This data release contains data in support of "Regional Analysis of the Dependence of Peak-Flow Quantiles on Climate with Application to Adjustment to Climate Trends" (Over and others, 2025). It contains input and output data used to analyze the effect of climate changes on trends in floods using three regression approaches. The input consists of two files. The first, "station_list.csv," contains streamgage information for the 404 streamgages considered for use in Over and others (2025). Only 330 of the 404 streamgages were considered non-redundant and used in the final analysis; these streamgages have a value of "Non-redundant" in the "redundancy_status" column. This file includes calibrated Monthly Water Balance Model (MWBM) parameters and basin characteristics. The second, "regression_input.csv," contains regression input data, including observed peak streamflow and precipitation. MWBM-simulated streamflow data was created using two sets of MWBM parameters: at-site calibrated parameters and median calibrated parameters. At-site calibrated parameters varied by station and represent the best-performing set of parameters per station. These parameters can be found in "station_list.csv". The median calibrated parameters were obtained by taking the median of all at-site calibrated parameters for the 330 streamgage basins used in analysis. See the Entity and Attribute section for details. The output files consist of nine Comma Separated Value (CSV) files. "Kendall_cor.csv" contains Mann-Kendall trend analysis results by streamgage. The regression results for annual maximum streamflow from at-site calibrated MWBM parameters by streamgage are provided in "byStation-sqrt_ann_max_MWBM_Q.csv". The regression results for annual maximum streamflow from median calibrated MWBM parameters by streamgage are provided in "byStation-sqrt_ann_max_MWBM_Q-medianMWBM.csv". "FixedEffects-sqrt_ann_max_MWBM_Q.csv" contains fixed effects for annual maximum streamflow from at-site calibrated MWBM parameters by streamgage. "FixedEffects-sqrt_ann_max_MWBM_Q-medianMWBM.csv" contains fixed effects for annual maximum streamflow from median calibrated MWBM parameters by streamgage. "MMQR-sqrt_ann_max_MWBM_Q_adjusted_moments.csv" contains observed and adjusted peak discharge moments from the method-of-moments quantile-regression (MMQR) method. "MMQR-sqrt_ann_max_MWBM_Q_adjusted_quantiles.csv" contains observed and adjusted discharge quantiles from the MMQR method. "QR-sqrt_ann_max_MWBM_Q_adjusted_moments.csv" contains observed and adjusted moments from the single-station quantile regression (QR) method. "QR-sqrt_ann_max_MWBM_Q_adjusted_quantiles.csv" contains observed and adjusted discharge quantiles from the QR method. Also included is "ModelArchive.zip", which contains the R scripts used to create the data provided in this data release and in Over and others, 2025. It contains the input data necessary to run the scripts and readMe files with directions for running the scripts locally.