The region of Lake Constance

Lake Constance

Lake Constance is a lake on the Rhine at the northern foot of the Alps, and consists of three bodies of water: the Obersee ("upper lake"), the Untersee ("lower lake"), and a connecting stretch of the Rhine, called the Seerhein. The lake is situated in Germany, Switzerland and Austria near the Alps. Specifically, its shorelines lie in the German states of Bavaria and Baden-Württemberg, the Austrian state of Vorarlberg, and the Swiss cantons of Thurgau and St. Gallen. The Rhine flows into it from the south. Lake Constance was first mentioned by the Roman geographer Pomponius Mela about AD 43. He noted that the Rhine flows through two lakes, and gave them the Latin names Lacus Venetus (Obersee) and Lacus Acronius (Untersee). Pliny the Elder used the name Lacus Brigantinus, after the Roman city of Brigantium (today Bregenz). The lake is also colloquially known as the Swabian Sea.

The freshwater lake sits at 395 m above sea level and is Central Europe's third largest, after Lake Balaton and Lake Geneva. It is 63 km long, and at its widest point, nearly 14 km. It covers approximately 571 km² (208 mi²) of total area.The greatest depth is 252 m in the middle of the eastern part (Obersee). Its volume is approximately 55 km³. The lake has four parts: Obersee (main, 476 km²), Überlinger See (north, 61 km²), Untersee (west, 63 km²), and the Zeller See and Gnadensee (northwest). The regulated Rhine flows into the lake in the southeast, through the Obersee, the city of Konstanz and the Untersee and flows out near Stein am Rhein. Lake Constance provides fresh water to many cities in south Germany.

Lake Constance was formed by the Rhine Glacier during the ice age. The Rhine, the Bregenzer Ache, and the Dornbirner Ache carry sediments from the Alps to the lake, thus gradually decreasing the depth of the lake in the southeast. The lake was frozen in the years 1077 (?), 1326 (partial), 1378 (partial), 1435, 1465 (partial), 1477 (partial), 1491 (partial?), 1517 (partial), 1571 (partial), 1573, 1600 (partial), 1684, 1695, 1709 (partial), 1795, 1830, 1880 (partial), and 1963. Approximately 1000 tons of fish were caught by 150 professional fishermen in 2001 which was below the previous ten year average of 1200 tons per year. The Lake Constance trout (Salmo trutta) was almost extinct in the 1980s due to pollution, but thanks to protective measures has made a significant return. The lake itself is an important drinking water source for south-west Germany called Bodenseewasserversorgung.