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 27. Examples of temporal concentration patterns at eight urban indicator sites. The upper plot for each site shows total herbicide concentrations, and the lower plot shows total insecticide concentrations. Total herbicide concentrations are shown on the left axis and total insecticide concentrations are shown on the right axis. The same 2-year period is shown for each site. The three urban sites that have a significant portion of agriculural land in their drainage basins--Cedar Run in Pennsylvania (lsus-cedar), Little Buck creek in Indiana (whit-little), and rush Creek in Texas (trin-rush)--are not included in these plots so that the concentration patterns shown are primarily the results of urban influences.

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