An analysis of the possibility of reconstruction and modernization of the Wełna river water way system in Nowy Młyn is presented in the paper. The system includes two weirs, channels of the river Wełna and młynówka and planned small hydroelectric power. Based on modeling results received from the HEC-RAS program, the most important factors affecting the work of the water way system for its current operating conditions and the planned redevelopment have been identified. In the assumptions of the planned reconstruction important role is played by the aspect of active tourism on the discussed section of the Wełna river. The conditions for the operating of the water way system were also determined taking into account the need to preserve the integrity of the river ecosystem including fish migration. The possibilities and limitations of the planned investment are outlined.