The United States Congress designated the Milpitas Wash Wilderness (map
) in 2019 and it now has a total of 17,250 acres
All of this wilderness is located in California
and is managed by the Bureau of Land Management.
The Milpitas Wash Wilderness is near the southern end of the Mule Mountains and the Opal Hill Mine. The landscape is primarily desert mountain foothills as well as wash and floodplain habitats. Visitors can see petrified palm roots that were once part of an ancient, lush landscape.
The Milpitas Wash Wilderness provides habitat for Desert tortoise, mountain lion, long-eared owl, leaf nose bat, Merriam and Desert kangaroo rat, long tail and little pocket mice, Bullock’s and hooded orioles, towhees, white-crowned sparrow, Brewer’s sparrow, warbler, black-headed grosbeak, diamondback rattler, and the endangered Gila woodpecker. The Milpitas Wash region supports the largest Sonoran Desert woodland in North America. Most of the trees are legumes: mesquites, acacias, palo verdes, and ironwoods; and there are also desert willows. The abundance of old-growth trees, with most standing over 15 feet high, gives the area a lush character unusual for the desert.