Corps of Engineers Procedures for Evaluating and Modifying Existing Dams to Safely Accommodate the Current Inflow Design Flood

Abstract

It is the Corps practice to design dams above populated areas to safely accommodate the largest flood considered physically possible. This magnitude of flood is refered to as the Probable Maximum Flood (PMF). The Corps existing dams are being evaluated to determine how safely they could accommodate inflow floods up to a PMF developed in accordance with todays standards. If it is found that failure of a dam could endanger peoples lives, a modification of the dam will be developed that would remove the threat to human life. Alternatives will be studied to determine the least costly modification that will meet the requirement, to not endanger lives. Economic analysis, that is comparing average annual benefits to average annual cost, will not be used as a basis for selecting the dam modification. Why economics is not considered to be an appropriate decision criteria is explained in some detail.