Summary
Lake Hurdalssjøen is regulated for hydro-electric power (HEP). The water level regulation is the main pressure in the lake. The aim of the survey was to describe the aquatic macrophyte community in the lake, and to assess the ecological status of this quality element. The aquatic macrophytes in Hurdalssjøen are dominated by isoetids, especially Isoetes lacustris, which make stands down to 4,2 m depth. The ecological status of aquatic macrophytes in Hurdalssjøen is good, both according to eutrophication and water level regulation.