Atrazine use (left) (left) is one of the most important factors used to predict atrazine and deethylatrazine concentrations in
groundwater (right). Within areas of high atrazine use, groundwater residence time, soil permeability, and other factors explain some of the differences in predicted concentrations. From Circular 1360 (Water quality in principal aquifers of the United States, 1991-2010) and modified from Stackelberg and others (1982).