This dataset provides a zipfile containing 20 shapefiles with geo-referenced longitudinal water temperature profiles (LTPs; .shp). Profiles were obtained from longitudinal “Lagrangian” drag-probe temperature surveys ("float surveys") of the Quillayute River. Near-streambed and near-surface water temperature and conductivity were measured at three-second intervals and the spatial locations of each measurement was recorded using a GPS from a kayak drifting downstream at ambient stream velocity following the method of Vaccaro and Maloy (2006). The study area consisted of the Quillayute River from its upstream-most point at the confluence of the Sol Duc and Bogachiel Rivers to its outlet at the Pacific Ocean (8 river kilometers). The float surveys were conducted August (Aug.) 10 and 11, 2021, and Aug. 2 and 3, 2022, during different tidal conditions. Three longitudinal profiles were measured near-simultaneously on each survey date, along the left bank, right bank, and thalweg. Each shapefile was named according to the depth of the measurements at near-surface (SRF) or near-streambed (BED), and whether it was along the left bank (L), right bank (R), or thalweg (C). Only twenty profiles are included because data from four surveys was unusable due to sensor malfunction. The missing profiles were from the following dates and sensor locations: Aug. 10, 2021, near-surface left bank; Aug. 10, 2021, near-streambed left bank; Aug. 11, 2021, near-surface right bank; and Aug. 3, 2022, near-streambed left bank. Two of the sensors used in the float surveys had temperature values adjusted by -0.2 degrees Celsius to correct for calibration drift, based on pre-survey verification readings. This correction was applied to the near-streambed thalweg surveys on Aug. 10 and 11, 2021, the near-surface right bank survey on Aug. 10, 2021, the near-streambed left bank survey on Aug. 11, 2021, and the near-surface thalweg and near-streambed right bank surveys on Aug. 2 and 3, 2022. Float surveys targeted a start time in the late morning and an end time in the late afternoon during the diurnal increase in water temperature such that deviations from the diurnal increase may be attributed to groundwater discharge, tributaries, or other sources of water that differ in temperature from the river. The data is projected in UTM10N and the horizontal datum is NAD83(2011). Reference Cited: Vaccaro, J.J., Keys, M.E., Julich, R.J., and Welch, W.B., 2008, Thermal profiles for selected river reaches in the Yakima River Basin, Washington: U.S. Geological Survey Data Series 342. [Also available online at https://pubs.usgs.gov/ds/342].