The aim of this study was to investigate how well the biological indexes in the north of Sweden matches with the physicochemical conditions in streams, and to evaluate whether the deformations of diatom shells has a connection to heavy metal conditions in streams. The sampling areas include nineteen different locations. As the water-chemical conditions in the water vary during the year and the sampling rate for each local has varied, therefore, an average has been calculated for each local. Diatoms in 13 of 165 sampling points had a deformation over 1%, the highest deformation percent was 10.5%, in that locality the heavy metals concentration for Zn, U, Ni, Cd and As were very high. In another locality with very high concentrations of Cd, Cu and Zn was the deformation only 0.24%. It may be a cocktail effect i.e. that elevated levels of several metals together give greater effect than the individual. If you compare the index for diatoms, IPS (Indice de Polluo-sensibilité Spécifique) and ACID (ACidity Index for Diatoms) to the water chemical data, there is no clear correlation. IPS shows high status at all premises except 3. These 3 locations that achieve good status have a relatively good water-chemical status. When comparing the benthos indexes, you can see a connection first when the physicochemical parameters show high values. According to ASPT (Average Score Per Taxon), there are no water streams that are considered to be affected even though at least five sampling sites where benthos was sampled showed an impact of heavy metals or acidity.