The reservoir collects the water on the eastern slopes of the rainy main crest of the Northern Black Forest, below the mountains of Hornisgrinde, Mehliskopf and Badener Höhe. The Schwarzenbach and Seebach streams are directly impounded, the water of the Biberach and Hundsbach (headstreams of the Raumünzach) are led by galleries from neighbouring valleys. In addition, the water of the Murg from the Murg Dam is pumped into the reservoir. The dam system provides load balancing in the energy supply. Its maximum output is .