Sentinel Plain Special Management Area

Size: 120,600 acres

Sentinel Plain, south of Interstate 8 is an extremely unique landscape in that it ranges only 150 feet in elevation across 32,000 acres.  It has a recent volcanic history and hosts an interesting array of plants, animals, and cultural history.  

Sentinel Plain lies within Maricopa County, Arizona. It is located roughly 70 miles southwest of the Phoenix metropolitan area and some thirty miles west of Gila Bend. The Barry M. Goldwater Air Force Range managed the land until 1999, at which time the Military Lands Withdraw Act passed, transferring the land back to the Bureau of Land Management.  In 2000, the Sentinel Plain was part of the Sonoran Desert National Monument proposal; it was left out only because it was not contiguous, not because it lacked in any of the values for which the Monument was designated. 

The unit contains representative plant species from the Arizona Uplands and Lower Colorado River Valley biotic subdivisions and is part of "one of the top 200 ecoregions worldwide that deserves special conservation attention" (Olson and Dinerstine 1998, as referenced in Marshall, R.M. et al. 2000).

Natural Values

The Sentinel Plain portion of this Special Management Area has a high degree of naturalness.  The vegetation found here is classified as part of the Creosotebush-White Bursage Series of the Lower Colorado River Valley Subdivision within the Sonoran Desertscrub biogeographic division. Also called the microphyllous desert by Shreve, this area is the largest and most arid subdivision within the Sonoran Desert. These low areas are characterized by open and simple vegetative communities reflecting the intense competition by plants for scarce water resources (Turner and Brown 1982). 

North of Interstate 8, the landscape becomes more varied.  The Painted Rock mountains shelter the eastern edge of the unit while flatter lands to the west hold many remnants of ancient civilizations. 

Recreational Opportunities and Cultural Significance


The Sentinel Plain allows a variety of primitive and unconfined recreational activities. Various levels of hiking, backpacking, hunting, horseback riding, photography, bird watching, and sightseeing for botanical, zoological, and especially geological features are all possible as well as primitive and unconfined recreational opportunities within the Sentinel Plain. The opportunities for primitive and unconfined recreation are outstanding in this area if visitors do as Henry Hunt suggests in his book, "Hidden Trails in the Sonoran Desert: Hiking the Desert Wilderness of South-Central Arizona": 

"...this area is ideal for hikers. Of course you must first rid yourself of the notion that to hike means to go somewhere, to climb a
mountain or visit a cave. Hiking is first and foremost an engagement with the land around you. It is the land that comes first in your thoughts, not the hiking. The Sentinel area can cure you of bad habits. Its vastness, its sameness, the uniqueness and the openness, all serve to center you into your awareness of yourself."

The area abounds with cultural significance, more so toward the Gila River but it would not be unlikely to stumble across remnants of ancient civilizations.  A number of known sites exist both north and south of Interstate 8. 

Benefits of a Special Management Area

The proposed Sentinel Plain Special Management Area (SMA) would protect the natural and cultural values of the lands within the designation, especially preserving wildlife connectivity from the Barry M. Goldwater Range northward toward the Gila River and Gila Bend Mountains.  The SMA will allow for appropriate infrastructure development like roadways and electrical transmission facilities but will remove the lands from withdrawal and disposal, retaining them in permanent federal ownership.  A management plan would be developed by the BLM with public input and engagement soon after the lands are designated.

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