Freshwater mussel communities are imperiled partly due to massive habitat alteration from damming rivers. This has resulted in the need to quantify mussel habitat characteristics to properly manage mussel populations. Because mussel abundance has been negatively associated with shear stress, and because increased shear stress can lead to substrate movement, it has been suggested that substrate stability may constrain mussel abundance. We conducted a field study combining these previous approaches with quantification of substrate characteristics to test the hypothesis that freshwater mussel abundance is higher in areas of lower substrate movement. We sampled substrate and modeled complex hydraulic variables at low and moderate discharge for 168 quadrats at 7 sites in the Little River, OK. Using quantile regression, we found that mussel abundance and species richness are constrained by both hydraulic and substrate variables, including Shield's entrainment function (a measure of substrate movement). Thus, our analyses suggest that substrate stability is an important factor for mussel habitat. Future studies investigating habitat characteristics of mussels should also incorporate both hydraulic and substrate variables to accurately quantify substrate stability.