Minnesota Fish Consumption Advisories: Mercury, PFAS, and Safe Eating

March 19, 2026

Why Advisories Exist

Minnesota’s lakes and rivers produce some of the best-eating freshwater fish in the country. Walleye, crappie, bluegill, and perch are table staples for hundreds of thousands of families. But all freshwater fish contain some level of mercury, and some waters have additional contaminants like PFAS or PCBs.

Fish consumption advisories are not warnings to stop eating fish. They are science-based guidelines that tell you how much fish you can safely eat from specific waters. The goal is to maximize the health benefits of eating fish (lean protein, omega-3 fatty acids) while minimizing contaminant exposure.

Mercury in Minnesota Fish

How Mercury Gets Into Fish

Mercury enters Minnesota’s lakes primarily through atmospheric deposition — coal-burning power plants, industrial emissions, and natural geological sources release mercury into the air, which falls with rain and snow into watersheds. Once in the water, bacteria convert mercury to methylmercury, which enters the food chain at the bottom and concentrates as it moves up.

Bioaccumulation

Small organisms absorb methylmercury from the water. Small fish eat those organisms. Larger fish eat the smaller fish. At each step, mercury concentration increases. This is why large predatory fish — walleye over 20 inches, big northern pike, muskellunge, largemouth bass — have higher mercury levels than panfish.

Mercury Levels by Species (General Pattern)

Lower mercury (safer for more frequent consumption):

• Bluegill and sunfish (all sizes)
• Crappie (all sizes)
• Yellow perch
• Bullhead
• Small walleye (under 16 inches)

Moderate mercury:

• Walleye (16-20 inches)
• Northern pike (under 24 inches)
• Smallmouth bass
• Channel catfish

Higher mercury (eat less frequently):

• Walleye over 20 inches
• Northern pike over 24 inches
• Largemouth bass over 16 inches
• Muskellunge (any size)
• Lake trout (larger fish)

These are general patterns. Actual mercury levels vary by lake — a walleye from a low-mercury lake may be safer than a crappie from a high-mercury lake.

PFAS Contamination

What Are PFAS?

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals used in firefighting foam, nonstick coatings, waterproof fabrics, and many industrial processes. They are called “forever chemicals” because they do not break down in the environment.

PFAS in Minnesota

Minnesota has several identified PFAS contamination areas:

• East metro (Washington County, Woodbury, Cottage Grove, Lake Elmo) — Historic 3M manufacturing and disposal sites contaminated groundwater and surface water. Several lakes and the Mississippi River downstream of these sites have PFAS advisories.
• Military installations — Areas around airports and military bases where PFAS-containing firefighting foam (AFFF) was used.
• Industrial sites — Various locations statewide where PFAS-using industries operated.

PFAS Advisories

The Minnesota Department of Health has issued PFAS-specific consumption advisories for affected waters. These are separate from (and in addition to) mercury advisories. A lake may have a mercury advisory, a PFAS advisory, both, or neither.

PFAS advisories are evolving as testing expands and the science improves. Lakes that had no PFAS advisory last year may receive one this year as more water bodies are tested.

How to Read an Advisory

The Minnesota Department of Health publishes advisories using a meal-frequency system:

For the General Population (men over 15, women over 50)

• Unrestricted — Eat as often as you like (within reason).
• 1 meal per week — Safe to eat weekly.
• 1 meal per month — Limit to one serving per month.
• Do not eat — Contaminant levels are too high for safe consumption.

For Sensitive Populations (women of childbearing age, children under 15)

The same scale applies, but the thresholds are lower. A fish that is “1 meal per week” for the general population may be “1 meal per month” for a pregnant woman.

Meal Size

One “meal” in the advisory system is approximately:

• 8 ounces (uncooked) for an adult
• 4 ounces for a child
• About the size of a deck of cards (cooked) for a child, or two decks for an adult

Looking Up Your Lake

The Minnesota Department of Health maintains a searchable database of fish consumption advisories by lake name:

1. Visit the MDH website and search for “fish consumption advisories.”
2. Search by lake name, county, or region.
3. The advisory will list specific species, size ranges, and recommended meal frequency for both general and sensitive populations.

If your lake is not listed, the statewide general advisory applies:

• Panfish (bluegill, crappie, sunfish, perch): Generally safe at 1 meal per week for all populations.
• Walleye under 20 inches: 1 meal per week for general population; 1 meal per month for sensitive populations.
• Walleye over 20 inches: 1 meal per month for general population; do not eat for sensitive populations.
• Northern pike, bass, muskellunge: Follow the size-based guidance above.

Reducing Your Exposure

Choose Smaller Fish

Keeping walleye in the 14-18 inch range rather than the 20-25 inch range significantly reduces mercury exposure while still providing excellent eating. Smaller fish have had less time to accumulate mercury.

Eat More Panfish

Crappie and bluegill have some of the lowest mercury levels of any Minnesota game fish. They are also delicious. Shifting your harvest toward panfish and away from large predators is the single easiest way to reduce contaminant exposure.

Preparation Matters (for Some Contaminants)

• Mercury is distributed throughout the fish flesh and cannot be removed by cooking or preparation.
• PCBs and some other organic contaminants concentrate in fat. Removing the skin, belly fat, and dark lateral line tissue before cooking can reduce PCB exposure.
• PFAS are water-soluble and concentrate in organs and blood. Removing organs helps, but PFAS in the flesh cannot be eliminated by cooking.

Vary Your Sources

If you fish multiple lakes, vary where your meals come from. Eating fish from several different lakes reduces the chance of concentrated exposure from any single contaminated water body.

The Bottom Line

Fish is healthy food. The omega-3 fatty acids, lean protein, and other nutrients in fish are genuinely beneficial. The Minnesota Department of Health explicitly recommends eating fish — they just want you to eat it smart.

Follow the advisories for your specific lakes. Choose smaller fish when keeping fish for the table. Pay attention to PFAS advisories if you fish in the east metro or near known contamination sites. And for women who are pregnant or may become pregnant and for young children, follow the sensitive-population guidelines carefully.

The advisory database is free, searchable, and updated regularly. Use it.