Breidvatn is a lake in Bykle municipality in Setesdal, in Agder County, southern Norway. It has an outlet to the south to the river Otra. The main inlets are BjÃÂ¥laupet, which enters from Sæsvatn in the north, and KaldsÃÂ¥i from the west. Together with Sæsvatn, Breivatn is regulated as a reservoir for the power plants further down the Otravassdraget.