Maxwel F. Schwid Mackenzie K. Keith Brandon T. Overstreet 20250826 tabular digital data https://doi.org/10.5066/P13VDSRG In cooperation with the U.S. Army Corps of Engineers (USACE), the U.S. Geological Survey (USGS) surveyed ground control points and coordinated aerial photograph acquisition of Cottage Grove Lake, a multi-purpose reservoir in western Oregon impounded by the 29-meter ([m]; 95-foot [ft]) tall Cottage Grove Dam. Aerial photographs were acquired by the Civil Air Patrol (CAP) in December 2023 when water levels were at or near typical annual “low pool” or minimum pool, a target elevation (229 m/751 ft National Geodetic Vertical Datum of 1929 [NGVD 29]) for flood risk management operations. Photographs were acquired at a single altitude with a WaldoAir XCAM Ultra 50 camera mounted on a Cessna aircraft and captured the entire reservoir area as defined by full pool (or maximum conservation pool elevation), including the major tributary entering the reservoir, the Coast Fork Willamette River. Dam operations at the 468-hectare (1156-acre) Cottage Grove Lake, located about 15 kilometers upstream of the confluence of the Coast Fork Willamette River and the Willamette River, along with other hydrogeomorphic conditions, result in a diverse array of geomorphic processes and landforms within the reservoir. To document reservoir floor geomorphology, the USGS applied structure-from-motion (SfM) techniques to these aerial photographs, following the workflow outlined in Over and others (2021) and used for similar datasets (Schwid and others, 2025), and generated a three-dimensional xyz point cloud, digital surface model (DSM), and orthomosaic of Cottage Grove Lake. This data release includes ground control points, dataset footprints, original aerial photographs, a point cloud, a DSM, and an orthomosaic of Cottage Grove Lake that were developed from imagery acquired on December 18, 2023. The point cloud has an average point density of 7.47 points per square meter, the DSM resolution is 36.6 centimeters per pixel, and the orthomosaic ground resolution is 9.15 centimeters per pixel. The DSM and orthomosaic are formatted as Cloud Optimized GeoTIFFs (COGs) for enhanced web visualization (GDAL, 2024). This documentation describes a CSV file containing ground control point locations collected on November 21, 2024, that were used to spatially register SfM datasets of Cottage Grove Lake, Oregon. References: Agisoft, 2025, Agisoft Metashape User Manual - Professional Edition Version 2.2: Agisoft LLC, 115 p., accessed August 11, 2025, at https://www.agisoft.com/pdf/metashape_2_2_en.pdf. American Society for Photogrammetry and Remote Sensing [ASPRS], 2008, LAS Specification Version 1.2: ASPRS, approved September 2, 2008, 13 p., accessed August 11, 2025, at https://www.asprs.org/wp-content/uploads/2010/12/asprs_las_format_v12.pdf. Geospatial Data Abstraction Library [GDAL], 2024, COG -- Cloud Optimized GeoTIFF generator: GDAL, webpage, accessed August 11, 2025, at https://gdal.org/drivers/raster/cog.html#raster-cog. Over, J.R., Ritchie, A.C., Kranenburg, C.J., Brown, J.A., Buscombe, D., Noble, T., Sherwood, C.R., Warrick, J.A., and Wernette, P.A., 2021, Processing coastal imagery with Agisoft Metashape Professional Edition, version 1.6—Structure from motion workflow documentation: U.S. Geological Survey Open-File Report 2021–1039, 46 p., https://doi.org/10.3133/ofr20211039. Schwid, M.F., Keith, M.K., and Overstreet, B.T., 2025, High-resolution orthoimagery and digital surface models of Fern Ridge Lake, Oregon, during annual low pool, January and February, 2023: U.S. Geological Survey data release, https://doi.org/10.5066/P1Q5K657. The original aerial photographs acquired by CAP, along with the point cloud, DSM, and orthomosaic covering Cottage Grove Lake were created to provide high-resolution datasets depicting the reservoir floor that is exposed during low pool (229 m/751 ft NGVD 29) conditions. These datasets are useful for evaluating geomorphic characteristics of the reservoir and assessing other landscape conditions; when compared with future datasets, these datasets will also be useful for tracking changes over time. 20241121 ground condition Complete None planned -123.07739 -123.04925 43.72014 43.67739 ISO 19115 Topic Categories biota elevation environment inlandWaters geoscientificInformation imageryBaseMapsEarthCover USGS Thesaurus structure from motion geospatial analysis aerial photography remote sensing geomorphology geospatial datasets digital elevation models image collections GPS measurement None fluvial geomorphology SfM photogrammetry orthoimagery orthophotograph orthomosaic GeoTIFF Cloud Optimized GeoTIFF dam reservoir drawdown river processes Civil Air Patrol Cessna Waldo USGS Metadata Identifier USGS:6813bf03d4be023163051824 Geographic Names Information System (GNIS) Coast Fork Willamette River Cottage Grove Lake Cottage Grove Lane County Shortridge Butte State of Oregon Willamette River None Willamette Valley none These data are in the public domain in accordance with Creative Commons Zero v1.0 Universal Public Domain Dedication (CC0-1.0) and have no use constraints. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data retrieved from the system. Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. The U.S. Geological Survey should be acknowledged as the data source in products derived from these data. Schwid, Maxwel F. U.S. Geological Survey Hydrologist Mailing and Physical

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Portland OR 97204 United States 503-758-5589 gs-w-or_sciencebase@usgs.gov These data were produced in cooperation with the U.S. Army Corps of Engineers. None Unclassified None Agisoft Metashape Professional Version 2.2.0; GDAL Version 3.6.2. An R12i Trimble global navigation satellite system (GNSS) receiver with Trimble’s real-time precise point positioning technology, Real Time eXtended (RTX), was used to collect the ground control points. Overall horizontal and vertical accuracy based on occupation of a Lane County Surveyors Office benchmark was within four centimeters. All data were acquired and handled in a consistent manner. A single crewed flight was contracted through the USACE to the Civil Air Patrol, Eugene, Oregon on December 18, 2023. A total of 400 aerial photographs were captured at an average flight altitude of about 1,300 meters above ground level, collectively covering about 15 square kilometers. Photographs were acquired as three-band (RGB) images in JPEG format using a WaldoAir XCAM Ultra 50 camera, consisting of two oblique-mounted Canon EOS 5DS R cameras that were triggered simultaneously, mounted to a Cessna 182 aircraft. A NovAtel OEMStar GPS recorded camera positions in the image file EXIF data in UTC time zone. All aerial photographs were contemporaneously aligned in Agisoft Metashape software. Agisoft software determined which aerial photographs were used in SfM product (point cloud, DSM, and orthomosaic) generation based on photograph alignment and the validity of identified tie points, which represent common pixels in photographs as determined by the software. To provide check points for model accuracies, a portion of the ground control points were excluded from SfM product generation and used for model validation. Specifically, 9 checkpoints out of the 23 survey points were excluded. The tie points were visually inspected and filtered to exclude obvious anomalous points from the derivative products (dense point cloud, DSM, and orthomosaic). The orthomosaic contains compression-derived artifacts occurring as erroneous pixel values that border the outer extent of the raster’s multiple overviews; these artifacts do not occur in, nor affect the underlying full-resolution image. The dataset is considered complete and consists of ground control points, a coverage footprint, raw aerial photographs, a dense point cloud, a DSM, and an orthomosaic. All 23 surveyed ground control points are listed in the CSV text file and all 400 aerial photographs are included in a zipped folder. All aerial photographs (excluding six that only captured cloud cover and could not be aligned) were used to create SfM products (point cloud, DSM, and orthomosaic). The dense point cloud was generated in the Agisoft Metashape software after a standardized filtering process that excludes low-certainty or anomalous points. The filtered dense point cloud was used to create the DSM and orthomosaic. The dense point cloud and DSM generated may contain false topography and high error propagated from the software’s identification of false tie points below the translucent, shallow water surface of the pool or in areas influenced by lake waves (Over and others, 2021). The DSM and orthomosaic were clipped during export from Agisoft software to exclude areas of high uncertainty or distortion, particularly in densely vegetated or forested areas or near edges where minimal photograph overlap inhibited photogrammetric processing. No formal horizontal accuracy tests were performed. Sources of potential error that affect the horizontal accuracy include ground control point accuracy and error incurred during alignment, optimization, and ground control processing procedures within the Agisoft Metashape software. Although the aerial photograph locations (recorded by a NovAtel OEMStar GPS located on the aircraft) are used by the photogrammetric software during initial alignment, these location data are not included in the generation of any derivative products and therefore the positional accuracy and potential errors do not contribute to the overall horizontal accuracy of the products (point cloud, DSM, and orthomosaic). Horizontal accuracy likely decreases with distance from ground control. Ground control points surveyed with an RTX-enabled GNSS receiver had a reported horizontal precision ranging from 0.01 to 0.03 meters. Though not an assessment of horizontal or vertical accuracy, horizontal positions of ground control points were used to calculate a root mean square (RMS) estimate of positional error at discrete locations by the photogrammetric software and are described here. Additionally, residuals between withheld ground control points (check points) and the model can serve as an indication of accuracy. Ground control and check point error is reported by the software with precision that is higher than provided by model inputs (RTX-GNSS precision) and thus has been rounded. For the model, 14 ground control points were used to construct SfM datasets, and the model had a horizontal error of 8 centimeters, vertical error of 6 centimeters, and overall error of 10 centimeters. The 9 ground control points withheld as check points were compared to the model and had a horizontal error of 28 centimeters, vertical error of 21 centimeters, and overall error of 35 centimeters. Visual comparison of the generated orthomosaic to publicly available aerial imagery indicated horizontal displacement was minimal for all datasets, although some obvious distortion (for example, holes, blurry areas, and discontinuity or irregularity of linear features) is noticeable where vegetation is present or there was very little photograph overlap. Increasing noise at surface water locations occurs within the model; these areas were not edited. No formal vertical accuracy tests were performed. However, vertical accuracy likely decreases with distance from ground control. Ground control points surveyed with an RTX-enabled GNSS receiver had a reported vertical precision ranging from 0.02 to 0.8 meters. Though not an assessment of horizontal or vertical accuracy, horizontal positions of ground control points were used to calculate an RMS estimate of positional error at discrete locations by the photogrammetric software and are described here. Additionally, residuals between withheld ground control points and the model can serve as an indication of accuracy. Ground control and check point error is reported by the software with precision that is higher than provided by model inputs (RTX-GNSS precision) and thus has been rounded. For the model, 14 ground control points were used to construct SfM datasets, and the model had a horizontal error of 8 centimeters, vertical error of 6 centimeters, and overall error of 10 centimeters. The 9 ground control points withheld as check points were compared to the model and had a horizontal error of 28 centimeters, vertical error of 21 centimeters, and overall error of 35 centimeters. Digital surface models, particularly in edge areas where photograph overlap was limited, may contain false topography as a result of the photogrammetric reconstruction process and/or model interpolation within sparse dense point cloud areas. American Society for Photogrammetry and Remote Sensing 20080902 publication online American Society for Photogrammetry and Remote Sensing https://www.asprs.org/wp-content/uploads/2010/12/asprs_las_format_v12.pdf Digital and/or Hardcopy 20080902 publication date ASPRS (2008) Laser file format specifications for point clouds. Jin-Si R. Over Andrew C. Ritchie Christine J. Kranenburg Jenna A. Brown Daniel D. Buscombe Tom Noble Christopher R. Sherwood Jonathan A. Warrick Phillipe A. Wernette 2021 publication online U.S. Geological Survey https://doi.org/10.3133/ofr20211039 Digital and/or Hardcopy 20210614 publication date Over and others (2021) Software settings and processing procedures. Maxwel F. Schwid Mackenzie Keith Brandon T. Overstreet 2025 dataset https://www.sciencebase.gov U.S. Geological Survey https://doi.org/10.5066/p1q5k657 Digital and/or Hardcopy 20250311 publication date Schwid and others (2025) Software settings and processing procedures. Agisoft 2025 publication online Agisoft https://www.agisoft.com/pdf/metashape_2_2_en.pdf Digital and/or Hardcopy 20250211 publication date Agisoft (2025) Software settings and processing procedures. Geospatial Data Abstraction Library (GDAL) 2024 3.6.2 application/service online Geospatial Data Abstraction Library (GDAL) https://gdal.org/drivers/raster/cog.html#raster-cog https://gdal.org/api/python_bindings.html Digital and/or Hardcopy 20240218 publication date GDAL (2024) Raster conversion program for Cloud Optimized GeoTIFF creation. Aerial photographs were acquired by the Civil Air Patrol on December 18, 2023, between 12:31 to 13:44 Pacific Standard Time (PST) covering approximately 15 square kilometers of the reservoir area. Photographs were acquired as high-resolution JPG images using a WaldoAir XCAM Ultra 50 camera, consisting of two oblique-mounted Canon EOS 5DS R cameras that are triggered simultaneously, mounted to a Cessna 182 aircraft. A NovAtel OEMStar GPS recorded camera positions in the image file EXIF data in UTC time zone. The pilot flew in sub-longitudinal passes at about 1,300 meters above ground level over Cottage Grove Lake. A total of 400 photos were taken from takeoff to landing of flight. 20231218 The USGS surveyed 23 control point features throughout Cottage Grove Lake on November 21, 2024, using an RTX-enabled GNSS receiver. The control points consisted of static infrastructure features (for example, parking lot pavement arrows, retaining-wall corners, stumps) that were visible in the photographs. 20241121 NAD 1983 UTM Zone 10N 0.9996 -123.0 0.0 500000.0 0.0 coordinate pair 0.000000002220024164500956 0.000000002220024164500956 meter D North American 1983 GRS 1980 6378137.0 298.257222101 North American Vertical Datum of 1988 (NAVD88) 0.001 meters Explicit elevation coordinate included with horizontal coordinates CottageGroveLake_20241121_groundcontrolpoints.csv A control point file (.csv) with # Name (name of the control point), ym (y coordinate in meters), xm (x coordinate in meters), zm (z coordinate in meters), HorzPrec and VertPrec (horizontal and vertical precision, respectively, in meters), PDOP, HDOP, and VDOP (position, horizontal, and vertical accuracy, respectively, in meters), and Pt Type (indicator of use as control point or check point). USGS # Name Name of the control point USGS Label to identify points. ym y coordinate of point USGS 4836045.216 4840791.851 Meters xm x coordinate of point USGS 493766.484 496029.802 Meters zm z coordinate of point USGS 224.48 247.625 Meters HorzPrec Horizontal precision from network-based RTK-GNSS USGS 0.01388 0.0315 Meters VertPrec Vertical precision from network-based RTK-GNSS USGS 0.02752 0.07808 Meters PDOP Position Dilution of Precision. PDOP indicates the three-dimensional geometry of the satellites. When satellites are widely spaced relative to each other, the DOP value is lower, and position accuracy is greater. When satellites are close together in the sky, the DOP is higher and GPS positions may contain a greater level of error. PDOP is related to HDOP and VDOP as follows: PDOP² = HDOP² + VDOP². RTK-GPS output 0.86608 1.21391 Unitless HDOP Horizontal Dilution of Precision. HDOP indicates the accuracy of horizontal measurements. When satellites are widely spaced relative to each other, the DOP value is lower, and position accuracy is greater. When satellites are close together in the sky, the DOP is higher and GPS positions may contain a greater level of error. RTK-GPS ouptut 0.48719 0.69117 Unitless VDOP Vertical Dilution of Precision. VDOP indicates the accuracy of vertical measurements. When satellites are widely spaced relative to each other, the DOP value is lower, and position accuracy is greater. When satellites are close together in the sky, the DOP is higher and GPS positions may contain a greater level of error. RTK-GPS output 0.69494 1.06979 Unitless Pt Type Indicates control point or check point. USGS Control Control point Producer defined Check Check point Producer defined U.S. Geological Survey - ScienceBase Mailing and Physical

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Denver CO 80225 United States 1-888-275-8747 sciencebase@usgs.gov Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of these data, software, or related materials. The use of firm, trade, or brand names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey. The names mentioned in this document may be trademarks or registered trademarks of their respective trademark owners. ASCII 0.00188 https://doi.org/10.5066/P13VDSRG None. This dataset is provided by USGS as a public service. 20250826 Schwid, Maxwel. F U.S. Geological Survey Hydrologist Mailing and Physical

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Portland Oregon 97204 United States 503-758-5589 gs-w-or_sciencebase@usgs.gov FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998 local time