# Berounka

The Berounka (Czech pronunciation: ) is a river in the Czech Republic, a left tributary of the Vltava River. It flows through the Plzeň and Central Bohemian regions to Prague. It is formed by the confluence of the Mže and Radbuza rivers in Plzeň. Together with the Mže, which is its main source, the Berounka is 244.6 km (152.0 mi) long, which makes it the fifth longest river in the Czech Republic. Without the Mže, it is 139.4 km (86.6 mi) long.

## Etymology

The river is named after the town of Beroun. Originally, the entire stream was called Mže (German: Mies) and the name first appeared in the 12th century, among others in Chronica Boemorum. The name was written as Mse, Msa and Misa. From the 17th century, the lower course started to be named Berounka, but the name Mže still appeared as a name for the entire stream at the end of the 19th century. In order to avoid confusion, an initiative to rename the lower course back to the historical name Mže was created in 2008, but its efforts were unsuccessful due to the strongly adopted current name.

## Characteristic

From a water management point of view, the Berounka and Mže are two different rivers with separate numbering of river kilometres. In a broader point of view, the Berounka (as Mže) originates in the territory of Mähring in the Upper Palatine Forest at an elevation of 726 m (2,382 ft) and flows to Prague-Lahovice, where it enters the Vltava River at an elevation of 189 m (620 ft). It is 244.57 km (151.97 mi) long, of which 2.34 km (1.45 mi) is in Germany. In the Czech Republic, it is 242.23 km (150.51 mi) long, which makes it the fifth longest river in the country. Its drainage basin has an area of 8,854.2 km$^2$ (3,418.6 sq mi). The name Berounka is used from the confluence of the Mže with the Radbuza in Plzeň and from this point to the confluence with the Vltava, the river is 139.4 km (86.6 mi) long.
The Berounka has many significant tributaries. The sources and longest tributaries of the Berounka are:
| Tributary | Length (km) | River km | Side |
| Radbuza | 109.7 | 138.9 | right |
| Mže | 105.1 | 138.9 | – |
| Střela | 101.7 | 102.7 | left |
| Úslava | 96.3 | 136.0 | right |
| Loděnice | 64.7 | 30.6 | left |
| Litavka | 54.9 | 34.3 | right |
| Klabava | 51.2 | 121.9 | right |
| Rakovnický potok | 48.5 | 62.4 | left |
| Třemošná | 43.7 | 111.4 | left |
| Javornice | 30.9 | 81.3 | left |
| Zbirožský potok | 28.8 | 77.3 | right |
| Radotínský potok | 22.9 | 3.7 | left |
| Klíčava | 22.3 | 53.8 | left |
| Radnický potok | 18.7 | 96.2 | right |

## Settlements

There are several large settlements on the river. The Mže flows through Tachov and Stříbro. After its confluence with the Radbuza in Plzeň, the Berounka flows through Beroun, Řevnice, Dobřichovice, Černošice and along the edge of Prague.

## Bodies of water

There are 7,502 bodies of water in the basin area; the largest of them is the Hracholusky Reservoir with an area of 352 ha (870 acres), built at the confluence of the Mže and the stream Úterský potok. There are no bodies of water built directly on the lower course of the Berounka.

## Fauna

The river is home to the mollusc Unio pictorum, which is critically endangered within the Czech Republic. The endemic species Bulgarica nitidosa lives by the river.

## Use

There is an artificial slalom course in Roztoky, on the 63rd river km.

## Tourism

The Berounka is considered one of the most beautiful rivers in the country and is among the most popular rivers for river tourism. Almost its entire flow from Plzeň is navigable. It is popular thanks to the sections in the protected landscape areas of Křivoklátsko and Český kras, which lead through unspoiled nature. The Berounka belongs to the undemanding rivers suitable for beginner paddlers. An 82 km long educational trail for paddlers runs along the river.