Milpitas Wash Wilderness is a protected area in Imperial County, California, south of the Palo Verde Mountains and west of Cibola National Wildlife Refuge and the Colorado River. Established by the U.S. Congress in 2019 and managed by the Bureau of Land Management, it contains the largest Sonoran Desert woodland in North America. Mesquite, acacia, palo verde, and ironwood create an unusually dense desert tree cover that supports diverse wildlife, including desert tortoise, mountain lion, long-eared owl, leaf-nosed bat, diamondback rattlesnake, and the endangered Gila woodpecker, as well as many small mammals and songbirds.