Jeffrey D. Martin Thomas J. Lopes David K. Mueller 1997 <p>The data-quality objectives of the National Water-Quality Assessment Program include estimating the extent to which contamination, matrix effects, and measurement variability affect interpretation of chemical analyses of surface-water samples. The quality-control samples used to make these estimates include field blanks, field matrix spikes, and replicates. This report describes the design for collection of these quality-control samples in National Water-Quality Assessment Program studies and the data management needed to properly identify these samples in the U.S. Geological Survey's national data base.</p> application/pdf 10.3133/ofr97223 en U.S. Geological Survey, Quality-control design for surface-water sampling in the National Water-Quality Assessment Program reports