Genesis Walchensee fills a tectonic valley, part of the
Bayerisches Synklinorium (Bavarian
Syncline) and from rocks of the
Triassic period (the main dolomite, Plattenkalke, and Kössener layers). The extreme depth of the lake, , is the result of this tectonic formation. The rock faces of the northwestern shore clearly show the steep arrangement of the rock layers. The creation of the lake from the forces of mountain building indicate that Walchensee could be one of the oldest lakes in Germany. During the
ice age, the Isar–Loisach glacier repeatedly left its mark on the morphology of the area and thereby the Walchensee.
Location and surrounding communities The lake has a shoreline of approximately and contains of water. The
Jachen is the natural outflow of the lake, eastwards through the valley of Jachenau to the
Isar.
Obernach is the largest natural inflow to the lake, entering from the southwest. Together with the artificial inflow (see "Peculiarities"), the lake has a catchment basin of . Walchensee lies at above sea level. It is surrounded by wooded mountains. To the northwest stands the
Herzogstand–
Heimgarten group at and respectively and to the west is the valley of the Eschenlaine. The south side of the Eschenlaine valley is the
Simetsberg (), which is the end of the
Ester Mountains. To the south of the lake, the Altlacher Hochkopf separates Walchensee from the valley of the Isar. On the eastern shore lies the Jachenau, a long alpine valley that stretches in the direction of
Lenggries. The northeast is dominated by the
Benediktenwand. A little further to the west is
Jochberg (), which completes the valley wall. Between Herzogstand and Jochberg is little
Kesselberg, which because of its relatively low prominence appears as a depression between the two higher peaks, but actually separates Walchensee from
Kochelsee, below. Directly on the west bank of the lake is the tiny
Luftkurort settlement of Walchensee, with only about 600 inhabitants. Walchensee belongs to the municipality of
Kochel as do the yet smaller settlements of
Urfeld at the northern tip of the lake, Zwergen on the western shore, and the houses of Einsiedl am Walchensee on the
orographic left bank of the Obernach at the far southwestern end of the lake. The houses of Einsiedl am Walchensee on the right bank of the Obernach and Altlach on the southern shore, the farmsteads of Matheis, Christopher, and Breitort, Sachenbach on the east shore, and Niedernach in the far southwest, belong to the municipality of
Jachenau. Between the settlements of Walchensee and Einsiedl, the Katzenkopf peninsula reaches into the lake. The settlement of Zwergen lies on this peninsula. The surface of the lake forms a north-facing triangle, with the southern shore forming a base from Einsiedl to Niedernach and the height reaching from Breitort to Urfeld.
Climate Due to its location in a valley, the lake is protected from northern and eastern winds. The relatively low mountains on the south shore let in the optimal amount of sunlight, giving Walchensee a milder climate than one might expect in the mountains. During the summer months, heat on southern side of Herzogstand and Jochberg create strong
thermals on sunny days. Stable thermal winds blow generally southwest. When the thermals carry saturated air masses from the Walchensee high into the air and mix with air from the more northerly Kochelsee by a prevailing wind from the northwest, it can lead to particularly violent thunderstorms. In contrast to a
foehn, when a
katabatic wind blows from south to north, the associated dry air ensures excellent visibility. ==History==