

grey heron The grey heron (''Ardea cinerea'') is a long-legged wading bird of the heron family, Ardeidae, native throughout temperate Europe and Asia and also parts of Africa. It is resident in much of its range, but some populations from the more northern ...

, mallard, Eurasian wigeon, striated heron, sharp-tailed sandpiper, bush warbler, wood sandpiper,

marsh grassbird The marsh grassbird (''Helopsaltes pryeri''), also known as the Japanese swamp warbler, is a species of Old World warbler in the family Locustellidae. It is found in China, Japan, South Korea, Mongolia, and Russia. Its natural habitat is swamps. ...

Japanese reed bunting The Japanese reed bunting or ochre-rumped bunting (''Emberiza yessoensis'') is a bird in the family Emberizidae. The species was first described by Robert Swinhoe in 1863. It is found in Manchuria, Korea and Japan. Its natural habitats are ...

, and the Eurasian coot are a few of the birds seen around the lake. Lake Kasumigaura provides over 60 tons of water per second; most goes to agriculture (83%). The rest is provided to local industry (13%) and public (4%) in the prefectures of Ibaraki, Chiba and

Challenges

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 phytopla ...

is a serious problem for Lake Kasumigaura. Legislation was enacted in 1982 to help prevent it, including a ban on the use and sale of phosphate-containing 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, and the control of nitrogen and phosphorus contents in the

effluent Effluent is wastewater from sewers or industrial outfalls that flows directly into surface waters either untreated or after being treated at a facility. The term has slightly different meanings in certain contexts, and may contain various pollut ...

from factories. In order to help maintain the lake, dredging work is being carried out around the lake and at the estuaries of main inflowing rivers, such as Sakura River (桜川).

References

External links

Page on Hobikisen

{{Authority control Kasumigaura Landforms of Ibaraki Prefecture Kasumigaura