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 19. Annual yields of (A) total herbicides and (B) insecticides for each of the three types of sites. Yields at agricultural sites were calculated by using the area of agricultural land (excluding pasture) in the drainage basin. Yields at urban sites were calculated by using the area of urban land in the drainage basin. Yields at integrator sites were calculated by using the sum of the areas of agricultural land (excluding pasture) and urban land in the drainage basin. Three urban sites with significant portions of agricultural land in their drainage basins are not included in these plots. Some agricultural indicator sites and integrator sites also were not included in these plots if the target compounds accounted for less than 50 percent of the total agricultural use of herbicides or insecticides in the drainage basin (see table 3).

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