The Olt (German Alt; Hungarian Olt; Latin alutus[1] from Latin lut = clay) is a left tributary of the Danube in Romania with a length of 615 kilometers. Shortly before it flows into the Danube, the river reaches a water flow of 190 m³/s. It is also the namesake of the Romanian district of Olt.
The Olt flows entirely on Romanian territory. It rises in the Eastern Carpathians, flows southwards to Bod (Brenndorf), where it bends and crosses the Perșani Mountains. It then flows westwards through the historic Altland and finally leaves Transylvania in a southerly direction. The Olt now crosses the Transylvanian Alps at the Rotenturm Pass towards the Getic Plateau or Wallachia, where it flows into the Danube in the extreme south of the country five kilometers west of Turnu Măgurele.
The river is dammed by a total of 24 dams, which were built for the purpose of generating electricity. The first is near Făgăraș. The length of the reservoirs varies and generally becomes longer towards the mouth. Most of the lakes are enclosed by a wall. The dams with the power stations are all of the same type. Shipping was carried out on the river until the 19th century.