Summary
This report presents suggestions for biotope-improvements along an 800 m channelized reach of the Nitelva river (at the school of Hakadal), based on previously reported knowledge and newly collected information on the status of river pearl mussel, noble crayfish and trout along this reach. These species were found to be absent or in low densities along the studied reach, and two main causes are identified. First, two power plants upstream frequently cause extremely low water depths along the reach. Second, the morphology of the channel is monotonous, without curves, deep points or local stream variation. We suggest measures for morphological improvements, focusing on riverbed morphology, mostly along the school Elvetangen. A pool should be established, and boulders and large rocks should be placed in the river, both singular and in groups. The stones should leave open space as shelter for crayfish, aquatic invertebrates and juvenile fish. The measures itself will allow flooding and river currents to work in more differentiated patterns and improve the development of increased habitat heterogeneity. The measures should be planned and implemented jointly with the local schools and other stakeholders, to ensure local ownership and evaluation monitoring after implementation, which is necessary to evaluate the effect of the measures.