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 6. Annual mean detection frequencies of all 46 target compounds at 50 sites during a 1-year period. Detection frequencies at each site were determined as the mean of 12 monthly detection frequencies. For each compound, the detection frequencies at all 50 sites were averaged.

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