The Lech (Latin: Licus, Licca) is a river in Austria and Germany. It is a right tributary of the Danube 255 kilometres (158 mi) in length with a drainage basin of 3,919 square kilometres (1,513 sq mi). Its average discharge at the mouth is 115 m/s (4,100 cu ft/s). Its source is located in the Austrian state of Vorarlberg, where the river rises from lake Formarinsee in the Alps at an altitude of 1,870 metres (6,120 ft). It flows in a north-north-easterly direction and crosses the German border, forming the Lechfall, a 12-metre-high (39 ft) waterfall; afterwards the river enters a narrow gorge (the Lechschlucht). Leaving the Alps, it enters the plains of the Allgäu at Füssen at an elevation of 790 metres (2,580 ft) in the German state of Bavaria, where it used to be the location of the boundary with Swabia. The river runs through the city of Füssen and through the Forggensee, a man-made lake which is drained in winter. Here, it forms rapids and a waterfall.

The river flows further northwards through a region called the Lechrain, and passes the cities of Schongau, Landsberg, Augsburg (where it receives the Wertach) and Rain before entering the Danube just below Donauwörth at an elevation of 410 metres (1,330 ft). It is not navigable, owing to its torrential character and the gravel beds which choke its channel. There are extensive views of the Lech valley from Neuschwanstein Castle, near Füssen.

Inscriptions from 8/7 B. C. prove that the river name is first mentioned in the Celtic tribe name Licates. The river itself is called Likios or Likias in the 2nd century. Around the year 570 the name Licca is found in records. In the 8th century, names such as Lecha and Lech appeared. The term Licus is still used in 1059.

The name stands in analogy to the Welsh word llech ("stone slab") and the Breton word lec'h ("gravestone"). In this context, the meaning of the word "Lech" is explained as "the stony".

On more than one occasion, historic events have been decided on the banks of this river.

• In 278 Roman emperor Probus vanquished a larger invasion force of Burgundians and Vandals, which had been raiding the Roman province of Rhaetia.
• At Lechfeld, a stony plain between the Lech and the Wertach near Augsburg, Otto I defeated the Magyars in August 955.
• In the Battle of Rain in April 1632, Gustavus Adolphus of Sweden defeated and mortally wounded Johan Tzerclaes, Count of Tilly.

Currently, there are 33 hydroelectric power plants on the Lech. The power plants are listed beginning at the headwaters:

Dam	Name	Installed capacity (MW)	Year of completion	Image
1	Lechstaustufe Horn	5.0	1952
2	Forggensee	45.5	1954
3	Premer Lechsee	19.2	1972
4	Lechstaustufe Lechbruck	5.0	1903/1958
5	Lechstaustufe 3 – Urspring	10.2	1971
6	Lechstaustufe 4 – Dessau	10.2	1971
7	Dornautalsperre	16.6	1960
8	Lechstaustufe 7 – Finsterau	7.7	1950
9	Lechstaustufe 8 – Sperber	7.3	1947
10	Lechstaustufe 8a – Kinsau	9.2	1992
11	Lechstaustufe 9 – Apfeldorf	7.2	1944
12	Lechstaustufe 10 – Epfach	8.3	1948
13	Lechstaustufe 11 – Lechblick	8.1	1943
14	Lechstaustufe 12 – Lechmühlen	7.9	1943
15	Lechstaustufe 13 – Dornstetten	8.2	1943
16	Lechstaustufe 14 – Pitzling	7.9	1944
17	Lechstaustufe 15 – Landsberg	8.0	1944
18	Lechstaustufe 18 – Kaufering	16.7	1975
19	Lechstaustufe 19 – Schwabstadl	12.0	1981
20	Lechstaustufe 20 – Scheuring	12.2	1980
21	Lechstaustufe 21 – Prittriching	12.1	1983
22	Lechstaustufe 22 – Unterbergen	12.4	1982
23	Lechstaustufe 23 – Mandichosee	12.0	1978
24	Hochablass	3.1	2013
25	Eisenbahnerwehr	3.2	2006
26	Wolfzahnauwehr	2.0	2010
27	Kraftwerk Gersthofen	9.9	1901
28	Kraftwerk Langweid	7.0	1908
29	Kraftwerk Meitingen	11.6	1922
30	Staustufe Ellgau	10.0	1952
31	Staustufe Oberpeiching	12.3	1954
32	Staustufe Rain	11.2	1955
33	Staustufe Feldheim	8.5	1960

• 
  The Lech in Augsburg
• 
  The Lech, in the background the city of Landsberg
• 
  The Lech between Weissenbach and Forchach
• 
  The Lech between Elmen and Stanzach
• 
  The Lech between Apfeldorf and Epfach
• 
  The Lech River by Andrei Gavrilița

• List of rivers of Bavaria
• List of rivers of Austria

• Eberhard Pfeuffer: Der Lech. Wissner-Verlag, Augsburg 2010, ISBN 3-89639-768-0.
• R. Zettl: Lechauf-lechab. Wißner-Verlag 2002, ISBN 3-89639-316-2.
• Dr. Peter Nowotny: Erlebnis Lech. Verlag – J. Eberl KG, Immenstadt 2001.
• Dr. Bernhard Raster: Nutzung und anthropogene Veränderung des Lechs in historischer Zeit. Diss. Würzburg 1979.
• Bayerisches Hauptstaatsarchiv (Hrsg.): Altbayerische Flusslandschaften an Donau, Lech, Isar und Inn. = Ausstellungskatalog, Anton H. Konrad, Verlag Weißenhorn 1998.
• Werner Gamerith: Lechtal. Tyrolia Verlag, Innsbruck-Wien 2002.
• Peter Nasemann: Lebensraum Füssener Lech. Holdenrieds Druck- und Verlags GmbH, o. J.
• Norbert Müller: Augsburger Ökologische Schriften, Heft 2: Der Lech. Stadt Augsburg 1991, ISSN 0941-2123

Specific

• Lech (river) in Austria-Forum (in German) (at AEIOU)
• The Lech in Füssen
• Hochwassernachrichtendienst Bayern Alle möglichen Daten über die bayerischen Flüsse: aktuelle Pegelstände, langjährige Abflussdaten, Einzugsgebiet, etc.
• Life-Naturschutzprojekt Tiroler Lech
• Lebensraum Lechtal
• Bericht über eine Kajaktour