Seerhein

The Seerhein ("Lake Rhine") is a river about four kilometres long, in the basin of Lake Constance. It is the outflow of the Upper Lake Constance and the main tributary of the Lower Lake Constance. The water level of the lower lake is about 30 cm below the level of the Upper Lake. It is considered part of the Rhine, which flows into Lake Constance as the Alpine Rhine and flows out of the Lake as the High Rhine. The Seerhein arose after the last ice age (the Würm glaciation, about 9650 BCE). Some time after this period, the water level of Lake Constance gradually dropped by about ten metres and the shallow parts fell dry. Some parts of the Seerhein still have a character a bit like a lake. The border between Germany and Switzerland runs down the center of the lower stretch of the river; the German city of Constance, the largest community on the river, is situated on both sides of the upper part. The Seerhein extends over a length of 4.3 km from the old bridge across the Rhine in Constance in the east to the island of Triboldingerbohl in the west. Narrow side channels extend between this island, the island of Mittler oder Langboh and the Wollmatinger Ried. The Seerhein is between 100 and 500 metres wide and between 7 and 25 metres deep. About halfway, there is an unnamed, shallow, widening, which looks a bit like a small lake. The Seerhein has some small streams as tributaries, both on the left side: the Dorfbach near Gottlieben and the Grenzbach ("Border Brook") on the western city limits of Constance. Most of the river, including the entire north shore and the eastern part of the southern shore, is located on German territory. On the western two kilometers, the border between Germany and Switzerland runs through the middle of the river. On the Swiss side the minucipalties of Tägerwilen and Gottlieben border the river; the German side the city of Constance and the Landkreis of municipality of Reichenau. The Swiss city of Kreuzlingen is considered part of the agglomeration centered on Constance.