The objective of this present thesis was to determine whether GEV (Generalized Extreme Value) itself can be a more conservative distribution than LP3 (Log Pearson III) associated with other methods, such as the B17B weighting procedure with Single Grubbs-Beck (SGB) for low outliers, when determining the projected floods in a flood frequency analysis (FFA) for Santa Ana and San Gabriel regions and other urbanized stream gages present in California. In this work, USGS PeakFQ was utilized. From the results obtained, it was possible to state that GEV fitting results were directly affected by the length of the data. When the length of the record is short, it is not accurate to use a projection of 100-year return period, for example, to represent future projection. Comparing the LP3 and GEV CDFs, for the majority of the stream gages analyzed in this project, GEV proves to be the most conservative method, with smaller return periods.