Quality Assurance of U.S. Geological Survey Water-Quality Field Measurements

Abstract

Each year many thousands of water-quality measurements are made in the field by personnel of the U.S. Geological Survey's Water Resources Division. To insure the accuracy of these measurements, an external quality assurance program was officially established in March 1979. The initial phase of this program was concerned with specific conductance and pH measurements. Reference samples are submitted semiannually to field analysts for measurement of these parameters with the same techniques and instruments used in the field. Both the personnel and the instruments involved in making the determinations are recorded. When the data are complete, a report defining the quality of the analytical results is prepared and circulated to appropriate District, Regional, and National offices. Field data, in addition to their immediate use, are normally placed in a national data base and are available to all hydrologists. As a result, the quality of field measurements can have a profound effect on their investigations. The quality assurance program described is designed to insure that the field data of the Water Resources Division are highly accurate.