When the Minnesota Pollution Control Agency (MPCA) released its draft list of impaired lakes and rivers in November of 2021, many local anglers took notice. Included in the list are 26 water bodies that were found to have high levels of perfluorinated alkylated substances (PFAS), also known as the “forever chemical.” The St. Croix River and 17 metro-area lakes are on the list, leading many people to ask, “Is it safe to eat the fish?”
The short answer is, it depends.
Minnesota has one of the most extensive fish monitoring programs in the United States, and the Department of Health (MDH) maintains a long list of fish consumption advisories for rivers and lakes that have been impacted by toxic chemicals, including mercury, PCBs, and PFAS. It can take months or even years of regularly eating fish for a person to accumulate dangerous levels of toxins, so you shouldn’t worry if you went fishing a few times last summer and ate the fish that you caught. However, the consumption advisories are intended to provide guidance on how often you can safely eat fish from impaired lakes and rivers without getting sick.
Mercury from the atmosphere is, by far, the leading source of water pollution that leads to fish consumption advisories in Minnesota. The element is released into the atmosphere during industrial processes, including gold and iron mining and burning coal for electricity. Once in the air, mercury “falls out” onto our landscape and ends up in water and fish. There are 1608 lakes and rivers in Minnesota that are listed as impaired due to too much mercury, including some of the most pristine lakes in northern Minnesota and within the Boundary Waters.
It can be particularly dangerous for pregnant women and children to be exposed to mercury. Mercury puts newborns at risk for learning disabilities and may also affect a child’s behavior. In adults, the first symptoms of mercury poisoning include loss of coordination and a burning or tingling sensation in the fingers and toes. Because mercury bio-accumulates as it travels up the food chain, mercury levels are highest in large walleye, northern pike, and other predatory fish.
In contrast with mercury, scientists are less sure about the long-term health impacts of PFAS. In some studies, higher levels of PFAS in a person’s body were associated with higher cholesterol, changes to liver function, reduced immune response (ie. making vaccines less effective), thyroid disease, and increased kidney and testicular cancer. The latest information also indicates that fetuses and infants are more vulnerable to the chemicals.
Data collected by the Pollution Control Agency shows that PFAS concentrations in fish can be 8000 times higher than in the surrounding environment, so it can be dangerous to eat fish caught from impaired lakes, even if the PFAS concentrations in the water are relatively low. For this reason, the Department of Health has issued DO NOT EAT advisories for fish caught in Lake Elmo and five other smaller nearby lakes in central Washington County where PFAS contamination is most pervasive.
When developing the 2022 impaired waters list, the MPCA caught and sampled fish from 80 lakes around the state, focusing on the locations where people most often fish and the species that they catch. In each of these lakes, the researchers sampled 15 fish total – five each of species from predator, rough fish, and panfish groups – and analyzed the fish tissue to measure mercury, PCB, and PFOS levels.
Taking all of this into consideration, the Minnesota Department of Health offers the following consumption advisories for lakes and rivers in the Twin Cities east metro area:
- Battle Creek Lake, Woodbury (PFOS) – eat no more than one meal per week of Sunfish
- Big Carnelian, Stillwater Twp. (mercury) – eat no more than one meal per week of bullheads (1/month for pregnant women and children under 15)
- Big Marine, May Twp./Scandia (mercury) – eat no more than two meals per week of bullheads, and one meal per week of crappie and small walleye (1/month for pregnant women and children). All people should eat no more than one meal per month of walleye larger than 21 inches.
- Clear Lake, Forest Lake (mercury and PFOS) – eat no more than two meals per week of bullheads, one meal per week of sunfish, and one meal per month of northern pike and walleye.
- Colby, Woodbury (mercury) – eat no more than one meal per week of crappie
- Demontreville, Lake Elmo (PFOS) – eat no more than two meals per week of crappie and one meal per week of sunfish.
- Eagle Point, Elmo, Horseshoe, Rest Area Pond, Tartan Pond, West Lakeland Ponds (PFOS) – All species – DO NOT EAT
- Jane, Lake Elmo (mercury) – eat no more than one meal per week of bullhead, sunfish, and small pike (1/month for pregnant women and children) and one meal per month of large pike >21-inches (Pregnant women and children – do not eat large pike)
- Johanna, Arden Hills (mercury and PFOS) – eat no more than one meal per month of crappie, bass, pike, sunfish, and walleye
- Josephine, Roseville (mercury and PFOS) – eat no more than one meal per week of bullheads (1/mo for pregnant women and children) and two meals per week of sunfish
- Keller, Maplewood (mercury and PFOS) – eat no more one meal per month of bass, and two meals per week of sunfish (1/mo for pregnant women and children)
- Kroon Lake, Chisago Lake Twp. (mercury) – eat no more than two meals per week of bullheads.
- Martin, Anoka Co. (mercury) – eat no more than 2 meals per week of sunfish
- Mississippi River Pool 2 (PCBs, PFOS, and mercury) (note that fish near Lock and Dam No. 2 may have higher levels of PFOS than those in other areas of Pool 2) – eat no more than on meal per week of crappie and one meal per month of catfish, drum, sunfish, white bass. DO NOT EAT carp.
- Olson, Lake Elmo (mercury) – eat no more than two meals per week of bullheads (1/month for pregnant women and children)
- Phalen, St. Paul (mercury and PFOS) – eat no more than one meal per week of crappie, sunfish, and perch and one meal per month of walleye (Pregnant women and children should not eat walleye)
- Peltier, Centerville (PFOS) – eat no more than one meal per week of sunfish.
- Powers, Woodbury (mercury and PFOS) – eat no more than one meal per week of crappie, sunfish, and perch; and no more than one meal per month of pike
- Ravine, Cottage Grove (PFOS) – eat no more than one meal per week of crappie and two meals per week of sunfish
- St. Croix River (mercury and PCBs) – eat no more than one meal per month of white bass (above Stillwater) and buffalo and catfish (below Stillwater). There are no new consumption advisories related to PFOS.
- Tanners, Oakdale (mercury and PFOS) – eat no more than one meal per week of crappie and one meal per month of bass and sunfish (1/mo for pregnant women and children)
In addition, there are more stringent guidelines for pregnant women and children under 15 that apply to both fresh-caught (anywhere in the state) and store-bought fish: no more than one meal per week of bullhead, crappie, trout, lake herring (cisco), whitefish, sunfish, yellow perch, and canned light tuna; and no more than one meal per month of bass, catfish, northern pike, walleye, canned “white” tuna (albacore), Chilean seabass, grouper, marlin, and tuna steak.
To find current fish consumption advisories for other lakes and rivers in Minnesota, go to: www.health.state.mn.us/communities/environment/fish.
East Metro Water 