Lilla Sjö is a lake in the municipality of Hässleholm in

Skåne Scania ( ), also known by its native name of Skåne (), is the southernmost of the historical provinces of Sweden, provinces () of Sweden. Located in the south tip of the geographical region of Götaland, the province is roughly conterminous w ...

and is part of the main catchment area of the

Helge River The river Helge or, in Swedish, Helgeån, alternatively Helge å (lit. The Holy river), is a river which flows through Småland and Skåne in southern Sweden. The course of the river takes it through Kristianstad and out to the Bay of in th ...

. The lake has an area of 0.144 square kilometers and has an elevation of 57.6

meters above sea level Height above mean sea level is a measure of a location's vertical distance (height, elevation or altitude) in reference to a vertical datum based on a historic mean sea level. In geodesy, it is formalized as orthometric height. The zero level vari ...

. During test fishing,

perch Perch is a common name for freshwater fish from the genus ''Perca'', which belongs to the family Percidae of the large order Perciformes. The name comes from , meaning the type species of this genus, the European perch (''P. fluviatilis'') ...

white bream ''Blicca'' is a monospecific genus of freshwater ray-finned fish belonging to the family Leuciscidae. The only species in the genus is ''Blicca bjoerkna'', the white bream or silver bream. This species is found in Europe and Western Asia. Distr ...

bream Bream (, ) are species of freshwater fish belonging to a variety of genera including '' Abramis'' (e.g., ''A. brama'', the common bream), '' Ballerus'', '' Blicca'', '' Brama'', '' Chilotilapia'', '' Etelis'', '' Lepomis'', '' Gymnocranius'', ...

and

pike Pike, Pikes or The Pike may refer to: Fish * Blue pike or blue walleye, an extinct color morph of the yellow walleye ''Sander vitreus'' * Ctenoluciidae, the "pike characins", some species of which are commonly known as pikes * ''Esox'', genus of ...

have been caught in the lake.Until the 1940s, the lake was a bathing lake with a sandy bottom and three bathing places: the ladies', the men's and the priest's. However, due to the lack of a functional

wastewater treatment Wastewater treatment is a process which removes and eliminates contaminants from wastewater. It thus converts it into an effluent that can be returned to the water cycle. Once back in the water cycle, the effluent creates an acceptable impact on ...

plant, non-existent filtration from peat mining at Åbuamossen, and phosphorus and nitrogen leaks from households and agriculture, it became difficult for the lake to survive on its own. There is a 2.6 km long illuminated exercise trail around Lilla Sjö. Additionally, there is an outdoor gym by the lake, which is connected to the exercise trail.

History and conservation

Lilla Sjö has been lowered twice by a total of about 1.8 meters. The first lake lowering occurred in the 1860s when the

Southern Main Line The Southern Main Line () is a long standard gauge electrified railway between Malmö and Katrineholm in Sweden. The trains continue further on to Stockholm Central Station along the Western Main Line and terminate there (at platforms 16–19). ...

was built. The second lowering took place in the early 1900s, with the aim of creating new agricultural land. Today, the water depth is approximately 0.8 to 1 meter For a long time, the lake has been polluted by untreated sewage, stormwater and peat and humus residues from peat mining at Åbuamossen via Kvarnabäcken. Additionally, residues from local slaughterhouses and dairies have been flushed directly into the lake, sometimes causing it to appear completely white. As a result of this extensive load of nutrients and humus, the lake became heavily eutrophied, which manifested itself partly through overgrowth and partly through heavy blooming of

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 ...

, mainly

Microcystis ''Microcystis'' is a genus of freshwater cyanobacteria that includes the harmful algal bloom-forming '' Microcystis aeruginosa''. Over the last few decades, cyanobacterial blooms caused by eutrophication have become a major environmental proble ...

. The first treatment plant was built in 1961. In 1977, the Lillasjön Nature Conservation Association was formed. In cooperation with Hässleholm Municipality, they developed an action program for the conservation of the lake. Restoration began in the early 1990s by regulating the water level, cutting reeds, and moving the outlet of the nearby sewage treatment plant to a wetland south of the lake. The first step in the restoration of Lilla sjö was an extensive water and sewage treatment of Kvarnabäcken, the lake's main tributary. In addition, the footbridge that separated the northern part of the lake from its southern part (which is a

wetland A wetland is a distinct semi-aquatic ecosystem whose groundcovers are flooded or saturated in water, either permanently, for years or decades, or only seasonally. Flooding results in oxygen-poor ( anoxic) processes taking place, especially ...

) was replaced with a dike that provided some regulation of the water level. Nutrient relief was achieved by relocating the outlet of the treatment plant from the northern to the southern part of the lake. There was an interest in revitalizing and expanding the wetland, prompting the construction of an elongated pond at its outer edge for the outlet. The water from this dam infiltrates the entire length of the wetland, thereby wetting previously dried-up outer areas. The combined effect of these measures was a significant reduction in phosphorus and nitrogen levels in the northern part of the lake, leading to a decrease in algal bloom. The relief of Kvarnabäcken and the relocation of the sewage treatment plant's discharge point greatly improved the situation in the northern part of the lake by the late 1990s. In 2016 and 2017, a study was carried out to investigate different options for removing some of the lake's bottom sediment. It is estimated that there is approximately 4 meters of bottom sediment, consisting of residues from peat mining on the Åbua bog. The downstream lakes Ottarpasjön and Ballingslövssjön are also under investigation regarding water conservation measures.{{Cite web , title=Projektplan – Vattenmiljö. Ballingslövssjön och Ottarpasjön , url=http://www.fiske.ballingslov.nu/projektplan.pdf , archive-url=https://web.archive.org/web/20170917194126/http://www.fiske.ballingslov.nu/projektplan.pdf , archive-date=September 17, 2017 , access-date=October 5, 2017 , publisher=Ballingslövssjöns och Ottarpssjöns Fiskevårdområdesförening , language=sv

Sub-catchment area

Lilla Sjö is part of the sub-catchment area (623467–137980) that SMHI calls 'Mynnar i Almaån.' The average altitude is 70 meters above sea level, and the area covers 43.87 square kilometers. There is an upstream catchment area, and when included, the accumulated area is 65.49 square kilometers. The Lilla å, which drains the catchment area, has a tributary order of 3, indicating that the water flows through a total of 3 watercourses before reaching the sea after traveling 70 kilometers. The catchment area mainly consists of forest (52%), open land (13%), and agriculture (23%). In terms of water surface, the catchment area encompasses 1.2 square kilometers, giving it a lake percentage of 2.7%. The settlements in the area cover 2.57 square kilometers or 6 percent of the catchment area.

Fish

During test fishing, the following fish have been caught in the lake: * Perch * White bream * Freshwater bream * Pike *

Roach Roach or The Roach may refer to: Animals * Cockroach, various insect species of the order Blattodea * Common roach (''Rutilus rutilus''), a fresh and brackish water fish of the family Cyprinidae ** ''Rutilus'' or roaches, a genus of fishes * Cal ...

Rudd ''Scardinius'' is a genus of freshwater ray-finned fishes belonging to the family Leuciscidae, which includes the daces, Eurasian minnows and related species. The fishes in this genus are commonly called rudds. Locally, the name "rudd" without ...

Tench The tench or doctor fish (''Tinca tinca'') is a freshwater, fresh- and brackish water, brackish-water fish of the order Cypriniformes found throughout Eurasia from Western Europe including Great Britain, Britain and Ireland east into Asia as far ...

Carp The term carp (: carp) is a generic common name for numerous species of freshwater fish from the family (biology), family Cyprinidae, a very large clade of ray-finned fish mostly native to Eurasia. While carp are prized game fish, quarries and a ...

are also reported to be found.

References

External links

SMHI: Sjöar, vattendrag och avrinningsområden

Delavrinningsområden
p�
SMHI Vattenwebb (S-HYPE)

Ladda ner data från Svenskt Vattenarkiv

Lilla sjö (Lilla Sjö) på VISS
Lakes of Sweden Lakes of Skåne County Hässleholm Municipality