This data release contains fiber-optic distributed temperature sensor (FO-DTS) data for three reaches of Mill Creek collected during two deployments between August 20, 2020, and September 4, 2020. Spatially continuous profiles of water temperature were collected with a Sensornet® Oryx DTS FO-DTS. At each of the three reaches, water temperature was spatially averaged over 1.015-meter intervals and collected at one-hour intervals. Independent water-temperature data collected at four locations per reach by Hobo® Water Temp Pro v2 data-logging thermistors and thermocouples integrated with the FO-DTS are also included. Water-temperature data from both thermistors and thermocouples were used to dynamically calibrate FO-DTS data using the methods of Hausner and others (2011) and estimate error of the calibrated FO-DTS data over ~10-meter lengths of the fiber-optic cable deployed in the stream and cold-water temperature baths deployed at the upstream and downstream ends of the fiber-optic cable. Independent water-temperature data for calibration was collected by data-logging thermistors verified by a National Institute of Standards and Technology (NIST)-certified thermistor with an accuracy of ±0.1 °C. Hausner, M.B., Suárez, F., Glander, K.E., Giesen, N., Selker, J.S., and Tyler, S.W., 2011, Calibrating single-ended fiber optic raman spectra distributed temperature sensing data: Sensors, v. 11, p. 10,859–10,879. [Also available at http://dx.doi.org/10.3390/s111110859.]