Constance, Lake, (Bodensee), Vorarlberg, alt. 396 m, area 538 km2, 63 m long, 15 km wide, up to 252 m deep. Lake Constance is part of the territory of Germany, Switzerland, and Austria; 27 km of the shoreline are on Austrian territory. The lake is considered comparatively clean. An early Celtic fishermen's settlement was situated near Bregenz; the Romans called the lake Lacus Brigantinus (first documented mention by Pliny the Elder, in use up to the 10th century) or Lacus Venetus. The German name "Bodensee" derives from the Carolingian Palatinate of Bodama (or "Bodman"). Southwest of Bregenz, the lake is supplied with water by the Bregenzerach river and the Rhine. Due to the estuary regulations of 1900 and 1923, the Rhine flows into the Fussach bay, which silts up very quickly. This is to be alleviated by shifting the river estuary further forward. In the west, the old Rhine delta has pushed the marshy promontories of Rheinspitz (on the Swiss border, bird protection area) and Rohrspitz far out into the lake; in between is the flat Wetterwinkel bay. In the Bregenz bay, the foothills of the Alpine foreland still reach a height of 60m above water level. The lake is rich in fish (35 species including whitefish, lake-trout, perch,); the fishing season in the deep waters of the lake, which warm up quickly, starts as early as May. The lake is also a paradise for birds (approx. 312 species in the Rhine delta alone). Other peculiarities of the lake are the "Rheinbrech", periodically occurring turbulences caused by a steep drop in the bed of the lake making the muddy river water fall rapidly into the clear lake water, the meter-high pounding waves at the eastern shore at times of strong westerly winds, and the furrowed rocks covered with blue-green algae. An unexplained phenomenon is the "Seeschiessen", a thunder-like noise coming up from the bottom of the lake. In spring, the lake is a truly extraordinary sight when it is covered in pollen. The Bregenz Festival takes place on the largest lake stage in the world. The Austrian harbour is situated at Bregenz. The Austrian shipping routes are 7 km (Bregenz-Lindau) and 55 km long (Lindau-Konstanz). The Austrian Federal Railways operate 5 large motor ships and 1 motor boat. In 1992, approx. 510,000 people travelled on these boats, all of which together covered 11 million km in 692 days. Altogether, the "Vereinigte Schiffahrtsunternehmen" (United Shipping Lines) own 36 ships in Austria, Germany and Switzerland with a capacity to transport 19,000 passengers (1992: 4,8 million passengers). In 1972, the "Internationale Bodenseekonferenz" (International Lake Constance Conference) was established, consisting of the province of Vorarlberg, the German states of Baden-Wuerttemberg and Bavaria and the Swiss cantons of Schaffhausen, St. Gallen and Thurgau. Cross-border cooperation serves the International commission for the protection of Lake Bodensee, the international shipping commission and the international Lake Constance fishing authorities.
Literature#E. and. O. Danesch, Oesterreich - Ein Land der Seen, 1979; E. Held, Vorarlberg und Liechtenstein, 1988; Eugen-Russ-Verlag (ed.), Land Vorarlberg, 1988; Oesterreichische Raumordnungskonferenz, (ed.), 7. Raumordnungsbericht, 1993.