Scott A. Olson James M. LeNoir Rena D. Kalmon Ellizabeth A. Ahearn 20250129 tabular digital data Reston, VA U.S. Geological Survey These high-water-mark data tables are part of the data release: Olson, S.A., LeNoir, J.M., Kalmon, R.D., and Ahearn, E.A., 2025, Vermont Flood of July 2023 Data: U.S. Geological Survey data release, https://doi.org/10.5066/P14XBBAT. https://doi.org/10.5066/P14XBBAT Travis L. Smith Scott A. Olson James M. Lenoir Rena D. Kalmon Elizabeth A. Ahearn 20250519 publication USGS Scientific Investigations Report 2025-5016 Reston, VA U.S. Geological Survey Smith, T.L., Olson, S.A., LeNoir, J.M., Kalmon, R.D., and Ahearn, E.A., 2025, Flood of July 2023 in Vermont: U.S. Geological Survey Scientific Investigations Report 2025–5016, 21 p., https://doi.org/10.3133/sir20255016. https://doi.org/10.3133/sir20255016 A major rain event caused catastrophic flooding from July 9 through 12, 2023 in various portions of the State of Vermont, resulting in millions of dollars of damage. These data are one of three datasets in the Vermont Flood of July 2023 Data data release. This part of the data release contains high-water mark (HWM) data from the Vermont flood of July 2023. The Comma-Separated Values (CSV) file table_JulyHWMs.csv contains 547 surveyed HWMs on 31 rivers from the Vermont flood of July 2023. In addition, a comparison between surveyed HWM data from the July 2023 flood and from Tropical Storm Irene in 2011 is included in the data release. The data from the two events--where HWMs were co-located and surveyed--are compared in the file table_HWMcompare.csv. Elevation differences were calculated as the July 2023 HWM surveyed elevation minus Tropical Storm Irene HWM surveyed elevation at the same site. Sites are defined as areas on a river that are expected to have the same hydraulic setting, for example, immediately downstream of a bridge. These data are also hosted on the USGS Flood Event Viewer (https://stn.wim.usgs.gov/FEV/). These data are used to document the July 2023 flood and to compare peak water-surface elevations in Vermont resulting from Tropical Storm Irene (2011) and the July 2023 flood. 20110828 20230712 Post-flood observations Complete None planned -73.6084 -71.3672 45.1665 42.6340 USGS Thesaurus High-water marks Flood USGS Metadata Identifier USGS:662bc7b1d34ea70bd5f11f4d 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. James M. LeNoir U.S. Geological Survey New England Water Science Center Hydrologist mailing

10 Bearfoot Road

Northborough MA 01532 508-330-6229 jlenoir@usgs.gov Python version 3.7 and Microsoft Excel version 2308 The accuracy of each HWM elevation is assigned in the field as excellent, good, fair, poor and very poor to account for the uncertainty in the mark as described in the USGS Techniques and Methods 3-A24 (Koenig and others, 2016). For detailed information see “HWM Quality” in the Entity and Attribute section of this metadata. The accuracy of the three-dimensional positioning recorded by Global Navigation Satellite Systems (GNSS) surveys is described as a level two quality survey in the USGS Techniques and Methods 11-D1 (Rydlund and Densmore, 2012). No formal logical accuracy tests were conducted Datasets are considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details. The surveying is described as a level two quality survey in the USGS Techniques and Methods 11-D1 (Rydlund and Densmore, 2012). The surveying is described as a level two quality survey in the USGS Techniques and Methods 11-D1 (Rydlund and Densmore, 2012). US Geological Survey 2024 tabular digital data Reston, VA U.S. Geological Survey The July 2023 flood data can be found at https://stn.wim.usgs.gov/FEV/#2023JulyMANYVTFlood. The Tropical Storm Irene flood data can be found at https://stn.wim.usgs.gov/FEV/#2011Irene. https://stn.wim.usgs.gov/FEV/ Digital and/or Hardcopy 20110828 20230712 ground condition USGS Flood Event Viewer The Flood Event Viewer hosts the Vermont Flood of July 2023 and the Tropical Storm Irene high-water mark data which were used in this study. Toby D. Feaster Todd A. Koenig 2017 publication n/a US Geological Survey Feaster, T.D., and Koenig, T.A, 2017, Field manual for identifying and preserving high-water mark data: U.S. Geological Survey Open-File Report 2017–1105, 67 p., https://doi.org/10.3133/ofr20171105. https://doi.org/10.3133/ofr20171105 Digital and/or Hardcopy 2017 publication date Feaster and Koenig, 2017 Guide to identify HWMs in fieldwork. Todd A. Koenig Jennifer L. Bruce Jim O'Connor Benton D. McGee Robert R. Holmes Ryan Hollins Brandon T. Forbes Michael S. Kohn Mathew Schellekens Zachary W. Martin Marie C. Peppler 2016 publication n/a US Geological Survey Koenig, T.A., Bruce, J.L., O’Connor, J.E., McGee, B.D., Holmes, R.R., Jr., Hollins, R., Forbes, B.T., Kohn, M.S., Schellekens, M.F., Martin, Z.W., and Peppler, M.C., 2016, Identifying and preserving high-water mark data: U.S. Geological Survey Techniques and Methods, book 3, chap. A24, 47 p., http://dx.doi.org/10.3133/tm3A24. https://doi.org/10.3133/tm3A24 Digital and/or Hardcopy 2016 publication date Koenig and others, 2016 Guide to identify and rate HWMs during fieldwork. Paul H. Rydlund, Jr. Brenda K. Densmore 2012 publication n/a US Geological Survey Rydlund, P.H., Jr., and Densmore, B.K., 2012, Methods of practice and guidelines for using survey-grade global navigation satellite systems (GNSS) to establish vertical datum in the United States Geological Survey: U.S. Geological Survey Techniques and Methods, book 11, chap. D1, 102 p. with appendixes, https://pubs.usgs.gov/tm/11d1/ https://doi.org/10.3133/tm11D1 Digital and/or Hardcopy 2012 publication date Rydlund and Densmore, 2012 Used as guide for surveying HWMs High-water mark data were surveyed and reported in feet referenced to the North American Vertical Datum of 1988 (NAVD 88) using best practice methods published in the USGS Techniques and Methods 11-D1(Rydlund and Densmore, 2012). Surveyed high-water mark from the Vermont Flood of July 2023 and Tropical Storm Irene are hosted on the US Geological Survey (USGS) Flood Event Viewer and were downloaded using Python version 3.7. The difference in the high-water mark elevations at the same sites from the two events were determined and compared using a script written in Python version 3.7 and Microsoft Excel. Elevation difference was determined as the July 2023 high-water mark surveyed elevation minus the Tropical Storm Irene surveyed high-water mark elevation at shared sites. At sites where multiple high-water marks were surveyed for a specific event, the average of the elevations was used in the calculation. USGS Flood Event Viewer Rydlund and Densmore, 2012 20240426 0.00001 0.00001 Decimal degrees North American Vertical Datum of 1988 0.01 feet Attribute values table_HWMcompare.csv Comma Separated Values (CSV) file containing high-water mark elevations from two floods in Vermont. Producer Defined Waterbody The name of the river where the high-water mark was collected. Producer Defined Name of river, creek, branches, and brooks. There are two Black Rivers in Vermont; the town name was added to Black River HWMs to clarify river location. Site Number Site identification number (ID) Producer Defined Site identification representing area on a river with the same hydraulic setting, such as upstream or downstream of a dam or bridge, and matches the site number column in table_JulyHWMs.csv. July2023_Average_Site_Elevation_ft Average of the surveyed elevations of the July 2023 high-water marks at each site. Feet referenced to the North American Vertical Datum of 1988 (NAVD 88). Producer Defined 146.26 1529.75 feet 0.01 Irene_Average_Site_Elevation_ft Average of the surveyed elevations of Tropical Storm Irene high-water marks at each site. Feet referenced to the North American Vertical Datum of 1988 (NAVD 88). Producer Defined 145.86 1534.58 feet 0.01 Elevation_Difference_ft July 2023 average elevation at a site minus Tropical Storm Irene average elevation at the same site Producer Defined -18.66 20.29 feet table_JulyHWMs.csv Comma Separated Values (CSV) file containing high-water mark elevation data downloaded from the USGS Flood Event Viewer for the July 2023 flood. Producer Defined Waterbody The name of the river where the high-water mark was collected. Producer Defined River and Creek names. There are two Black Rivers in Vermont; the town name was added to Black River HWMs to clarify river location. State US State Producer Defined VT Vermont Producer defined County The county where the high-water mark was collected. Producer Defined Vermont County name Site Number 10-character site identification number comprised of 2-character state abbreviation, 3-character county abbreviation, and 5-digit value from Site ID column (county abbreviations are not unique). Flood Event Viewer: 2023 July MA NY VT Flood Site identification including state and county identifiers as well as Site ID. This identification number is the "site_no" from the USGS Flood Event Viewer. In addition, the site identification number represents an area on a river with the same hydraulic setting, such as upstream or downstream of a dam or bridge, and matches the site identification number in table_HWMcompare.csv. Marks with non-unique site numbers are within close proximity of each other. Site ID 5-digit site identification number Flood Event Viewer: 2023 July MA NY VT Flood Site identification number. This identification number is the "site_id" from the USGS Flood Event Viewer. Site IDs not unique because some sites have multiple high-water marks (see HWM Label column to distinguish). Site Description Location description of HWM site Producer Defined Blank No description provided Producer defined Location description of HWM site. This description is from the "siteDescription" from the USGS Flood Event Viewer. Site Latitude Latitude of site location. Sites are defined as areas on a river that are expected to have the same hydraulic setting, for example, immediately downstream of a bridge. Sites are used for identifying comparable Tropical Storm Irene HWMs. Producer Defined 42.84830093 44.9571991 decimal degrees Site Longitude Longitude of site location. Sites are defined as areas on a river that are expected to have the same hydraulic setting, for example, immediately downstream of a bridge. Sites are used for identifying comparable Tropical Storm Irene HWMs. Producer Defined -73.25630188 -71.963968 decimal degrees HWM Label An individual identifier for each high-water mark. Producer Defined State- County Code- Town abbreviation- HWM number. Several marks on the Lamoille River were only identified with "HWM#", where # represents a number. HWM ID 5-digit HWM identification number Producer Defined HWM identification number HWM Location Description Description of the HWM location Producer Defined << empty cell >> No description available. Producer defined Description of the high-water mark location. LEW and REW are abbreviations for left edge of water and right edge of water, respectively. HWM Type Evidence of HWM Feaster and Koenig (2017), Koenig and others (2016) Debris Sticks, trash, or other coarse material left on the ground near the edge of the water Producer defined Other Other evidence of peak water surface Producer defined Mud Sediment stain or general discoloration from water contact Producer defined Seed line Seeds or other fine material left in a line Producer defined Stain line A line left on porous materials such as wood and concrete. Producer defined Vegetation line Line of other vegetation (leaves, grass) Producer defined Wash line Line on a bank indicating the removal of loose material from the top of the ground surface Producer defined HWM Quality Measure of HWM identification uncertainty Koenig and others, 2016 Excellent: +/- 0.05 ft Full confidence in accuracy of mark placement. Producer defined Good: +/- 0.10 ft Confident in accuracy of mark placement. Producer defined Fair: +/- 0.20 ft Moderate confidence in accuracy of mark placement. Producer defined Poor: +/- 0.40 ft Peak water surface believed to be within 0.4 foot of tagged HWM. Producer defined Very Poor: > 0.40 ft Very little confidence in the accuracy of mark placement. Producer defined Unknown/Historical Unknown confidence Producer defined Height Above Ground (ft) Measured height of HWM above ground Producer Defined << empty cell >> No Data Producer defined -1.05 9.9 feet HWM Latitude Surveyed latitude of HWM Producer Defined 42.84831392 44.95720647 decimal degrees HWM Longitude Surveyed longitude of HWM Producer Defined -73.25628133 -71.96366639 decimal degrees HWM Elevation (ft) Surveyed elevation of HWM. Feet referenced to the North American Vertical Datum of 1988 (NAVD 88). Producer Defined 103.75 1529.75 feet 0.01 GS ScienceBase U.S. Geological Survey mailing address

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 United States 1-888-275-8747 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 on any other system or for general or scientific purposes, 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/P14XBBAT None 20250519 James M. LeNoir U.S. Geological Survey New England Water Science Center mailing and physical

10 Bearfoot Road

Northborough MA 01532 508-330-6229 jlenoir@usgs.gov FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998