The Hornberg Basin is the upper reservoir of the Wehr power station, whose lower reservoir is impounded by the Wehra Dam. It lies near Herrischried (Hornberg) and near the town of Wehr in the county of Waldshut in Baden-Württemberg on the dome of the Langer Eck, the highest hill in the Hotzenwald. It was opened in 1975, is only used to generate pumped-storage power and is operated by the Schluchseewerk.