Before the civil war in Bosnia Herzegovina (1992-1995), the municipality of Stolac was mainly devoted to agriculture with 70 percent of population living in rural areas. After the war, the irrigation systems of the municipality have been abandoned from the public bodies, causing problems of maintenance operations and, then, limit in the use of irrigation water. In addition to that, the migration of people to safer countries contributed to limit the development of agriculture and the renewal of the activities of the region. The solution to that problem may be found in the rehabilitation of the existing irrigation systems, in order to guarantee satisfactory efficiency levels in the water transport. The note presents the first results of the application of the diagnostic analysis procedure (an investigation process which aims at revealing problems, causes and effects related to the relevant actors involved in the system) to an existing irrigation system in Vidovo Polje, located at roughly 33 km from Mostar in Bosnia Herzegovina. Since the focal point of such a methodology is the user participation, information has been collected directly on the field, and the problems have been singled out, and classified according to cause-effect relations and structured into a problem tree. Both internal social conflicts and technical inefficiency of the conveyance network came out from the survey and allowed the identification of the critical aspects of the irrigation system of Vidovo Polje.