Agua Caliente Hot Springs

Agua Caliente Hot Springs in Mesa, Arizona—within the Maricopa County park system—is a historically significant natural hot spring in the Salt River Valley of the Sonoran Desert, where the warm bicarbonate-enriched waters have been used by the Hohokam people and their descendants, the Akimel O'odham (Pima), for centuries before European settlers developed the springs into a resort in the late 19th century and the county subsequently preserved the site as a natural park. The warm waters represent one of the few surviving natural thermal springs in the rapidly urbanized Phoenix metropolitan area, providing a connection to the pre-suburban desert landscape of the Salt River Valley and the ancient irrigation civilization that made the Sonoran Desert bloom long before European contact. The surrounding Usery Mountain Regional Park, the McDowell Sonoran Preserve, and the archaeological remains of Hohokam canal systems give Agua Caliente an ecological and archaeological depth unusual in one of America's fastest-growing urban regions.