We are working to characterize the types of streams and riparian ecosystems occurring in the western Sonoran Desert of Arizona, and the factors the influence their hydrologic characteristics and biota. This program is supported by the Department of Defense’s Strategic Environmental Research and Development Program (SERDP). In addition to myself, three other Principal Investigators (Dr. Ellen Wohl, Stephanie Kampf, and Dennis Harry) are working on this project. Three graduate students, Ph.D. student Jeremy Shaw and MS students Nicholas Sutfin and Joshua Faulconer, and technician Andrew Carlson are devoted to this program. Our overall project goals are to develop and test a watershed and stream classification system that would be usable throughout the Sonoran Desert to provide a foundation for managing streams, their vegetation, and disturbance regimes. Within out classification framework, we are selecting different stream reaches for detailed on site investigation of subsurface and surface geology and hydrologic processes, soil water storage, and vegetation composition and water and carbon relations.