The Minnesota Pollution Control Agency is advising people to keep away from foam in an east Twin Cities metro-area creek, after samples of it have again tested positive for elevated levels of the chemicals known as PFAS.
The MPCA said minor and infrequent contact with the foam in Battle Creek does not pose a health risk, and drinking water for homes along the creek, which runs through St. Paul and Maplewood, is not affected.
Per- and polyfluoroalkyl substances, or PFAS, are a broad class of man-made chemicals known for their durability and used in a variety of consumer products. Their tendency not to break down made them useful for consumer products ranging from Teflon pans to Scotchgard fabric protectors.
The MPCA first announced in January that researchers had found foam containing PFAS in two streams in the east Twin Cities metro area — Raleigh Creek in Washington County and Battle Creek in Ramsey County.
On Monday, the MPCA announced that additional samples of foam it collected from Battle Creek also had elevated levels of PFAS. Surface water samples collected in the areas showed much lower levels, however.
PFAS chemicals tend to hang out at the top of the water. Foam is created by friction caused by wind, or when water rushes over rocks. The foam tends to have a higher concentration of chemicals than the stream itself.
While PFAS foam hasn’t been commonly found in Minnesota, the phenomenon is seen frequently in other states such as Michigan.
Maplewood-based 3M produced two PFAS compounds in the eastern Twin Cities for decades, beginning in the 1950s. Waste containing PFAS chemicals was legally disposed of in landfills in the eastern metro area, where the chemicals leached into the groundwater, and contaminated the drinking water supplies of several communities.
The state of Minnesota sued 3M over its role in the contamination. In 2018, 3M agreed to pay $850 million to provide clean drinking water to the affected communities and clean up natural resources.
MPCA officials believe the PFAS contamination in Raleigh Creek originated at nearby sites where 3M disposed of waste containing the chemicals in the past. They also think that a large flood control project built in the late 1980s likely played a role.
The PFAS foam in Battle Creek is more of a mystery, because that area is not part of the 3M investigation. It was first discovered by researchers collecting samples because of a Minnesota Department of Transportation project nearby.
The MPCA sent a letter last week to residents who live next to Battle Creek between McKnight Road and Battle Creek Lake, informing them of the findings. The agency advises people and pets to avoid contact with the foam, and to wash skin with soap and water if they come into contact with it.
The MPCA says it will continue to assess PFAS in Battle Creek and look for the source of the contamination.