Biggesee

Biggesee
Name	Biggesee
Location	Olpe district, North Rhine-Westphalia, Germany
Type	Reservoir
Inflow	Lenne, Sieg tributaries
Outflow	Sieg
Catchment	307 km2
Area	8.76 km2
Max-depth	52 m
Volume	150 million m3
Shore	c. 46 km
Coordinates	51°03′N 7°52′E

Biggesee

Biggesee is a large artificial reservoir in the Olpe district of North Rhine-Westphalia in Germany. The reservoir lies in the Sauerland uplands, formed by damming tributaries of the Sieg to provide flood control, drinking water and hydroelectricity for cities such as Dortmund, Düsseldorf, and Cologne. The lake and surrounding landscape intersect municipal areas including Attendorn, Finnentrop, and Wenden, and form part of regional recreation networks linked to the Rheinland and Ruhr conurbations.

Geography

Biggesee sits within the Sauerland near the Rothaargebirge foothills, bordered by municipalities Attendorn, Finnentrop, Wenden, and Lennestadt and lying in the river basin of the Sieg. The reservoir occupies valleys carved by tributaries such as the Lister and the Rönkhausen streams, creating a shoreline with numerous peninsulas and inlets similar to reservoirs like Möhnesee and Edersee. Surrounded by mixed forests that include managed tracts of state forest and private woodlands, the lake is connected by road networks to the A45 autobahn via local roads toward Olpe, and served by rail links through Finnentrop station on routes to Siegen and Dortmund.

History and construction

The decision to impound the valley followed major 20th-century flood events that affected cities including Cologne, Dortmund, and Essen, prompting regional agencies such as the North Rhine-Westphalia Ministry of the Interior and Local Affairs and utility companies like RWE and local water boards to plan storage reservoirs. Construction began after planning by engineers influenced by projects like the Edersee scheme and guidance from civil engineering firms that had worked on the Möhne Dam. The dam wall, completed in the mid-20th century, was built using techniques from contemporaneous projects such as the Barrage de la Gileppe and employed concrete and earth-fill methods overseen by contractors and overseers with ties to institutions like the Technische Hochschule Darmstadt and consulting engineers who consulted archives from the Bundesanstalt für Wasserbau. The inundation required relocation of settlements and infrastructure, negotiations with municipalities including Attendorn and Finnentrop, and compensation schemes administered in coordination with courts such as the Administrative Court of Arnsberg.

Hydrology and water management

The reservoir regulates flows of the Sieg catchment, integrating inflows from tributaries monitored by agencies including the German Weather Service (DWD), the Wupperverband modelers, and regional water authorities like the Wasserverband Eder. Biggesee contributes to flood mitigation downstream in towns such as Siegen, Betzdorf, and Altenkirchen, and to municipal water supplies for urban areas including Dortmund, Hagen, and Wuppertal. Hydropower installations at the dam produce regulated electricity feeding grids managed by operators such as E.ON and RWE, while water quality is monitored under standards aligned with the European Union Water Framework Directive and laboratories connected to universities like the University of Bonn and RWTH Aachen University.

Ecology and biodiversity

The reservoir and its riparian zones provide habitat for species documented by conservation organizations including NABU and the Bundesamt für Naturschutz. Aquatic fauna include populations of pike, perch, and brown trout, and the shoreline supports birds such as great crested grebe, grey heron, and migratory common loon visitors recorded in regional bird atlases coordinated with the Ornithological Society of North Rhine-Westphalia. Terrestrial habitats around the lake host mammals like red deer, roe deer, and smaller carnivores such as red fox and European badger, managed within hunting regulations enforced by local hunting associations affiliated with the German Hunting Association. Conservation efforts reference habitats listed under the Natura 2000 framework and coordinate with the State Office for Nature, Environment and Consumer Protection North Rhine-Westphalia on measures addressing invasive species and eutrophication.

Recreation and tourism

Biggesee is a regional destination for boating, sailing, angling and hiking, attracting visitors from the Ruhrgebiet and Rhineland and feeding hospitality sectors in towns such as Attendorn and Finnentrop. Facilities include marinas, campgrounds and trails connected to long-distance routes like the Rothaarsteig and local cycling networks linked to the RuhrtalRadweg. Events organized by clubs affiliated with the German Sailing Association and sport organizations such as Deutscher Angelfischerverband draw competitors, while visitor services coordinate with tourism offices like the Tourismus NRW and regional marketing bodies promoting attractions such as the nearby Atta Cave and cultural sites in Attendorn.

Economic and social impact

The reservoir supports regional water supply and hydroelectric revenue streams that benefit municipalities and companies including Olpe (district), RWE, and local utilities, while recreational tourism generates income for hospitality businesses, marinas and outdoor outfitters. Land use changes from construction influenced agriculture and forestry in parishes governed by municipal councils in Attendorn, Finnentrop, and Wenden, and relocation compensation involved legal processes in courts such as the District Court of Olpe. Infrastructure investments improved road and rail links to labor markets in Dortmund, Siegen, and Düsseldorf, influencing commuting patterns studied by research centers like the Institute for Employment Research.

Management and conservation

The reservoir is managed by regional water authorities in coordination with agencies including the State Agency for Nature, Environment and Consumer Protection North Rhine-Westphalia and municipal governments of Attendorn and Finnentrop. Management tasks encompass flood control planning using models developed with universities such as University of Duisburg-Essen, water quality monitoring aligned with the European Union Water Framework Directive, biodiversity measures coordinated with NABU, and recreational zoning enforced under local ordinances adjudicated in administrative bodies like the Arnsberg Government District. Long-term conservation strategies reference national initiatives such as the German Strategy for Biological Diversity and integrate stakeholder dialogues involving energy firms like E.ON, community groups, and scientific partners at institutions such as the University of Münster.

Category:Lakes of North Rhine-Westphalia