The Bigge dam and reservoir were constructed in the 1960s in the immediate vicinity of the town of Attendorn. The reservoir serves primarily to store and discharge water on demand, thus ensuring a balanced water level of the River Ruhr. Up to 40 per cent of the required compensation water for all dams and reservoirs can be discharged from the Bigge Reservoir via the Bigge and Lenne rivers into the Ruhr river system.
Another important purpose is flood protection for inhabitants downstream of the dam and reservoir. During the flood risk period between 1 November and 1 February, a flood control storage space of 32 million cubic metres is kept available, which is then released for refilling in the period between 1 February and 1 May.
Water is primarily discharge from the reservoir via the Bigge hydropower station. The Bigge and Lister hydropower stations operated by the company Lister- und Lennekraftwerke GmbH generate about 24 million kW/h per year. The maximum capacity of the five turbines amounts to approx. 18 megawatts.
The Lister Reservoir was completed as early as 1912. Upon completion of the Bigge Dam and Reservoir, the Lister Reservoir became one of its five preliminary reservoirs. The Bigge Dam’s main reservoir floods two thirds of the 40m-high masonry dam from the downstream side. The difference in water head between the Lister and Bigge Reservoirs is used for power generation. Moreover, the District Waterworks in Olpe abstract a large part of the drinking water required for supplying the region from the Lister Reservoir.
The impounded lake at Ahausen is situated downstream of Attendorn in the Bigge Valley. It was created in 1938 to regulate the River Bigge. Moroever, it has served as a compensating reservoir for the Bigge Dam and Reservoir hydropower station since its inception. The lake is impounded by an earth-fill dam and a weir, with a power station located in between. The weir has two shutters and two fixed sections.