Foam

There are two types of foam:

  • Foam on lakes, streams, and creeks
  • Firefighting foam

Foam on lakes, streams, and creeks

Most foam observed in lakes or streams is naturally occurring, and not an indicator of pollution. Foam is created when air mixes with natural organic compounds, such as decomposing plant material. The mixing or agitation in lakes is commonly caused by wind and wave action; in streams, it may result from water flowing through rapids or over a dam. Natural foam tends to be off-white, tan, or brown and have a fishy odor. Foam caused by detergents will often be white and may have a perfume smell.

PFAS-containing foam

PFAS can also sometimes cause foaming on surface waters. In Minnesota, foam containing PFAS has been found in surface water pathways in the east metropolitan area of the Twin Cities which is a known area of PFAS contamination in groundwater and surface waters that was traced back to four landfills or dump sites.

As part of the 2018 3M Settlement, the MPCA is looking at how a flood-control project from the late 1980s, known as Project 1007, may be contributing to the movement of PFAS in the east metro area.

During a surface water investigation in the Project 1007 area, foam was observed on Raleigh Creek in Oakdale. Because this area is located near two of the disposal sites, the foam samples taken from Raleigh Creek had elevated levels of PFAS. Surface water samples collected in the same areas showed much lower levels of PFAS.

The map on the right depicts the foam sampling locations on Raleigh Creek.

Additional monitoring and sampling is taking place and will continue to learn more about PFAS impacts in surface water, soil, and groundwater.

Other locations

PFAS-containing foam was also encountered on Battle Creek in St. Paul. Battle Creek is being investigated further through MPCA’s superfund site assessment program and is not part of Project 1007.

The map on the right depicts where the initial foam sample was taken on Battle Creek in St. Paul.

For more information, visit the Minnesota Pollution Control Agency website.

If in doubt, stay out.

PFAS-containing foam on surface water does not pose a risk to human health if skin contact with foam is minor and infrequent. The Minnesota Department of Health (MDH) recommends:

  • People and pets should avoid contact with foam on surface waters in this area.
  • Wash skin that has come into contact with PFAS-containing foam with soap and water.

Firefighting foam

Class B firefighting foam – also known as aqueous film-forming foam (AFFF) – is designed to extinguish fuel or flammable liquid fires. Some AFFF formulations contain PFAS.

MDH and MPCA have evaluated places where PFAS may have been released to the environment, including fire training facilities where special PFAS foams were reportedly used, chrome plating plants, wastewater treatment plants, and landfills. Although PFAS have been detected at many of these locations, most do not pose a risk to public health.

In 2019, the Legislature passed a law requiring that any class B firefighting foam containing PFAS that is used on a fire must be reported to the State Fire Reporting System within 24 hours. The law is set to take effect July 1, 2020. The law also outlines the use and containment of firefighting foam use during testing and training.