Fish sampling data, stream temperature data, and observations of the locations of groundwater springs within the upper Snake River basin, Wyoming. These datasets were created to assess how stream temperature and groundwater spring sources are associated with the growth and production of young-of-year Yellowstone cutthroat trout (Oncorhynchus virginalis bouvieri; formerly Oncorhynchus clarkii bouvieri). Surveys were collected in tributaries and rivers within the upper Snake River Basin, Wyoming. The fisheries data represents seasonal sampling of young-of-year Yellowstone cutthroat trout (2021 - 2023) using dipnetting and standard backpack electrofishing methods. The stream temperature data were purposively collected in streams where we collected fish data. The groundwater spring data were opportunistically collected across the study area. Data were collected by the U.S. Geological Survey and the University of Wyoming and/or affiliated field crews with support from the U.S. Geological Survey, the University of Wyoming, and the Wyoming Game and Fish Department.