Evaluating technologies and approaches to detect the infiltration of fines into coarser materials has implications for monitoring the condition of habitat restoration sites. This goal motivated testing the efficacy of Fiber Optic Distributed Temperature Sensing (FO-DTS) as a technique for detecting the infiltration of fine sediment into gravels. Experiments were conducted in a laboratory flume at the USGS Geomorphology and Sediment Transport Laboratory (GSTL) in Golden, Colorado. A 10 meter fiber optic cable was placed in the flume with one half of the cable buried approximately 6 centimeters in a substrate (gravel, sand, and mixtures of the two) along the length of the flume, while the other half was placed at the sediment/water interface. The gravel had a median grain size of approximately 10 millimeters and the sand 0.6 millimeters. In order to differentiate the halves of the cable we adopted the convention of referring to the cable at the sediment-water interface being located on the left side of the flume and the buried section on the right side. The terms left and right are taken from the viewpoint of an observer facing in the direction of flow in the flume. Water in the tail tank was heated for 12 hours and then the heater was shut off for 12 hours. Water from the tank was circulated through the flume during this cycle and a temperature profile was recorded with a Silixa XT-DTS along the entire length of the FO cable once every minute . This data set contains the results of 6 experiments conducted at GSTL during the spring of 2018. The first experiment is referred to as a "control" wherein both the left and right side of the cable were exposed with no substrate present. A gravel only and sand only substrate were used in experiments 2 and 3 respectively. Experiments 4 through 6 consisted of a mixture of gravel with progressively greater volumes of sand added for each successive experiment. These are referred to as mixture 1, mixture 2, and mixture 3 respectively.