Cover : A map of the Ogallala Aquifer illustrates the wide range in groundwater availability throughout the High Plains of the central United States region-from zero in some sections to more than 1,000 feet in west central Nebraska. See page 310 for a discussion of the economic and social consequences of groundwater use in the High Plains. Artwork adapted from a US. Geological Survey map by John B. Weeks and Edwin D. Gutentag.