Altevatnet is an 80 km ² large reservoir in the municipality Bardu in the county of Troms in Norway north of the small lake Geavdnjajávri and the Swedish Tornetrask.

It is the eleventh largest lake in Norway and the largest in the Fylke Troms. It is 35 km long and 2 km wide on average. The lake is provided with a dam 's degree, which can control the altitude of 472-489 moh. His discharge forms the Barduelva, which opens into the Målselva, which in turn flows into the Malangen fjord. The power plants Innset, Straumsmo in Bardu and Bardufoss along the Barduelva use the water storage Altevatnet 1,027 million m³. It is connected with the Leinavatn By Ousto channel on its eastern side.