Impassable water barriers for aquatic organisms can have a negative impact on aquatic environment.
In watercourses, that are not influenced by human interventions, the fish can swim up and
downstream. With building barriers we block their migration paths and by that reduce diversity and
abundance of fish species and other aquatic organisms. It is important that we try to find and realize
the solutions for longitudinal connectivity of running waters. One of the best solutions is to built fish
passes, which allow fish to pass obstacles. In the first part of the thesis, the theoretical bases of
designing fish passages are introduced. Design factors that must me taken into account when planing,
legalisation, design of specific elements of the fish pass, monitoring, maintenance and protection of
the fish passes from possible negative influences are discussed. The situation related to fish passes in
Slovenia is also described. In the second part, the example of designing a fish pass on Homec weir on
Kamniška Bistrica river is discussed. The local conditions are described, along with criteria, that must
be taken into account when designing a fish passage on present area. Further, the design of the fish
pass and suggested positioning of the fish passage is made.