Freshwater mussels are facing a global extinction crisis. Information on species habitat use can inform reintroduction and restoration strategies to identify suitable locations and habitat preferences. Given that most freshwater mussels are rare (i.e., low density, narrow and patchy distribution), imperfect species detection can affect occupancy estimates, leading to inaccurate species distribution maps and misallocation of limited resources. However, accounting for imperfect species detection can improve model estimates and the efficient use of resources. Therefore, we examined how habitat and co-occurring freshwater mussel species presence affects the presence of Brook Floater (Alasmidonta varicosa), a declining IUCN vulnerable species, across their historic range of the Atlantic slope, United States. Data were collected following a standardized rapid assessment sampling protocol from 2016 through 2024 across eight states (n =355 sites). We used a hierarchical occupancy modeling approach to account for imperfect species detection. Preliminary analyses at the watershed level (n = 18 watersheds) suggest that Brook Floater presence is positively influenced by more coarse gravel substrate, increased distance upstream from a road-stream crossing, and less riffle habitat. Additionally, increased water depth increased detection estimates of Brook Floater. The influence of these variables varied slightly across watersheds, suggesting watershed conditions may shift habitat preferences. Eastern Elliptio (Elliptio complanata) and Creeper (Strophitus undulatus) co-occurred most often with Brook Floater, while Corbicula and Eastern Pearlshell (Margaritifera margaritifera) co-occurred least often with Brook Floater. These findings highlight the habitat use of Brook Floater across their historic range to aid conservation efforts for stocking and restoration decisions.