Fiber-optic distributed temperature data collected along a reach of the Tuolumne River, CA, February 2026, adjacent to restored and agricultural floodplain areas

Fiber-Optic Distributed Temperature Sensing (FO-DTS) measurements were collected along the Tuolumne River within the Dos Rios Ranch area of River Partners restored floodplain properties, located downstream of Modesto, California. The deployment site was selected because the river at this location flows between a restored riparian floodplain on the left bank and an rip-rap bank stabilized, unrestored agricultural area on the right bank, providing an opportunity to compare groundwater seepage patterns across contrasting land-use conditions. Deployment was conducted during winter low-flow conditions, when groundwater temperatures exceeded ambient stream temperatures, maximizing the thermal contrast required for seepage detection. Two fiber-optic cables were installed along the riverbed interface, one along each bank. On Day 1 of the deployment, February 3, 2026, only the left bank cable was laid for a length of 580 meters; data collection began at 5:45 PM and continued until 10:00 AM on February 4. (Note: All times reported here are in local time during the acquisition period, Pacific Standard Time, but for the data files time is Coordinated Universal Time). On Day 2, February 4, 2026, data acquisition along the left bank cable was paused while the cable was extended by 260 meters to a total length of 840 meters. The right bank cable was also installed on Day 2, reaching a total length of 950 meters. Data collection then resumed, and measurements from both cables were recorded from approximately 1:00 PM on February 4, 2026, to 12:00 PM on February 5, 2026. The measurements were integrated at 0.5-meter spatial increments and 4-minute time intervals. Both cables were georeferenced at 10–20 meter intervals to enable spatial mapping of temperature observations to corresponding riverbed locations.