Hot springs in Arizona

Southern and western Arizona lie in the Basin and Range Province, where faulting has broken the crust into alternating mountain blocks and desert basins. Thermal springs in the state rise mostly along those faults and in canyons cut deep by the Colorado, Verde and Gila rivers, where groundwater that circulated at depth reaches the surface. The best-known group is in Black Canyon of the Colorado River below Hoover Dam, where warm water issues from the volcanic rock of the canyon walls. The Arizona Geological Survey at the University of Arizona maps the state's geothermal springs and wells.

Most of the undeveloped springs are on federal land. Lake Mead National Recreation Area, a National Park Service unit, manages Black Canyon on both the Arizona and Nevada sides, including the Arizona Hot Springs trail. Along the Verde River, the Coconino and Tonto national forests manage the canyon around the old Childs power plant site. In the southeast, the Bureau of Land Management's Safford Field Office manages the Gila Box Riparian National Conservation Area and the Hot Well Dunes Recreation Area.

Summer heat is the main seasonal limit. Lake Mead National Recreation Area closes the Arizona Hot Springs and Goldstrike Canyon trails every year from May 15 through September 30 because of extreme heat, and the springs can still be reached from the Colorado River during the closure. The forest roads to the Verde River are unpaved and narrow, with a high-clearance vehicle recommended on the unpaved sections, and storms can wash them out. Winter brings snow to the Mogollon Rim and the high country above the Verde, while the desert canyons stay open.