National Surface Water Survey: Eastern Lake Survey (Phase 1 - synoptic chemistry). Quality-assurance report

This report provides an overview of the quality-assurance activities and results of the Eastern Lake Survey - Phase I. The quality-assurance program used a combination of blank, duplicate, and audit samples to provide an external check on the data quality of 32 physiochemical parameters measured and to allow early detection of problems in sample collection, processing, and analysis. Field sampling, field and analytical laboratory, and data-base quality-control protocols also were standardized to ensure the reliability of the data. The statistical analysis of the verified data set included estimates of instrumental and system detection limits, system decision limits, overall and analytical within-batch precision, and overall and analytical among-batch precision.