The use of mathematical models for environmental decision making has increased significantly in recent years. The reasons for this are many, including scientific advances in the understanding of certain environmental processes, the wide availability of computational resources, the increased number of scientists and engineers trained in mathematical formulation and solution techniques, and a general recognition of the power and potential benefits of quantitative assessment methods. Within the US Environmental Protection Agency (EPA) environmental models which integrate release, transport, fate, ecological effects and human exposure are being used for rule making decisions and regulatory impact assessments. This report is directed to the development and validation of such models, an issue which was first addressed in December 1984 by Norton Nelson, Chairman of the Executive Committee of the SAB.

"January 1989" "EPA-SAB-EEC-89-012"