The entire population of the Wood River Valley depends on ground water for domestic supply, either from domestic or municipal-supply wells, rapid population growth since the 1970s has raised concerns about the continued availability of ground and surface water to support existing uses and streamflow. To help address these concerns, ground- and surface-water conditions in the area before and during the population growth that started in the 1970s was evaluated. This dataset helps analyze trends in ground-water data, documents 2006 hydrologic conditions, and is used to compare 2006 and historic ground-water data of the Wood River Valley of south-central Idaho. It represents ground-water conditions in the unconfined aquifer during October 2006 constructed from 88 water-level measurements in the main valley and 8 tributary canyons.