The Obere Schleuse in Hinterhermsdorf is a barrage system on the German-Czech border river of Kirnitzsch and impounds the water over a length of 700 metres. It was originally a facility for timber rafting. There are boat rides on the reservoir today during the summer months. At the boat landing point the water depth is 1 metre; by the dam it is 4 metres. The water temperature rarely climbs above 8 °C in summer. In the winter months, during when there are no boat trips, the water is not impounded and the Kirnitzsch flows in its original river bed.