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Course and catchment area of ​​the Iller, with the middle upper reaches Stillach to about Oberstdorf

Course and catchment area of ​​the Iller, with the middle upper reaches Stillach to about Oberstdorf

Water code EN : 114
location Germany , Bavaria , Baden-Wuerttemberg
River system Danube
Drain over Danube  → Black Sea
origin Confluence of Breitach (left), Stillach (center) and Trettach (right) near Oberstdorf im Allgäu
47 ° 25 ′ 38 ″  N , 10 ° 16 ′ 26 ″  E
Source height 783  m above sea level NHN
muzzle At Ulm in the Danube coordinates: 48 ° 22 '53 "  N , 9 ° 58' 23"  E 48 ° 22 '53 "  N , 9 ° 58' 23"  E
Mouth height 468.3  m above sea level NHN
Height difference 314.7 m
Bottom slope 2.1 ‰
length 147 km
Catchment area 2152 km²
Discharge at the Wiblingen
A Eo gauge : 2115 km²
Location: 2.1 km above the mouth
NNQ (02/16/1971)
MNQ 1921–2006
MQ 1921–2006
Mq 1921–2006
MHQ 1921–2006
HHQ (05/23/1999)
10.9 m³ / s
21.3 m³ / s
70.1 m³ / s
33.1 l / (s km²)
465 m³ / s
922 m³ / s
Left tributaries Gunzesrieder Ach , Konstanzer Ach , Aitrach
Right tributaries Ostrach , Rottach , Durach , Leubas , Buxach , Memminger Ach
Big cities Ulm
Medium-sized cities Sonthofen , Kempten (Allgäu) , Memmingen , Senden , Neu-Ulm
Small towns Illertissen , Voehringen
Navigable only on larger reservoirs possible
13 power plants and 4 reservoirs
Aerial view of the Upper Illertal

Aerial view of the Upper Illertal

Iller origin
Iller breakthrough near Kalden - panoramio.jpg
Iller breakthrough near Kalden
Under the Illerbrücken, Kempten.jpg
upper Illerbrücken, Kempten
Impact slopes on the Iller nö Kempten (Photo Hilarmont) (9) .JPG
Impact slopes north of Kempten
Railway bridge Iller - Legauer Straße.jpg
Railway bridge on the disused Memmingen – Legau railway line near Illerbeuren
Iller Kardorfer Reservoir.jpg
Kardorf Reservoir
Railway bridgeBuxheim1.jpg
Railway bridge of the Memmingen-Leutkirch railway line over the canalized Iller, which only carries residual water
Upper Iller.jpg
Upper Illertal to the north at around river kilometer 15, the castle church Schöllang at the top left
Aerials Bavaria. 2006 08-33-28.jpg
Power plant on the Iller
Citizens' Bridge Altusried (2) .JPG
The so-called Bürgerbrücke near Altusried, built in 2007, spans the Iller with a span of 84 meters.

The Iller is a right tributary of the Danube . Her Latin name was Hilaria or Hilara . The name is of Celtic origin and comes from the word ilara for 'in a hurry'; later the Latin term hilaris , which can be translated as 'cheerful, friendly', was used for interpretation. In the Latin Vita of St. Magnus , the name is interpreted in such a way that it is called friendly, precisely because, as a wild mountain river, it is not. For better legibility, the river name is sometimes written in atlases and on street signs Jller .

The 147 kilometer long river arises from the Breitach , Stillach and Trettach streams at the source of the Iller near Oberstdorf in the Oberallgäu district . It flows into the Danube near Ulm . Measured against its catchment area of ​​2152 km², the discharge of the mountain river is large. Its water flow of 70.9 m³ / s clearly exceeds that of the Danube, which only brings 53 m³ / s to the confluence and could thus be considered hydrologically as a tributary of the Iller; With this water flow, the Iller ranks seventh in the list of rivers in Bavaria and fifth in Baden-Württemberg. From the late 3rd century to around 488 AD it was part of the Roman defense system Danube-Iller-Rhein-Limes . Even in Roman times it sailed the Iller from Kempten, then Cambodunum , with rafts . For the majority of its course until shortly before Ulm, the body of water formed the border between the dioceses of Constance and Augsburg , which is significant under canon law, until the dissolution of the Diocese of Constance in 1821 .


The source of the Iller is near Oberstdorf in the upper Allgäu , where the Iller arises from the confluence of the Trettach (right upper course), Stillach (middle upper course) and Breitach (left upper course). The Breitach arises in the Austrian Kleinwalsertal , the other two source rivers arise in Bavarian territory. On its way north, the Iller first crosses the Allgäu and passes the cities of Sonthofen , Immenstadt and Kempten . In the second half of its course, it flows through Upper Swabia , where it roughly forms the state border between Baden-Württemberg and Bavaria , before it flows into the Danube, which comes from the west, southwest of the Ulm city center.

Tributaries of the Iller

The tributaries of the Iller in their order (south to north), divided into left and right tributaries:



The consecration was up to the transfer of its lowest section in 2003, also a left tributary of the river Iller. Now it flows directly into the Danube.

Valley sections

The natural spatial structure of the Institute for Regional Studies distinguishes several natural spatial units of very different types in the course of the Iller from the Alps to the Alpine foothills :

Energy generation

The river is used heavily to generate energy. Three of the four large German energy supply companies operate a total of thirteen run-of-river power plants on barrages and side canals of the Iller. On the upper reaches, Bayerische Elektrizitätswerke GmbH (a subsidiary of Lechwerke AG (LEW), which in turn belongs to around 90% of RWE Energy ) operates five power plants between Altusried and Lautrach with a maximum output of 31  MW . The Allgäu overland plant operates four run-of-river power plants in Kempten . Down the river follow the five Illerkraftwerke of EnBW Energie Baden-Württemberg AG between Aitrach and Dettingen with an output of 47 MW. After all, there are three power plants owned by the majority of E.ON Wasserkraft GmbH, Unteren Iller AG, on the Illerkanal between Altenstadt and Illertissen . Another hydropower plant is being planned near Bellenberg .

In the following list, the hydropower plants on the Iller are incomplete:

power plant Surname location River km design type Water level
above sea level. NN
power operator construction time
power plant Felsenwehr hydroelectric power station Kempten 107 Run-of-river power plant - 6.1 m 2.9 MW AÜW 1851
power plant Keselstrasse hydropower plant Kempten 104 Run-of-river power plant - - 1.2 MW AÜW 1958/2010
power plant Hydroelectric power station Illerstrasse Kempten 103 Run-of-river power plant - 6.1 m 1.05 MW AÜW 1901
Barrage 4 Iller barrage 4 - Altusried Altusried 84 Run-of-river power plant 640.0 m 9.6 m 7.8 MW MOVE 1961
Barrage 5 Iller barrage 5 - Fluhmühle Altusried 78 Run-of-river power plant 630.0 m 7.0 m 5.2 MW MOVE 1944
Barrage 6 Iller dam level 6 - Legau Legau 71 Run-of-river power plant 622.0 m 8.2 m 6.2 MW MOVE 1943
Barrage 7 Iller dam 7 - Maria Steinbach Maria Steinbach 65 Run-of-river power plant 612.0 m 8.1 m 6.0 MW MOVE 1937-1938
Barrage 8 Iller dam 8 - Lautrach Lautrach 59 Run-of-river power plant 602.0 m 8.0 m 7.7 MW MOVE 1948
power plant Aitrach hydropower plant Aitrach 57 Run-of-river power plant 593.8 m 9.45 m 9.0 MW EnBW 1950
Canal power plant Canal power plant Tannheim Tannheim 47 Canal power plant 583.2 m 15.1 m 12.4 MW EnBW 1923
Canal power plant Canal power station Unteropfingen Unteropfingen 41 Canal power plant - 17.0 m 14.2 MW EnBW 1924
Canal power plant Dettingen canal power station Dettingen 35 Canal power plant 547.9 m 14.1 m 11.0 MW EnBW 1927
Canal power plant Canal power plant in Untereichen Altenstadt 28 Canal power plant 532.1 m 14.5 m 10.0 MW UIAG 1930
Canal power plant Canal power plant Au Au 21st Canal power plant 516.8 m 14.4 m 10.0 MW UIAG 1930

Cities and villages on the Iller

The following locations are located on the Iller, in brackets, if applicable, the height of the regular Iller level / congestion destination above sea level:

District of Oberallgäu

Kempter Illertal :

Illerbeurer Illertal :

District of Unterallgäu , Bavaria

State border
(l) Baden-Württemberg
/ (r) Bavaria
Upper Illergriess :

Lower Illergriess :

  • (l) Illerrieden , UL
  • (r) Vöhringen , NU, opposite Illerrieden
    • (at Illerzell just below: 487  m )
  • (r) Send , NU
    • (just below the core town: 480  m )
  • (l) Illerkirchberg , UL, opposite Senden
  • (r) Neu-Ulm . NU
  • (l) Ulm , district free
    • (Mouth: 468.3  m )
ü Kernort lies well above the Iller.
e Kernort is a little away from the Iller.

Straightening and renovation

After constantly recurring damage to the bank and the costs of securing it, the kingdoms of Bavaria and Württemberg decided to “correct” the Iller in 1859; this straightening was completed in 1893. The course of the river from Memmingen to Ulm was shortened from 67.15 km to 56.6 km by means of several loop punctures, the gradient increased from 1.77 ‰ to 2.15 ‰. After that, the Iller dug in more deeply , at the level of Regglisweiler by around three and a half meters since 1926. The groundwater level sank and the Iller floodplains fell dry.

For this reason and in order to give the river a natural appearance again, work began in 1996 to build thresholds and ramps into it and to reset its banks.

Tourism and sport


Iller water stair.jpg
Lower course with fish ladder, Illerauwald near Dietenheim
Mouth of the Iller (behind) into the Danube

Before the Illerkanal was built in 1917, the body of water was an unrestrained and unpredictable mountain river. After heavy thunderstorms and two days of heavy rain on June 13 and 14, 1910, several floods occurred in the entire upper area of ​​the Iller. On June 14, 1910, the floods tore the Iller Bridge at Egelsee near Memmingen with them. Parts of the dam between Illertissen and Dietenheim also burst. On Friday, June 16, 1910 at around 11 p.m., the masses of water brought the mighty wooden bridge between the two villages to collapse. Then soldiers of the Royal Württemberg Pioneer Battalion No. 13 from Ulm were called to help.

When Iller disaster in 1957, 15 drowned during an exercise  conscript soldiers of the Bundeswehr in the Iller, as a sergeant in the 2nd Company of the Airborne Police Battalion 19 from the Prince Franz barracks in Kempten his subordinates ordered unsecured to cross the river.

At the Fischen railway bridge on the Immenstadt – Oberstdorf route over the Obere Iller, there were repeated blockages on the central pillar during flooding , which led to flooding. This problem is to be solved by a new pillarless bridge, the construction of which was carried out in autumn 2011. The Iller is the first tributary of the Danube that was important for rafting . See main article Rafting on the Iller . At the end of the 19th century, the section of the river Iller north of Memmingen, where it flows in a wide bed, was deepened and thus made navigable.

The Iller is crossed by three historical bridges in Kempten: the König-Ludwig-Brücke , the only one of its kind in Germany, and the Upper Illerbrücken , the largest stamped concrete bridges in the world. All three bridges cross the deep gorge in the south of Kempten, were used at least temporarily for rail traffic and are close together.


The motto for the Bavarian tributaries of the Danube begins with the Iller:

“Iller, Lech, Isar, Inn
flow right towards the Danube.
Altmühl, Naab and Regen
come towards the left. "


  • Franz X. Bogner: Allgäu and Iller from the air. Theiss-Verlag, Stuttgart 2009, ISBN 978-3-8062-2236-4 .
  • Otto Kettemann, Ursula Winkler (ed.): The Iller. Stories by the water of need and strength. 2nd expanded edition, 2000, ISBN 3-931915-05-0 .
  • Peter Nowotny: The Iller and its valley. Lovable living space between the Alps and the Danube. Verlag Eberl, Immenstadt 1999, ISBN 3-920269-08-X .

Web links

Commons : Iller  - Collection of Images
Wiktionary: Iller  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ^ German Hydrological Yearbook Danube Region 2006 Bavarian State Office for the Environment, p. 98, accessed on October 4, 2017, from: (PDF, German, 24.2 MB).
  2. ^ Hansjörg Dongus: Geographical land survey: The natural space units on sheet 188/194 Kaufbeuren / Mittenwald. Federal Institute for Regional Studies, Bad Godesberg 1993. → Online map (PDF; 6.6 MB)
  3. a b c Hansjörg Dongus: Geographical land survey: The natural spatial units on sheet 187/193 Lindau / Oberstdorf. Federal Institute for Regional Studies, Bad Godesberg 1991. → Online map (PDF; 6.3 MB)
  4. ^ Emil Meynen , Josef Schmithüsen : Handbook of the natural spatial structure of Germany . Federal Institute for Regional Studies, Remagen / Bad Godesberg 1953–1962 (9 deliveries in 8 books, updated map 1: 1,000,000 with main units in 1960), now unit 901.0.
  5. ^ H. Graul: Geographische Landesaufnahme: The natural space units on sheet 179 Ulm. Federal Institute for Regional Studies, Bad Godesberg 1952. → Online map (PDF; 5 MB)
  6. See Bayerische Elektrizitätswerke GmbH, power plant data. (No longer available online.) Archived from the original on October 30, 2013 ; Retrieved April 26, 2013 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot /
  7. See EnBW Energie Baden-Württemberg AG, Wasserkraft, page 14ff. (PDF; 8.4 MB) Retrieved June 13, 2014 .
  8. According to the 2007 annual financial statements, 60 percent of the shares are held by E.ON Wasserkraft GmbH (Landshut) and 40 percent by Bayerische Elektrizitätswerke GmbH (Augsburg). Operations are managed by E.ON Wasserkraft GmbH; see. Electronic Federal Gazette. January 22, 2009. Retrieved June 21, 2009 .
  9. See "Untere Iller AG (UIAG) invests in ecological measures on the Iller", press release from May 7, 2009, p. 3. (PDF) (No longer available online.) Formerly in the original ; Retrieved June 21, 2009 .  ( Page no longer available , search in web archivesInfo: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.@1@ 2Template: Toter Link /  
  10. Agnes Mayer: Second attempt for controversial hydropower plant. Stadtwerke Neu-Ulm / Ulm start planning approval procedure again. Augsburger Allgemeine , October 4, 2012, accessed April 3, 2015 .
  11. ^ BayernAtlas. Retrieved February 19, 2019 .
  12. J. Laubach, H. Wühlbeck: The competitiveness of large run-of-river power stations in the liberalized electricity market - final report (long version), client: Federal Ministry of Economics and Labor, project no. 45/02 . Ed .: Fichtner. Stuttgart December 2003.
  13. Map services of the Federal Agency for Nature Conservation ( information )
  14. Back to the original. Retrieved March 22, 2020 .
  15. Augsburger Allgemeine : The day when the bridge broke on June 14, 2006, accessed on October 28, 2010.
  16. Bavarian State Ministry for Economic Affairs, Infrastructure, Transport and Technology, "Contract for the renewal of the Iller Bridge in Fischen signed", press release from June 19, 2009. (No longer available online.) Formerly in the original ; Retrieved June 19, 2009 .  ( Page no longer available , search in web archivesInfo: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.@1@ 2Template: Toter Link /