Hjartdøla river will freeze more often during the winter than is currently the case. The water downstream of the power plant outlet will have greater temperature variations throughout the day than is currently the case, in summertime as well as winter. The average daily temperature downstream of the power plant will change somewhat: it will be slightly higher in winter and slightly lower in summer.
Between the power plant outlet and Heddalsvatn lake, variable freezing conditions will occur. The river will therefore mainly run freely, except for in still, deep sections closest to Heddalsvatn lake.
In Skogsåa river, no significant changes in temperature conditions are expected. However, the river could freeze a few days earlier as a result of lower water volume.
Small changes are expected in the temperature and freezing conditions of Hjartsjåvatn, Sønderlandsvatn and their side streams.