This report is intended to aid public officials and water users in the lower Bear River drainage basin to develop, conserve, and administer their water resources. Although the report is primarily about ground water, it describes the relation of ground water to surface water and presents a general water-budget analysis. It discusses the sources, occurrence, availability, quantity, movement, chemical quality, and development of the ground water and the effects of climate, geology, and development on the ground water. The appendix of the report describes the well- and spring-numbering system and defines some units and terms.