Global Range: Bonytails were formerly abundant throughout the Colorado River and its larger tributaries, including the Green River north to the reach now inundated by Flaming Gorge Reservoir in Wyoming and Utah, the Yampa and Gunnison rivers in Colorado, and the Colorado River in Arizona, Colorado, Nevada, and California), and likely also the San Juan River in New Mexico and the Gila and Salt rivers in Arizona (Lee et al. 1980, USFWS 1990, Muth et al. 2000). Documented records exist for Lake Havasu, Lake Mohave, and Grand Canyon in the Lower Colorado River Basin; and Lake Powell, the Colorado River (Cataract Canyon, Green River confluence, Utah; Black Rocks, Colorado), Gunnison River near Delta, Colorado, Green River (Gray Canyon, Utah; Dinosaur National Monument, Colorado and Utah; Hideout Canyon, Utah), and lower Yampa River, Dinosaur National Monument, Colorado), in the Upper Colorado River Basin (USFWS 2002).
An unknown but small number of wild adults exist in Lake Mohave on the mainstem Colorado River of the Lower Colorado River Basin (i.e., downstream of Glen Canyon Dam, Arizona), and there are small numbers of wild individuals in the Green River and upper Colorado River subbasins of the Upper Colorado River Basin (USFWS 2002). USFWS (2002) listed only two locations (Lake Mohave on the Arizona-Nevada border and Lake Havasu along the Arizona-California border) where wild bonytails have been documented since 1990.
As of the early 1990s, populations were being established in urban lakes in Tempe, on the Buenos Aires NWR, and at TNC's Hassayampa Reserve, all in Arizona; plans called for stocking of experimental populations into Arizona streams (Minckley and Deacon 1991).