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Red River of the North Basin

National Water-Quality Assessment Program

Menheer, M.A. and Brigham, M.E., 1997, Ground-water sampling methods and quality-control data for the Red River of the North Basin, Minnesota, North Dakota, and South Dakota, 1993-95: U.S. Geological Survey WRIR 96-4317. 34 p.

Abstract

Ground-water quality samples were collected for the intensive data-collection phase of the Red River of the North study unit, one of 60 study units of the National Water Quality Assessment (NAWQA) Program throughout the United States. The sampling protocols used were designed for the NAWQA Program. The protocols include sampling equipment, cleaning procedures, sample collection methods, and quality-control plans to monitor the accuracy of the data collected. One of the goals of the NAWQA Program was to collect data using similar methods to build a nationally consistent water-quality data base.

Quality control (QC) data demonstrated that most constituents measured for this study yielded reproducible data, with low to undetectable contamination from the sampling and analytical procedures. Several constituents were occasionally or frequently detected in blank samples at levels similar to low-concentration ground-water-quality samples. For example, iron was detected in 75 percent of the blank samples, with a maximum concentration of 27 (g/L, indicating that iron contamination may interfere with its determination at low levels in ground waters. Copper, aluminum, and dissolved organic carbon concentrations in blank samples overlap those determined in ground-water-quality samples, thereby precluding quantitative reporting of those constituents. Most pesticide data are reproducible, with minimal bias. Some pesticides had low but consistent recoveries; these data may be useful if spike and surrogate data are carefully considered. Data for some pesticides measured in this study should not be quantitatively reported or used, because they may underestimate the concentrations of those pesticides in ground waters.

U.S. Geological Reports | Study Unit Publications | Red River of the North Basin, NAWQA | U.S. Geological Survey in Minnesota | NAWQA Program
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