The Ohře (Czech pronunciation: [ˈoɦr̝ɛ]), also known in English and German as Eger (German pronunciation: [ˈeːɡɐ]), is a river in Germany and the Czech Republic, a left tributary of the Elbe River. It flows through the Bavarian district of Upper Franconia in Germany, and through the Karlovy Vary and Ústí nad Labem regions in the Czech Republic. It is 304.6 km (189.3 mi) long, 256 km (159 mi) of which are in the Czech Republic, which makes it the fourth longest river in the country.

The name is of Celtic or pre-Celtic origin. In the 9th century, it appeared as Agara. According to one theory, its meaning was 'salmon river' (composed of the words ag, eg – 'salmon', and are, ara – 'flowing water').^[1] According to the second theory, the name was derived from agriā and meant a fast-moving, fast-flowing river. In the 12th century, Ohře was written as Egre, Oegre and Ogre.^[2][3]

The Ohře originates in the territory of Weißenstadt in the Fichtel Mountains at the elevation of 752 m (2,467 ft), below the Mt. Schneeberg. It flows to Litoměřice, where it enters the Elbe River at the elevation of 143 m (469 ft).^[4]

The Ohře flows through the Fichtel Mountains in an eastward direction, through Lake Weissenstadt (Weißenstädter See) and through the towns of Röslau and Marktleuthen, and, after about 60 km, reaches the Czech border near Hohenberg an der Eger. It then flows through parts of the Czech Republic which were known until 1945 as Egerland. The river passes the towns of Cheb, (German: Eger, like the river), Loket, Sokolov, Karlovy Vary, Klášterec nad Ohří, Kadaň, Žatec, Louny, Libochovice, Budyně nad Ohří and Terezín before flowing into the river Elbe at Litoměřice.

The river is 304.6 km (189.3 mi) long,^[5] of which 256 km (159 mi) is in the Czech Republic,^{[1][lower-alpha 1][lower-alpha 2][lower-alpha 3]} which makes it the fourth longest river in the Czech Republic. The German part of the river (including the border section) is 49.8 km (30.9 mi) long.^[7]

The highest volume flow rate occurs in spring. The average volume flow rate at the mouth is 37.94 m³/s.^[8] The lower part of the river flows through areas with the lowest average precipitation in the Czech Republic (400–500 mm).^[4]

The Ohře is primarily used for irrigation and hydroelectric energy. There are two reservoirs: Skalka (built in 1962–1964, area 378 ha (930 acres)^[9]) and Nechranice (built 1961–1968, area 1,338 ha (3,310 acres)^[10]).