HEC-FFA is used to compute flood frequencies in accordance with 'Guidelines for Determining Flood Flow Frequencies' Bulletin 17B of the U.S. Water Resources Council (WRC), March 1982. This guideline is designed 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. This guideline is specifically developed for the treatment of annual flood peak discharge. | 
