Fig. 8. Concentrations of chloroacetanilide (a) herbicides and (b) their metabolites for surface water samples collected at the United States Geological Survey (USGS) gage site in the Upper Embarras River watershed. Data from March to June 1999 and May through July 2000, the period of tile flow in the watershed. ESA, ethanesulfonic acid; OA, oxanilic acid. Box plot shows median (line in center of box), 25th and 75th percentiles (bottom and top of box, respectively), 10th and 90th percentiles (bottom and top error bars, respectively), and values < 10th percentile and > 90th percentile (solid circles below and above error bars, respectively).