The Rhine, which forms 27km of the country's western border with Switzerland, is the most important river in Liechtenstein. The Samina in the Alps measures 12km and is the second-longest river (stream) in the Principality, running from its source in the Valünatal Valley before joining the Ill and flowing into the Rhine in Austria. The only natural lake is the Gampriner Seele, which was formed in 1927 when the Rhine burst its banks.
Liechtenstein has many more rivers than lakes. The "Binnenkanal" canal and the Spiersbach and Samina rivers transport excess water away from the country. The "Binnenkanal" has the largest drainage area (117km²). Since completion in 1943 it has been used to transport the water that used to flow along the other rivers (except the Ruggeller Mölibach) directly into the Rhine. The Samina has a drainage area of 50km² in the mountains, the Spiersbach has a drainage area of 11km² in the north of the country.
The Gampriner Seele is the only natural lake in Liechtenstein and has a surface area of 1.53 hectares. The ponds in Hälos in Triesen (3.56 hectares) and Schwabbrünna-Äscher near Nendeln (0.4 hectares) are protected areas and important habitats for a wide range of animals and plants. The Spörriweier and the Steger Stausee reservoir were built to generate hydroelectricity.
Due to the destructive power of water, the country's rivers (in particular the Rhine) and rockfall have always been a source of potential danger. The swamp-like climate that existed on the valley floor until the 19th century contributed to the emergence of diseases such as malaria.
Rivers and lakes have always been and are still used for various different purposes. As well as providing water, they were employed as early as the Middle Ages to generate energy (mills) as well as to transport people (Rhine) and wood (Samina). Fishing also used to be of great importance as a source of food. The dangers posed by the rivers have been significantly reduced through the construction of protection measures and dams. Defences have also been built to protect the population from rockfalls and avalanches.