The History of the Sorpe Lake

Water Supply, Power Generation and Recreation Area

Like the Biggesee, the Möhnesee, the Hennesee and the Versetalsperre, the Sorpesee is one of the large reservoirs of the Ruhrverband in the Sauerland. In addition to regulating the water of the Ruhr, it serves as a water supply and power generation facility as well as a leisure and recreation area.

The Deepest Reservoir in the Ruhrverband

The Sorpesee is located in the north of the Sauerland-Rothaargebirge Nature Park, in the area belonging to the town of Sundern between the districts of Langscheid and Amecke. With a depth of over 70 meters, the Sorpesee is the deepest reservoir in the Ruhrverband. The Sorpe flows through it.

Europe’s Largest Construction Site in the Late 1920s

The increasing demand for water in the decade after the end of the First World War and the experiences from the dry period of 1920/21 prompted the then Ruhrtalsperrenverein to build the dam. A key prerequisite for the construction of the Sorpe Dam was the Röhrtalbahn, which connects Sundern with the Obere Ruhrtalbahn in Neheim-Hüsten. The steam locomotives of the Röhrtalbahn transported heavy construction trains over a construction track laid at the time and a newly built viaduct to the construction site at the Sorpe dam. From 1926 to 1935, this was the largest construction site in Europe. The steam freight trains transported over 300,000 tons of construction material to the Sorpe dam. There, small field railways took over the onward transport.

The Sorpe Dam in World War II

During the Second World War, the dam of the Sorpesee was, like the dams of the Eder and Möhne dams, the target of bomber attacks as part of Operation Chastise on the night of May 16 to 17, 1943. The Allies tried to destroy the dam with rolling bombs. However, it withstood the attacks and was only slightly damaged because – unlike the brick dams from the imperial era on the Möhne and Eder – it had been built from concrete with earth covering. A renewed British attack on October 15, 1944 with five-ton Tallboy bombs in direct target throwing also failed, resulting only in several bomb craters and little water splashed over. However, several people were killed in the attacks, including a 15-year-old girl.

After the war, when the water of the Sorpe was completely drained at the end of 1958 for repair work, construction workers discovered a dud of a five-ton Tallboy bomb from the second attack shortly before Christmas. On January 6, 1959, Langscheid was completely evacuated. North Rhine-Westphalia’s then chief pyrotechnician Walter Mietzke and First Lieutenant James M. Waters of the British Armed Forces jointly defused the 3.6-meter-long bomb, which contained 2.5 tons of explosives and an unpredictable acid detonator. With its original catchment area of the Sorpe, the Sorpe Dam took over 3 years to fill. To increase its efficiency, the catchment area was subsequently enlarged by leading water from the neighboring valleys into the dam via a bypass system. This increased the catchment area from originally 53 km² to 100.3 km².

Pumped-storage Power Plant at the Sorpe Dam

Although the dam was mainly planned for water regulation, a power plant was integrated during construction. This power plant is designed as a pumped-storage power plant. In order to use the energy of the water as effectively as possible, a Kaplan turbine (220 kW output) is arranged after the two Francis turbines with horizontal shaft (3.6 MW output each) in the power plant. The turbines date from the construction period of the power plant, while the control system, which was renewed in 2002/2003, is the most modern in the Ruhrverband. At night, the two Francis turbines are operated as pumps with an output of 3.2 MW each and pump the water from the compensation basin back up into the reservoir. If water is discharged into the Ruhr (i.e. not pumped back), the power plant effectively serves to generate electricity.

Further Information about the Sorpe Dam

Further information about the Sorpe Dam can be found on the Ruhrverband website:

The Sorpesee not only serves for water regulation and supply as well as power generation, but is also important as a leisure and recreation area for the entire region. Here you will find information on our site about the leisure regulations of the Sorpesee.