River otters (Lontra canadensis) select specific habitat features when establishing latrines, but no studies have described latrine features in arid and semiarid environments. We developed a model describing those habitat features that influence otter latrine site selection on rivers in arid and semiarid watersheds of western Colorado, USA. River otters selected latrine sites with the presence of beaver (Castor canadensis) activity, large prominent rocks, adjacent to deeper water, with shading over the site, and rock or cliff overstory. Our model provides a robust predictive tool for identifying river otter latrine sites in arid environments of southwestern North America.