Every St. Croix River fish that scientists tested for new toxins had high levels

Fish samples from the lower river contain high enough amounts to limit consumption.




2 minute read

White bass (Duane Raver/USFWS)

Last week, the Minnesota Pollution Control Agency announced it had found elevated amounts of industrial chemicals called PFAS in the flesh of fish from the St. Croix River. The substances are toxic, hurting child development, They originate from sources like 3M’s closed landfills in Oakdale.

Agency scientists have now shared more details about just how much PFAS they found. The average amount in the fish sampled from the river was 32 nanogram per gram, said Miranda Nichols of the Water Assessment Section.

Anything above 0.37 ng/g is considered impaired and possibly harmful.

Sampling efforts included taking fish from Taylors Falls all the way down to Prescott. Researchers collected 31 fish of five species: smallmouth bass, largemouth bass, bluegill, common carp, and freshwater drum, reported MPCA scientist Bruce Monson. The lowest level of PFAS detected was 1 ng/g — still above the threshold. The highest level was 295 ng/g in a smallmouth bass.

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PFAS are particular problems for pregnant and nursing women and children. The chemicals interfere in neurological development. Much remains unknown about their effects on human health and the environment. They are often called “forever chemicals” because they do not break down in the environment.

The designation of the lower St. Croix River as impaired for fish consumption is part of a process to regularly update the state’s list as required by the Clean Water Act. This year marked a significant addition to waters contaminated by PFAS. The substances were used for products like Scotchgard and many other industrial purposes.

While it may change in the future, general guidance is now to limit meals of St. Croix River fish to once per month. That’s the same recommendation for white bass, buffalo, and channel catfish because of mercury and PCBs.

Provide input

The MPCA is accepting written comments on the draft 2022 list of impaired waters through 4:30 p.m. on Friday, Jan. 7, 2022. After the comment period and any changes to the list based on public input, the state will submit the draft list, and the comments and responses, to the U.S. Environmental Protection Agency for final approval. Details on how to comment.

Public information meetings

Attend an online public information meeting via Webex.

  • Statewide assessments, including discussion of PFOS in fish tissue and sulfate in wild rice production waters
    Thursday, Dec. 9, 2 p.m.
    Join the meeting
    Meeting number (access code): 2486 889 4793
    Meeting password: RjVaYfgu847
  • Central Minnesota regional meeting, including Sauk, Mississippi River – St. Cloud, and Lower St. Croix river watersheds
    Monday, Dec. 20, 2 p.m.
    Join the meeting
    Meeting number (access code): 2489 358 6002
    Meeting password: PpetMP4ex39


6 responses to “Every St. Croix River fish that scientists tested for new toxins had high levels”

  1. Ray Valley Avatar
    Ray Valley

    Thanks for publishing Greg and please continue to track/update this story. I’d like to see more sampling and species by species guidelines (which I would expect). Would help to publish limits whereby the PCA/MDH/DNR advises against ALL consumption.

  2. Ray Valley Avatar
    Ray Valley

    So where does the 0.37 ng/g threshold come from?

  3. R E Reamer Avatar
    R E Reamer

    The only fish people eat out of the St.Croix is Walleye, and you didn’t test that specie’s, wake the Hell Up!

    1. Greg Seitz Avatar
      Greg Seitz

      That is simply not true. People eat white bass, drum, crappie, catfish, and more. And there’s a very very good chance that these levels in these species also match the levels in walleye. I wish they would sample walleye too, but for now, the problem is definitely real. Sweet dreams.

  4. Tominator Avatar

    Is 3M going to do anything about this? Are they going to pay for the cleanup or let the American taxpayer pay the bill? Or does another large Republican owned, pro-pollution, anti-EPA company get off scott free?

    1. Greg Seitz Avatar
      Greg Seitz

      They settled with the state in 2018 for contamination of groundwater. Big question if they could have additional legal liabilities now that new pollution has been detected, but also more difficult to prove the responsibility. It will be an issue to investigate.


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Every St. Croix River fish that scientists tested for new toxins had high levels