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Concentrations of pesticides and pesticide degradates in the Croton River Watershed in southeastern New York, July-September 2000

Water-Resources Investigations Report 2002-4063
By:  and 
https://doi.org/10.3133/wri024063

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Abstract

Thirty-seven pesticides and (or) pesticide degradates were detected in baseflow samples collected from 47 stream sites in the Croton River Watershed (374 square miles) in southeastern New York in the summer of 2000. The Croton Reservoir provides about 10 percent of New York City's water supply. Maximum concentrations of most pesticides detected did not exceed 0.1 μg/L (micrograms per liter). This study, by the U.S. Geological Survey in cooperation with the New York State Department of Environmental Conservation, was conducted from July through September 2000 and entailed analysis of the samples for more than 150 pesticides and their degradates. Nine compounds were detected at a concentration greater than 0.10 μg/L; three of these were insecticides (diazinon, carbaryl, and imidacloprid), one was a fungicide (mycobutanil), and five were herbicides (simazine, 2,4-D, diuron, hexazinone, and 2,4-D methyl esther). Only two of these compounds (simazine and 2,4-D) were detected at a concentration exceeding 1 μg/L; the simazine concentration exceeded the New York State surface-water standard of 0.5 μg/L. Two insecticides (diazinon and azinphos-methyl) exceeded aquatic-life-protection standard in one sample each. Concentrations of three insecticides (chlorpyrifos, carbaryl, and malathion) were more than 50 percent of the aquatic-life-protection standards in one sample each.

Total concentrations of insecticides and herbicides (the sum of the concentrations, whereby all concentrations below the detection limit were set to zero), and the concentrations of the herbicide prometon and the insecticide diazinon, were highest in samples from watersheds with population densities greater than 510 per square mile (21 sites); therefore, the presence of these compounds is attributable to urban, residential, and other developed land uses.

The data obtained in this study are useful for making general comparisons among watersheds with differing land uses, but the concentrations represent baseflow conditions and, thus, are probably lower than the annual maximum concentrations in these streams. A July baseflow sample had total insecticide and fungicide concentrations of less than 0.03 μg/L, whereas a stormflow sample collected at the same site 2 weeks later had a corresponding concentration greater than 0.10 μg/L. Total herbicide concentrations for the July baseflow and stormflow samples were around 0.03 μg/L, but that for a stormflow sample collected at the same site 2 months later was greater than 20 μg/L.

Suggested Citation

Phillips, P.J., and Bode, R.W., 2002, Concentrations of pesticides and pesticide degradates in the Croton River Watershed in southeastern New York, July-September 2000: U.S. Geological Survey Water-Resources Investigations Report 2002–4063, 20 p., https://pubs.er.usgs.gov/publication/wri024063.

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Study Methods
  • Concentrations of Pesticides and Pesticide Degradates
  • Pesticide Concentrations in Relation to Federal and State Water-Quality Standards
  • Relation of Pesticide Concentrations to Land Use
  • Baseflow Concentrations in Relation to Stormflow Concentrations
  • Summary
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Concentrations of pesticides and pesticide degradates in the Croton River Watershed in southeastern New York, July-September 2000
Series title Water-Resources Investigations Report
Series number 2002-4063
DOI 10.3133/wri024063
Year Published 2002
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) New York Water Science Center
Description 20 p.
Country United States
State Connecticut, New York
Other Geospatial Croton River Watershed
Online Only (Y/N) N
Google Analytic Metrics Metrics page
Additional publication details