If aquifers are named, the names should be derived from lithologic terms, rock-stratigraphic units, or geographic names. The following items are not recommended as sources of aquifer names: time-stratigraphic names, relative position, alphanumeric designations, depositional environment, depth of occurence, acronyms, and hydro!ogic conditions. Confining units should not be named unless doing so clearly promotes understanding of a particular aquifer system. Sources of names for confining units are similar to those for aquifer names, i.e., lithologic terms, rockstratigraphic units or geographic names. The report contains examples of comparison charts and tables that are used to define the hydrogeologic framework. Aquifers are defined in 11 hypothetical examples that characterize hydrogeologic settings throughout the country.

The Regional Aquifer-System Analysis Program of the U.S. Geological Survey began in 1978. The overall purpose of this program is to define the geologic, hydrologic, and geochemical framework of the Nation's most important aquifers and aquifer systems. This report summarizes the aquifer or aquifer system name, geographic area, rock units, equivalent names, lithology, thickness, hydrologic characteristicJr~ater quality, water use, and references for 157 aquifers in 23 areas of the United States. A .s::t14":inch floppy disk containing the aquifer data and data search programs (in compressed ASCII format) is included in the report.