Quality-assurance data for routine water analysis in the laboratories of the US Geological Survey; 1981 annual report

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 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 of trihalomethanes and samples containing unknown concentrations of chlorophyll a were analyzed in both laboratories, and these results also are presented. (USGS)