Köhniönjärvi () is a lake in the Kypärämäki

district A district is a type of administrative division that in some countries is managed by the local government. Across the world, areas known as "districts" vary greatly in size, spanning regions or county, counties, several municipality, municip ...

Jyväskylä Jyväskylä () is a city in Finland and the regional capital of Central Finland. It is located in the Finnish Lakeland. The population of Jyväskylä is approximately , while the Jyväskylä sub-region, sub-region has a population of approximately ...

Finland Finland, officially the Republic of Finland, is a Nordic country in Northern Europe. It borders Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bothnia to the west and the Gulf of Finland to the south, ...

, covering an area of . The residential area of Köhniö is located to its east, though it does not extend to its shores. The

Haapamäki Haapamäki is a village in the municipality of Keuruu, Finland. It has historically been an important meeting point of major railway lines, which converge at Haapamäki railway station. It is from Haapamäki to the center of Keuruu and to the ...

–Jyväskylä railroad passes by the lake's southern shore. The lake's average depth is and its maximum depth is , the deepest point is located in its southeastern part. The surface level of the lake is above sea level.

Geography

Köhniönjärvi is located in the

Kymijoki The Kymi (, ) is a river in Finland. It begins at Lake Päijänne, flows through the provinces of Päijänne Tavastia, Uusimaa and Kymenlaakso, and discharges into the Gulf of Finland. The river passes the towns of Heinola and Kouvola. The to ...

main basin and is part of its second-order Päijänne basin (). The catchment area of Köhniönjärvi itself covers an area of , of which 66% is dense forest, 9.1% is sparse forest, 3.9% is water and 0.2% is wetland. The rest of the area is residential or industrial. The catchment area extends to the southern slopes of the hill Laajavuori in the north and to the settlement of Taka-Keljo in the south, also covering much of the Kypärämäki and Keltinmäki districts. There are multiple smaller lakes or ponds within the catchment area, including Soidenlampi, Mustalampi and Kotalampi in the south as well as Rimminlampi, Killervä and Riihilampi in the north. Köhniönjärvi itself discharges into the

Jyväsjärvi Lake Jyväsjärvi () is a lake situated in the centre of Jyväskylä in Finland. The lake is sometimes seen as a part of the Päijänne, as both lakes are on the same level ( from sea level) and are connected by the Äijälänsalmi strait. Par ...

via the long Köyhänoja, which follows the Haapamäki–Jyväskylä railroad for much of its course, also passing through the residential areas of Tarhamäki and Kukkumäki.

Environmental values

Water quality

There is a public beach maintained by the town on the eastern shore of the lake, making water sampling necessary. The water of the Köhniönjärvi is rich in nutrients; based on samples taken from a metre below surface level in October 2019, the water of the lake had a nitrogen level of 630 μg/l and a phosphorus level of 15 μg/l. Due to high nutrient levels and the small size of the lake causing its water to warm up quickly,

cyanobacteria Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (cyan) color, which forms the basis of cyanobacteri ...

is found almost every summer, however generally not to an extent where swimming would be unsafe. ''

E. coli ''Escherichia coli'' ( )Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Escherichia'' that is commonly foun ...

'' and ''

Enterococcus ''Enterococcus'' is a large genus of lactic acid bacteria of the phylum Bacillota. Enterococci are Gram-positive cocci that often occur in pairs ( diplococci) or short chains, and are difficult to distinguish from streptococci on physical ch ...

'' bacteria levels have also remained low between 2019 and 2022 and the water has been deemed safe for swimming. There have been some exceptions, such as a

norovirus Norovirus, also known as Norwalk virus and sometimes referred to as the winter vomiting disease, is the most common cause of gastroenteritis. Infection is characterized by non-bloody diarrhea, vomiting, and stomach pain. Fever or headaches may ...

contamination for a brief period in 2022.

Shores

The southern shores of the lake are covered by relatively old spruce-dominated forest, providing habitat for Siberian flying squirrels, which are endangered in Finland. Notable plants found in the area include ''

Platanthera bifolia ''Platanthera bifolia'', commonly known as the lesser butterfly-orchid, is a species of orchid in the genus ''Platanthera'', having certain relations with the genus ''Orchis'', where it was previously included and also with the genus '' Habenar ...

'' and ''

Goodyera repens ''Goodyera repens'', an orchid in the genus ''Goodyera'', is called by the common name creeping lady's-tresses in Anglophone Europe and dwarf rattlesnake plantain or lesser rattlesnake plantain in North America. It is a green underground creeper ...

''.

References

{{reflist, refs= *{{Cite web, title=Köhniönjärvi (location on a map) - Karttapaikka, url=https://asiointi.maanmittauslaitos.fi/karttapaikka/?lang=fi&share=customMarker&n=6902038.032209022&e=430637.4360934294&title=&desc=&zoom=10&layers=W3siaWQiOjIsIm9wYWNpdHkiOjEwMH1d-z, publisher=National Land Survey of Finland (Maanmittauslaitos), access-date=2024-11-11, website=asiointi.maanmittauslaitos.fi *{{Cite web, title=Köhniönjärvi in the Paikkatietoikkuna map service, url=https://kartta.paikkatietoikkuna.fi/?zoomLevel=9&coord=432515.04494336084_6900919.858579077&mapLayers=801+39+default,4045+100+ranta10_jarvi,104+100+HY.PhysicalWaters.Catchments.DrainageBasin.Default,200+100+HY.Network.Default,201+100+HY.Network.HydroNode.Default&uuid=90246d84-3958-fd8c-cb2c-2510cccca1d3&noSavedState=true&showIntro=false, publisher=National Land Survey of Finland (Maanmittauslaitos); hydrographic data: Finnish Environment Institute (SYKE)., access-date=2024-11-11, website=kartta.paikkatietoikkuna.fi *{{Cite web, title=Uimavesiprofiili / Köhniö - Jyväskylän seudun ympäristöterveys, url=https://www.jyvaskyla.fi/sites/default/files/2023-06/uimavesiprofiili_kohnio.pdf, author=, date=2023-06-07, publisher=City of Jyväskylä, access-date=2024-11-11, website=jyvaskyla.fi, language=fi *{{Cite web, title=VALUE - Valuma-alueen rajaustyökalu, trans-title=Drainage basin measurement tool, url=https://paikkatieto.ymparisto.fi/value?runWorkflow=CatchmentFromId&jarviUomaId=2006012717174, publisher=Finnish Environment Institute (SYKE), access-date=2024-11-11, website=paikkatieto.ymparisto.fi, language=fi *{{Cite web, last=Paavilainen, first=Päivi, date=2009-11-09, title=Jyväskylän kaupunki: Valuma-alueselvitys – Kartta 1 (Päävaluma-alueet ja pääuomat), trans-title=Drainage basin report – Map 1 (Main catchment areas), url=https://www2.jkl.fi/kaavakartat/valuma-alueselvitys/kartta1.pdf, publisher=Ramboll, access-date=2024-11-09, website=jkl.fi, language=fi *{{Cite web, title=Jyväskylän kaupunki - Valuma-alueselvitys, Kartta 4 (Kaupunkialueen valuma-alueet ja pääreitit), trans-title=Drainage basin report - map 4: catchment areas within the urban area, url=https://www2.jkl.fi/kaavakartat/Valuma-alueselvitys/kartta4.pdf, author=Paavilainen, Päivi, date=2009-11-09, publisher=Ramboll, access-date=2024-11-11, website=jyvaskyla.fi, language=fi *{{Cite web, last1=Pietarinen, first1=Päivi, last2=Sihvonen, first2=Heikki, date=2007-10-01, title=Jyväskylän merkittävät luontokohteet, trans-title=Notable nature sites of Jyväskylä, url=https://www2.jkl.fi/kaavakartat/viherosayleiskaava/luontoselvitys_2007.pdf, page=19, publisher=City of Jyväskylä, access-date=2024-11-11, website=jkl.fi, language=fi Lakes of Jyväskylä Kymi basin