Lake Constance (, ) refers to three bodies of water on the Rhine at the northern foot of the Alps: Upper Lake Constance (Obersee), Lower Lake Constance (Untersee), and a connecting stretch of the Rhine, called the Seerhein (). These water bodies lie within the Lake Constance Basin () in the Alpine Foreland through which the Rhine flows. The nearby Mindelsee is not considered part of Lake Constance. The lake is situated where Germany, Switzerland, and Austria meet. Its shorelines lie in the German states of Baden-Württemberg and Bavaria; the Swiss cantons of St. Gallen, Thurgau, and Schaffhausen; and the Austrian state of Vorarlberg. The actual locations of the country borders within the lake are disputed, with Austria, Germany and Switzerland all holding different opinions on the matter.
The Alpine Rhine forms, in its original course (Alter Rhein), the Austro-Swiss border and flows into the lake from the south. The High Rhine flows westbound out of the lake and forms (with the exception of the Canton of Schaffhausen, Rafzerfeld and Basel-Stadt) the German-Swiss border as far as to the city of Basel. The Leiblach forms the Austria–Germany border east of the lake.
The most populous towns on the Upper Lake are Constance (), Friedrichshafen, Bregenz, Lindau, Überlingen and Kreuzlingen. The largest town on the Lower Lake is Radolfzell. The largest islands are Reichenau in the Lower Lake, and Lindau and Mainau in the Upper Lake. Bodanrück, a large peninsula, separates the Upper and Lower Lake.
While in English and in the Romance languages, the lake is named after the city of Constance from Roman emperor Constantius II, the German name derives from the village of Bodman (municipality of Bodman-Ludwigshafen), in the northwesternmost corner of the lake.
Description Lake Constance is located along the Rhine between the Alpine Rhine, its main tributary, and the High Rhine, its outflow. It is the third largest freshwater lake by surface area in Central and Western Europe (and the second largest in volume), after Lake Geneva and (in surface area) Lake Balaton.
It is long, and, nearly at its widest point. It covers about , and is above sea level. Its greatest depth is , exactly in the middle of the Upper Lake. Its volume is about .
The lake has two parts. The main east section, called Obersee or "Upper Lake", covers about , including its northwestern arm, the Überlinger See (); the smaller west section, called Untersee or "Lower Lake", covers an area of about .
The connection between these two lakes is the Seerhein (lit.: "Rhine of the Lake(s)"). Geographically, usually it is not considered to be part of the lake, but a very short river.
The Lower Lake Constance is loosely divided into three sections around the Island of Reichenau. The two German parts, the Gnadensee (lit.: "calm lake") north of the island and north of the peninsula of Mettnau (the Markelfinger Winkel), and the Zeller See, south of Radolfzell and to the northwest of the Reichenau island, and the mainly Swiss Rheinsee (lit.: "Lake Rhine") – not to be mistaken for the Seerhein (lit.: "Rhine of the Lake(s)") at its start – to the south of the island and with its southwestern arm leading to its effluent in Stein am Rhein.
The water of the regulated Alpine Rhine flows into the lake in the southeast near Bregenz, Austria, then through the Upper Lake Constance hardly targeting the Überlinger See, into the Seerhein in the town of Konstanz, then through the Rheinsee virtually without feeding both German parts of the Lower Lake, and finally feeds the start of the High Rhine in Swiss town Stein am Rhein.
The lake itself is an important source of drinking water for southwestern Germany.
The culminating point of the lake's drainage basin is the Swiss peak Piz Russein of the Tödi massif of the Glarus Alps at above sea level. It starts with the creek Aua da Russein (lit.: "Water of the Russein").
History Lake Constance was formed by the Rhine Glacier during the Quaternary glaciation ice age and is a Zungenbecken or Tongue lake. After the end of the last glacial period, about 10,000 years ago, the Obersee and Untersee still formed a single lake. The downward erosion of the High Rhine caused the lake level to gradually sink and a sill, the Konstanzer Schwelle, to emerge.
The Rhine, the Bregenzer Ach, and the Dornbirner Ach carry sediments from the Alps to the lake, thus gradually decreasing the depth and reducing the extension of the lake in the southeast.
In antiquity, the two lakes had different names; later, for reasons which are unknown, they came to have the same name.
In the 19th century, there were five different local time zones around Lake Constance. Constance, belonging to the Grand Duchy of Baden, adhered to Karlsruhe time, Friedrichshafen used the time of the Duchy of Württemberg, in Lindau, the Bavarian Munich time was observed, and Bregenz used Prague time, while the Swiss shore used Berne time. One would have needed to travel only to visit five time zones. Given the amount of trade and traffic over Lake Constance, this led to serious confusion. Public clocks in harbors used three different clock faces, depending on the destinations offered by the boat companies. In 1892, all German territories used CET, the Austrian railways had already introduced CET the previous year and Switzerland followed in 1894. Because traffic timetables had not been yet updated, CET became the sole valid time around and on Lake Constance in 1895."Fünf Ortszeiten am Bodensee" in the German Wikipedia, version used 2018-01-08.
Name The earliest recorded reference to the lakes is by Roman geographer Pomponius Mela around AD 43, calling the upper lake Lacus Venetus and the lower lake Lacus Acronius, the Rhine passing through both. Around AD 75, the naturalist Pliny the Elder called them both Lacus Raetiae Brigantinus after the main Roman town on the lake, Brigantium (later Bregenz). This name is associated with the Celtic Brigantii who lived here, although it is not clear whether the place was named after the tribe or the inhabitants of the region were named after their main settlement. Ammianus Marcellinus later used the form Lacus Brigantiae.
The current German name of Bodensee derives from the place name Bodman, which probably originally derived from the Old High German bodamon which meant "on the soils", indicating a place on level terrain by the lake. This place, situated at the west end of Lake Überlingen (Überlinger See), had a more supraregional character for a certain period in the early Middle Ages as a Frankish imperial palace (Königspfalz), Alamannian ducal seat and mint, which is why the name may have been transferred to the lake which Bodman is situated (Bodmansee, "Bodman's lake"). From 833 or 834, the place name appears in Latin sources as form lacus potamicus and the Bodman Pfalz Latinised as Potamum; but monastic scholars like Walahfrid Strabo wrongly assumed Potamum to be derived from the Greek word potamos for "river" and meant "river lake". They may also have been influenced by the fact that the Rhine flowed through the lake.
Wolfram von Eschenbach describes it in Middle High German as the Bodemensee or Bodemsee which has finally evolved into the present German name, Bodensee. The name may be linked to that of the Bodanrück, the hill range between Lake Überlingen and the Lower Lake, and the history of the House of Bodman. The German name of the lake, Bodensee, has been adopted by many other languages, for example: Dutch: Bodenmeer, Danish: Bodensøen, Norwegian: Bodensjøen, Swedish: Bodensjön, Finnish: Bodenjärvi, Russian: Боденское озеро, Polish: Jezioro Bodeńskie, Czech: Bodamské jezero, Slovak: Bodamské jazero, Hungarian: Bodeni-tó, Serbo-Croatian: Bodensko jezero, Albanian: Liqeni i Bodenit.
After the Council of Constance in the 15th century, the alternative name Lacus Constantinus was used in the (Roman Catholic) Romance language area. This name, which had been attested as early as 1187 in the form Lacus Constantiensis, came from the town of Konstanz at the outflow of the Rhine from the Obersee, whose original name, Constantia, was in turn derived from the Roman emperor, Constantius Chlorus (around 300 AD).
Even in Romance-influenced English the name "Lake Constance" gained a foothold and was then exported into other languages such as Hebrew: ימת קונסטנץ yamat Konstanz and Swahili: Ziwa la Konstanz. In many languages both forms exist in parallel e.g. Romansh: Lai da Constanza and Lai Bodan, Esperanto: Konstanca Lago and Bodenlago.
The poetic name, "Swabian Sea", was adopted by authors of the early modern era and the Enlightenment from ancient authors, possibly Tacitus. However, this assumption was based on an error (similar to that of the Teutoburg Forest and the Taunus): the Romans sometimes used the name Mare Suebicum for the Baltic Sea, not Lake Constance. In times when the Romans had located the so-called "Suebi", then an Elbe Germanic tribe near a sea, this was understandable. The authors of the Early Modern Period overlooked this and adopted the name for the largest lake in the middle of the former Duchy of Swabia, which also included parts of today's Switzerland. Today the name Swabian Sea (Schwäbisches Meer) is only used jocularly as a hyperbolic term for Lake Constance.
Key facts
No Paleolithic finds have been made in the immediate vicinity of the lake, because the region of Lake Constance was long covered by the Rhine Glacier. The discovery of stone tools (microliths) indicate that hunters and gatherers of the Mesolithic period (Middle Stone Age, 8,000–5,500 BC) frequented the area without settling, however. Only hunting camps have been confirmed. The earliest Neolithic farmers, who belonged to the Linear Pottery culture, also left no traces behind, because the Alpine foreland lay away from the routes along which they had spread during the 6th millennium BC. This changed only in the middle and late Neolithic when shore settlements were established, the so-called pile dwelling and wetland settlements, which have now been uncovered mainly on Lake Überlingen, the Constance Hopper and on the Obersee. At Unteruhldingen, a pile dwelling village has been reconstructed, and now forms an open air museum. In 2015, a 20 km line of about 170 man-made dated in the Neolithic period or early Bronze Age was discovered on the south-west shore of the lake between Bottighofen and Romanshorn. (3 pages) [0:49]
Grave finds from Singen am Hohentwiel to the north date to the beginning of the Early Bronze Age and shore settlements were repeatedly built during the Neolithic Period and the Bronze Age (up to 800 BC). During the following Iron Age the settlement history is interrupted. The settlement of the shore of Lake Constance during the Hallstatt period is attested by grave mounds, which today are usually found in forests where they have been protected from the destruction by agriculture. Since the late Hallstatt period, the peoples living on Lake Constance are referred to as the Celts. During the La Tène period from 450 BC, the population density decreases, as can be deduced partly due from the fact that no more grave mounds were built. For the first time, written reports on Lake Constance have survived. Thus, we learn that the Helvetians settled by the lake in the south, the Rhaetians in the area of the Alpine Rhine Valley and the Vindelici in the north-east. The most important places on the lake were Bregenz (Celtic Brigantion) and today's Constance.