By now it has become a widespread, consistent practice in the European Union to consider very carefully and to regard as fundamental the basic needs of man, such as health and safety, in relation to all productive activities which may be regarded as a possible source of environmental deterioration. At the national legislative level, factors and elements regarding the environment (water, atmosphere, soil, subsoil, landscape, etc.) have been pointed out which require the state of quality to be characterised and vulnerability to the pressures caused by man's activities to be evaluated.This has brought about an evolution in the concept itself of environmental quality, which is understood more and more as actual satisfying of man's needs through the proper use of resources and the maintaining of an environmental equilibrium.Environmental quality can be pursued, therefore, by studying the most appropriate usage of the territory and by considering quality no longer as a hindrance, rule or imposition, but as a goal shared by all in improving the quality of life.In this study a few instruments are proposed for evaluating the overall capacity of a given environmental element or group of elements to withstand deterioration caused by outside pressure, which in this specific case is pollution from farming and livestock waste and sewage.Territorial vulnerability can thus be evaluated through a decision support tool (fuzzy logic), which allows different categories of people (researchers, politicians, planning technicians, citizens, etc.) to be involved in the evaluation process.For this study, the vulnerability evaluation was applied to a complex, homogenous territorial system, the Tiber watershed, where there are environmental resources which are particularly sensitive, owing both to their intrinsic characteristics as well as to the pressures stemming from livestock production activities, which is one of the major pollution risks along the regional drainage pattern.The use of GIS software has allowed the method of analysis and prioritising to be applied to environmental factors (weighting) as well as the rapid management of initial territorial data, also of differing types (qualitative and quantitative).The resulting product is a vulnerability map where the territory is classified on the basis of the evaluations of the degree of response to stresses induced by the livestock production activities.