A year''s observations were made on the settling of benthonic organisms on experimental slabs placed in the intake and in the outfall water of the power station. No growth of algae was found in the intake, but there was very prolific growth in the outfall. No difference in the specific composition of benthonic invertebrates was found between the intake and the outfall slabs. It is supposed that the outfall area is beneficial in some respect as the benthonic forms appear earlier than in the intake. The general characteristic of the environment, and the factors introduced by the power station into the aquatic medium are given.