Lake Superior contaminants face year of scrutiny

In February, the Minnesota Pollution Control Agency will release a blueprint on how it plans to begin to deal with "forever chemicals."

The Lester River empties into Lake Superior earlier this month. The Lester River and other streams can carry contaminants like PFAS from runoff to the lake. (Steve Kuchera /
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In Lake Superior, the sediment at the bottom of its watery depths tells a story.

It’s where things settle and accumulate, including contaminants. In its way, the sediment serves as a historical record of the lake.

In core samples, research scientists can see when concentrations of, say, mercury were highest, and how now-much-lower concentrations at the top layers of the sample means the contaminant is no longer being so heavily put into the lake.

But time and human ingenuity accumulate, too, and legacy contaminants are not the only toxins worthy of concern. There are new contaminants that appear to be stressing the lake.

“We are approving using chemicals in the United States, and we really don’t react to it until we start to see the problem,” said Bridget Ulrich, an aqueous geochemist with the University of Minnesota Duluth’s Natural Resources Research Institute. “With PFAS, it’s the same story.”


Bridget Ulrich

PFAS, or per- and polyfluoroalkyl substances, are known as “forever chemicals” found in coatings that keep your burger’s cheese from sticking to a wrapper. It’s in firefighting foam . Scores of industries use PFAS in scores of ways, sometimes as an additive, sometimes a coating. Sometimes in aerospace.

When built up in the human body, the substances are increasingly known to have a variety of adverse health effects, including high cholesterol, low birth weights and cancer, says the U.S. Environmental Protection Agency’s PFAS profile .

This promises to be a year the collective understanding of PFAS increases in the communities of people locally who strive to understand the lake, and contaminants working to degrade it.

In February, the Minnesota Pollution Control Agency will release a blueprint for PFAS outlining gaps in knowledge and policy, while also laying out how to fill those gaps.

It’s the first expected guidance from the agency since Minnesota learned of PFAS contamination early this century, when substances made by 3M Co., "polluted more than 150 square miles of groundwater across southern Washington County, affecting the drinking water of 14 communities and more than 170,000 Minnesotans,” according to the Minneapolis Star Tribune.

The big-picture result was an $850 million settlement from 3M, along with untold personal outcomes.


The MPCA would not get into many details about its PFAS blueprint, municipal manager Jim Ziegler said, but he described it as the culmination of a journey, borrowing on the state's nearly 20 years of experience dealing with the substances.

“When Minnesota first encountered PFAS as a contaminant around the Twin Cities, it wasn’t on the EPA’s radar,” Ziegler said. “No other state had heard of it either.”

The blueprint will address the interconnection between landfills and wastewater treatment facilities, Ziegler said.

In the state, only a few of the entirety of MPCA-permitted wastewater treatment plants sample for PFAS, and there are no facilities with state-enforced limits or treatments in place.

Locally, the Western Lake Superior Sanitary District in Duluth doesn’t test or screen for PFAS. And that’s unlikely to change when WLSSD undergoes its five-year permit renewal with the MPCA later this year.

PREVIOUSLY: State pollution control deems Duluth drinking water safe
The News Tribune asked Executive Director Marianne Bohren if she expected new contaminants to enter the equation.

Marianne Bohren1.jpg
Marianne Bohren


"We don’t anticipate that," she said. "But that will be dependent on if the MPCA has new regulations."

The WLSSD plant treats 13.9 billion gallons of effluent annually at the plant located on the St. Louis River estuary leading into Lake Superior. It uses a physical, chemical and biological treatment to remove 95% of regulated contaminants, but the process doesn't remove PFAS.

“I would imagine that there will be more attention placed looking at what the sources are,” Bohren said. “And our hope would be if there are actions taken that they’re really focused on dealing with products.”

File: Western Lake Superior Sanitary District
The Western Lake Superior Sanitary District provides waste services for a 530-square-mile area that includes Duluth, Cloquet, Proctor, Hermantown and surrounding communities. (Bob King / 2010 file / News Tribune)

PFAS substances are versatile with endless uses. Containing it would take a monumental campaign.

Sophie Greene is the PFAS coordinator for the MPCA. She described PFAS as hard to compare to other substances.

“It’s not one contaminant,” she said. “It’s a huge family of contaminants.”

Not designed to stick to anything, the substances move fast through standing water and can travel long distances.

Many of the suggested processes to treat PFAS — burning it, hazardous waste landfilling, advanced filtration that would “soak it like a sponge,” according to Greene — are new and costly.

“These PFAS have engineering complexities that make them difficult to manage when it comes to treatment,” Greene said. “They don’t break down under normal processes. You need special technologies in order to remove them.”

The St. Louis County Board began prodding WLSSD about its attention to PFAS in a letter last year, when it said 5 million gallons of PFAS-containing landfill leachate discharged annually by the facility was going unchecked into Lake Superior. WLSSD and the state defended themselves by reporting tests of the city’s drinking water to not include any signs of PFAS .

But Commissioner Keith Nelson noted the sampling was more than 10 miles downstream from WLSSD.

"It h its surface water and it's getting diluted massively," he said. "It's no surprise there's no PFAS at the intake."

WLSSD doesn’t sample for PFAS in the leachate it takes in, or the effluent into the lake.

“What you’re doing is adding a really bad actor to a plant that’s not capable of treating it,” Commissioner Keith Nelson said. “I’m not trying to condemn them, but what I’m saying is, 'Be honest.' Let’s start looking for a solution.”

Keith Nelson.jpg
St. Louis County Commissioner Keith Nelson. (Steve Kuchera /

The Wisconsin Department of Natural Resources alerted the region to a real-world example of PFAS contamination earlier this month, when it advised people not to eat more than one meal of Lake Superior rainbow smelt per month due to high levels of PFAS.

The contaminant was detected in fish tissue following routine testing at two sites 30 miles apart off the South Shore of Lake Superior. It was so concerned about the PFAS in the fish, the DNR bypassed a one-meal-per-week advisory on what is normally a gradual scale.

“There’s concern about how PFAS is going to move through the food web,” said Brad Ray, Lake Superior Fisheries Unit supervisor for the Wisconsin DNR.

Ray expects the results to yield even more fish sampling.

Meanwhile, lake trout tissues have not tested high for PFAS, Ray said, but nobody’s drawing conclusions yet. With mercury in water, the contamination accumulated up the food chain, where predators showed the highest levels.

Bay added that this year the EPA’s Cooperative Science and Monitoring Initiative will monitor Lake Superior water quality, and PFAS will be a part of that.

“We do have concern,” he said. “It’s important enough to list on our consumption advisory.”

All of the activity surrounding PFAS this year could mean the prospect of PFAS regulation is bearing down.

And while treatment solutions would be costly now: “You make it up down the line,” the St. Louis County Commissioner, Nelson, said. “You’re not passing it off onto the next generation. Somebody will have to deal with this. What I’m saying is it’s not somebody else’s job. It’s our job to deal with it.”

A small spot of open water runs between ice on Coffee Creek. (Steve Kuchera /

The MPCA’s Ziegler acknowledged that “at times the public might get upset we haven’t moved fast enough.”

The blueprint for PFAS figures to at last set some direction for the agency as it heads into decision-making about if and how to address PFAS.

"New contaminants need to be dealt with in a broad way before getting to permits," Ziegler said. "There needs to be some agency-wide decisions made about new contaminants," including cooperation with the state department of health, he added.

The MPCA blueprint is in its last stages of internal review. It's conceivable what's in it may require WLSSD's new permit to include language about PFAS for the first time.

“It’s certainly within the realm of possibility the facility will be asked to sample,” Ziegler said.

Knowing the chemical data of what's coming into the plant, and what it's putting into the water would provide valuable information, he said.

""We know PFAS is an issue, but before we can say in a permit that a (plant) must do A, B, and C, we have to understand the implications first," Ziegler said, including an "understanding of cost benefit."

WLSSD submitted its five-year permit application this month.

“Right now what the future holds is really in the hands of the regulators,” Bohren said, adding later: “We’re part of the solution and we think of ourselves as part of the solution. And we continue to look at how to get better.”

For Ulrich, the aqueous geochemist, 2021 promises to be an important year in sediment and the stories it tells about PFAS.

Last fall, the Natural Resource Research Institute received $3 million in federal funds to collect and analyze Lake Superior sediment.

Bridget Ulrich works in a Natural Resources Research Institute lab in July. Ulrich is part of a team working with a $3 million grant to collect and analyze emerging chemical contaminants in Lake Superior. (Photo courtesy of NRRI)

“It makes sense to really sort of focus on them,” she said on the topic of PFAS. “They behave differently in the environment, and that’s all the more reason to understand how they move through the Great Lakes.”

A team of scientists expects to finish sample collections by October. Preliminary data could be available before the end of 2021.

Lake Superior is already known to have the lowest overall concentrations of PFAS, Ulrich said, due to it being less populated than the more eastern lakes. As a result, there are fewer discharge locations, where cities and municipalities are inputting into the lake.

Ulrich said that as older PFAS are grandfathered out, some newer, shorter-chain PFAS compounds are emerging to be even more confounding, capable of getting into a lake by traveling long distances through the air, inputting into a water source without wastewater discharge at all.

Some of the compounds the team of scientists is planning to look at in sediment have not been part of larger scale monitoring efforts. The creation of more data sets is important, because better information can inform regulation, Ulrich said.

A contaminated drinking source would be much more damaging and expensive to correct, she added, than treating or preventing it in the first place.

"It's very important to recognize these potential threats early to avoid that type of scenario," Ulrich said, before later illustrating a scientist's exasperation: "We identify one compound that is problematic, and then replace it with an alternative compound that we understand less. It’s sort of a cycle.”

This story was updated at 8:37 a.m., Jan. 28 to correct the spelling of MPCA PFAS coordinator Sophie Greene. It was originally posted at 7 a.m., Jan. 27.

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