The Schluchsee is a reservoir lake in the district of Breisgau-Hochschwarzwald, southeast of the Titisee in the Black Forest near Freiburg im Breisgau, Germany. Name In the Alemannic dialects of the region the name of the lake is the Schluechs or Schlues . Historical sources also spell it with a diphthong: 983 lacus Sluochse, 1095 Schluochsee, 1125 predium Sluocse, 1312 der sê ze Sluoze. Thus it cannot be claimed that the name, as is often asserted, from the Middle High German slûch ="pipe, tube" (Alemannic Schluuch), because in this case in the present dialect and the historical sources no diphthong was available. Albert Krieger links the name to the Middle High German sluocht "ravine". But this meaning is also not accurate. Location The Schluchsee, with its height of above sea level, is the highest reservoir in Germany and also the largest lake in the Black Forest. By contrast, the Hornberg Basin (Hornbergbecken) is 1,048 metres above sea level, but is the upper basin of a pumped storage hydropower station, rather than a reservoir. The water of the reservoir is relatively cool even in summer because of its high elevation. The best-known settlements around the Schluchsee are on its northern shores and include the eponymous town of Schluchsee and the hamlets of Seebrugg by the dam itself and Aha. The Three Lakes Railway, an extension of the Höllentalbahn, runs from Titisee station along the northern shore to the terminus at Seebrugg. History The surface of the original, undammed Schluchsee, a glacier lake, was around 30 metres lower than that of today's reservoir. Despite the dam, the Schluchsee appears natural. The lake is 7.3 km long by 1.4 km across. Its 63.5 m high dam was built between 1929 and 1932, impounding the river Schwarza. In order to construct this gravity dam, the natural lake had first to be deepened by 13 metres. That was achieved in 1930 by a blasting out a tunnel in the rock. After that the intake structure of the dam could be built. Today the lake has a maximum depth of 61 m. The Schluchsee is part of the Schluchsee hydropower station complex run by the Schluchseewerk which has a number of reservoirs of different heights linked by pumping stations. This complex stretches from Häusern to Waldshut. The Schluchsee is therefore the upper basin of the Häusern pump storage hydropower station. The average power generated by the