Lauren E. Eng Nathaniel K. Pasley Brian S. Caruso Andrew R. Bock 20250709 raster digital data Reston, VA U.S. Geological Survey https://doi.org/10.5066/P13ZTSGR This data release contains grids, in geographic tagged imaged file(.tif) format, summarizing inundation frequency of the U. S. Geological Survey (USGS) Dynamic Surface Water Extent (DSWE) Landsat Science Product at 114 National Wildlife Refuges throughout the U.S. Fish and Wildlife Service (USFWS) Mountain-Prairie Region (Colorado, Kansas, Montana, Nebraska, North Dakota, South Dakota, Utah, and Wyoming). The DSWE product provides long-term (1982 to present), high temporal resolution data (30-meter) on surface water inundation patterns that can help identify locations of past or current drought conditions. For each refuge, three files were produced using data from different periods: the baseline period (1982-2000), the evaluation period (2001–20), and the period of record (1982-2020). Inundation frequencies for each pixel were derived by dividing the total number of observations classified as any one of the DSWE water classes by the total number of observations of water extent or presence. This child item contains data for wildlife refuges within the state of North Dakota (ND). See keywords for specific refuges. The purpose of this data release is to provide accurate and reliable information regarding DSWE data inundation dynamics through time at 114 National Wildlife Refuges within the USFWS Mountain-Prairie Region. The following is a list of commonly used acronyms within the data release--DSWE: Dynamic Surface Water Extent; TIF: tagged image file; USFWS: U.S. Fish and Wildlife Service; NWR, National Wildlife Refuge; FIPS Code (2 Digit State ID), Federal Information Processing Standard Code (2-Digit State Identification); FIPS PUB 5-2 NIST, Federal Information Processing standards publication 5-2 National Institute of Standards and Technology. 19821101 20201231 ground condition Complete None planned -104.0600 -96.5500 49.0000 45.9300 ISO 19115 Topic Category environment Marine Realms Information Bank (MRIB) keywords National Wildlife Refuge USGS Thesaurus hydrology remote sensing surface water (non-marine) droughts USGS Metadata Identifier USGS:67449491d34eacadb5a4afa6 Common geographic areas North Dakota Appert Lake National Wildlife Refuge Ardoch National Wildlife Refuge Arrowwood National Wildlife Refuge Audubon National Wildlife Refuge Bone Hill National Wildlife Refuge Brumba National Wildlife Refuge Buffalo National Wildlife Refuge Camp Lake National Wildlife Refuge Canfield National Wildlife Refuge Chase Lake National Wildlife Refuge Cottonwood National Wildlife Refuge Dakota Lake National Wildlife Refuge Des Lacs National Wildlife Refuge Florence National Wildlife Refuge Half-Way Lake National Wildlife Refuge Hiddenwood National Wildlife Refuge Hobart Lake National Wildlife Refuge Hutchinson Lake National Wildlife Refuge J. Clark Salyer National Wildlife Refuge Johnson Lake National Wildlife Refuge Kellys Slough National Wildlife Refuge Lake Alice National Wildlife Refuge Lake George National Wildlife Refuge Lake Ilo National Wildlife Refuge Lake Nettie National Wildlife Refuge Lake Otis National Wildlife Refuge Lake Patricia National Wildlife Refuge Lake Zahl National Wildlife Refuge Lambs Lake National Wildlife Refuge Little Goose National Wildlife Refuge Long Lake National Wildlife Refuge Lords Lake National Wildlife Refuge Lost Lake National Wildlife Refuge Lostwood National Wildlife Refuge Maple River National Wildlife Refuge McLean National Wildlife Refuge Pleasant Lake National Wildlife Refuge Rabb Lake National Wildlife Refuge Rock Lake National Wildlife Refuge Rose Lake National Wildlife Refuge School Section Lake National Wildlife Refuge Shell Lake National Wildlife Refuge Sheyenne Lake National Wildlife Refuge Sibley Lake National Wildlife Refuge Silver Lake National Wildlife Refuge Slade National Wildlife Refuge Snyder Lake National Wildlife Refuge Springwater National Wildlife Refuge Stewart National Wildlife Refuge Stoney Slough National Wildlife Refuge Storm Lake National Wildlife Refuge Stump Lake National Wildlife Refuge Sunburst Lake National Wildlife Refuge Tewaukon National Wildlife Refuge Tomahawk National Wildlife Refuge Upper Souris National Wildlife Refuge White Horse Hill National Game Preserve White Lake National Wildlife Refuge Wild Rice Lake National Wildlife Refuge Willow Lake National Wildlife Refuge Wintering River National Wildlife Refuge Wood Lake National Wildlife Refuge None. Please see 'Distribution Info' for details. None. Users are advised to read the accompanying metadata file thoroughly to understand appropriate use and data limitations. Lauren Eng U.S. Geological Survey, ROCKY MOUNTAIN REGION Hydrologist mailing

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Pueblo Colorado 81003 US 719-601-6705 leng@usgs.gov Cooperative funding and assistance with data analysis for this project was provided in part by the USFWS. Original DSWE data files were processed in Python, version 3.9.15, on an internal USGS cloud-computing platform. Parallelization of project workflows was performed using the Python packages Xarray, version 2022.12.0, and Dask, version 2022.12.1. U. S. Geological Survey 20190923 2 raster digital data Jones, J. W., 2019, Improved Automated Detection of Subpixel-Scale Inundation—Revised Dynamic Surface Water Extent (DSWE) Partial Surface Water Tests: Remote Sensing, v. 11, no. 4, 374, https://doi.org/10.3390/rs11040374. https://doi.org/10.5066/P9DPWBUS S. C. Hoyer J. J. Hamman 20221201 2022.12.0 application/service Hoyer, S. C., and Hamman, J. J., 2022, Xarray (Version 2022.12.0) [Software], available from https://xarray.pydata.org/. https://github.com/pydata/xarray/blob/v2022.12.0/CITATION.cf Dask Development Team 20221201 2022.12.1 application/service Dask Development Team, 2022, Dask (Version 2022.12.1) [Software], available from https://dask.org/ https://docs.dask.org/en/stable U.S. Geological Survey 20250401 publication https://earth.google.com/web/ Esri 2023 3.4.0 application/service ESRI 2023. ArcGIS Pro: Release 2.9.5. Redlands, CA: Environmental Systems Research Institute. https://pro.arcgis.com/en/pro-app/3.4/get-started/get-started.htm Python 2022 3.9.15 application/service https://www.python.org/ No formal attribute accuracy tests were conducted. The data may have higher inundation frequencies in mountainous terrain, potentially because of environmental challenges affecting precision, including high terrain slope and shadows produced by dense forest. Additionally, the evaluation period contains more data than the baseline period because of the increased temporal frequency beginning with Landsat 7 (1999) through the present. This could explain differences for more channelized areas between the two periods. All inundation frequency values are based on all available empirical observations for the respective time periods, and identical processing steps were used for both periods. All inundation frequency values are within the expected range of 0-100 percent. The hydrologic systems depicted in output files were visually compared to historical imagery in Google Earth (Alphabet Inc., 2025) to ensure the validity of the physical locations where inundation occurred. This dataset represents the frequency that a given location within a USFWS Mountain-Prairie Region property, and a surrounding 10-kilometer (km) buffer, experienced surface water inundation for a given period. DSWE is derived from published Landsat spectral products (EROS Center, 2021), therefore accuracy is largely determined by Landsat extent and resolution. DSWE is derived from published Landsat spectral products (EROS Center, 2021), therefore accuracy is largely determined by Landsat extent and resolution. U.S. Fish and Wildlife Service 20250311 vector digital data https://gis-fws.opendata.arcgis.com/datasets/fws::u-s-fish-and-wildlife-service-national-realty-tracts/explore Digital and/or Hardcopy 20250311 publication date USFWS (2025) Used to derive USFWS National Wildlife Refuge (NWR) boundaries. John W. Jones 20150923 publication Remote Sensing MDPI Jones, J. W., 2015, Efficient Wetland Surface Water Detection and Monitoring via Landsat: Comparison with in situ Data from the Everglades Depth Estimation Network: Remote Sensing, v. 7, no. 9, 12503-12538, https://doi.org/10.3390/rs70912503. https://doi.org/10.3390/rs70912503 Digital and/or Hardcopy 20150923 publication date Jones (2015) Publication for the original Dynamic Surface Water Extent (DSWE) algorithm. John W. Jones 20190213 publication Remote Sensing MDPI Jones, J. W., 2019, Improved Automated Detection of Subpixel-Scale Inundation—Revised Dynamic Surface Water Extent (DSWE) Partial Surface Water Tests: Remote Sensing, v. 11, no. 4, 374, https://doi.org/10.3390/rs11040374. https://doi.org/10.3390/rs11040374 Digital and/or Hardcopy 20190213 publication date Jones (2019) Publication for the revised Dynamic Surface Water Extent (DSWE) algorithm. Earth Resources Observation and Science Center 20210720 raster digital data Earth Resources Observation and Science (EROS) Center, 2021, Landsat 4-9 U.S. Analysis Ready Data, Collection 2 [dataset]. U.S. Geological Survey. https://doi.org/10.5066/P960F8OC. https://doi.org/10.5066/P960F8OC Digital and/or Hardcopy 19821101 20250131 observed EROS Center (2021) For each USGS Landsat Collection 2 U.S. Analysis Ready Data (ARD) product published, a corresponding Landsat Collection 2 Level-3 DSWE product is produced. U.S. Geological Survey 20250501 tabular digital data https://www.usgs.gov/landsat-missions/spatiotemporal-asset-catalog-stac Digital and/or Hardcopy 19821101 20201231 observed USGS (2025) The ‘Interpreted Layer with All Masks Applied’ (INWAM) layer produced on a 1:1 basis with Landsat Spectral Reflectance data was accessed from the Landsat SpatioTemporal Asset Catalog (STAC) via Python for the period 1982-2024. Step 1: Access The U.S. Fish and Wildlife Service (USFWS) Mountain-Prairie Region 6 includes eight states: Colorado (CO), Kansas (KS), Montana (MT), North Dakota (ND), Nebraska (NE), South Dakota (SD), Utah (UT), and Wyoming (WY). Among these 8 states, there are 114 unique National Wildlife Refuges (NWRs) managed by the USFWS. The spatial boundaries of the Region 6 NWRs were downloaded as a polygon feature dataset in a geodatabase from the USFWS National Realty Tracts open source dataset (NWR Boundaries, 2025). DSWE is a Landsat Collection 2 (EROS Center, 2021) Level-3 derivative product. For every Landsat Surface Reflectance image published, a series of 5 diagnostic tests of remote sensing indices is run. The indices combine multiple wavelengths upon which thresholds are tested to enhance spectral features like surface water bodies. Each output pixel is classified according to the presence or absence of open water, potential wetland, or cloud, cloud shadow, or snow/ice. Each DSWE product contains a total of eight individual files. The ‘Interpreted Layer with All Masks Applied’ (INWAM) layer produced on a 1:1 basis with Landsat Spectral Reflectance data was accessed from the Landsat SpatioTemporal Asset Catalog (STAC; USGS, 2025) via Python (Python, 2022) for the period 1982-2024. 20240601 Step 2: Pre-process Individual DSWE files were saved to cloud storage to aide in the development of the processing workflow by offering more direct access and shorter load times. The NWR Boundary geometries were then used to access corresponding DSWE Zarr files. The files were loaded into Python as individual Xarray (Hoyer and Hamman, 2022) data arrays and clipped to a 10 km buffer surrounding the NWR Boundary before being concatenated into an Xarray dataset using a distributed Dask (Dask Development Team, 2022) cluster. The dataset was then subsetted into three periods-- baseline (1982-2000), evaluation (2001–20), and period of record (1982-2020). The selected periods were chosen to ensure an adequate dataset for calculating inundation frequencies, to provide a robust historical representation, and to maintain a consistent duration of analysis between the baseline and evaluation period. 20240801 Step 3: Process Within each subset, pixels labelled by the DSWE algorithm (Jones, 2019) as containing cloud, cloud shadow, or snow/ice were reclassified as NoData. Next, pixels labelled as any of the four DSWE classes used to identify the presence of water (Open Water-High Confidence, Open Water-Moderate Confidence, Partial Surface Water-Conservative, and Partial Surface Water-Aggressive) were reclassified to the integer 1. This created a binary water/not-water dataset, as the integer 0 is used by DSWE to identify non-water pixels. The mathematical formula for calculating DSWE-based inundation frequencies ((water observations / total observations) * 100) was then applied in the time dimension at each pixel location, resulting in a single output layer containing the percentage of observations that were labelled as any one of DSWE water classes for the given period. 20241101 Vector G-polygon 62 Albers Conical Equal Area 29.5 45.5 -96.0 23.0 0.0 0.0 coordinate pair 0.6096 0.6096 meters D North American 1983 GRS 1980 6378137.0 298.257222101 ND_NWR_Boundaries Shapefile of National Wildlife Refuges in North Dakota USFWS (2025) FID Internal feature number. ESRI 0 62 Shape Geometry data type ESRI Type of ESRI-derived geometry represented by the shapefile ORGNAME Name of USFWS National Wildlife Refuge Producer Defined Name of USFWS National Wildlife Refuge State State within which all or majority of the refuge is located. Producer Defined FIPS Code (2-Digit State Identification) FIPS PUB 5-2 (NIST) *REFUGE*.zip Subfolders for each NWR in the state containing raster images of DSWE-based inundation frequencies. Refer to Process Step 3 for more information regarding the inundation frequencies. Producer Defined period_of_record_*REF*.tif TIF file for USFWS NWR *REFUGE* Producer Defined TIF file for the period of record (1982-2020) for the refuge *REF*. Each tif file contains a single output layer containing the frequency that a pixel is classified by DSWE as displaying the presence of surface water. Refer to Process Step 3 for more information regarding the inundation frequencies. baseline_period_*REF*.tif TIF file for USFWS NWR *REFUGE* Producer Defined TIF file for the baseline period (1982-2000) for the refuge *REF*. Each tif file contains a single output layer containing the frequency that a pixel is classified by DSWE as displaying the presence or absence of surface water. Refer to Process Step 3 for more information regarding the inundation frequencies. evaluation_period_*REF*.tif TIF file for USFWS NWR *REFUGE* Producer Defined TIF file for the evaluation period (2001–20) for the refuge *REF*. Each tif file contains a single output layer containing the frequency that a pixel is classified by DSWE as displaying the presence of surface water. Refer to Process Step 3 for more information regarding the inundation frequencies. U.S. Geological Survey - ScienceBase mailing address

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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 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/P13ZTSGR None 20250709 Lauren E. Eng U.S. Geological Survey, ROCKY MOUNTAIN REGION Hydrologist mailing

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Pueblo CO 81003 US 719-601-6705 leng@usgs.gov FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998