
Lower Colorado River Basin
The Lower Colorado River Basin encompasses nearly all of Arizona, and parts of California, Nevada, Utah, New Mexico, and Mexico. Although most of the water used within the basin originates in the Upper Colorado River Basin, tributaries within the Lower Basin, most notably the Gila, Salt, and Verde Rivers, are critical in supplying municipal and agricultural needs and supporting unique riparian and aquatic ecosystems.
Map of the HUC 6 watershed sub-basins in the Lower Colorado River basin that were used for this analysis. Click on the polygons to obtain information about listed species by taxa in each HUC 6 watershed (as of 25 January 2025). Or click here to open the map online.
The following is a summary of the listed species and critical habitats found in the Lower Colorado River Basin. Click on the blocks below to obtain more detailed information about the listed species and critical habitats in each HUC 6 (as of 23 January 2025).
The following table is a summary of listed species and critical habitats by taxa with in the Lower Colorado River Basin.
Amphibians

Photo credit: By Jim Rorabaugh/USFWS
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Chiricahua Leopard Frog (Rana chiricahuensis) (T) (CH)
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Sonoran Tiger Salamander (Ambystoma mavortium stebbinsi) (E)
Ferns and Allies

Photo credit: Linda Swarz
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American Hart's-tongue Fern (Asplenium scolopendrium var. americanum) (T)
Insects

Photo credit: Thomas Dunkerton Neal-Smith NWR, Thomas Dunkerton/USFWS
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Monarch Butterfly (Danaus plexippus) (C)
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Mount Charleston Blue Butterfly (Icaricia shasta) (E) (CH)
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Silverspot (Speyeria nokomis nokomis) (T)
Snails

Photo credit: Jeff Sorensen
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Alamosa Springsnail (Tryonia alamosae) (E)
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Three Forks Springsnail (Pyrgulopsis trivialis) (E) (CH)
Flowering Plants

​Photo credit: Ashlee Wolf
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Acuna Cactus (Echinomastus erectocentrus acunensisa) (E) (CH)
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Arizona Cliffrose (Purshia subintegra) (E)
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Arizona Eryngo (Eryngium sparganophyllum) (E) (CH)
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Arizona Hedgehog Cactus (Echinocereus arizonicus arizonicus) (E)
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Barneby Reed-mustard (Schoenocrambe barnebyi) (E)
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Bartram's Stonecrop (Graptopetalum bartramii) (T) (proposed CH)
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Beardless Chinchweed (Pectis imberbis) (E) (CH)
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Brady Pincushion Cactus (Pediocactus bradyi) (E)
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Canelo Hills Ladies'-tresses (Spiranthes delitescens) (E)
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Cochise Pincushion Cactus (Coryphantha robbinsorum) (T)
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Dwarf Bear-poppy (Arctomecon humilis) (E)
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Fickeisen Plains Cactus (Pediocactus peeblesianus spp.) (E) (CH)
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Gierisch Mallow (Sphaeralcea gierischii) (E) (CH)
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Heliotrope Milk-vetch (Astragalus montii) (T) (CH)
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Holmgren Milk-vetch (Astragalus holmgreniorum) (E) (CH)
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Huachuca Water-umbel (Lilaeopsis schaffneriana recurva) (E) (CH)
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Jones Cycladenia (Cycladenia humilis var. jonesii) (T)
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Kearney's Blue-star (Amsonia kearneyana) (E)
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Kodachrome Bladderpod (Lesquerella tumulosa) (E)
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Last Chance Townsendia (Townsendia aprica) (T)
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Mesa Verde Cactus (Sclerocactus mesae-verdae) (T)
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Navajo Sedge (Carex specuicola) (T) (CH)
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Nichol's Turk's Head Cactus (Echinocactus horizonthalonius nicholii) (E)
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Pecos Sunflower (Helianthus paradoxus) (T)
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Peebles Navajo Cactus (Pediocactus peeblesianus) (E)
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Pima Pineapple Cactus (Coryphantha scheeri robustispina) (E)
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San Francisco Peaks Ragwort (Packera franciscana) (T) (CH)
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San Rafael Cactus (Pediocactus despainii) (E)
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Sentry Milk-vetch (Astragalus cremnophylax) (E)
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Shivwits Milk-vetch (Astragalus ampullarioides) (E) (CH)
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Siler Pincushion Cactus (Pediocactus sileri) (T)
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Swale Paintbrush (Castilleja ornataa) (Proposed E)
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Todsen's Pennyroyal (Hedeoma todseniia) (E)
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Ute Ladies'-tresses (Spiranthes diluvialis) (T)
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Welsh's Milkweed (Asclepias welshii) (T) (CH)
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Winkler Cactus (Pediocactus winkleri) (T)
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Wright Fishhook Cactus (Sclerocactus wrightiae) (E)
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Wrights Marsh Thistle (Cirsium wrightii) (T)
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Zuni Fleabane (Erigeron rhizomatus) (T)
Birds

Photo credit: Steve Hillebrand, USFWS
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Cactus Ferruginous Pygmy-owl (Glaucidium brasilianum) (T)
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California Condor (Gymnogyps californianus) (EXPN) (proposed CH)
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California Least Tern (Sternula antillarum browni) (E)
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​Masked Bobwhite (Coliinus virginianus ridgwayi) (E)
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Mexican Spotted Owl (Strix occidentalis lucida) (T) (CH)
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Northern Aplomado Falcon (Falco femoralis septentrionalis) (EXPN)
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Southwestern Willow Flycatcher (Empidonas traillii extimus) (E) (CH)
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Yellow-billed Cuckoo (Coccyzus americanus) (T) (CH)
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Yuma Ridgway's Rail (Rallus obsoletus yumanensis) (E)
Fishes
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Photo credit: B. Gratwicke
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Apache Trout (Oncorhynchus apache) (T)
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Big Spring Spinedace (Lepidomeda mollispinis pratensis) (T) (CH)
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Bonytail (Gila elegans) (E) (CH)
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Chihuahua Chub (Gila nigrescens) (T) (proposed CH)
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Colorado Pikeminnow (Ptychocheilus lucius) (E) (CH)
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Desert Pupfish (Cyprinodon macularius) (E) (CH)
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Devils Hole Pupfish (Cyprinodon diabolis) (E)
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Gila Chub (Gila intermedia) (E) (CH)
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Gila Topminnow (Poeciliopsis occidentalis) (E)
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Gila Trout (Oncorhynchus gilae) (T)
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Hiko White River Springfish (Crenichthys baileyi grandis) (E) (CH)
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Humpback Chub (Gila cypha) (T) (CH)
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Little Colorado Spinedace (Lepidomeda vittata) (T) (CH)
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Loach Minnow (Tiaroga cobitis) (E) (CH)
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Moapa Dace (Moapa coriacea) (E)
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Pahranagat Roundtail Chub (Gila robusta jordani) (E)
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Pahrump Poolfish (Empetrichthys latos) (E)
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Railroad Valley Springfish (Crenichthys nevadae) (T)
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Razorback Sucker (Xyrauchen texanus) (E) (CH)
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Rio Grande Cutthroat Trout (Oncorhynchus clarkii virginalis) (C)
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Rio Grande Silvery Minnow (Hybognathus amarus) (E)
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Sonora Chub (Gila ditaenia) (T) (CH)
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Spikedace (Meda fulgida) (E) (CH)
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Virgin River Chub (Gila seminuda) (E) (CH)
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White River Spinedace (Lepidomeda albivallis) (E) (CH)
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White River Springfish (Crenichthys baileyi baileyi) (E) (CH)
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Woundfin (Plagopterus argentissimus) (E) (CH), (EXPN)
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Yaqui Catfish (Ictalurus pricei) (T)
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Yaqui Chub (Gila purpurea) (E)
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Zuni Bluehead Sucker (Catostomus discobolus yarrowi) (E) (CH)
Mammals

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Black-footed Ferret (Mustela nigripes) (EXPN), (E)
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Jaguar (Panthera onca) (E) (CH)
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Mexican Wolf (Canis lupus baileyi) (E), (EXPN)
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Mexican Long-nosed Bat (Leptonycteris nivalis) (E)
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Mount Graham Red Squirrel (Tamiasciurus fremonti) (E) (CH)
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New Mexico Meadow Jumping Mouse (Zapus hudsonius luteus) (E) (CH)
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Ocelot (Leopardus pardalis) (E)
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Sonoran Pronghorn (Antilocapra americana sonoriensis) (E), (EXPN)
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Utah Prairie Dog (Cynomys parvidens) (T)
Reptiles

​Photo credit: Mohave Desert Tortoise, USFWS
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Desert Tortoise (Gopherus agassizii) (T) (CH)
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Narrow-headed Gartersnake (Thamnophis rufipunctatus) (T) (CH)
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New Mexican Ridge-nosed Rattlesnake (Crotalus willardi) (T) (CH)
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Northern Mexican Gartersnake (Thamnophis eques megalops) (T) (CH)
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​Sonoyta Mud Turtle (Kinosternon sonoriense longifemorale) (E) (CH)
Lead USFWS Offices in the Lower Colorado River Basin
Arizona Ecological Services Field Office​
9828 North 31st Avenue
Suite C3
Phoenix,AZ 85051-2517
(602) 242-0210
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Utah Ecological Services Field Office
2369 West Orton Circle, Suite 50
West Valley City, UT 84119-7603
(801) 975-3330
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New Mexico Ecological Services Field Office
2105 Osuna Road NE
Albuquerque, NM 87113-1001
(505) 346-2525​
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