At-site flood frequency estimates for 154 urban streamgages in Washington D.C. and parts of Delaware, Maryland, New Jersey, Pennsylvania, and Virginia using data through water year 2022

This dataset contains site information and results of flood frequency analysis for 154 urban streamflow gaging stations (streamgages) operated by the U.S. Geological Survey (USGS) in Washington D.C. and parts of Delaware, Maryland, New Jersey, Pennsylvania, and Virginia. Site information and annual peak-flow data from the 1924 - 2022 water years were obtained from the USGS National Water Information System (NWIS) database (U.S. Geological Survey, 2025). Flood frequency analysis was conducted in version 8.1.0 of USGS PeakFQ software (Siefken and others, 2024) in the R environment (R Core Team, 2024) following the guidelines set forth in Bulletin 17C (England and others, 2018) and using the approaches described in the most recent flood frequency reports for Pennsylvania and North Carolina (Roland and Stuckey, 2020; Feaster and others, 2023). Site information is provided in .csv format ("DCStreamStats_FFreq_SiteInfo.csv"). Peak-flow ("DCStreamStats_FFREQ.pkf"), specification ("DCStreamStats_FFreq.psf"), and output files from PeakFQ ("DCStreamStats_FFreq_emp.csv", "DCStreamStats_FFreq_lp3.csv", "DCStreamStats_FFreq_mgb.csv", "DCStreamStats_FFreq_qnt.csv", and "DCStreamStats_FFreq_trd.csv") are provided. Estimates of the 0.5, 0.2, 0.1, 0.04, 0.02, 0.01, 0.005, and 0.002 annual exceedance probabilities (the 2-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-year recurrence intervals, respectively) are in file "DCStreamStats_FFreq_qnt.csv".