The application of a dynamic generation cost indicator (DGC) as a method to evaluate the effi ciency of investments, which allow to select an investment project with the lowest possible cost. The DGC indicator consist of investment costs at the stage of implementation, and operating costs, occurring throughout the period of the economic life of the project. The comparative analysis of the three alternative solutions was made on the example of the Skórzynka catchment with the use of DGC indicator. It helped in the selection of the most optimal solution in social aspect. It has also shown that this method can be successfully used in the initial phase of the decision-making process in the selection of the most eff ective solutions which shape the retention capacity of the river catchment in urban areas.