The refuge encompasses approximately 68 riparian miles of the Patuxent, Little Patuxent, and Anacostia River watersheds. The Patuxent and Little Patuxent rivers both cross directly through the refuge. These forested river and stream habitats, or riparian areas, provide spawning, nursery, migration, and year-round habitat for many species in Maryland. Riparian areas are rich in plant and wildlife diversity and are vital in protecting our valuable water sources. Riparian areas also serve as filtration buffers for excess sediment and nutrient overloads, in addition to maintaining temperature control for nearby air and water.