Otra

Otra
View of the river Otra running through the city of Kristiansand, where it is also called Torridalselva or Torridalselven
Show map of Vest-Agder Show map of Aust-Agder Show map of Norway Location of the river mouth
Other name(s)	Torridalselva, Torridalselven
Country	Norway
Counties	Aust-Agder, Vest-Agder
Municipalities	Bykle, Valle, Bygland, Evje og Hornnes, Iveland, Vennesla, Kristiansand
Basin features
Main source	Setesdalsheiene, Bykle, Norway 896 metres (2,940 ft) 59°37′42″N 7°25′56″E / 59.6284°N 07.4321°E / 59.6284; 07.4321
River mouth	Skagerrak, Kristiansand, Norway 0 metres (0 ft) 58°08′36″N 8°00′48″E / 58.1434°N 08.0134°E / 58.1434; 08.0134Coordinates: 58°08′36″N 8°00′48″E / 58.1434°N 08.0134°E / 58.1434; 08.0134
River system	Otra
Basin size	3,752 km2 (1,449 sq mi)
Physical characteristics
Length	245 km (152 mi)
Discharge	Average rate: 150 m3/s (5,300 cu ft/s)

The Otra is the largest river in the Sørlandet region of Norway. It begins in the Setesdalsheiene mountains at the lake Breidvatnet in Bykle municipality in Aust-Agder county, just south of the border with Vinje municipality in Telemark county. The river then flows south through Bykle, Valle, Bygland, Evje og Hornnes, and Iveland municipalities in Aust-Agder before passing into Vest-Agder county and flowing through Vennesla and Kristiansand municipalities. The river empties into the Skagerrak in the center of the city of Kristiansand on the southern coast of Norway.

The Otra is 245 kilometres (152 mi) long, making it Norway's eighth-longest river in Norway. There are many large lakes along the river including: Åraksfjorden, Byglandsfjorden, Hartevatnet, and Kilefjorden. There are 12 hydroelectric power plants built along the river, which produce much of the electricity for the southern part of Norway.

The salmon do well in the Otra river because the water is not too acidic. The calcareous rocks in the catchment area at the northern end of the Setesdal valley give the water a certain buffer capacity against .