Jizera (river)
The Jizera is a river in the Czech Republic and for a brief stretch in Poland. It is a right tributary of the Elbe and flows through the Liberec and Central Bohemian regions. It is long, making it the 10th longest river in the Czech Republic.
Etymology
The first written mention of Jizera is from the 13th century. The origin of the name is most likely Celtic and is derived from the verbal root -eis, -ois, -is, meaning 'to flow briskly'. It has the same etymology as the Isar in Germany, the Yser/IJzer in Belgium and France, the Isère in France and probably the River Aire in England.Characteristic
The Jizera originates in the Jizera Mountains. Two sources of the river are defined. The first spring is located on the slopes of the Smrk mountain in the territory of Lázně Libverda on the Czech side of the border at an elevation of, and for centuries it was considered the only source of the Jizera. In the 1990s, the so-called "Polish spring of the Jizera" was determined, as the source of a headwater that is longer and more substantial than the Czech one, but historically it was a separate stream with a different name.The Jizera flows to Lázně Toušeň, where it enters the Elbe at an elevation of. Considering the "Czech spring of the Jizera", it is long, making it the 10th longest river in the Czech Republic. Considering the "Polish spring of the Jizera", it is long, of which is in Poland. The Czech-Polish border is formed by of the river. Its drainage basin has an area of, of which is in the Czech Republic.
The longest tributaries of the Jizera are:
| Tributary | Length | River km | Side |
| Mohelka | 41.6 | 61.4 | right |
| Kamenice | 36.9 | 101.0 | right |
| Oleška | 36.0 | 106.3 | left |
| Klenice | 29.3 | 36.9 | left |
| Žehrovka | 26.3 | 66.9 | left |
| Zábrdka | 24.5 | 55.2 | right |
| Jizerka | 21.5 | 121.7 | left |
| Libuňka | 21.4 | 78.4 | left |
| Strenický potok | 20.3 | 30.6 | right |
| Bělá | 15.0 | 49.1 | right |
A notable tributary is also the Mumlava, which has an average discharge near estuary at.
Course
The largest settlement on the river is the city of Mladá Boleslav. The river flows past Kořenov, Rokytnice nad Jizerou, Jablonec nad Jizerou, Semily, Železný Brod, Malá Skála, Turnov, Mnichovo Hradiště, Bakov nad Jizerou, Mladá Boleslav, Benátky nad Jizerou, Předměřice nad Labem, Tuřice, Nový Vestec, Káraný and Lázně Toušeň.Bodies of water
There are no reservoirs and fishponds built directly on the Jizera. The largest body of water in the basin area is the Josefův Důl Reservoir with an area of, built on the Kamenice. There are 1,350 bodies of water in the basin area.Fauna
There are many species of molluscs in the river. Among the most endangered species are Cochlodina dubiosa corcontica, Daudebardia brevipes, Planorbis carinatus, Clausilia cruciata, Euconulus praticola, Pseudotrichia rubiginosa, Ruthenica filograna, Semilimax kotulae, Vertigo alpestris, Vertigo antivertigo and Vitrea subrimata.The Jizera is one of the cleanest rivers in the country and there is a high density of fish, which is why it is popular for fishing. The upper and middle courses are mainly inhabited by brown trout and grayling.