Fig. 4. Bivariate plots of metolachlor ethanesulfonic acid (ESA) as a function of (A) metolachlor oxanilic acid (OXA), (B) age of ground water, and (C) depth of screened interval. "0" indicates no metolachlor ESA is present while other related compounds (either metolachlor and/or metolachlor OXA) are present.