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.
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U.S. Department of the Interior |
U.S. Geological Survey
