|This study was conducted to aid administrators in overcoming some barriers to implementation and maintenance of programs for monitoring visitor impact to Brazilian protected areas. One of the problems refers to continuity in collecting field data due in part to lack of institutional commitment. In order to verify the effectiveness of surveys carried out by park employees, the difference between data collected by park rangers and those collected by specialists was studied so that simple and dependable indicators could be selected. 26 indicators of physical attributes were analyzed for four intensive-use trails at Intervales State Park through systematic sampling of points. Results indicate that the group of rangers produced more homogeneous data than the group of specialists did. Significant differences were more frequent among quantitative indicators. Indicators chosen according to their dependability criterion were: bird sighting and hearing, vandalism to park facilities, rock graffiti, number of damaged or carved trees, number of perceptions of vehicle noise, number of exposed rocks, visible erosion, trail depth, traces of fauna and trash litter.