Numedalslågen

Numedalslågen
Numedalslågen at Godfarfossen
Country	Norway
Basin features
Main source	Hardangervidda
River mouth	Larvik, Skagerrak
Physical characteristics
Length	250 kilometres (160 mi) (approx.)

Numedalslågen is a river located in the counties of Vestfold and Buskerud in southeastern Norway. It is one of the longest rivers in Norway.

Numedalslågen stretches for over 250 kilometres (160 mi) through the counties of Vestfold and Buskerud, beginning at the Hardangervidda plateau and meeting the ocean at Larvik in Vestfold. Numedalslågen is one of Norway's longest rivers. The river runs through the municipalities Larvik, Lardal, Kongsberg, Flesberg, Rollag and Nore og Uvdal. 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 in the higher range of Numedalslågen. Most of the power potential of the main river is developed, except the stretch between Hvittingfoss and Larvik and Godfarfossen in Dagali. Nore I kraftverk, the first power plant built in the Nore municipality in Buskerud used Norefallene between Tunhovdfjorden and Rødberg. It was completed in 1928 and was designed by Norwegian architects Carl Buch and Lorentz Harboe Ree. Nore II kraftverk uses the drop between Rødberg dam and Norefjord and was completed in 1947.

Numedalslågen is known for being a good location for salmon fishing, although a parasite known as Gyrodactylus salaris has recently been found in Numedalslågen that may pose a threat to its salmon stock. Among the other fish species of Numedalslågen are trout, eel, and pike.