Freshwater mussels continue to experience declines in population numbers in response to changing environments. Identifying aspects of the environment associated with the presence and abundance of mussels in small streams is challenging where past records are minimal. Thus, we sought to produce models of habitat favoring mussel species richness and abundance in the upper Mahoning River using data collected in 2 ways: (1) surveying sites deemed as suitable habitat via observation and (2) surveying existing Ohio Environmental Protection Agency (OEPA) sites used to evaluate water quality and aquatic life through biotic indices. Detailed physical measurements were added at each survey site. Surveys identified 963 freshwater mussels of 11 species. The more-forested Eagle Creek contained an abundant mussel assemblage compared to the rest of the Upper Mahoning River, yet this stream was still dominated by just 1 common species, Lampsilis siliquoidea (Fatmucket). Drainage area alone correlated with mussel richness and abundance, but a complex model of multiple characteristics provided equivalent predictive power to assess how variation in environmental components may enhance the likelihood of mussel presence. The OEPA composite qualitative habitat evaluation index, which encompasses substrate, instream cover, channel morphology, riparian zone, pool quality, and map gradient, also was indicative of greater mussel diversity.