Airborne Thermal Infrared and True-color Imagery and Longitudinal Profiles of Stream Temperatures, Tualatin River Basin, Oregon, July 1999

This dataset includes high-resolution thermal infrared (TIR) and true-color images collected from crewed aircraft and a point shapefile and corresponding comma-delimited tabular data representing the longitudinal spatial patterns of water surface temperature in the surveyed streams in Tualatin River basin, Oregon. The Oregon Department of Environmental Quality (ODEQ) contracted Watershed Sciences, LLC to conduct the aerial surveys and analysis. Surveys covering approximately 395 river kilometers (km) across the Tualatin River and 13 tributaries were conducted from July 27–30, 1999, timed to capture daily maximum water temperatures (generally 14:00–18:00, local time). Individual ungeoreferenced TIR image frames are provided in tag image file format (TIFF) and true-color image frames are provided in joint photographic experts group (JPEG) format. Radiant temperatures were evaluated against kinetic temperatures from 33 in-stream data loggers positioned where water velocity was assumed sufficient for vertical mixing; 28 data loggers met the contract specification of ±0.5°C difference between FLIR-derived radiant image temperature and in-stream measurements. The longitudinal stream temperatures are provided in geospatial format (i.e., point shapefiles [.shp] modified in ESRI ArcGIS Pro 3.4) and in comma-separated value (CSV) tabular format. The shapefile point features spaced along the survey flight paths approximately every 15-75 m were linearly referenced with respect to their distance upstream in river km using ARC/INFO geographic information system (GIS) software based on “routed” 1:100,000-scale hydrography from the U.S. Environmental Protection Agency (EPA) River Reach File Version 3.0 hydrographic database of surface waters (https://archive.epa.gov/esd/archive-nerl-esd1/web/html/nvgeo_gis10_rf3_…). Stream temperature statistics in the shapefiles and tabular data were derived by manually selecting and sampling pure-water pixels in each TIR image (ARC/INFO GRID format) with a semi-automated Avenue script in ESRI ArcView GIS 3.1 along the main channel of each stream reach. The resulting longitudinal temperature information supports identification of spatial thermal patterns, tributary influences, and potential cold-water refugia for basin temperature management.