The Hengsteysee (Lake Hengstey) is a

reservoir A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including contro ...

on the

Ruhr The Ruhr ( ; german: Ruhrgebiet , also ''Ruhrpott'' ), also referred to as the Ruhr area, sometimes Ruhr district, Ruhr region, or Ruhr valley, is a polycentric urban area in North Rhine-Westphalia, Germany. With a population density of 2,800/km ...

river between the cities of

Hagen Hagen () is the Largest cities in Germany, 41st-largest List of cities and towns in Germany, city in Germany. The municipality is located in the States of Germany, state of North Rhine-Westphalia. It is located on the south eastern edge of the R ...

Dortmund Dortmund (; Westphalian nds, Düörpm ; la, Tremonia) is the third-largest city in North Rhine-Westphalia after Cologne and Düsseldorf, and the eighth-largest city of Germany, with a population of 588,250 inhabitants as of 2021. It is the la ...

and

Herdecke Herdecke () is a town in the district of Ennepe-Ruhr-Kreis, North Rhine-Westphalia in Germany. It is located south of Dortmund in the Ruhr Area. Its location between the two Ruhr reservoirs Hengsteysee and Harkortsee has earned it the nickname ...

North Rhine-Westphalia North Rhine-Westphalia (german: Nordrhein-Westfalen, ; li, Noordrien-Wesfale ; nds, Noordrhien-Westfalen; ksh, Noodrhing-Wäßßfaale), commonly shortened to NRW (), is a States of Germany, state (''Land'') in Western Germany. With more tha ...

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

. It was built in 1929 and is one of five reservoirs on the Ruhr. The reservoir is about long and has an average width of . It begins near the point where the

Lenne The Lenne is a tributary of the river Ruhr in the Sauerland hills, western Germany. It has caused flooding in recent years. Having its source on top of the ''Kahler Asten'' near Winterberg in an intermittent spring at an elevation of , the Le ...

flows into the Ruhr, and ends with the

weir A weir or low head dam is a barrier across the width of a river that alters the flow characteristics of water and usually results in a change in the height of the river level. Weirs are also used to control the flow of water for outlets of l ...

and

hydroelectric plant Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined and ...

of Hengsteysee. The

Klusenberg The Klusenberg is, at , the highest elevation on the territory of the city of Dortmund. The Klusenberg part of the Ardey Hills lies west of the Hohensyburg The Syberg is a hill in the Ruhr in the southern part of Dortmund, 240 m above Normalnul ...

, a hill that is part of the Ardey range, is located just north of the Hengsteysee. There is also a pumped-storage plant on this reservoir (called the Koepchenwerk after

Arthur Koepchen Arthur is a common male given name of Brittonic languages, Brythonic origin. Its popularity derives from it being the name of the legendary hero King Arthur. The etymology is disputed. It may derive from the Celtic ''Artos'' meaning “Bear”. An ...

), along with a 4.5 MWh

grid services Ancillary services are the services necessary to support the transmission of electric power from generators to consumers given the obligations of control areas and transmission utilities within those control areas to maintain reliable operations of ...

battery Battery most often refers to: * Electric battery, a device that provides electrical power * Battery (crime), a crime involving unlawful physical contact Battery may also refer to: Energy source *Automotive battery, a device to provide power t ...

repurposed from electric cars. Hengsteysee fulfills the following four functions: *functions as the lower reservoir of the Koepchenwerk pumped-storage plant *performs biological purification of water from the Lenne *deposit of sediment from the Lenne *venue for

water sport Water sports or aquatic sports are sport activities conducted on waterbodies, and can be categorized according to the degree of immersion by the participants. On the water * Boat racing, the use of powerboats to participate in races * Boatin ...

s and tourism

Water sports

The Hengsteysee is a water sports area, especially for

sailing Sailing employs the wind—acting on sails, wingsails or kites—to propel a craft on the surface of the ''water'' (sailing ship, sailboat, raft, windsurfer, or kitesurfer), on ''ice'' (iceboat) or on ''land'' (land yacht) over a chosen cour ...

rowing Rowing is the act of propelling a human-powered watercraft using the sweeping motions of oars to displace water and generate reactional propulsion. Rowing is functionally similar to paddling, but rowing requires oars to be mechanically atta ...

and

canoe A canoe is a lightweight narrow water vessel, typically pointed at both ends and open on top, propelled by one or more seated or kneeling paddlers facing the direction of travel and using a single-bladed paddle. In British English, the term ...

ing. Several

sports clubs A sports club or sporting club, sometimes an athletics club or sports society or sports association, is a group of people formed for the purpose of playing sports. Sports clubs range from organisations whose members play together, unpaid, and ...

are based on the lake shore: the Hengsteysee Sailing Club (SGHS), Dortmund University Sailing Club (USC), the sailing group of the Hagen Disabled Sports Association (BSG) with its boathouse on ''Seestraße'', the Syburg Sailing Club, the Hagen Canoe Club and the Dortmund Sports Club (''Freier Sportverein Dortmund 1898'', FS 98). The DLRG groups of the county of Dortmund (there is a water rescue station on ''Hengsteystrasse'') and OG Hagen (water rescue station on ''Seestrasse'') ensure safety on the water. However, the Hengsteysee is unsuitable for swimming and bathing - it is not a

bathing lake A bathing lake is a natural or artificial lake that is used for public bathing and swimming. In the water, bathers mostly remain close to the shore and use the area for recreational purposes, such as sport, games and sunbathing. In Europe, because ...

, and the

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 tr ...

of the Ruhr is not good enough for a suitable permit. The health department has also expressly warned against this since September 2008, when several people had to seek medical treatment after coming into contact with the lake water. Hengsteysee 2008 Wasserpest 3

Due to the low water depth (less than 50 cm in some places) at times and especially due to the mass proliferation of the

waterweed ''Elodea'' is a genus of 6 species of aquatic plants often called the waterweeds described as a genus in 1803. Classified in the frog’s-bit family (Hydrocharitaceae), ''Elodea'' is native to the Americas and is also widely used as aquarium vege ...

''Elodea'' in summer since the late 1990s, water sports on the Hengsteysee have been severely curtailed.

References

Reservoirs in North Rhine-Westphalia RHengsteysee {{NorthRhineWestphalia-geo-stub