Midwest states send mixed messages on fish safety

Contamination testing and environmental recommendations vary

Maria Christensen, of Waterloo, fishes May 21 at Big Woods Lake in Cedar Falls. She said she worries about the health of eating contamination fish, but thinks the waters are safe. (Sabine Martin/Tiger Hi-Line and IowaWatch)
Maria Christensen, of Waterloo, fishes May 21 at Big Woods Lake in Cedar Falls. She said she worries about the health of eating contamination fish, but thinks the waters are safe. (Sabine Martin/Tiger Hi-Line and IowaWatch)

On a chilly April morning, Gunwoo Yoon, his wife and two sons joined about 100 anglers at Prairie Lakes in Cedar Falls. They were fishing for trout, and plenty were available since the Iowa Department of National Resources had just done its annual stocking of the lake.

“We moved last year to Cedar Falls, and it was the first time that we went fishing at the trout stocking event,” said Yoon, a University of Northern Iowa assistant professor of marketing. “It was a super family-oriented fishing event, so we were there. I would say that we go fishing about one time per month since then.”

The rainbow trout released into Prairie Lakes were fine to eat because they came from a hatchery. But trying to distinguish what fish to safely eat from one Midwest state to the next can be difficult, an IowaWatch/Cedar Falls Tiger Hi-Line investigation showed.

That’s because rules guiding what’s safe to eat vary in each state. And despite fish sampling by the states, knowing where best to go is hard to find out because fish from only a few waterways where people fish are tested each year, the investigation showed. Anglers at farm ponds are on their own when it comes to the health of the fish they catch because the state does not sample fish in private water bodies for contamination.

Iowa warns anglers to limit their consumption of wild caught fish in 22 lakes and river sections around the state because of contaminants like mercury and PCBs. Yet 78 percent of Iowans do not limit consumption, a 2018 Angler Survey the state conducted found.

Mercury and PCBs are industrial byproducts and tend to concentrate in the fatty tissues of many fish. States issue fish consumption advisories for contaminants like those, plus lead, chlordane, dioxin, perfluorochemicals and perfluorooctane.

The Iowa Department of Natural Resources lists advisories on its website. But interviews from sporting goods stores revealed that people are not always told to look at the guidelines online or to pick up a guideline pamphlet when they buy a fishing license.


“We do have little booklets, straight from the DNR that are free that have anything that you want to know about fishing,” said Coleman Waters, a customer service employee at the Cedar Falls SCHEELS. “but we don’t hand them out.”

Yoon got his fishing license from a sporting goods store. “But no one told me or informed me about these chemicals in the fish,” he said.

A 2018 Iowa DNR survey of 1,628 anglers by Responsive Management of Harrisonburg, Va., which was just released, showed that 80 percent of Iowa anglers consumed in an estimated 4.6 million meals at least some of the fish they harvested in Iowa the past year.

An overwhelming majority — 84 percent — said they consider Iowa’s fish to be safe for eating, the survey showed. Additionally, 28 percent said they think Iowa’s water quality is better than it was 10 years ago; 31 percent said they thought it was worse.

“I don’t know how that goes, for the chemicals and stuff,” said Maria Christensen, fishing in Waterloo during a recent spring day. She said she worries about the health of eating fish, but thinks the waters are safe.

“But if it was contaminated, I know they wouldn’t allow you to go there,” she said.


The standards for what makes a fish healthy for eating can change over time.

In 2018, the Minnesota Department of Health changed its risk assessment for perfluorooctane sulfonate chemicals, or PFOS. Based on updated science, the department announced it had lowered the level at which it advises people to refrain from eating fish from 800 ng/g (nanograms per gram) to 200 ng/g. The new standards meant anglers were advised not to eat any fish from Lake Elmo, just east of the Minneapolis-St. Paul metro area.

But learning what makes a fish healthy to eat also depends on who’s giving the information, and where.


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Iowa defines fish portion sizes as 6 ounces for an adult. But Nebraska advisories are based on “an 8-ounce meal because we believe that it is realistically more of what a person would sit down and consume for a meal,” said Greg Michl, Nebraska’s fish tissue program coordinator.

Midwest states also vary on how much testing they do.

Iowa tests 20 locations from its rivers and lakes, with a different group of locations each year.

South Dakota tested 14 water bodies in 2018.

Nebraska tests about 40 or 50 preselected streams and publicly owned lakes in two or three of Nebraska’s 13 major river basins.

Illinois tests 40-50 streams, rivers and inland lakes and four Lake Michigan open water stations each year.

Wisconsin collects fish from about 50 to 100 sites each year.

Minnesota tests fish samples from about 130 lakes and river segments each year.

The Iowa DNR recommends people eat no more than one meal per week of any predator fish caught in the Iowa River stretch between the upper end of Coralville Lake near Swisher and the Coralville Dam southeast of North Liberty because of potential mercury contamination.

Likewise, the Iowa DNR recommends no more than one meal per week on any channel catfish caught in McKinley Lake in Union County because of the PCB contamination.

Nebraska recommends limiting fish consumption to one 8-ounce serving per week because of mercury levels.

In Wisconsin, state officials recommend that women of childbearing age, or under 50, and children under 15 eat only one serving per week of bluegills, crappies and yellow perch; one serving per month of walleye, pike and bass; and no muskies. The state does not restrict the consumption of bluegills, crappies or yellow perch for women over 50 or men but recommends one serving per week of walleye, pike and bass; and one serving per month of muskies.

Minnesota says smaller fish like crappies, yellow perch, bullheads and sunfish do not need to be limited, but recommends that larger fish like walleyes, northern pike and lake trout be eaten only once a week.


Patricia McCann, a research scientist with the Minnesota Department of Health, said Minnesota writes its guidelines with a risk-based approach and communicates that to the public. “We want people to follow our guidelines, and if they follow our guidelines, then I’m not concerned about their exposure,” she said.

Barry Eastman, an angler from Cedar Falls, said he does not consume fish regularly. “Since we only eat fish only half a dozen times a year, I’m not too worried about it. If I was going out and catching fish in the river every day, that’s not good ’cause I know the water is polluted. It’s full of nitrates and bad stuff,” he said.

Although the Iowa’s DNR and those in other states publish guidelines, these are only recommendations.

“Fish consumption advisories are not legal requirements, and there is no penalty if an individual chooses not to follow these recommendations. The Iowa DNR does not set regulations or restrictions related to contaminants in fish flesh,” Ken Krier, who does fish tissue sampling for the agency, wrote in an email.

Fish consumption guidelines provided by Iowa, Wisconsin, Minnesota, Illinois, Nebraska, South Dakota and Missouri and reviewed by IowaWatch and the Tiger Hi-Line address the size and frequency of fish an average person should consume, taking account factors such as age and gender.

The most sensitive populations for fish contaminants are pregnant women and children.

Iowa’s fish consumption guidelines suggest that people who are pregnant, planning to become pregnant, nursing or under age 12 limit consumption of predator fish like walleye and bass to one meal per week.

Nevertheless, officials in the various Midwest states still want to promote fishing and the consumption of fish.

“An important factor to this whole situation is fish are very good for people to eat,” Michl said.


Fishing in Iowa is a big business and heavily promoted by the Iowa DNR, with lists of fishing locations and hot spots on its website. In 2018, Iowa earned more than $8 million in revenue on fishing licenses.


Fishing also is big business and recreational activity in the Midwestern states adjacent to Iowa: Missouri, South Dakota, Nebraska, Illinois, Wisconsin and Minnesota. Wisconsin has the largest fishing economy of these states, earning more than $39 million annually in fishing licenses.

Mercury is the most common fish contaminant across the country, largely due to pollution from coal-burning power plants that settles into water bodies. Mercury tends to concentrate in the fatty tissue of fish. But larger predator fish tend to have higher concentrations of mercury because they eat the smaller fish.

According to the World Health Organization, mercury may pose a threat to child’s development in utero and health early in life. Mercury can have toxic effects on nervous, digestive and immune systems and on skin, lungs, kidneys and eyes.

Cedar Falls fisherman Troy Slater said he is aware of the health effects of eating fish contaminated with chemicals. “I’ve talked to kids who have grown up in Cedar Falls who have fished the Cedar (River) but won’t eat anything out of it just because of all of the runoff. I think about it,” he said.

For anglers in the Midwest, trying to distinguish which fish are safest to eat is a dizzying task because of each state’s different guidelines. According to a 2018 report by Michl, the disparities between states lead to confusion.

“While nearly every state in the U.S. has a fish tissue monitoring program in place, differences exist in the way fish samples are analyzed and assessed between states,” the report stated. “These differences create a lack of comparability between states and can cause confusion for people who enjoy fishing in their home state, shared waters and other states’ waters.”

Even with annual fish tissue sampling, it is impossible in some Midwestern states to know the fish quality in every location. Minnesota has sampled about 1,200 lakes, or only 22 percent of the state’s 5,500 fishing lakes, since it started testing fish for contaminants since 1967. Similarly, Wisconsin, with 15,000 lakes and 32,000 miles of rivers has tested fish from only about 1,700 sites since the 1970s.

The Iowa DNR has collected samples of fish tissue annually since 1980. The goal is to regularly take fish samples from popular public fishing sites every 10 years and from key river segments every five years, the agency’s Krier wrote in his email to IowaWatch and the Tiger Hi-Line.


But about 130 lakes tabbed by the state as significant publicly-owned lakes and thousands of miles of fishable rivers exist and largely are missed in testing because of “the very large demands on funding and staff time,” Krier wrote. He said that of the 301 sites sampled since 1980, 126 sites have been sampled once, 50 have been sampled twice, 40 have been sampled three times, 26 have been sampled four times, 19 have been sampled five times and 40 sites have been sampled more than five times.

In addition, the Iowa DNR maintains some sites to find trends, charting their long-term health of fish stock in certain bodies of water. Since 2016, it has followed 15 sites, sampling the fish every other year.

Erin McRae and Taylor Hunt of the Cedar Falls Tiger Hi-Line did additional reporting and research for this story, a collaboration of the Iowa Center for Public Affairs Journalism-IowaWatch, Tiger Hi-Line and University of Northern Iowa Science in the Media project. Read more at

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