A US Geological Survey Next Generation Water Observing Systems (NGWOS) Research and Development 'testbed' site was established near the Kankakee River in LaPorte County, IN for the purpose of quantifying the effects of groundwater and surface water interactions on the fate and transport of excess nutrients, specifically nitrate. A Fiber Optic Distributed Temperature Sensing (FO-DTS) survey was conducted within the stream reach adjacent to a well cluster to pinpoint areas of discrete groundwater discharge to the river. DTS data were used to identify locations where longer-term deployments of vertical temperature profilers (VTP) were conducted to indirectly estimate vertical groundwater discharge (m/d) at the shallow streambed interface through time using collected temperature time-series. Point measurements of streambed thermal properties were made using a Tempos thermal property analyzer where the DTS survey suggested discrete groundwater seepage was occurring. This was done in efforts to support the future modeling of groundwater discharge rates (1D, i.e., L/T) using collected vertical temperature profiles from installed VTP's. VTP data from Kankakee are still actively being collected so these data are not included in this data release, however; thermal properties of the sediments are included. Seepage meter measurements were made at select locations on the streambed to better understand flux occurring at the streambed interface using direct measurements of discharge. When these meters were emplaced piezometers were installed next to them for determining vertical hydraulic gradients. This information was used to determine estimates of vertical hydraulic conductivity when combined with measured groundwater discharge rates from the seepage meters. Piezometers were pumped and instantaneous water quality information was collected using water quality sondes (YSI EXO2) in the field. Continuous water level information was also collected (In-Situ LevelTroll and AquaTroll) in some of the piezometers to monitor diurnal changes that might occur during the deployment period. This data release includes 5 compressed folders: 1) FO_DTS_PROCESSED_KANKAKEE.zip includes all processed FO-DTS data including a local readme.txt file that explains the contents in detail. 2) FO_DTS_RAW_KANKAKEE.zip includes all raw FO-DTS data including a local readme.txt file that explains the contents in detail. 3) SEEPAGE_AND_GRADIENTS_KANKAKEE.zip includes all the information related to piezometers and seepage meters including a local readme.txt file that explains the contents in detail. This folder also contains data on the thermal properties of the streambed sediments. 4) KANKAKEE_DTSCABLELINE.zip includes an ESRI ArcGIS shapefile and associated files that show the FODTS line layout as interpolated between GPS points collected along the line for georeferencing 5) KANKAKEE_MEASUREMENT_LOCATIONS includes an ESRI ArcGIS shapefile and associated files that show locations where measurements contained in this data release were made. References for methods and data contained in this data release: Barclay, J. R., Briggs, M. A., Moore, E. M., Starn, J. J., Hanson, A. E. H., & Helton, A. M. (2022). Where groundwater seeps: Evaluating modeled groundwater discharge patterns with thermal infrared surveys at the river-network scale. Advances in Water Resources, 160. https://doi.org/10.1016/j.advwatres.2021.104108 Briggs, M. A., Jackson, K. E., Liu, F., Moore, E. M., Bisson, A., & Helton, A. M. (2022). Exploring Local Riverbank Sediment Controls on the Occurrence of Preferential Groundwater Discharge Points. Water, 14(1). https://doi.org/10.3390/w14010011 Tyler, S.W., Selker, J.S., Hausner, M.B., Hatch C.E., Torgersen, T., Thodal C.E., Schladow, G.S. (2008). Environmental temperature sensing using Raman spectra DTS fiber-optic methods. Water Resources Research, Vol. 45. doi:10.1029/2008WR007052, 2009 Rosenberry & Hayashi (2013). Assessing and Measuring Wetland Hydrology, Chpt. 3. Cunningham, W.L., and Schalk, C.W., comps., 2011, Groundwater Technical Procedures of the U.S. Geological Survey: U.S. Geological Survey Techniques and Methods, book 1, chap. A1, 151 p.https://doi.org/10.3133/tm1A1