The Otra is the largest

river A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...

in the

Sørlandet Southern Norway (; lit. "The Southland") is the geographical List of regions of Norway, region (''landsdel'') along the Skagerrak coast of southern Norway. The region is an informal description since it does not have any governmental function ...

region of

Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...

. It begins in

Setesdalsheiene Setesdalsheiene () is the collective term for the mountains to the west and east of the Setesdalen valley in Agder county in Southern Norway. The river Otra flows through the valley between the mountains. This area is primarily located in the m ...

mountains at the lake Breidvatnet in

Bykle Bykle is a List of municipalities of Norway, municipality in Agder county, Norway. It is located in the Traditional districts of Norway, traditional district of Setesdal. The administrative centre of the municipality is the village of Bykle (vil ...

municipality in

Agder Agder is a counties of Norway, county () and districts of Norway, traditional region in the southern part of Norway and is coextensive with the Southern Norway region. The county was established on 1 January 2020, when the old Vest-Agder and Au ...

county, just south of the border with

Vinje Vinje is a municipality in Telemark county, Norway. It is located in the traditional district of Vest-Telemark which is part of Øvre Telemark. The administrative centre of the municipality is the village of Åmot. Other villages in the muni ...

municipality in

Telemark Telemark () is a Counties of Norway, county and a current electoral district in Norway. Telemark borders the counties of Vestfold, Buskerud, Vestland, Rogaland and Agder. In 2020, Telemark merged with the county of Vestfold to form the county o ...

county. The river then flows south through

Valle Valle may refer to: * Valle (surname) Geography *"Valle", the cultural and climatic zone of the dry subtropical Interandean Valles of the Andes of Peru, Bolivia, and northwest Argentina * University of Valle, a public university in Cali, Colomb ...

Bygland Bygland is a List of municipalities of Norway, municipality in Agder county, Norway. It is located in the Traditional districts of Norway, traditional district of Setesdal. The administrative centre of the municipality is the village of Bygland ...

Evje og Hornnes Evje og Hornnes is a municipality in Agder county, Norway. It is located in the traditional district of Setesdal. The administrative centre of the municipality is the village of Evje. Other villages in the municipality include Åneland, Dåsn ...

Iveland Iveland is a List of municipalities of Norway, municipality in Agder County, Norway. It is located in the Traditional districts of Norway, traditional district of Setesdal. The administrative centre of the municipality is the village of Birketvei ...

Vennesla Vennesla is a List of municipalities of Norway, municipality in Agder county, Norway. It is located in the Traditional districts of Norway, traditional district of Sørlandet. The administrative centre of the municipality is the village of Venn ...

, and

Kristiansand Kristiansand is a city and Municipalities of Norway, municipality in Agder county, Norway. The city is the fifth-largest and the municipality is the sixth-largest in Norway, with a population of around 116,000 as of January 2020, following th ...

municipalities. The river empties into the

Skagerrak The Skagerrak (; , , ) is a strait running between the North Jutlandic Island of Denmark, the east coast of Norway and the west coast of Sweden, connecting the North Sea and the Kattegat sea. The Skagerrak contains some of the busiest shipping ...

in the center of the city of

on the southern coast of Norway. The Otra is long, making it Norway's eighth-longest river. There are many large lakes along the river including:

Åraksfjorden Åraksfjorden is a lake in the municipality of Bygland in Agder county, Norway. The lake is part of the Otra drainage basin. The northern part of the lake is fed directly by the river Otra. The southern part of the lake goes through a narrow ...

Byglandsfjorden Byglandsfjorden is a lake in Agder county, Norway. The lake lies on the river Otra, primarily in the municipality of Bygland, but the far southern tip of the lake extends into the neighboring municipality of Evje og Hornnes. The river flows ou ...

Hartevatnet Hartevatnet or Hartevatn is a lake in the municipality of Bykle in Agder county, Norway. It is located along the river Otra, on the south side of the village of Hovden. The lake is a good fishing spot and contains many brown trout. The Norwegian ...

, and

Kilefjorden Kilefjorden is a lake on in Agder county, Norway. The lake is located on the border of the municipalities of Evje og Hornnes, Iveland, and Vennesla. The lake is part of the river Otra. The lake is located about west of the village of Birketv ...

. There are 12

hydroelectric Hydroelectricity, or hydroelectric power, is Electricity generation, electricity generated from hydropower (water power). Hydropower supplies 15% of the world's electricity, almost 4,210 TWh in 2023, which is more than all other Renewable energ ...

power plants built along the river, which produce much of the electricity for the southern part of Norway. The

salmon Salmon (; : salmon) are any of several list of commercially important fish species, commercially important species of euryhaline ray-finned fish from the genera ''Salmo'' and ''Oncorhynchus'' of the family (biology), family Salmonidae, native ...

do well in the Otra river because the water is not too

acidic An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen cation, H+), known as a Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid. The first category of acids are the ...

. The

calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime (mineral), lime or being chalky. The term is used in a wide variety of Science, scientific disciplines. In zoology ''Calcare ...

rocks in the catchment area at the northern end of the

Setesdal Setesdal (; older name: Sætersdal) is a valley and a traditional district in Agder County in southern Norway. It consists of the municipalities of Bykle, Valle, Bygland, Iveland, and Evje og Hornnes. The Otra river flows through the val ...

valley give the water a certain buffer capacity against

acidification Acidification may refer to: * Ocean acidification, decrease in the pH of the Earth's oceans * Freshwater acidification, atmospheric depositions and soil leaching of SOx and NOx * Soil acidification, buildup of hydrogen cations, which reduces the ...

References

External links

* Rivers of Agder Setesdal Geography of Kristiansand Vennesla Iveland Evje og Hornnes Bygland Valle, Norway Bykle Rivers of Norway {{Norway-river-stub