This research was conducted in the southeastern United States, one of the most rapidly developing regions in the country. The study included two sets of predictor variables: environmental experiences and perceptions (i.e., observation of pollution and assessment of pollution’s impact) and residential factors (i.e., rural vs. urban residence and upstream vs. downstream watershed location); sociodemographic characteristics served as control variables. Sequential regression was performed on survey data of watershed residents to isolate the predictors of environmentalism. Observation of pollution and assessment of pollution’s impact on water quality were most important for explaining environmental concern, self-reported household-based behaviors, and self-reported likelihood of engaging in water quality improvement efforts. The sociodemographic variables were also significant predictors; the residential variables had limited influence on the dependent variables. These results indicate that stormwater educators should account for experiential factors and perceptions of pollution when designing strategies for encouraging environmentalism.