Supporting data for "A chemical prioritization process: Applications to contaminants of emerging concern in freshwater ecosystems (Phase 1)". These data describe contaminants of emerging concern (CECs) detected in subsistence fish species and freshwater ecosystems on the Grand Portage Indian Reservation and adjacent 1854 Ceded Territory in Northeastern Minnesota, USA. They also contain chemical-specific information, including acute toxicity, endocrine activity, physicochemical properties, and frequency of occurrence data used to prioritize detected CECs based on their potential environmental hazard. Citation information for this dataset can be found in the EDG's Metadata Reference Information section and Data.gov's References section.