With the undeniable evidence of shrinking icecaps and disappearing inland glaciers, scientists are increasingly viewing fresh water as a vital but shrinking resource. At a time governmental officials dealing with the increasing demands of agriculture, industry and home consumption are seeing water supplies reduced by changing weather patterns and groundwater pollution. The recognition of these threats to our traditional ways of life has helped spur both government and science to improve the management of water supplies. Hydrogeology, “the study of the interrelationship of geologic materials and processes with water,” has benefitted from this growing need to understand and manage a vital resource. Like geology and environmental science in general, the field is attracting growing numbers of researchers and students. This new guide is intended to introduce the specialized terminology of hydrogeology to those new to the field. From “abandoned wells” to “wettability,” this dictionary defines more than 2,000 key concepts in geology, hydrology, environmental science, computer modeling and related fields. more than 340 graphs, diagrams and charts are used to help illustrate such ideas as a gaining water table, stream discharge rates, or salt water intrusion. While many entries explore scientific theory, there is considerable emphasis on such practical applications as drilling and water quality evaluation. Appendices provide numerous conversion formulas, the properties of water and organic chemicals, water quality parameters and other data. This technical dictionary, designed for the specialist, is highly recommended for academic libraries supporting programs in geology, hydrology, geography, environmental or water science.