Great Lake Plön

Great Lake Plön
	View of the islands in Lake Plön. On the right the southern tip of Prince Island
Geographical location	eastern Schleswig-Holstein
Tributaries	Schwentine
Drain	Schwentine
Places on the shore	Plön , Dersau , Bosau , Ascheberg , Sepel , Godau
	Data
Coordinates	54 ° 7 '49 " N , 10 ° 24' 51" E Coordinates: 54 ° 7 '49 " N , 10 ° 24' 51" E
Altitude above sea level	21 m above sea level NN
surface	28.4 km²
length	7.75 km
width	7 km
volume	0.384.6 km³
scope	49.6 km
Maximum depth	56.2 m
Middle deep	13.54 m
Catchment area	382 km²
particularities	One of the few nutrient-poor lakes in Schleswig-Holstein, since 2003 in a stable mesotrophic state.

The Große Plöner See , also just Plöner See , is the largest lake in Schleswig-Holstein and the tenth largest lake in Germany with a good 28 km² . It extends southwest of the city of Plön , which lies on its bank.

geography

General

With a lake area of 28 km² and a depth of up to 56 m, the lake, which lies entirely in the Holstein Switzerland Nature Park , is the largest and deepest in Schleswig-Holstein. On the north bank lies the district town of Plön , with the landmark of the lake, the Plön Castle , located on a hill . Other places on the shores of the Großer Plöner See are Bosau , Dersau and Ascheberg .

Emergence

The Great Plöner See was created as a result of the glaciation of Schleswig-Holstein after the last ice age. It is a typical Vistula tongue basin , the shape of which is particularly easy to understand on the southern bank between Bosau and Nehmten . Two glaciers essentially formed the eastern Plön basin, which is 58 m deeper, and the western Ascheberg basin, which is 30 m shallower. The northern boundary of the lake consists of a land bridge between the Great and Small Plöner See , which was created as a terminal moraine during a later ice advance.

Islands

The eastern and western parts of the lake are connected by a shallow water area that has been designated as a nature reserve " Islands in the Great Plön Lake and the Störland Peninsula " since 1992 . Most of the islands are located in this area. They offer various bird species such as white-tailed eagles , golden- tailed ducks , goosander and greylag goose, breeding and moulting areas with little disruption and sheltered from the wind.

The Prince's Island , which became a peninsula in the 19th century due to the artificial lowering of the water level, extends from here over a length of 2 km to the north and is a popular destination for tourists in summer.

With the " Ascheberger Warder in Großer Plöner See " there is another nature reserve that has existed since 1955 in the western part of the lake around the Ascheberger Warder. In total, more than 20 islands are spread over the area of the Great Plön Lake. The islands of Olsborg and Bischofswarder are historically important as former Slavic settlements .

Water levels

Originally (at the beginning of the postglacial ) the water level of the lake was 15 to 18 m above today's level and covered the entire area of the lakes of Holstein Switzerland through which the Schwentine flows today .

Sediment samples that were taken from the bottom of the lake at a depth of 41 m show that the first dams were built as early as the 13th century.

After the damming right of the old mill (already mentioned in 1221) and the right to catch eel, the water level of the lake was lowered by 1.14 m. The associated goal of land reclamation was thus achieved, but the land that was gained turned out to be a stony, low-yielding area. With the lowering of the water level, the receiving water was also improved.

The water level of the lake is currently about 21 m above sea level. NN and varies depending on the season by about 40 cm.

Chemical condition

Mercury pollution

Mercury compounds are toxic to bacteria due to their ability to bind to the hydrogen sulfide groups of protein. Mercury accumulates in the food chain in the form of the toxic methylmercury. According to the Biota environmental quality standard, the mercury content in the fish fillet (muscle meat) is decisive for the assessment of the chemical situation in water .

In 2013 and 2016, 8 and 9 rivers and 6 lakes in Schleswig-Holstein were examined for their mercury content in the fish fillet. All measured values were above the biota EQS of 20 μg / kg. The examined lakes also included the Great Plön Lake, where in 2013 almost 300 μg / kg and in 2016 just over 150 μg / kg of mercury were found in the fish fillet.

According to Annex X of Directive 2000/60 / EC, mercury is classified as a priority hazardous substance; if it is exceeded, the chemical status is assessed as poor.

AMPA

Aminomethylphosphonic acid (AMPA) is the main breakdown product of glyphosate in the soil zone. AMPA has traction properties similar to glyphosate, but is considerably more stable. AMPA is broken down into carbon dioxide in soil and water. The half-life DT ₅₀ for soils is 44 to 215 days, for water it is 14 days.

The AMPA content was examined in 33 lakes in 2008 and 2012 and could be detected in 59% of the samples, including in the large Plön lake. AMPA occurs throughout Schleswig-Holstein and exceeds the assumed drinking water reserve value of 0.1 μg / L several times.

history

First settlement

The lakeshore was used by hunters, gatherers and fishermen in the Middle Stone Age (approx. 10,000–4300 BC). Lived since the Younger Stone Age (approx. 4300–2300 BC), through the Bronze Age (approx. 2300–550 BC) and into the Iron Age (approx. 550 BC – 400 AD) here more or less continuously farmers.

Olsburg

From the 8th to the 12th century AD, the area around Lake Plön was a Slavic settlement area. Olsborg, an island south of Plön, which was provided with extensive fortifications, still bears witness to this. Presumably it is identical to the castrum Plune mentioned by the chroniclers Adam von Bremen and Helmold von Bosau , whose Slavic name Plune means "ice-free water", from which the current place name Plön is derived. In 1139 the Holstein Count Adolf II von Schauenburg destroyed the fortress and thus ended the Slavic rule over the Plön area.

Economic use

The lake area is shared by various private owners and the state of Schleswig-Holstein. Around 900 hectares of the lake are leased by 2020.

The lake is fished by several professional fishermen. There are eel, perch, bream, pike, tench, carp, whitefish and vendace , among others .

Tourism and recreational activities

Sailboat on the Great Plöner See

The lake and its surroundings are a popular local recreation area for residents of the greater Kiel, Lübeck and Hamburg areas and a center of tourism in Holstein Switzerland. A total of 15 bathing areas are designated. Some campsites (including in Bosau and Ruhleben) are located directly on the lake shore. There is a wide range of leisure activities such as water hiking, sailing, diving and fishing. Private use of motor boats is not permitted with either an electric or a combustion engine. Commercial excursion boats operate on the lake in the summer months.

and display information about the image

Panorama of the lake

literature

Uwe Muuß, Marcus Petersen, Dietrich König: The inland waters of Schleswig-Holstein. 162 p., Numerous Fig., Wachholtz-Verlag Neumünster, 1973. ISBN 3-529-05302-3

Web links

Commons : Großer Plöner See - Collection of images, videos and audio files

Individual evidence

↑ ^a ^b ^c ^d ^e ^f Großer Plöner See: Characteristic data . In: Ministry for Energy Transition, Agriculture, Environment and Rural Areas Schleswig-Holstein: Lakes (accessed on September 18, 2012)
^ ^A ^b Brigitte Nixdorf, Mike Hemm, Anja Hoffmann, Peggy Richter: Documentation of the condition and development of the most important lakes in Germany: Part 1 Schleswig-Holstein . Final report R&D project FKZ 299 24 274 on behalf of the Federal Environment Agency, 2004 ( PDF file; 2.1 MB )
↑ ^a ^b ^c ^d ^e Maren Jarosch: Report on the chemical situation of rivers and lakes in Schleswig-Holstein . Ed .: State Office for Agriculture, Environment and Rural Areas of the State of Schleswig-Holstein, Waters Department. 1st edition. Flintbek November 2018 ( schleswig-holstein.de [PDF]).
↑ Ulrich Mueller: The Olsborg - an island settlement around the year 1000 . In: F. Biermann u. a. (Ed.): The change around 1000. Contribution. Prehistory and early history of Central Europe 60 (Langenweissbach 2011), pp. 85–96.

[Daten-1] ↑ ^a ^b ^c ^d ^e ^f Großer Plöner See: Characteristic data . In: Ministry for Energy Transition, Agriculture, Environment and Rural Areas Schleswig-Holstein: Lakes (accessed on September 18, 2012)

[BTU-2] A ^b Brigitte Nixdorf, Mike Hemm, Anja Hoffmann, Peggy Richter: Documentation of the condition and development of the most important lakes in Germany: Part 1 Schleswig-Holstein . Final report R&D project FKZ 299 24 274 on behalf of the Federal Environment Agency, 2004 ( PDF file; 2.1 MB )

[:0-3] Maren Jarosch: Report on the chemical situation of rivers and lakes in Schleswig-Holstein . Ed .: State Office for Agriculture, Environment and Rural Areas of the State of Schleswig-Holstein, Waters Department. 1st edition. Flintbek November 2018 ( schleswig-holstein.de [PDF]).

[4] Ulrich Mueller: The Olsborg - an island settlement around the year 1000 . In: F. Biermann u. a. (Ed.): The change around 1000. Contribution. Prehistory and early history of Central Europe 60 (Langenweissbach 2011), pp. 85–96.