Agriculture, urbanization, and industrialization are some of the anthropogenic activities that constantly generate negative impacts on natural environments. Part of this degradation directly affects aquatic systems. This study aimed to evaluate the visual characteristics of the Araras Stream, located in the municipality of Araras, São Paulo state, Brazil. Data was collected at six different assessment sites along the river in both rural and urban areas. The evaluation used a Rapid Habitat Diversity Assessment (RHDA) protocol composed of 22 parameters, which define levels of preservation of ecological conditions. According to this protocol, the 32 Km-long study transect along the Araras Stream was rated as impacted (39.6 points). A separate assessment by transects showed that only Transect 1 presented a natural level of preservation (71.8 points). Transects located in the urban area contributed the most to impacts on the aquatic environment. The RHDA protocol proved to be an important tool to evaluate and monitor aquatic environments.
