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 4. Sampling frequency at the 58 sampling sites. Each "+" symbol indicates the date of sample collection. Red symbols show samples collected during a 5-month critical period when pesticide concentrations were highest and sampling frequency was relatively high. Site codes are defined in table 1. Sampling site locations are shown in figure 2.

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