The Massachusetts Department of Health (DPH) issues Fish Consumption Advisories based on industrial contaminants in fish tissue, such as PCBs, PFAS, and heavy metals like mercury. These pollutants harm humans and wildlife when ingested, making their way into human diets when people eat fish that have lived in contaminated rivers. The DPH has published advisories for maximum fish consumption for all three rivers based on mercury contamination. If a fish contains mercury, there is no way to remove it. Mercury cannot be cut, cleaned, or cooked out. Advisories specify which groups of people are most susceptible and should limit or avoid eating the fish and which fish species to avoid.
Data are not yet available for PFAS in river fish, although Lake Cochituate and Walden Pond fish were determined to have PFAS contamination, and DPH has issued Fish Consumption Advisories for those water bodies in the Sudbury watershed.