National Water-Quality Assessment (NAWQA) Project
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U.S. GEOLOGICAL SURVEY
Water-Resources Investigations Report 98-4245
Sacramento, California, 1999
General Features
Analytical Coverage of the Subject Compounds
Spatial Scope
Spatial Bias Toward Potentially Contaminated Areas
Comparisons Between Agricultural and Nonagricultural Areas
Atrazine
Prometon
Simazine
Metolachlor
Alachlor
Cyanazine
Acetochlor
1. Graph showing total nationwide agricultural use of the seven herbicides of interest
from 1964 to 1994
2-5. Maps showing:
2. Study units of the NAWQA Program
3. Areas sampled for the NAWQA land-use studies discussed in this report
4. Areas sampled for the NAWQA subunit surveys discussed in this report
5. Hydrogeologic settings tapped by the 94 wells sampled in 1992 for the MWPS
6-13. Graphs showing:
6. Pesticide compounds detected most frequently in ground water for the NAWQA study
7. Frequencies of herbicide detection in ground water during the NAWQA (1993-1995) and
MWPS (1992) investigations
8. Frequencies of herbicide detection for individual ground-water studies of NAWQA,
relative to land-use setting and well depth
9. Percentages of sampled sites with multiple herbicide detections, on the basis of their original
reporting limits, for the NAWQA and MWPS investigations
10. Frequencies of PMP herbicide detection in shallow ground water beneath urban areas for the
NAWQA study in relation to nationwide nonagricultural use
11. Frequencies of PMP herbicide detection in shallow ground water for the 39 NAWQA studies
undertaken in agricultural areas in relation to agricultural use within a 1-kilometer radius
surrounding all sites sampled for each study
12. Ratio of the frequency of detection of any degradate of a given herbicide to the frequency of
detection of the parent compound in 88 municipal wells in Iowa in relation to the transformation
half-life of the parent compound in aerobic soil
13. Frequencies of herbicide detection in ground water for the various stages of the MWPS
14. Map showing physical divisions of the United States
15. Graph showing frequencies of atrazine detection in ground water for the multistate studies in
relation to reporting limits
16-17. Maps showing
16. Atrazine occurrence in ground water for the NAWQA study in relation to agricultural use
(A) Frequencies of detection. (B) Upper 90th-percentile concentrations
17. Concentrations of atrazine in near-surface aquifers of the northern midcontinent for the 1992
sampling of the MWPS in relation to agricultural use
18. Graph showing frequencies of prometon detection in ground water for the multistate studies in
relation to reporting limits
19-20. Maps showing:
19. Prometon occurrence in ground water for the NAWQA study (A) Frequencies of detection.
(B) Upper 90th-percentile concentrations
20. Prometon concentrations measured in near-surface aquifers of the northern midcontinent for the
1992 sampling of the MWPS
21. Graph showing frequencies of simazine detection in ground water for the multistate studies in
relation to reporting limits
22-23. Maps showing:
22. Simazine occurrence in ground water for the NAWQA study in relation to agricultural use
(A) Frequencies of detection. (B) Upper 90th-percentile concentrations
23. Concentrations of simazine in near-surface aquifers of the northern midcontinent for the
1992 sampling of the MWPS in relation to agricultural use
24. Graph showing frequencies of metolachlor detection in ground water for the multistate studies in
relation to reporting limits
25-26. Maps showing:
25. Metolachlor occurrence in ground water for the NAWQA study in relation to agricultural use
(A) Frequencies of detection. (B) Upper 90th-percentile concentrations
26. Concentrations of metolachlor in near-surface aquifers of the northern midcontinent for the
1992 sampling of the MWPS in relation to agricultural use
27. Graph showing frequencies of alachlor detection in ground water for the multistate studies
in relation to reporting limits
28-29. Maps showing:
28. Alachlor occurrence in ground water for the NAWQA study in relation to agricultural use
(A) Frequencies of detection. (B) Upper 90th-percentile concentrations
29. Concentrations of alachlor in near-surface aquifers of the northern midcontinent for the 1992
sampling of the MWPS in relation to agricultural use
30. Graph showing frequencies of cyanazine detection in ground water for the multistate studies
in relation to reporting limits
31-32. Maps showing:
31. Cyanazine occurrence in ground water for the NAWQA study in relation to agricultural use
(A) Frequencies of detection. (B) Upper 90th-percentile concentrations
32. Concentrations of cyanazine in near-surface aquifers of the northern midcontinent for the 1992
sampling of the MWPS in relation to agricultural use
33. Graph showing concentrations of herbicides measured in ground water at individual sites during
the NAWQA and MWPS investigations in relation to drinking-water criteria
1. Factors associated with pesticide detections in ground water and the nature of supporting evidence
in the literature
2. Annual nationwide agricultural and nonagricultural use of the herbicides of interest to this report
3. Selected physical and chemical properties of the seven parent compounds of interest to this report and
their degradates examined in ground water
4. Principal characteristics of multistate studies
5. Comparison of principal design features of the multistate investigations of pesticides in ground water
6. Degradates examined by the multistate studies for the seven herbicides
7. Criteria used by multistate studies for selection of sampling sites
8. Principal characteristics of the NAWQA land-use studies and subunit surveys discussed in this report
9. Co-occurrence of herbicide compounds at sites with two or more of the compounds detected at or above
their original reporting limits during the NAWQA and MWPS investigations
10. Upper 90th-percentile concentrations of the seven herbicides of interest measured in ground water by the
NAWQA and MWPS investigations
11. Frequencies of detection of herbicide degradates in comparison with those for the corresponding
parent compounds
12. Frequencies of detection of the herbicides of interest and selected degradates during the 1996 statewide
sampling of 88 municipal wells in Iowa
13. Frequencies of detection of the seven herbicides of interest at or above 0.05 microgram per liter
during the NAWQA and MWPS investigations
Conversion Factors
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Multiply By To obtain
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foot (ft) 0.3048 meter (m)
mile (mi) 1.609 kilometer (km)
pound, avoirdupois (lb) 0.45359 kilogram (kg)
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Temperature is given in degrees Celsius (°C), which can be converted to degrees Fahrenheit (°F) by the following equation:
°F=1.8(°C)+32.
Abbreviations and Acronyms
(Additional information noted in parentheses)
kg/km2, kilogram per square kilometer
km, kilometer
lb a.i., pound active ingredient
m, meter
µg/L, microgram per liter
mg/L, milligram per liter
mL/g, milliliter per gram
Copies of this report can be purchased from:
U.S. Geological Survey
Branch of Information Services
Box 25286
Denver, CO 80225-0286
U.S. Department of the Interior | U.S. Geological Survey
URL: http://water.usgs.gov/nawqa/pnsp/pubs/wrir984245/index.html
Page Contact Information: gs-w_nawqa_whq@usgs.gov
Page Last Modified: Tuesday, 04-Mar-2014 14:44:41 EST