The Blau () is a

river A river is a natural flowing watercourse, usually freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the ...

Baden-Württemberg Baden-Württemberg (; ), commonly shortened to BW or BaWü, is a German state () in Southwest Germany, east of the Rhine, which forms the southern part of Germany's western border with France. With more than 11.07 million inhabitants across a ...

, southern

Germany Germany, officially the Federal Republic of Germany (FRG),, is a country in Central Europe. It is the most populous member state of the European Union. Germany lies between the Baltic and North Sea to the north and the Alps to the sou ...

, and a left tributary of the

Danube The Danube ( ; ) is a river that was once a long-standing frontier of the Roman Empire and today connects 10 European countries, running through their territories or being a border. Originating in Germany, the Danube flows southeast for , ...

. The source of the Blau is the

karst spring A karst spring or karstic spring is a spring (outflow of groundwater) that is part of a karst hydrological system. Description Because of their often conical or inverted bowl shape, karst springs are also known in German-speaking lands as a ''T ...

of ''

Blautopf The Blautopf (German for ''Blue pot'') is a spring that serves as the source of the river Blau in the karst landscape on the Swabian Jura's southern edge. It is located in Blaubeuren, Alb-Donau-Kreis, Baden-Württemberg, Germany (approximately ...

'', in the town

Blaubeuren Blaubeuren () is a town in the district of Alb-Donau near Ulm in Baden-Württemberg, Germany. it had 11,963 inhabitants. Geography Geographical location The core city Blaubeuren lies at the foot of the Swabian Jura, west of Ulm. Neighbori ...

, in the

Swabian Jura The Swabian Jura (german: Schwäbische Alb , more rarely ), sometimes also named Swabian Alps in English, is a mountain range in Baden-Württemberg, Germany, extending from southwest to northeast and in width. It is named after the region of ...

. It flows east through

Blaustein Blaustein () is a town in the district of Alb-Donau Baden-Württemberg in Germany. It is situated on the Blau River, 6 km west of Ulm and has about 15,000 inhabitants. Before 1968, Blaustein was known as Herrlingen. It was created in 196 ...

to the city of

Ulm Ulm () is a city in the German state of Baden-Württemberg, situated on the river Danube on the border with Bavaria. The city, which has an estimated population of more than 126,000 (2018), forms an urban district of its own (german: link=no, ...

, where it empties into the

Blau valley

The valley of the Blau was formed by the Danube. When the Swabian Jura rose, the Danube initially incised a deeper and deeper valley but finally chose a course to the southwest. In the valley it left behind today, the

Schmiech Schmiech is a small river in the Swabian Alb, Baden-Württemberg, Germany. Its source is a karst spring. It flows into the Danube in Ehingen. See also *List of rivers of Baden-Württemberg A list of rivers of Baden-Württemberg, Germany: A * ...

river flows south meeting the Danube in

Ehingen (Donau) Ehingen (Donau) (; Swabian: ''Eegne'') is a town in the Alb-Donau district in Baden-Württemberg, Germany, situated on the left bank of the Danube, approx. southwest of Ulm and southeast of Stuttgart. The city, like the entire district of ...

, whereas the Blau flows east towards

References

Rivers of Baden-Württemberg Rivers of Germany {{BadenWürttemberg-river-stub