Flood-frequency analyses for 141 streamgages in Connecticut were updated using the U.S. Geological Survey program PeakFQ, version 7.2 (https://water.usgs.gov/software/PeakFQ/; Veilleux and others, 2014). The PeakFQ program follows Bulletin 17C national guidelines for flood-frequency analysis (https://doi.org/10.3133/tm4B5). The input and output files to PeakFQ that were used in the Connecticut flood-frequency update are presented. Individual file folders for the 141 streamgages using the streamgage identification number as the folder name contain three files: ".TXT" file used as input to PeakFQ contains the annual peak flows for the streamgage in standard PeakFQ (WATSTORE) text format available from NWIS web at https://nwis.waterdata.usgs.gov/usa/nwis/peak; ".PRT" text file provides estimates of flood magnitudes and their corresponding variance for a range of annual exceedance probabilities, estimates of the parameters of the log-Pearson Type III frequency distribution, including the logarithmic mean, standard deviation, skew, and mean square error of the skew; and ".JPG" image file shows the fitted frequency curve, systematic peaks, confidence limits, and associated information on low outliers, censored peaks, interval peaks, historic peaks, and thresholds if applicable.