Scott A. Olson 20250818 Various formats U.S. Geological Survey - ScienceBase U.S. Geological Survey Data release citation: Olson, S.A., 2025, Data for the estimation of flood discharges at selected annual exceedance probabilities for unregulated, rural streams in Vermont, 2023: U.S. Geological Survey data release, https://doi.org/10.5066/P1MGCBK9. https://doi.org/10.5066/P1MGCBK9 Scott A. Olson 2025 publication USGS Scientific Investigations Report 2025-xxxx Reston, VA U.S. Geological Survey These data include flood-frequency data for the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities (pfqprocessed.zip) and the basin characteristics (siteinfoVT.txt) for 156 streamgages in Vermont and adjacent areas in surrounding states. These data were used as input to the regression model developed for estimating the magnitude of floods at the selected annual exceedance probabilities on ungaged, unregulated, rural streams in Vermont. The model code is provided in R script language (R Core Team, 2024) and utilized the generalized-least-squares regression tools in the WREG package (Farmer, 2021) to develop the regression equations to estimated flood discharge in Vermont. The model output (VT_Regression_Equations.pdf) provides code and the regression equations. Farmer, W.H., 2021, WREG—Weighted least squares regression for streamflow frequency statistics (ver. 3.0): U.S. Geological Survey software release, accessed January 31, 2025, at https://doi.org/10.5066/P9ZCGLI1. R Core Team, 2024, R: A language and environment for statistical computing version 4.4.0: R Foundation for Statistical Computing, Vienna, Austria, accessed July 18, 2024 at, https://www.R-project.org. The data and model were used develop regression equations for estimating the magnitude of floods at selected annual exceedance probabilities on ungaged, unregulated, rural streams in Vermont. The contents of these folders are viewed by downloading the zipped file, unzipping the folder and extracting files, then double-clicking on a filename to open. .PRT files and .EXP files can be viewed in a text editor. 1904 20230930 observed Complete None planned -74.4030 -71.0436 45.3839 42.4365 USGS Thesaurus Flood Frequency USGS Metadata Identifier USGS:679d0ccbd34e89501cd2d77d Geographic Names Information System (GNIS) Vermont None. Please see 'Distribution Info' for details. None. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. Although these data have been processed successfully on a computer system at the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. The USGS or the U.S. Government shall not be held liable for improper or incorrect use of the data described and/or contained herein. Pamela Lombard U.S. Geological Survey New England Water Science Center mailing and physical

196 Whitten Rd

Augusta ME 04330 USA 207-626-6630 plombard@usgs.gov Federal Emergency Management Agency Windows operating system, Windows 11. Regression analysis was completed using the WREG package (Farmer, W.H., 2021, WREG—Weighted least squares regression for streamflow frequency statistics, ver. 3.0: U.S. Geological Survey software release, accessed January 31, 2025, at https://doi.org/10.5066/P9ZCGLI1) for R software (R Core Team, 2024, R: A language and environment for statistical computing version 4.4.0: R Foundation for Statistical Computing, Vienna, Austria, accessed July 18, 2024 at, https://www.R-project.org). No formal attribute accuracy tests were conducted. No formal logical accuracy tests were conducted. The datasets are considered complete for the information presented, as described in the abstracts on each landing page. Users are advised to read all metadata records carefully for additional details. No formal positional accuracy tests were conducted. No formal positional accuracy tests were conducted. These data include flood-frequency data for the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities and the basin characteristics for 156 streamgages in Vermont and adjacent areas in surrounding states that were used as input to the regression model developed for estimating the magnitude of floods at the selected annual exceedance probabilities on ungaged, unregulated, rural streams in Vermont. The output from the PeakFQ software, which is described on the main page of this data release, was reorganized to the flood-frequency data set provided in this sub-page by the WREG package (Farmer, 2021). This reorganization into the data sets provided in this sub-page is the format used by the WREG package to do the generalized-least square regression. The model code for developing the regression equations is provided in R script language (R Core Team, 2024) and utilizes the generalized-least-squares regression tools in the WREG package (Farmer, 2021). The model output data provides the regression equations. Farmer, W.H., 2021, WREG—Weighted least squares regression for streamflow frequency statistics (ver. 3.0): U.S. Geological Survey software release, accessed January 31, 2025, at https://doi.org/10.5066/P9ZCGLI1. R Core Team, 2024, R: A language and environment for statistical computing version 4.4.0: R Foundation for Statistical Computing, Vienna, Austria, accessed July 18, 2024 at, https://www.R-project.org. 20250131 SiteInfoVT.txt Basin characteristics computed for the streamgages and used in the regression equations. Producer Defined Station.ID USGS streamgage identification number, 8-digit (with leading zeros). USGS USGS streamgage identification number. Lat Latitude of the streamgage site. Producer Defined 42.45509 45.13505 Degrees Long Longitude of the streamgage site. Producer Defined -73.91639 -71.05750 Degrees Horizontal Datum Latitude and longitude datum of streamgage Producer Defined NAD 27 North American Datum of 1927 Producer defined NAD 83 North American Datum of 1982 Producer defined No.Annual.Series Number of years of observed annual maximum discharge data. Producer Defined 10 120 Years regionalSkew The regional skew used in the flood-frequency analysis. All values are 0.445 taken from a Vermont regional skew regression analysis (Olson, S.A., 2014, Estimation of flood discharges at selected annual exceedance probabilities for unregulated, rural streams in Vermont, with a section on Vermont regional skew regression, by Veilleux, A.G.: U.S. Geological Survey Scientific Investigations Report 2014–5078, 27 p. plus appendixes, http://dx.doi.org/10.3133/sir20145078). Producer Defined 0.445 0.445 Logarithmic units da Drainage area of the basin in square miles determined from drainage boundaries from StreamStats (https://streamstats.usgs.gov/ss) Producer Defined 0.47 851 Square miles wetland Percent of wetland cover in basin. This includes water and wetland land cover extracted from land cover data of the "North American Land Change Monitoring System, North American Land Cover, 2020" (Canada Centre for Mapping and Earth Observation, 2023, https:// www.cec.org/nalcms). Producer Defined 0 20.980 Percent prism_aafc Average Annual Precipitation for the basin computed using annual precipitation rasters from PRISM Climate Group, Oregon State University (2022, https://prism.oregonstate.edu) combined with annual precipitation rasters from Agriculture and Agri-food Canada (2023, https://open.canada.ca/data/en/dataset/acd4c9f2-0598-47e8-aa4d-0a8a0964ce55) for basins extending into Canada. Producer Defined 33.8 75.2 Inches pfqprocessed\gage#\gage#.PRT PeakFQ output (.PRT) text files show annual peak flow frequency analysis and are described in Appendix D.3 of the PeakFQ User's Manual (https://doi.org/10.3133/tm4B4). The "gage#" in the label represents the 8-digit streamgage identification number. U.S. Geological Survey PeakFQ output (.PRT) files PeakFQ output (.PRT) files are described in Appendix D.3 of the PeakFQ User Manual. Flynn, K.M., Kirby, W.H., and Hummel, P.R., 2006, User’s Manual for Program PeakFQ Annual Flood-Frequency Analysis Using Bulletin 17B Guidelines: U.S. Geological Survey, Techniques and Methods Book 4, Chapter B4; 42 pgs., https://doi.org/10.3133/tm4B4 The PeakFQ output files (.PRT) are an output format from the PeakFQ software during a flood-frequency analysis. For a description of the files see PeakFQ User's Manual (https://doi.org/10.3133/tm4B4). These .PRT output files are used as input to the WREG package (Farmer, W.H., 2021, WREG—Weighted least squares regression for streamflow frequency statistics (ver. 3.0): U.S. Geological Survey software release, accessed January 31, 2025, at https://doi.org/10.5066/P9ZCGLI1). The folders and files are divided up by the 8-digit USGS station identification number. These files, in the format and directory structure provided, are required for the WREG input. pfqprocessed\gage#\gage#.EXP The PeakFQ export files (.EXP) are text files are output from the PeakFQ software. See PeakFQ User's Manual (https://doi.org/10.3133/tm4B4). The "gage#" in the label represents the 8-digit streamgage identification number. U.S. Geological Survey PeakFQ output (.PRT) files The PeakFQ export files (.EXP) are output from PeakFQ during a flood-frequency analysis. The files are used as input to the regression model. Flynn, K.M., Kirby, W.H., and Hummel, P.R., 2006, User’s Manual for Program PeakFQ Annual Flood-Frequency Analysis Using Bulletin 17B Guidelines: U.S. Geological Survey, Techniques and Methods Book 4, Chapter B4; 42 pgs., https://doi.org/10.3133/tm4B4 The PeakFQ export files (.EXP) are an output format from the PeakFQ software during a flood-frequency analysis. See PeakFQ User's Manual (https://doi.org/10.3133/tm4B4). These .EXP output files are used as input to the WREG package (Farmer, W.H., 2021, WREG—Weighted least squares regression for streamflow frequency statistics (ver. 3.0): U.S. Geological Survey software release, accessed January 31, 2025, at https://doi.org/10.5066/P9ZCGLI1). The folders and files are divided up by the 8-digit USGS station identification number. These files, in the format and directory structure provided, are required for the WREG input. VT_Regression_Equations.pdf A Portable Document Format (.pdf) file of the model scripts and model output. Producer Defined Vermont Regression Equations to Estimate Flood Discharges.pdf The file contains the model code followed immediately by the model output for the respective lines of code. Producer Defined A Portable Document Format (.pdf) file of the model scripts and model output. The model code are those that ran the WREG package (Farmer, W.H., 2021, WREG—Weighted least squares regression for streamflow frequency statistics (ver. 3.0): U.S. Geological Survey software release, accessed January 31, 2025, at https://doi.org/10.5066/P9ZCGLI1) in R (R Core Team, 2024, R: A language and environment for statistical computing version 4.4.0: R Foundation for Statistical Computing, Vienna, Austria, accessed July 18, 2024 at, https://www.R-project.org). In the .pdf file the model code is followed by the WREG output. Pamela Lombard U.S. Geological Survey mailing address

196 Whitten Rd

Pembroke ME 04330 United States 1-603-226-7800 sciencebase@usgs.gov Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government Digital Data https://doi.org/10.5066/P1MGCBK9 None 20250818 Pamela Lombard U.S. Geological Survey New England Water Science Center mailing and physical

196 Whitten Rd

Augusta ME 04330 USA 207-626-6630 plombard@usgs.gov FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998