The Kiamichi River, a major tributary of the Red River, flows through the Ouachita Mountains and Gulf Coastal Plain of southeastern Oklahoma. The river is 272 km long and has a drainage area of 4,800 km2.
The Kiamichi is known for its clean water and high aquatic biodiversity, including more than 100 fish species and 30 species of mussels, more than half the mussels known from the entire state of Oklahoma. The Kiamichi River contains an important population of the federally listed Ouachita Rock-Pocketbook mussel (Arkansia wheeleri) and seven other vulnerable or imperiled mussel species including the recently re-discovered Scaleshell mussel (Leptodea leptodon).
The Kiamichi River was recently selected by The Nature Conservancy as one of the most critical watersheds in the U.S. for protecting biodiversity, based on its diverse and abundant aquatic fauna and the fact that the Kiamichi is one of the few tributaries of the Red River that has not been significantly influenced by major land use changes or water diversion. However, mussel populations in the Kiamichi now face significant threat from several years of drought conditions combined with high demand for water in the region.