The master’s thesis deals with the design of measures for improving passability at transverse river structures, which can also influence on the improvement of longitudinal connectivity of the river. The master’s thesis is structured in such a way, that the first part deals with theoretical background, which must be taken into account at designing measures for ensuring migration at newly and at existing transverse river structures. Construction of the fish pass is one of the most effective measures. Based on the considered theoretical background, the conceptual design of the restoration of the passability on Sava Bohinjka River at Soteska HPP Dam was made in the second part of the thesis. Insured passability would have a great positive influence on the longitudinal connectivity of the entire river. In order to ensure passability at the dam, we designed a plan, which takes into account, first the restoration of passability of the main river section and second the conceptual design of the fish pass, consisting of a technical pool type with vertical slots and natural-technical pool type. The operation of fish pass is enabled by exploiting part of the ecologically acceptable flow. In designing the restoration of passability, the ichthyologic factors, determined by the fish species of Sava Bohinjka River, were taken into account. In order to provide additional attraction flow at the fish pass entrance and to use part of the ecologically acceptable flow, we planned the construction of small hydropower plant. Finally, by analysing the investment costs of the entire restoration of passability for aquatic organisms at the Soteska HPP Dam, we showed that the total investment cost of the design, which includes construction of small hydropower plant, would be refunded after approximately 16 years. The proposed design would have a positive influence on the improvement of the longitudinal connectivity of the river, and at the same time with the possibility of producing electricity in the small hydropower plant, the potential investor would more likely finance the investment.