The location of large hog barns in relation to neighbours, communities and highways is a major factor in establishing public attitudes towards these operations. Little data exists to assist planners determine proper siting by establishing how local topography and weather condition affect the odour plumes created by these operations. This project studied six southern Manitoba hog operations located in locations ranging from sparsely- wooded flat terrain to heavily-treed rolling land. Two-person “odour panels” evaluated the relative strengths of the odour plumes produced under various wind directions and velocities, temperatures and humidity levels. Panelists rated odour concentrations on a scale of 1 to10 at various distances from the odour source under varying weather conditions. The study concluded odours essentially travel in the direction of the wind (longitudinal) and that there is little lateral dispersement in other directions provided the wind is in a constant direction. Neither trees nor rolling terrain have significant effects on odour movement although they tend to deflect wind direction and may dilute odour concentrations. Widest odour plumes occurred during manure spreading operations rather than from barns or earthen manure storages and there appeared to be some correlation between the number of Animal Units on a site and the maximum distance odour plumes traveled.