Atrazine is the most widely used herbicide for corn and sorghum and the most commonly encountered in surface water and groundwater. In addition to water quality problems, atrazine poses hazards through atmospheric transport, food residues, and exposure of applicators and wildlife. If atrazine use is restricted, substitute herbicides will come into wider use, increasing the likelihood of occurrence of their own sets of undesirable side effects and imposing cost or efficacy penalties. This paper describes a configuration of the Comprehensive Environmental Economic Policy Evaluation System (CEEPES) to provide decision support for regulation of atrazine and related corn and sorghum herbicides.