The principal purpose of the past research program on geohydrology at the NRTS has been to acquire information on the physical and geochemical environment of the station. This requires a knowledge of the composition and structure of the earth materials underlying the plain, the inventory of the water resources, the dynamics of natural and man-produced changes in the hydrologic regimen, details of the hydrologic cycle, and relevant geochemical processes. The Geological Survey in the course of its early studies by Nace and others (IDO 22033-34-USGS) obtained, compiled, and analyzed a considerable amount of basic geologic and hydrologic information on these subjects. These basic goals were expanded and carried forward to guide the continuing research work. Jones (IDO 22042-USGS) emphasized the use of borehole geophysics and specialized down-hole techniques. Olmsted (IDO 22043-USGS) made a preliminary appraisal of the nature and distribution of the quality of ground water beneath the Station. Their work has been continued and elaborated upon by Morris and others (IDO 22044-USGS, 46-USGS) and the present report with greater emphasis on the regional geology and hydrology. This involved some procurement of needed information but, for the most part, involved a continued evaluation and refinement of data and results that had been acquired in the past. The Geological Survey also encouraged a more comprehensive study of the regional geologic structure including the use of aeromagnetic, gravity, and seismic geophysical techniques and cosponsored a seminar on it in 1964. Along with this investigation and study of the regional geology and of hydrologic principles operative in the basalt environment, and made possible because of it, research continues on the-hydrologic aspects of the disposal of low-level aqueous waste to the environment.
