Stanley N. Davis, emeritus professor of hydrology and water resources at the University of Arizona, died on November 18, 2007 at the age of 83. He was one of the most senior and honored members of the ground water profession. His research career spanned from the era when well hydraulics was the frontier of ground water research to today's supercomputers and accelerator mass spectrometry. He wrote the textbook Hydrogeology, for many years the standard in the field. He was influential in the development of ground water geochemistry, the application of cosmogenic nuclides to interpreting ground water systems, the development of ground water tracers such as chlorofluorocarbons, and the history of hydrogeology. Presenters in this session discuss Dr. Davis' contributions and importance to the scietific community.