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.
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.
In late summer of 2019, one sample of PFAS-containing foam was encountered on Battle Creek in St. Paul. In January 2020, additional samples were collected along Battle Creek from Battle Creek Lake to Highway 61.
MPCA confirmed that the foam samples, collected in January 2020, had elevated levels of PFAS. Surface water samples collected in the same areas showed much lower levels of PFAS.
MPCA will continue to assess PFAS in Battle Creek though a formal site assessment process in the agency’s Superfund program. The next step in the site assessment process is to gather additional information to assist in finding the source or sources of the PFAS contamination, to better understand the extent of the PFAS contamination, and to evaluate potential cleanup options.
Public drinking water not impacted
Drinking water for homes in Maplewood and St. Paul near and along Battle Creek is provided by the St. Paul Regional Water System, which has not been impacted by PFAS.
As part of the 2018 3M Settlement, the MPCA is looking at how a flood-control project from the late 80s, known as Project 1007, may be contributing to the movement of PFAS in the east metro area. More information about Project 1007 can be found at the Minnesota 3M Settlement 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.
Surface water concentrations of PFAS are much lower, indicating water is safe for recreation.
- PFAS are poorly absorbed through skin and swallowing small amounts of water while swimming will not result in significant exposure.
- There is little evaporation of PFAS from water into the air, breathing them in while swimming or bathing is not a health concern.