The Imperial NWR lies within the Lower Colorado Subdivision of the Sonoran Desert, a region characterized by a scarcity of precipitation and high summer temperatures. A 30-mile reach of the Colorado River bisects the refuge. Over 14,000 acres of the Refuge's desert upland habitats are designated Wilderness. Major resource initiatives on the refuge currently include restoration of native riparian habitats to benefit several declining populations of neotropical migratory birds and other riparian-obligate species, Colorado River native fish management, wetland restoration and moist soil management to benefit migratory bird species, development of baseline biological databases, and environmental education and public outreach.
Spring and Fall offer the greatest variety of birds and the best birding opportunities. 275 species have been observed on the refuge. Also, the refuge is important as a wintering area for Canada geese and many species of ducks. Canada,& White-fronted Geese, Tundra Swan (rare, winter), Clark's & Western Grebes (breed), Black and Clapper Rails (breed), Least Bittern (breeds), Sandhill Crane (rare, migration & winter), Bald Eagle (winter) , Peregrine & Prairie Falcons (winter), Common Poorwill (breeds) , Ladder-backed & Gila Woodpeckers (residents), Willow Flycatcher (migrant), Crissal Thrasher (breeds), Warblers (wintering, migrants), Summer Tanager, Abert's Towhee (breeds), Sage Sparrow. Desert birds include Phainopepla, Verdin, and Lucy's Warbler (early spring). Three Marshbird surveys have been established in 2008 as a part of the Multi-species Conservation Plan. A rapid survey is being conducted at the area which will be planted with cottonwood-willow land cover type, and adjacent habitat. The area which will be planted was bare ground in the summer of 2007 and no birds were present, but the adjacent cottonwood nursery and a thin strip cottonwoods and willows planted on the west side were also surveyed as these areas will serve as sources for bird populations that will colonize the cottonwood-willow site, when planted. In these areas four LCR MSCP listed bird species were detected. These species were the: summer tanager (1 detected), yellow-billed cuckoo (Coccyzus americanus) (1 detected), Gila woodpecker (Melanerpes uropygialis) (1 detected), and yellow warbler (1 detected). (MSCP unpub. 2008 progress report-Chris Dodge).
Highest threat are invasive plants, primarily tamarisk, and animals such as zebra mussel.
Historic loss of cottonwood and willow and marshlands habitats from the impacts of dikes, diversion canals and dams on natural hydrologic regime. These losses are currently being mitigated through the LCR-MSCP.
The Lower Colorado River Multi-Species Conservation Plan is implementing riparian forest restoration projects.
The Visitor Center is open from 7:30 am to 4:00 pm, Monday through Friday. From November 15 to March 31, also open Saturdays and Sundays from 9:00 am to 4:00 pm. Camping is not permitted on the refuge but available at Martinez Lake in the community of Fisher?s Landing. More than 15,000 acres of Imperial National Wildlife Refuge is federally designated wilderness. Travel in wilderness areas is by foot or horseback only. Hunting and fishing are permitted, according to state regulations, in some areas. Please contact the Visitor Center for more information. Unconfined domestic animals are not allowed. Pets are permitted only if under your control at all times.
Vehicles are permitted on designated roads only. All off-road vehicle travel is prohibited. All motorized vehicles, including all-terrain vehicles and motorcycles, and all operators must be licensed and insured for highway driving. Speed limit is 25 mph unless posted otherwise.
Primary habitat type: Freshwater Marshes and Riparian (Low elev. <4000 ft) Secondary habitat type: Sonoran-Mohave Desert scrub.