Cold-water adapted Eastern Brook Trout were historically widely distributed across the Eastern US from Georgia up to northern Quebec. However, due to factors associated with climate change, such as increased stream temperature and changing water flow, the number of streams containing brook trout is declining. Yet in some warming streams brook trout populations have persisted. To determine to what extent brook trout were utilizing cold-water refugia (groundwater input), in the spring we implanted temperature recording tags at six known brook trout sites representing warm, intermediate, and cold stream temperatures. We recovered fish at these six sites in the fall and brought them back to the laboratory where thermal tolerance was evaluated via a thermal challenge and physiological metrics. Data collected from downloaded temperature tags revealed water temperatures fish experienced throughout the summer which we compared to in stream temperature loggers. We relate this information to their performance in thermal challenges and physiological endpoints.