Nidelva in Trondheim, view upstream
|River mouth||Trondheim Fjord|
|Length||30 km (19 mi)|
Nidelva (or Nidelven) is a river in the county Sør-Trøndelag, Norway. It travels through Trondheim and Klæbu municipalities. The name translates to "River Nid", Elva or Elven being Norwegian for river.
Nidelva starts at the Hyttfossen waterfall which rises from Bjørsjøen, a small lake located just below Selbusjøen, the largest lake in Sør-Trøndelag County. Nidelva runs via Tiller and through the city of Trondheim before reaching Trondheim Fjord by the island of Brattøra near Trondheim Central Station. Nidelva is at its deepest at Trongfossen, a deep ravine in the village of Klæbu. There are six hydro-electric power stations along the river. Nidelva forms the last part of the Nea-Nidelv watershed (Nea-Nidelvvassdraget). Nea River is a tributary which empties into Selbusjøen. 
The popular Norwegian waltz, "Nidelven quiet and beautiful you are" (Nidelven Stille og Vakker du er), was written by composer Oskar Hoddø (1916–1943). According to tradition, Hoddø wrote the waltz about the Nidelva River one night in late April 1940 while he was standing at Gamle Bybro in Trondheim.
- Øksendal, Asbjørn (1969) Lurøy-affæren - Operasjon Oleander: Gestapo i Trondheim og Leksvik-affæren 1942-44 ISBN 978-82-7005-023-9
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