Three Montana state agencies issued a joint advisory on April 23 directing residents to limit how much fish they eat from Fort Peck Reservoir and other contaminated waters across the state, citing elevated levels of PFAS — a class of synthetic chemicals linked to cancer, thyroid disease, and other serious health conditions.

PFAS, sometimes called "forever chemicals" because they don't break down in the environment or the human body, have been detected in fish tissue at levels that prompted the agencies to draw up species-specific consumption guidelines. The advisory affects some of the most popular fishing destinations in Montana, and the guidance varies depending on which fish species a person is eating and how often.

The contamination at Fort Peck is particularly notable given the reservoir's size and its role as a recreational and subsistence fishing destination for communities across northeastern Montana, including tribal communities for whom fish is a significant part of diet and culture. Whether the advisory adequately accounts for those populations — and who bears responsibility for the contamination — remained unaddressed in the agencies' announcement.

Residents who fish Fort Peck or other affected waters and want specific guidance on safe consumption limits are directed to contact the Montana Department of Environmental Quality, the Department of Fish, Wildlife and Parks, or the Department of Public Health and Human Services, the three agencies that issued the joint advisory.