The Möhne dam is the eighth largest dam in Germany
The Möhne Dam, which went into operation in 1913 as the largest dam in Europe, is still a key element in controlling the water flow of the Ruhr today, accounting for over 25 per cent of the total reservoir storage space in the Ruhr catchment area. With its 650 metre long and up to 40 metre high gravity dam made of quarry stone, 134.5 million cubic metres of water can be dammed up.
The water released from the dam during normal operation is used to generate energy in a power station (main power station) located below the wall. However, the release of water is only based on the requirements of the water volume management of the Ruhr. Electricity generation is a secondary use, but favours CO2-free energy production. From the main power station, the water flows into the equalising pond, from where the water is discharged evenly throughout the day via a smaller power station (secondary power station) into the lower reaches of the Möhne. The power stations are operated by Lister- und Lennekraftwerke GmbH in Olpe, a wholly owned subsidiary of the Ruhrverband.
Two bottom outlet groups, each with two independent bottom outlets, are available for releasing water from the dam if the main power station fails or if its capacity is exceeded. The discharge devices of each group consist of a ring valve, which allows the discharge to be regulated continuously, and a housing slide valve with a conical nozzle. All four bottom outlets flow into the equalising pond. There are 105 openings with a total length of 262.5 metres in the top of the wall for flood relief. The distribution of these openings over around three quarters of the length of the crown gives the impression that the wall is flooded over almost its entire length when it overflows. The air side of the wall is made so rough by protruding stones that this already causes a partial energy conversion of the water flowing down. The actual conversion then takes place in the equalising pond, which acts as a stilling basin. Larger quantities of water can be discharged from the equalising pond via a fish belly flap located at the secondary power station. In the reservoir root area, i.e. where the Möhne and Heve rivers flow into the dam, two forebays were created during the construction of the Möhne dam. The two fixed weirs of the forebay dams ensure a relatively even water level, which prevents swamping in the shallow inlet area of the dam. This also creates a water body with special water-biological conditions that is separate from the main dam, which is desirable for water quality reasons.
Tasks and function
During our tours, you will learn interesting facts about the construction, water supply and operation of our dams.
The energy from the water is converted into electricity in the main power plant at the Möhne dam. This means that around 3,000 households can be supplied with environmentally friendly and climate-neutral electricity.
The Möhne dam offers numerous opportunities to spend your leisure time actively or relaxing. Whether fishing, cycling or diving - discover the various sports and leisure activities on offer.
Sport & Leisure
With a water surface area of 1,037 hectares, Lake Möhne is the largest Ruhrverband dam in terms of surface area. It stretches over a length of 8 kilometres on the north-western edge of the Arnsberg Forest Nature Park. Lake Möhne is up to 800 metres wide and reaches a maximum water depth of 32 metres when fully dammed.
You can find more detailed information about fishing at the Möhne dam on our fishing website.
Our leisure map provides you with an overview of the designated bathing areas at the Möhne dam. The North Rhine-Westphalia State Agency for Nature, Environment and Consumer Protection (LANUV) also provides an overview of the designated bathing areas in NRW in accordance with the EC Bathing Water Directive in an interactive map.
Outside the designated bathing areas, bathing is prohibited in the Ruhrverband reservoirs.
In the summer months, various passenger boats on Lake Möhne invite you to take a trip.
Using the Möhne dam with rowing boats, canoes or rubber dinghies falls under public use and can therefore be practised free of charge. Various clubs have set up on the lakes, from which further information on water sports activities can be obtained.
The following sailing clubs and schools are based at the Möhne dam:
Water sports and sailing schools
Möhnesee water sports school Herbst
Sailing clubs
Sailing Club 77 Möhnesee e. V.
Sailing Club Möhnesee Süd e. V.
Möhnesee Südufer sailing community
Möhnesee Delecke Sailing Club e. V.
Westphalian Yacht Club Delecke e.V.
Sailing group of the workers' welfare organisation
Yacht Club Westfalia Arnsberg e.V.
Körbecke-Möhnesee Water Sports Club e.V.
Yacht Club Sauerland Möhnesee e.V.
British-Möhnesee-Sailing-Club (Nato-Club)
Regatta- und Fahrtensegler-Club Möhnesee e.V.
Jetty community Mertens
Jetty community Delecker Becken Südufer
The dive site on Lake Möhne is located on the southern shore, west of the Delecker Bridge in Delecker Bay. The diving area, a former quarry with a sandy bottom, is demarcated by buoys. Diving is not permitted outside the marked diving area. The piers of the Delecker Bridge are not part of the diving area. A path along the edge of the quarry leads from the car park, which is particularly busy in the summer months, to the entry point. Diving is possible all year round in the Möhne dam - the PRO DIVE diving school operates the diving site (subject to a fee).
Registration (procedure, costs, terms of use) at PRO DIVE - Der Tauchplatz
History
History
Construction of the Möhne Dam began in 1908 on the edge of the Arnsberg Forest. The construction of the Möhne Dam, the first major project of the then still young Ruhr Valley Dam Association (RTV), which was merged with the Ruhrverband in 1990, cost the enormous sum of 25 million marks for the time.
When it was completed, the Möhne Dam was the largest dam in Europe with a reservoir capacity of 130 million cubic metres. The dam wall designed by Franz Brantzky with its striking archways is now a listed building.
The Möhne Dam was destroyed by a British bombing raid during the Second World War. During the attack on the night of 16/17 May 1943, so-called rotation bombs were used, which were designed to bounce over the safety nets in the direction of the dam wall and detonate at a depth of around ten metres. Of the bombs dropped over the Möhne dam, one hit its target. The explosive effect of the bomb initially created a small crack in the dam wall, which quickly widened due to the pressure of the escaping water masses and finally resulted in a 77 metre wide trapezoidal gap in the centre of the wall.
The dam was full at the time of the attack. Within a few hours, more than 100 million cubic metres of water poured out far into the Ruhr valley. At least 1,500 people died in the flood wave, which caused more than 100 millioncubic metres of water to flow out in less than 9 hours. Most of them in a prisoner-of-war or labour camp five kilometres below the barrier wall. Today, a memorial at the former Himmelpforten monastery, which was completely destroyed, commemorates the dead in this camp. In Neheim, which today belongs to Arnsberg and was badly hit by the flood, a memorial in the town centre also commemorates the victims of the disaster.
The reconstruction of the dam wall by the Organisation Todt, a Nazi construction unit organised according to military principles, began a few days after the attack. A large number of prisoners of war and forced labourers were also used. The wall was dammed up again after repairs in September 1943. However, the Ruhrtalsperrenverein did not begin rebuilding the damaged bottom outlets until 1950, when a new power station was built at the outlet of the former diversion tunnel for the Möhne and Heve rivers to replace the main power station, which had been completely destroyed in the attack. The old secondary power station was demolished and - together with a significantly enlarged compensating pond - also replaced by a new power station, which was built 400 metres west of the old position.
An extensive investigation in 1970 showed that comprehensive remediation measures were necessary. First of all, a working, drainage and inspection tunnel was constructed in the transition area from the masonry to the subsoil using normal blasting operations. The barrier structure and the subsoil were sealed from the tunnel and from the top of the wall. The water flow was thus reduced to a harmless level. The control and drainage boreholes created in the process allow the flow conditions to be continuously monitored.
In the 1990s, the 80-year-old drains were replaced and the slide gate towers were sealed. The bottom outlet pipes were completely renewed. Extensive renovation work was also carried out on the air-side dam surface (approx. 20,000 square metres), which had been damaged by the weather.
