Iller River: A Vital Waterway of Bavaria and Baden-Württemberg
The Iller (known in ancient times as the Ilargus) is a significant river flowing through southern Germany. Serving as a major right tributary of the Danube, it traverses the scenic landscapes of Bavaria and Baden-Württemberg, carving a path from the high peaks of the Alps to the heart of the city of Ulm.
The Journey of the Iller
The river begins its journey in the Northern Limestone Alps within the Allgäu region, situated close to the Austrian border. The Iller is formed by the confluence—the meeting point—of three smaller rivers: the Breitach, the Stillach, and the Trettach near Oberstdorf.
From its alpine origins, the river flows northwards, passing through several key towns including Sonthofen, Immenstadt, and Kempten. As it progresses, the Iller plays a geopolitical role; between Lautrach (near Memmingen) and Ulm, it serves as the border between the German states of Bavaria and Baden-Württemberg for approximately 50 kilometres (31 mi).
![The Iller near Steinheim [de] (district of Memmingen)](/images/d5/31/d53116d1c8c71f6d3a0e804bca3c2e86e9483a7128c62cea20fb73da58b9e8dd.jpg)
The river's journey concludes in the city centre of Ulm, where it merges into the Danube, eventually contributing its waters to the Black Sea.
Hydrology and Infrastructure
With a total length of 145.9 kilometres (90.7 mi), the Iller manages a catchment area—the total land area where precipitation collects and drains into the river—of 2,147 square kilometres (829 sq mi). In terms of water volume, it is the seventh largest river in Bavaria by flow.
At Senden, located shortly before the river reaches the Danube, the average discharge (the volume of water moving past a point per second) is 90 cubic metres per second (3,200 cu ft/s). This consistent flow is harnessed for energy; the river supports eight hydroelectric power stations which, as of 1998, provided a total net capacity of 51 MW.
Recreation and Tourism
Beyond its industrial and geographical importance, the Iller is a hub for outdoor enthusiasts. The riverbanks feature a dedicated bicycle route, making it a popular destination for cyclists. Additionally, the river's currents and natural beauty attract visitors for trekking and rafting.
Key Facts
- Total Length: 145.9 km (90.7 mi).
- Source: Confluence of the Breitach, Stillach, and Trettach in the Northern Limestone Alps.
- Mouth: The Danube in Ulm.
- State Border: Forms the boundary between Bavaria and Baden-Württemberg for 50 km.
- Energy Production: 8 power stations with a combined net capacity of 51 MW (1998).
- Average Discharge: 90 m³/s at Senden.
| Feature | Detail |
|---|---|
| Country | Germany |
| States | Bavaria, Baden-Württemberg |
| Basin Size | 2,147 km² (829 sq mi) |
| Progression | Iller → Danube → Black Sea |
| Coordinates of Mouth | 48°22′53″N 9°58′23″E |
Frequently Asked Questions
Where does the Iller River start?
The Iller is formed near Oberstdorf in the Allgäu region of the Northern Limestone Alps, where the Breitach, Stillach, and Trettach rivers meet.
Which major river does the Iller flow into?
The Iller is a right tributary of the Danube, joining it in the city centre of Ulm.
Does the Iller serve as a political boundary?
Yes, for about 50 kilometres between Lautrach and Ulm, the river marks the border between the states of Bavaria and Baden-Württemberg.
How is the Iller used for energy?
The river is used for hydroelectricity production via eight different power stations, which had a total net capacity of 51 MW as of 1998.
What activities can tourists do along the Iller?
The river is a popular location for rafting, trekking, and cycling, with a dedicated bicycle route following its course.