Namsen
or is one of the longest rivers in Trøndelag county, in the central part of Norway. The long river flows through the municipalities of Røyrvik, Namsskogan, Grong, Overhalla, and Namsos before emptying into the Namsenfjorden. The river is the namesake for the whole Namdalen region. The river traditionally has been used for floating timber down from the forests to the town of Namsos, where the sawmills were located. Today, parts of the Namsen are regulated by several dams.
Location
The river begins in springs in Børgefjell National Park, just over the border in Nordland county. This water feeds the large lake Namsvatnet. The Namsen river itself starts when the water passes through the dam on the northwest side of the lake Namsvatnet in Røyrvik Municipality.The river then travels through the Namdalen valley towards the coast, ending at the town of Namsos where it flows into the Namsenfjorden, the same fjord into which the smaller river Årgårdselva flows. There are two major tributaries to the Namsen: Tunnsjøelva and Sanddøla.
The total watershed is approximately and at Namsos, the water discharges into the fjord at about.