Location

Numedalslågen stretches for over 250 kilometres through the counties of Vestfold

Vestfold

is a county in Norway, bordering Buskerud and Telemark. The county administration is in Tønsberg.Vestfold is located west of the Oslofjord, as the name indicates. It includes many smaller, but well-known towns in Norway, such as Larvik, Sandefjord, Tønsberg and Horten. The river Numedalslågen runs...

 and Buskerud

Buskerud

is a county in Norway, bordering Akershus, Oslo, Oppland, Sogn og Fjordane, Hordaland, Telemark, and Vestfold. The county administration is located in Drammen.-Geography:...

, beginning at the Hardangervidda

Hardangervidda

The Hardangervidda is a mountain plateau in the Hardanger region of western Norway. It is the largest such plateau in Europe, with a cold year-round alpine climate and is the site of one of Norway's largest glaciers. Much of the plateau is protected as part of Hardangervidda National Park; it is a...

 plateau and meeting the ocean at Larvik

Larvik

is a city and municipality in Vestfold county, Norway. The administrative centre of the municipality is the city of Larvik. Larvik kommune - has about 41 364 inhabitants and covers 530 km2....

 in Vestfold

Vestfold

is a county in Norway, bordering Buskerud and Telemark. The county administration is in Tønsberg.Vestfold is located west of the Oslofjord, as the name indicates. It includes many smaller, but well-known towns in Norway, such as Larvik, Sandefjord, Tønsberg and Horten. The river Numedalslågen runs...

. Numedalslågen is one of Norway's longest rivers. The rivers runs through the municipalities Larvik

Larvik

is a city and municipality in Vestfold county, Norway. The administrative centre of the municipality is the city of Larvik. Larvik kommune - has about 41 364 inhabitants and covers 530 km2....

, Lardal

Lardal

Lardal is a municipality in Vestfold county, Norway. The administrative centre of the municipality is the village of Svarstad. The parish of Laurdal was established as a municipality on 1 January 1838 . The municipality is divided into the parishes of Svarstad, Styrvoll, and Hem.-Name:The Old...

, Kongsberg

Kongsberg

is a town and municipality in Buskerud county, Norway. It is located at the southern end of the traditional region of Numedal. The administrative centre of the municipality is the town of Kongsberg....

, Flesberg

Flesberg

Flesberg is a municipality in Buskerud county, Norway. It is part of the traditional region of Numedal. The administrative centre of the municipality is the village of Lampeland....

, Rollag

Rollag

Rollag is a municipality in Buskerud county, Norway. It is part of the traditional region of Numedal. The municipality of Rollag was established on 1 January 1838 . Nore og Uvdal was separated from Rollag in 1858....

 and Nore og Uvdal

Nore og Uvdal

Nore og Uvdal is a municipality in Buskerud county, Norway. It is part of the traditional region of Numedal. The administrative centre of the municipality is the village of Rødberg....

. These municipalities cooperate in the administration and use of resources connected to the river in various projects under the Green Valley (Grønn Dal) umbrella.

There are a number of hydroelectric plants

Hydroelectricity

Hydroelectricity is the term referring to electricity generated by hydropower; the production of electrical power through the use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy...

 located in the higher range of Numedalslågen. Most of the power potential of the main river is developed, except the stretch between Hvittingfoss

Hvittingfoss

Hvittingfoss is a village in the municipality of Kongsberg, in the county of Buskerud, Norway. Hvittingfoss has traditionally been associated with the manufacture of pulp, paper and paper products....

 and Larvik

Larvik

is a city and municipality in Vestfold county, Norway. The administrative centre of the municipality is the city of Larvik. Larvik kommune - has about 41 364 inhabitants and covers 530 km2....

 and Godfarfossen in Dagali

Dagali

Dagali is a village in Hol municipality, Norway. Dagali also has an airport, Geilo Airport, that is no longer in use and currently used by Dagali Opplevelser. The river Numedalslågen runs though the village.-External links:*...

. Nore I kraftverk, the first power plant built in the Nore municipality

Nore og Uvdal

Nore og Uvdal is a municipality in Buskerud county, Norway. It is part of the traditional region of Numedal. The administrative centre of the municipality is the village of Rødberg....

 in Buskerud

Buskerud

is a county in Norway, bordering Akershus, Oslo, Oppland, Sogn og Fjordane, Hordaland, Telemark, and Vestfold. The county administration is located in Drammen.-Geography:...

 utilized Norefallene between Tunhovdfjorden

Tunhovdfjorden

Tunhovdfjorden is a lake in the River Nore and Uvdal municipality in Buskerud county, Norway. It has an area of 25.30 km² and a circumference of 62.79 km....

 and Rødberg

Rødberg

Rødberg is the administrative centre of Nore og Uvdal municipality, Norway.Rødberg is located in the Norwegian traditional district and valley of Numedal. Its population is 468, and it is located on the Rødberg dam on the Numedalslågen River....

. It was completed in 1928 and was designed by Norwegian architects Carl Buch and Lorentz Harboe Ree

Lorentz Harboe Ree

Lorentz Harboe Ree was a Norwegian architect.He was born in Stange, and graduated from the Norwegian Institute of Technology in 1915. Early on he worked with Harald Aars on several projects....

. Nore II kraftverk utilizes drop between Rødberg dam and Norefjord and was completed in 1947.

Numedalslågen is known for being a good location for salmon

Salmon

Salmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true...

 fishing, although a parasite known as Gyrodactylus salaris

Gyrodactylus salaris

Gyrodactylus salaris is a small monogenean ectoparasite which mainly lives on the skin of freshwater fish, especially Atlantic salmon. This species is a leech-like parasite that has been implicated in some diminution of Atlantic salmon populations in the Norwegian fjords. Its common name is Salmon...

 has recently been found in Numedalslågen that may pose a threat to its salmon stock. Among the other fish species of Numedalslågen are trout

Trout

Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water...

, eel

Eel

Eels are an order of fish, which consists of four suborders, 20 families, 111 genera and approximately 800 species. Most eels are predators...

, and pike

Esox

Esox is a genus of freshwater fish, the only living genus in the family Esocidae — the esocids which were endemic to North America, Europe and Eurasia during the Paleogene through present.The type species is E. lucius, the northern pike...

.

The name

The river is named after the valley Numedal

Numedal

Numedal is a traditional district and valley Buskerud, Norway. Running north–south, it extends between Kongsberg in the south to Rødberg in the north, passing through the municipalities of Kongsberg, Flesberg, Rollag and Nore og Uvdal.. The river Numedalslågen, the third-longest in the country,...

 - the last element is the finite form of låg (Norse lǫgr m) 'water; river'. But the old and original name of the river was Nauma, and the valley is named after this name.

Other sources

• Nasjonalgalleriet and Riksantikvaren (1982) Norsk Kunstnerleksikon (Oslo: Universitetsforlaget) ISBN 82-00-05689-9
• Tråen, Even, Tor Bjørvik & Sølver Sjulstad (2001) Livet langs Numedalslågen (Oslo) ISBN 82-996056-0-1