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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Figure 7. Distribution of annual mean detection frequencies of all target (A) herbicides and (B) insecticides. Each boxplot represents the distribution of detection frequencies for a specific compound among 50 sampling sites for a 1-year period. A common reporting level of 0.01 microgram per liter was used for calculation of detection frequencies for all compounds. See figure 5A for an explanation of boxplots.

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