The Blau () is a

river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of ...

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, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwee ...

, 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 , pa ...

. 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 ''To ...

of '' Blautopf'', 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. Neighborin ...

, 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 19 ...

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 river flows south meeting the Danube in Ehingen (Donau), whereas the Blau flows east towards

References

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