Abstract: The U.S. Geological Survey maintains a quality-assurance program based on the analysis of reference samples for its two water-analysis laboratories located in Atlanta, Georgia, and Denver, Colorado. Reference samples containing inorganic constituents are prepared at the U.S. Geological Survey's Ocala, Florida office and disguised as routine samples, and sent daily to each laboratory through other U.S. Geological Survey offices. The results are permanently stored in the National Water Data Storage and Retrieval System (WATSTORE), the U.S. Geological Survey's data base for all water data. These data are analyzed statistically for precision and bias. The results of these statistical analyses are presented for data collected during the 1981 calendar year. In addition, one sample containing known concentrations chlorophyll a were analyzed in both laboratories, and these results also are presented.

From abstract: A knowledge of the magnitude and frequency of floods is needed for the design of highway drainage structures, for establishing flood insurance rates, and for many other uses by urban planners and engineers. This report presents a method for estimating the magnitude and frequency of floods on small streams in the Atlanta, Georgia, metropolitan area.