From purposes of approach of study: The purposes of this study were to: (1) Define, on a reconnaissance level, current (1979) water-quality conditions in major aquifers (water-yielding rock formations) in the eastern Snake River basin; (2) present available geologic and hydrologic data to assist in understanding the natural and man-caused factors that affect water-quality conditions; and (3) establish a hydrologic base upon which future comparisons can be made to evaluate changes.

Purpose and scope: The purpose of the study was to determine whether a thin layer of volcanic ash measurably affects aquatic environments. Study objectives were to: (1) Determine the amount of ash initially deposited in Big Creek basin and the amount remaining 1 year after the eruption, and (2) describe the impact of ash on water quality and benthic invertebrate communities.

From purposes and approach of study: The primary purposes of this study were to: (1) Define, on a reconnaissance level, current (1980) water-quality conditions in major aquifers (water-yielding rock formations) in the western Snake River basin, Swan Falls to Glenns Ferry; (2) summarize and interpret available geologic and hydrologic data to assist in understanding the natural and man-cause factors that affect present and future understanding the natural and man-caused factors that affect present and future water-quality conditions; and (3) establish a hydrologic data base on which future data can be compared to evaluate changes. A secondary purpose was to evaluate the possible effects percolation of thermal water applied for irrigation may have on the quality of local, less mineralized, nonthermal ground water.