This guide describes the data and procedures for computing flood flow frequency curves where systematic stream gaging records of sufficient length (at least 10 years) to warrant statistical analysis are available as the basis for determination. The procedures do not cover watersheds where flood flows are appreciably altered by reservoir regulation or where the possibility of unusual events, such as dam failures, must be considered. The guide was specifically developed for the treatment of annual flood peak discharge. It is recognized that the same techniques could also be used to treat other hydrologic elements, such as flood volumes. Such applications, however, were not evaluated and are not intended.