Donald Siegel’s career spans over 40 years of doing research, consulting and teaching on problems related the aqueous geochemistry and hydrogeology of natural and contaminated waters. He earned his BS in Geology from the University of Rhode Island, his MS in Geology at Penn State University, and his PhD in Hydrogeology from the University of Minnesota. After working for 8 years as an aqueous geochemist and hydrologist for the U.S. Geological Survey, Siegel joined Syracuse University where he has been employed since 1982. Siegel served as Chairman of the Hydrogeology Division of the Geological Society of America (GSA), is a GSA Fellow, was GSA’s Birdsall Distinguished Lecturer, won its Distinguished Service Award, and its prestigious Meinzer Award For Hydrogeological Research. Siegel is Life Time Associate Member of the National Research Council (NRC) of the National Academy of Sciences and Engineering and has served on numerous panels of the NRC as well as its Chairman of the Water Science and Technology Board. He was elected as fellow of American Geophysical Union and also to American Association for the Advancement of Science for his contributions in water science and hydrogeology. Siegel has served as Associate Editor of Water Resources Research, Wetlands, Ground Water, and Geosphere, and as the book editor of the Geological Society of America and has published ~160 peer reviewed papers and books and has provided expertise to multiple governmental bodies, industry and legal firms. Of his aqueous geochemical work, Siegel has studied almost every kind of water problem over his career, from precipitation chemistry to brines; cold waters to hot waters, natural to contaminated by salt, solvents, gasoline, pesticides, metals, and methane and other gases. In his tool set, Siegel also incorporates isotope geochemistry as well as groundwater and solute transport models when appropriate.