# Ploučnice

The Ploučnice (German: Polzen) is a river in the Czech Republic, a right tributary of the Elbe River. It flows through the Liberec and Ústí nad Labem regions. It is 101.4 km (63.0 mi) long, making it the 23rd longest river in the Czech Republic.

## Etymology

The name of the river is derived from the Czech word plž (meaning 'mollusc'). The river was probably originally called plžčnice (meaning "a stream full of molluscs").

## Characteristic

The Ploučnice originates in the territory of Osečná in the Ralsko Uplands at an elevation of 387 m (1,270 ft). The spring area is considered to be one of the most abundant in Central Europe, which is why this spring is the main one. The secondary spring of the Ploučnice is located in the territory of Světlá pod Ještědem, on the slopes of Mt. Ještěd in the Ještěd–Kozákov Ridge at an elevation of 613 m (2,011 ft). The river flows to Děčín, where it enters the Elbe River at an elevation of 124 m (407 ft). It is 101.4 km (63.0 mi) long, making it the 23rd longest river in the Czech Republic. Its drainage basin has an area of 1,188.1 km$^2$ (458.7 sq mi).
The longest tributaries of the Ploučnice are:
| Tributary | Length (km) | River km | Side |
| Svitavka / Zwittebach | 37.1 | 50.5 | right |
| Panenský potok | 30.1 | 73.4 | right |
| Robečský potok | 27.2 | 32.9 | left |
| Šporka | 23.2 | 34.2 | right |
| Bystrá | 19.6 | 10.9 | right |
| Dobranovský potok | 18.4 | 44.0 | right |
| Ještědský potok | 18.4 | 84.9 | right |

## Settlements

The most notable settlements on the river are the town of Česká Lípa and the city of Děčín. The river flows through the municipal territories of Osečná, Hamr na Jezeře, Stráž pod Ralskem, Noviny pod Ralskem, Mimoň, Ralsko, Zákupy, Česká Lípa, Stružnice, Horní Police, Žandov, Starý Šachov, Františkov nad Ploučnicí, Benešov nad Ploučnicí and Děčín.

## Bodies of water

There are 99 bodies of water larger than 1 ha in the basin area. The largest of them is Lake Mácha with an area of 284 ha (700 acres). The largest bodies of water built directly on the Ploučnice are the Stráž pod Ralskem Reservoir and the pond Hamerské jezero. There is also the Jenišovský Pond built just beyond the main spring of the river.

## Fauna

In 2007–2011, 66 species of molluscs (27% of the species living in the Czech Republic) was founded in and around the river. Among the most endangered species are Clausilia bidentata, Daudebardia brevipes, Ruthenica filograna, Vertigo angustior and Vertigo antivertigo.
Near Mimoň, the river meanders and this area is protected as Meandry Ploučnice u Mimoně Nature Monument. It has an area of 49.4 ha (122 acres). The river and the surrounding wetlands are home to green snaketail, scarce large blue, large copper, Atlantic salmon and Eurasian otter.

## Tourism

The Ploučnice is suitable for river tourism. Due to the high volume of water, the river is navigable all year round up to Benešov nad Ploučnicí. The river meanders a lot throughout its course and flows through an intact landscape (including the Ralsko Military Training Area), which makes it one of the most attractive rivers in the Czech Republic for paddlers.
A popular tourist section of the river is the Ploučnice Gap, located in Noviny pod Ralskem. It is an artificially created tunnel through the rock, which served the operation of a hammer mill. It is several centuries old and is protected as a cultural monument.