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

---

Figure 22. Monthly median concentrations of total herbicides and the six herbicides detected most frequently at the 37 agricultural indicator sites during a 1-year period. Each value represents the median concentration for 1 month. The annual median for each site is shown in red. Monthly median concentrations less than the detection limit are shown as points on the x-axis. For sites at which all 12 monthly values were below the detection limit, the annual median value is plotted on the x-axis. The sites are arranged by crop group classification an presented in the same order as in table 1. Site codes are defined in table 1 and crop group codes are define in table 4.

---

Figures: | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 |