Constance, Lake

Lake bounded by Germany, Austria, and Switzerland, through which the River Rhine flows; area 539 sq km/208 sq mi. It is about 72 km/45 mi long, 13 km/8 mi wide, and lies 396 m/1,300 ft above sea level. At its northwestern end it divides into two lakes, the northern being the Überlingen, and the southern – joined to Lake Constance by a short stretch of the River Rhine – the Untersee. The main part of the lake is known as the Obersee.

There are two islands in the lake, Reichenau and Mainau, both in Germany, and several towns are sited on its banks, including Bregenz in Austria, Lindau, Friedrichshafen, Überlingen, and Constance in Germany, and Romanshorn and Rorschach in Switzerland. Approximately 2.2 million people live on the banks of Lake Constance, and the urban development of the area has contributed to pollution concerns.

With more than 55,000 boats on the lake, and problems with phosphate and atmospheric pollution from local industries, environmental conditions are being monitored. The lake is home to around 200,000 water birds, and is the drinking reservoir for 4.5 million people.

The lake sometimes rises considerably above its usual height, owing to melting snow in spring, but hardly ever freezes over. There are regular ferry services on the lake (between mid-April and mid-October) that run between Germany and Austria, and Germany and Switzerland.