The National Water-Quality Assessment Program was organized, in part, to measure, document, and quantify water quality in the United States. In 1993, 33 wells were chosen in and about the city of Las Vegas, Nevada, to determine the effects of land use on underlying water quality. Ground-water samples collected from these wells were analyzed for major, minor, and trace constituents. Details of the onsite and laboratory procedures were adapted from previous studies and are described by Reddy and others (1989) . Sample preparation, analytical procedures, and laboratory quality-control protocols used by the U.S. Geological Survey laboratory are described by Fishman and Freidman (1985) , Garbarino and Taylor (1979, 1980) , and Schroder and others (1980) . Onsite procedures and equipment were adapted from a trace metal protocol developed by the U.S. Geological Survey National Research Program (Taylor and others 1995) .
This work has been done in conjunction with the NAWQA ( Emmett and others, 1993 , and Clary and others, 1994 ). The purpose of this report is to make available to the water-quality research community the results of our investigation in a prompt and widely available manner.
