especially thank the site owners and water purveyors for their generosity in allowing the U.S. Geological Survey (USGS) to collect samples from their wells. We thank Anna Garcia of the Mojave Water Agency and Scott Hynek and Mark Brigham of the USGS for providing thoughtful reviews of this report. For consistent presentation of results from the California Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP), parts of this report were written following a template originally developed by Landon and others (2010).