Pesticides in Streams of the United States--Initial Results from the National Water-Quality Assessment Program

By Steven J. Larson, Robert J. Gilliom, and Paul D. Capel

U.S. GEOLOGICAL SURVEY
Water-Resources Investigations Report 98-4222
Sacramento, California, 1999

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CONTENTS

Abstract
Introduction
Site Selection and Characteristics
Target Compound Selection and Characteristics
Methods for Sample Collection and Analysis
Methods for Data Analysis
National Overview of Pesticide Occurrence
Effects of Land Use on Occurrence of Pesticides in Streams (74K)
Pesticide Load in Relation to Use
Environmental Significance of Pesticide Concentrations (38K)
Summary and Conclusions
References Cited

FIGURES

   1. Map showing National Water-Quality Assessment study units 
   2. Map showing locations of stream sampling sites 
3-41. Graphs showing:
   3. Distribution of land use in agricultural indicator basins, urban 
      indicator basins, and integrator basins
   4. Sampling frequency at the 58 sampling sites
   5. Hypothetical plots as examples of boxplots and concentration distribution
      plots
   6. Annual mean detection frequencies of all 46 target compounds at 50 sites 
      during a 1-year period
   7. Distribution of annual mean detection frequencies of all target 
      herbicides and insecticides
   8. Distribution of monthly median concentrations of total herbicides and 
      insecticides at 50 sites during a 1-year period
   9. Distributions of monthly median concentrations of the seven most 
      frequently detected herbicides and the five most frequently detected 
      insecticides at 50 sites during a 1-year period
  10. Distribution of the number of different compounds detected in each sample 
      collected from the 58 sites each month during 1993-95
  11. Distribution of total pesticide concentrations in all samples collected 
      from the 58 sites each month during 1993-95
  12. Distribution of the number of compounds detected at each site for each of
      the three types of sites 
  13. Distribution of the mean number of compounds detected in each sample for 
      each of the three types of sites
  14. Annual mean detection frequencies for all 46 target compounds for each of 
      the three types of sites during a 1-year period
  15. Distributions of annual mean detection frequencies of the most commonly 
      detected compounds for each of the three types of sites
  16. Concentration distribution plots of monthly median total herbicide and 
      insecticide concentrations for each of the three types of sites during a 
      1-year period
  17. Distribution of the mean number of compounds detected in each sample at 
      any concentration	for a 5-month critical period and for the rest of the 
      year for each of the three types of sites
  18. Distribution of median total pesticide concentrations for each month for 
      each of the three types of sites
  19. Annual yields of total herbicides and insecticides for each of the three 
      types of sites	
  20. Intensity of annual agricultural use of herbicides and insecticides in 
      37 agricultural basins
  21. Annual mean detection frequency in relation to agricultural use for 
      herbicides and insecticides at 32 agricultural sites
  22. Monthly median concentrations of total herbicides and the six herbicides 
      detected most frequently at the 37 agricultural indicator sites during a 
      1-year period 
  23. Monthly median concentrations of total insecticides and the four 
      insecticides detected most frequently at the 37 agricultural indicator 
      sites during a 1-year period
  24. Examples of temporal concentration patterns at eight agricultural 
      indicator sites
  25. Distribution of annual mean detection frequencies of compounds 
      consistently detected more frequently at urban indicator sites than at 
      most agricultural indicator sites
  26. Monthly median concentrations of selected compounds at 11 urban indicator 
      sites during a 1-year period
  27. Examples of temporal concentration patterns at eight urban indicator sites
  28. Monthly median concentrations of selected compounds at 10 integrator sites
      during a 1-year period
  29. Annual load of herbicides and insecticides in streams in relation to 
      agricultural use in the drainage basin of a particular stream
  30. Annual load of total herbicides and insecticides in streams in relation 
      to agricultural use in the drainage basin of a particular stream
  31. Annual load of specific compounds in streams in relation to agricultural 
      use in the drainage basin of a particular stream
  32. Comparison of estimated loads of total herbicides and insecticides for 25
      sites with sufficient data for load estimates for 2 different years 
  33. Estimated annual mean concentrations and time-weighted mean concentrations
      for selected compounds for all 58 sites for a 5-month critical period
  34. Concentrations of malathion in Las Vegas Wash, Nevada
  35. Concentrations of azinphos-methyl at two sites
  36. Concentrations of chlorpyrifos at two sites
  37. Concentrations of diazinon at five sites
  38. Concentrations of diazinon at three urban sites
  39. Concentrations of atrazine at three sites 
  40. Concentrations of cyanazine at three sites
  41. Concentrations of co-occurring compounds at various sites 

TABLES

 1. Characteristics of  sampling sites (45K)
 2. Target compounds and their national agricultural use, analytical recovery, 
    method detection limit, and primary uses 		
 3. Coverage of pesticide use by the target compounds for agricultural indicator
    basins and integrator basins
 4. Agricultural land use in agricultural indicator basins
 5. Detection frequencies of agricultural pesticides at agricultural indicator 
    sites (83K)
 6. Agricultural use of selected pesticides per square kilometer of drainage 
    basin
 7. Load of total herbicides and insecticides and selected individual pesticides 
    in streams as a percentage of agricultural use in the basin (81K)
 8. Human-health and aquatic-life criteria established for target compounds and
    the number of sites where the criterion value was exceeded 
 9. Estimated mean concentrations of selected compounds for a one-year period
10. Compounds with concentrations greater than the aquatic-life criterion in at 
    least one sample, by type of site
11. Estimated number of days per year that selected compounds exceeded an 
    aquatic-life criterion value, by type of site (76K)

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CONVERSION FACTORS, WATER QUALITY UNITS, AND ABBREVIATIONS AND ACRONYMS

Conversion Factors

--------------------------------------------------------------------------------------------
                                        Multiply    By       To obtain
--------------------------------------------------------------------------------------------                                        
                                     kilogram (kg)    2.205      pound, avoirdupous
            kilogram per square kilometer (kg/km2)    0.00893    pound per acre
kilogram per square kilometer per year (kg/km2/yr)    0.00893    pound per acre per year
                                    kilometer (km)    0.6214     mile  
                                         liter (L)   33.82       ounce, fluid
                            square kilometer (km2)    0.3861     square mile 
--------------------------------------------------------------------------------------------

Temperature is given in degrees Celsius (C), which can be converted to degrees Fahrenheit (F) by the following equation:

°F = 1.8(°C) + 32.

Water Quality Units

Concentrations of constituents in water samples are given in either milligrams per liter (mg/L) or micrograms per liter (µg/L). Milligrams per liter is equivalent to "parts per million" and micrograms per liter is equivalent to "parts per billion."

Abbreviations and Acronyms

µg/L	microgram per liter
µm      micrometer
a.i.	active ingredient
CCRM	Canadian Council of Resource and Environment Ministers
CRP     Conservation Reserve Program
DEA     deethylatrazine (a transformation product of atrazine)
GC/MS	gas chromatography/mass spectrometry
GIRAS	Geographic Information Retrieval and Analysis System
HAL     health advisory level
HPLC	high-performance liquid chromatography
IJC     International Joint Commission
LULC	land use and land cover
MCL     maximum contaminant level
MCLG	maximum contaminant level goal
MDL     method detection limit
NAWQA	National Water-Quality Assessment (Program)
NCFAP	National Center for Food and Agricultural Policy
RSD     risk specific dose
RSD5	risk-specific dose associated with an excess cancer risk of 
        1 in 100,000 for a concentration in drinking water equal to the RSD
SPE     solid-phase extraction
SIM     selected-ion monitoring
TWM     time-weighted mean
USEPA   U.S. Environmental Protection Agency
USGS    U.S. Geological Survey