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Data Series 667

Toxic Substances Hydrology Program

Dissolved Pesticides, Dissolved Organic Carbon, and Water-Quality Characteristics in Selected Idaho Streams, April–December 2010

By Timothy J. Reilly, Kelly L. Smalling, Emma R. Wilson, and William A. Battaglin

Thumbnail of and link to report PDF (1.3 MB) Abstract

Water-quality samples were collected from April through December 2010 from four streams in Idaho and analyzed for a suite of pesticides, including fungicides, by the U.S. Geological Survey. Water samples were collected from two agricultural and two nonagricultural (control) streams approximately biweekly from the beginning of the growing season (April) through the end of the calendar year (December). Samples were analyzed for 90 pesticides using gas chromatography/mass spectrometry. Twenty-three pesticides, including 8 fungicides, 10 herbicides, 3 insecticides, and 2 pesticide degradates, were detected in 45 water samples. The most frequently detected compounds in the two agricultural streams and their detection frequencies were metolachlor, 96 percent; azoxystrobin, 79 percent; boscalid, 79 percent; atrazine, 46 percent; pendimethalin, 33 percent; and trifluralin, 33 percent. Dissolved-pesticide concentrations ranged from below instrumental limits of detection (0.5–1.0 nanograms per liter) to 771 nanograms per liter (hexazinone). The total number of pesticides detected in any given water sample ranged from 0 to 11. Only three pesticides (atrazine, fipronil, and simazine) were detected in samples from the control streams during the sampling period.

First posted May 21, 2012

For additional information contact:
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U.S. Geological Survey
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West Trenton, New Jersey 08628
http://nj.usgs.gov/

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Suggested citation:

Reilly, T.J., Smalling, K.L., Wilson, E.R., and Battaglin, W.A., 2012, Dissolved pesticides, dissolved organic carbon, and water-quality characteristics in selected Idaho streams, April–December 2010: U.S. Geological Survey Data Series 667, 17 p.



Contents

Abstract

Introduction

Purpose and Scope

Description of Sampling Sites and Watershed Characteristics

Methods of Study

Watershed Delineation and Land-Use Characterization

Sampling Methods

Analysis of Dissolved Pesticides

Instrument Calibration

Quality Assurance/Quality Control

Method Detection Limits

Analysis of Dissolved Organic Carbon

Dissolved Pesticides in Streams

Dissolved Organic Carbon and Water-Quality Characteristics in Streams

Summary

References Cited