Loke foom by Jennifer Heitz
I've often wondered what lake foam is and how it develops. You may have noticed it on our lakes' shores in the summertime on a windy day. While it can look like it is from a bubble bath or soap contamination, surface water foam a common and natural occurrence. Surface water foam can form on any waterbody under the right conditions. It is caused when the surface tension of water is decreased and air is mixed into the water. Organic materials from natura decaying plants and animals can reduce the surface tension of the water and when the wind blows across the water, the waves hit the shore, bubbles are produced. On lakes, foam tends to accumulate on windswept shorelines. Foam can vary in quantity and in color, from brilliant white to tan to brownish. It begins white, but can pick up color as it accumulates matter and debris.
Foam can not only develop naturally, but also from pollution such as where there is PFAS contamination. Some communities where there is PFAS (per- and poly-fluoroalkyl substances) contamination have found concentrations of PFAS in their water and have also found it in the foam.
According to the DNR, "regardless of whether foam is the result of natural causes, pollution or a combination of the tv it should not be ingested. All surface waters contain algae, viruses, bacteria, decaying matter and other contaminants that, if consumed, pose a health risk to humans and pets. Surface water foam, even when it is naturally occurring, can concentrate pathogens and synthetic compounds. Refrain from contact with surface foam to avoid accidental exposu or ingestion."
*Foam information is from the Wisconsin DNR Foam Fact Sheet and UWSP College of Natural Resources Lake Tides Spring/Summer 2020 Newsletter.