PFAS contamination works its way to the St. Croix River

On Monday, November 8, the Minnesota Pollution Control Agency (MPCA) released a draft list of lakes, rivers and streams to be added to the state’s impaired waters list in 2022. Included are six water bodies in Washington County that have recently been found to have high levels of perfluorinated alkylated substances (PFAS), also known as the “forever chemical.” The affected waters include Tanners Lake (Oakdale), Eagle Point wetland and H.J. Brown Pond (Lake Elmo Park Reserve), Clear Lake (City of Forest Lake) and the St. Croix River/Lake St. Croix from Taylors Falls to Prescott.

Image from Minnesota Pollution Control Agency.

The journey of PFAS into our local waterways began in the 1950s and 60s when 3M began making Scotchguard, nonstick coatings, and fire-fighting foams. The company disposed of manufacturing waste in landfills on Hwy 14 in Oakdale and near Lake Jane in Lake Elmo, as well as at two smaller sites in Woodbury and Cottage Grove.

Over time, the chemicals leached deep into the ground and contaminated aquifers used as a source of drinking water for municipal and private wells in the area. The MPCA first discovered the groundwater contamination in 2002 and has been continuously working with 3M, local communities, and the Minnesota Department of Health (MDH) ever since to ensure that east metro residents have safe drinking water.

Above: click to access an interactive map of the PFAS well-water testing area.

The groundwater contamination plume has been gradually spreading eastward for decades, but recently, the MPCA determined that PFAS has been accumulating in some lakes and streams in the east metro as well. Three years ago, the MN Department of Health issued a fish consumption advisory for Lake Elmo, after measuring high levels of perfluorooctane sulfonic acid (PFOS), a specific type of PFAS, in fish from that lake. At the time, MDH noted that fish in Raleigh Creek, Eagle Point Lake, Horseshoe Lake, Tartan Pond, Rest Area Pond, and West Lakeland Ponds likely had PFOS levels as high, or higher, than what was found in Lake Elmo.

Scientists are still not entirely sure what the long term health effects of PFAS and PFOS may be. In some studies, higher levels of PFAS in a person’s body were associated with higher cholesterol, changes to liver function, reduced immune response, thyroid disease, and increased kidney and testicular cancer. The latest information also indicates that fetuses and infants are more vulnerable to the chemicals.

Now, after years of slow-moving travel, the “forever chemicals” in contaminated groundwater have finally reached the St. Croix River. The proposed new listing for Lake St Croix is based on site-specific criteria of 0.37 parts per billion PFOS in fish tissue. Because fish are mobile and able to travel both up and down river, the impairment will apply to the entire length of the Lower St. Croix River, south of the Taylor’s Fall dam. Fish consumption advisories for the St. Croix River are already in place due to mercury and PCB, but the guidance will be updated to include information about PFOS as well. The river is still considered safe for swimming and recreation.

The new PFOS impairments affecting the St. Croix River and several lakes in Minnesota will include a fish consumption advisory with info on how often it is safe to eat fish caught in these waters.

If the MPCA’s proposed changes are approved, there will be a total of 26 water bodies in Minnesota listed as impaired due to PFOS. Outside of the east metro, the chemical has also impacted Winona Lake in Alexandria, Wild Rice Lake and Fish Lake Flowage in St. Louis County, the Mississippi River, and Bde Maka Ska Lake in Minneapolis.

Minnesota’s draft impaired waters list will be on public notice through Jan. 7, 2022. The MPCA invites Minnesotans to submit comments on whether additional waters should be placed on the list or be removed. Email or mail comments to: Miranda Nichols, impaired waters list coordinator, at or 520 Lafayette Road N, St. Paul, MN 55155-4194.

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