Basic water data on the lower Santiam River basin is preliminary to a comprehensive hydrologic study of this productive and intensely irrigated area where expanding population and industry increases the demand for water. Highest yielding wells are in shallow alluvial aquifers near the main streams; yields range from several hundred to more than a thousand gpm. Wells in lacustrine and older alluvial aquifers that underlie low, flat terraces have yields from a few tens to a few hundred gpm. Wells in the Salem Hills and in the Cascade Range foothills yield moderate to small quantities of water and tap a variety of geologic units. Tabulated material includes records of representative wells, drillers' logs, and chemical and spectrographic analyses of the ground water.