Christopher C. Bemelmans Chelsea A. Stalk James G. Flocks 20250402 tabular and raster digital data Christopher C. Bemelmans Chelsea A. Stalk James G. Flocks 20250402 U.S. Geological Survey data release doi:10.5066/P13BWAJC St. Petersburg, Florida U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center https://doi.org/10.5066/P13BWAJC An Ellipsoidally Referenced Survey (ERS) using two Teledyne Reson SeaBat T50-P multibeam echosounders, in dual-head configuration, was conducted by the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center (SPCMSC) covering the nearshore, Gulf side of Breton Island, Louisiana (LA), from August 6-9, 2024. This dataset, Breton_2024_MBES_xyz.zip, includes the processed elevation point data (x,y,z), as derived from a 1-meter (m) bathymetric grid. The download file, Breton_2024_MBES_Backscatter.zip, includes acoustic backscatter intensity data in 32-bit floating point GeoTIFF (Geographic Tagged Image File Format, .tif) format. The purpose of the survey was to develop a digital elevation model of the seafloor environment around Breton Island for comparison with both previous and future elevation assessments, and to evaluate elevation change following island restoration. Data were collected during USGS Field Activity Number (FAN) 2024-320-FA. Seismic reflection data were acquired as a part of the same field activity, please see Forde and others (2025) for further details. Additional survey and data details are available from the USGS Coastal and Marine Geoscience Data System (CMGDS) at, https://cmgds.marine.usgs.gov/services/activity.php?fan=2024-320-FA. The processed sonar data are provided as American Standard Code for Information Interchange (ASCII) x,y,z point data files. These values are not the individual soundings, but nodes from a 1-m bathymetric grid. The Z value for the node is generated by utilizing a Combined Uncertainty and Bathymetry Estimator (CUBE) surface and has an estimated total value of uncertainty (Calder and Wells, 2007). The bathymetry data were collected and processed in the World Geodetic System of 1984 (WGS84) (G1150 realization) horizontal and vertical datums, and were subsequently transformed using the National Oceanic and Atmospheric Administration's (NOAA) VDatum version 4.7 (v.4.7) transformation software (https://vdatum.noaa.gov/) horizontally to the North American Datum of 1983 (NAD83 [2011]) and vertically to the North American Vertical Datum of 1988 (NAVD88) relative to the GEOID model of 2018 (GEOID18). 20240806 20240809 ground condition Complete None planned -89.20431444 -89.05087613 29.4974589 29.4324337 USGS Metadata Identifier USGS:9dff9ee2-1678-4ad4-888e-582b992eaa6a ISO 19115 Topic Category oceans elevation location geoscientificInformation imageryBaseMapsEarthCover USGS Thesaurus marine geology marine geophysics geophysics bathymetry multibeam sonar ocean characteristics ocean processes None hydrography seafloor mapping Teledyne Reson T50-P Applanix POS MV Wavemaster II U.S. Geological Survey USGS St. Petersburg Coastal and Marine Science Center SPCMSC Geographic Names Information System (GNIS) State of Louisiana Breton Islands None Breton Island, Louisiana Mid-Gulf Coast None August 2024 None. There are no access constraints associated with this data. Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. The U.S. Geological Survey requests to be acknowledged as originator of these data in future products or derivative research. Christopher C. Bemelmans U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center Electronics Technician (Marine Instrumentation) mailing and physical

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St. Petersburg FL 33701 USA (727) 502-8000 cbemelmans@usgs.gov U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center Microsoft Windows 11 Enterprise (Build 19045.4046); NOAA VDatum (version 4.7); HYPACK®, A Xylem Brand and HYPACK HYSWEEP® (version 2023 Q3); Applanix POSPac MMS (POSPac) software (version 9.1, Service Pack 1); Teledyne CARIS™ Hydrographic processing software HIPS and SIPS (version 11.4.28). International Hydrographic Organization (IHO) 20191031 Monaco International Hydrographic Organization, Intergovernmental Oceanographic Commission pages 81-83 https://www.gebco.net/data_and_products/gebco_cook_book/ Caris 20150601 Fredericton, NB, Canada Caris pages 1-446 Dr. Bruno Scherzinger Joe Hutton 2025 Westminster, Colorado Trimble pages 1-9 https://applanix.trimble.com/en/resources/flipbooks/applanix-in-fusion-plus-the-ultimate-solution-for-enhanced-spatial Brian R. Calder David E. Wells 20070129 Durham, NH University of New Hampshire, Center for Coastal and Ocean Mapping pages 1-54 https://scholars.unh.edu/ccom/1217 International Hydrographic Organization (IHO) 200802 4, quai Antoine 1er B.P. 445 - MC 98011 MONACO Cedex Principaute de Monaco International Hydrographic Bureau pages 1-28 https://iho.int/uploads/user/pubs/standards/s-44/S-44_5E.pdf Arnell S. Forde Chelsea A. Stalk James G. Flocks 20250312 U.S. Geological Survey data release doi:10.5066/P13SMFT7 St. Petersburg, Florida U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center https://doi.org/10.5066/P13SMFT7 This dataset was from a single research cruise with exact instrumentation and set up and were therefore internally consistent. Methods were employed to maintain data collection consistency aboard the platform. During mobilization, each piece of equipment was isolated to obtain internal and external offset measurements with respect to the survey platform. All the critical measurements were recorded manually and digitally entered into their respective programs. These files represent the post-processed bathymetric data (x,y,z) and acoustic intensity (.tif) during a multibeam bathymetry survey. These are complete, post-processed x,y,z bathymetric and backscatter data points from multibeam data collected nearshore Breton Island, Louisiana, August 2024. All data were collected and processed to meet or exceed International Hydrographic Organization (IHO) Special Order standards for positioning and depth (IHO, 2008). Individual Total Propagated Uncertainty (TPU) values associated with each node are available in the x,y,z file, with a mean value of 0.051 m. All data were collected and processed to meet or exceed IHO Special Order standards for positioning and depth (IHO, 2008). Individual TPU values associated with each node are available in the x,y,z file, with a mean value of 0.051 m. Data transformed using VDatum have an additional reported vertical transformation error of 5.991 centimeters (cm). Acquisition: An ERS consisting of multibeam bathymetry was conducted using two Teledyne Reson SeaBat T50-P multibeam echosounders, in dual-head configuration. The pair of Mills Cross (configuration) transmit and receive arrays, were placed side-by-side within a bracket that oriented them at opposing 30-degree angles (relative to horizontal). The bracket was pole-mounted on the starboard gunnel of the research vessel (R/V) Sallenger, a 26-foot fiberglass vessel. The sonar arrays were oriented athwartships (primary and secondary arrays facing outward and down to port and starboard, respectively) and located approximately 1-m below the waterline when deployed. An Applanix Pos MV Wavemaster II V5 inertially aided navigation system was used for timing, positioning, and attitude. The Inertial Measurement Unit (IMU) was mounted atop the sonar bracket just aft of the pole. Two Trimble GA830 Global Navigation Satellite System (GNSS) antennas were affixed atop the cabin approximately amidships of the vessel, two meters apart, port-starboard. An AML Oceanographic Micro-X sound velocity sensor was used for speed of sound readings at the sonar head. A Sontek CastAway CTD was used for measuring sound velocity profiles. Hydrographic survey acquisition and processing software, HYPACK® and HYPACK HYSWEEP® (version 2023 Q3) managed data inputs from sensors and produced two files (.RAW and .HSX). Data were collected in WGS84 (G1150) Universal Transverse Mercator (UTM) Zone 16 North (16N) coordinates. 20240810 Christopher C. Bemelmans U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center mailing and physical

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St. Petersburg FL 33701 USA (727) 502-8000 cbemelmans@usgs.gov Processing: Positioning and attitude data were post-processed in POSPac software version 9.1 Service Pack 1. Raw position files were imported into POSPac and processed with the IN-Fusion PP-RTX processing mode utilizing Trimble CenterPoint RTX technology (Scherzinger and Hutton, 2025), creating smoothed best estimate of trajectory (SBET) files and dynamic error files (SMRMSG) for each day of the survey. Bathymetric data were post-processed in Teledyne CARIS™ Hydrographic processing software HIPS and SIPS version 11.4.28. HYPACK® acquisition files (.HSX) were first imported into CARIS™ and then post-processed navigation files (SBET and SMRMSG) were imported and applied (Caris, 2015). Additionally, Global Positioning System (GPS) tide (GPS tidal corrections utilize GPS height information from real time survey observations to obtain an ellipsoid height) was computed and sound velocity profiles were applied (IHO, 2019). Roll calibration was also performed, as necessary, and values were applied to the data. TPU was calculated from real time values recorded in the HSX and the SMRMSG files (IHO, 2019). Data were filtered to exclude any points with RESON Quality flags of 0, 1, and 2 (these flags are assigned to individual soundings at the time of acquisition and are a metric of pass/fail in regard to both brightness and collinearity: 0 = fail both, 1 = pass brightness only, 2 = pass collinearity only), as well as soundings that had a TPU greater than stated IHO Special Order standards (IHO, 2008). Refraction artifacts were addressed using Refraction Editor. Further editing was performed in Subset Editor. A 1-m bathymetric CUBE surface was computed and a visual and statistical inspection of the data effecting the surface was performed and edited as needed to serve as quality control (Calder and Wells, 2007). Gaps in the continuous surface were caused by limitations in swath width and planned line navigation within shallow waters. The final surface was exported as an x,y,z ASCII file using the 'Base Surface to ASCII' function. 2024 2024-320-FA_MBES_Breton_ 1m_WGS84_UTM16N.txt Christopher C. Bemelmans U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center mailing and physical

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St. Petersburg FL 33701 USA (727) 502-8000 cbemelmans@usgs.gov Backscatter Mosaic Creation: Acoustic Intensity Backscatter data (.7k) were loaded in CARIS Hydrographic processing software HIPS/SIPS version 11.4.28 using the SIPS Backscatter tool. The final CUBE bathymetry surface serves as input for geometric corrections and average temperature and salinity data (derived from the Sontek CastAway CTD measurements taken during acquisition) are utilized by the program to calculate local absorption and transmission loss. These inputs, along with the following settings were entered into the tool, and then processing was initiated [Weighted Average = blending, image type = beam average, weighting = swath, and an Angle-Varying gain = 200]. During processing, the tool automatically creates a pattern file (.bbp) which is used to correct for variations in the beam pattern of the system. Upon completion, a 1-m backscatter mosaic with intensity values ranging from 21.327 to -37.204 dB (decibels) was created and the mosaic was exported as a 32-bit float GeoTIFF (.tif) using the 'surface to GeoTIFF' function. 2024 2024-320-FA_Breton_MBES_1m_Backscatter.tif Christopher C. Bemelmans U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center mailing and physical

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St. Petersburg FL 33701 USA (727) 502-8000 cbemelmans@usgs.gov Datum Transformation: Final x,y,z data were converted using NOAA's VDatum v.4.7 software conversion tool from the WGS84 [G1150] realization to NAD83 [2011] NAVD88, using the GEOID18 model (orthometric height). 2024 2024-320-FA_MBES_Breton_1m_NAD83_UTM16N_NAVD88_G18.txt Christopher C. Bemelmans U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center mailing and physical

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St. Petersburg FL 33701 USA (727) 502-8000 cbemelmans@usgs.gov Point Point 15,303,492 Universal Transverse Mercator 16 0.999600 -87.000000 0.0 500000.0 0.0 coordinate pair 0.6096 0.6096 meters World Geodetic System of 1984 WGS_84 6378137.0 298.257223563 World Geodetic System of 1984 0.001 meters Attribute values 2024-320-FA_MBES_Breton_1m_WGS84_UTM16N.txt ASCII text (.txt) file containing the processed 1-m bathymetric grid x,y,z data in the WGS84 [G1150] realization (ellipsoid height). HYPACK® WGS84_UTM16N_X WGS84 UTM Zone 16N X-coordinate (easting) of sample point, in meters. HYPACK® 287728.000 296774.000 0.001 WGS84_UTM16N_Y WGS84 UTM Zone 16N Y-coordinate (northing) of sample point, in meters. HYPACK® 3263610.000 3258937.000 0.001 WGS84_Z (m) WGS84 (ellipsoid height) of sample point, in meters. HYPACK® -39.776 -28.204 0.001 TPU (m) TPU = Total Propagated Uncertainty, in meters. Teledyne CARIS™ 0.040 0.254 0.001 2024-320-FA_MBES_Breton_1m_NAD83_UTM16N_NAVD88_G18.txt ASCII text (.txt) file containing the processed 1-m bathymetric grid x,y,z data in NAD83 [2011], NAVD88, which were derived using the GEOID18 model (orthometric height). VDatum NAD83_UTM16N_X NAD83 UTM Zone 16N X-coordinate (easting) of sample point, in meters. VDatum 287728.87000 296774.86700 0.00001 NAD83_UTM16N_Y NAD83 UTM Zone 16N Y-coordinate (northing) of sample point, in meters. VDatum 3258936.45000 3263609.44800 0.00001 NAVD88_GEOID18_Z (m) NAVD88 (orthometric height) of sample point, in meters, with respect to GEOID12B. VDatum -14.072 -2.529 0.001 TPU_WGS84 (m) Total Propagated Uncertainty, in meters, as reported for WGS84 (G1150) data. A static uncertainty value of 5.991 cm is associated with the transformation of this data. Teledyne CARIS™ 0.040 0.254 0.001 2024-320-FA_Breton_MBES_1m_Backscatter.tif: Dataset is a GeoTIFF included in the download file, Breton_2024_MBES_Backscatter.zip, which is acoustic backscatter intensity data in 32-bit floating point GeoTIFF (.tif) format with 14761 columns and 6940 rows. Dataset is projected to the WGS 1984 UTM Zone 16N coordinate system, with intensity values ranging from 21.327 to -37.204 dB. The entity and attribute information were generated by the individual and/or agency identified as the originator of the dataset. Please review the rest of the metadata record for additional details and information. U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center USGS SPCMSC Data Management mailing and physical

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Saint Petersburg FL 33701 United States 727-502-8000 gs-g-spcmsc_data_inquiries@usgs.gov 2024-320-FA_MBES_Breton_1m_WGS84_UTM16N.txt, 2024-320-FA_MBES_Breton_1m_NAD83_UTM16N_NAVD88_G18.txt, 2024-320-FA_Breton_MBES_1m_Backscatter.tif 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. columnar text, GeoTIFF ZIP 226 https://coastal.er.usgs.gov/data-release/doi-P13BWAJC/data/Breton_2024_MBES_xyz.zip https://coastal.er.usgs.gov/data-release/doi-P13BWAJC/data/Breton_2024_MBES_Backscatter.zip None 20250402 U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center USGS SPCMSC Data Management mailing and physical

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Saint Petersburg FL 33701 United States 727-502-8000 gs-g-spcmsc_data_inquiries@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998