Skip to main content

FOAM:  A naturally occurring phenomenon

A clump of white foam tinged brown on top of a river
Environment, Great Lakes, and Energy

FOAM:  A naturally occurring phenomenon

EGLE often receives complaints that “someone discharged laundry detergents into the lake” or that there are suds on the river or stream. This phenomenon is often the result of natural processes, not environmental pollution.  Foam can be formed when the physical characteristics of the water are altered by the presence of organic materials in the water.



naturally occurring white foam along lakeshore

The foam that appears along lakeshores is most often the result of the natural die-off of aquatic plants. Plants are made up of organic material, including oils (e.g., corn oil and vegetable oil). When the plants die and decompose, the oils contained in the plant cells are released and float to the surface. Once the oils reach the lake surface, wind and wave action pushes them to the shore. The concentration of the oil changes the physical nature of the water, making foam formation easier. The turbulence and wave action at the beach introduces air into the organically enriched water, which forms the bubbles.

brownish naturally occurring foam in rocky stream

Foam commonly occurs in waters with high organic content such as productive lakes, bog lakes, and in streams that originate from bog lakes, wetlands, or woody areas. Oftentimes, streams that originate from woody areas will have a brown tint in the water. The brown tint is often caused by the presence of tannin, which is a substance that gives wood its brown color. The tannin is released during the decomposition of wood along with other materials that cause foaming when they are introduced in water. It is quite common to find foam in dark-colored streams, especially during late fall and winter, when plant materials are decomposing in the water.

foam from pollution swirling and floating on o a stream

Some foam in water can indicate pollution. When deciding if the foam is natural or caused by pollution, consider the following:

View/download a pdf of this brochure.

For more information, including tips to help reduce the amount of nutrients that can enter a lake from your home activities, contact any EGLE district office or call the State of Michigan’s Environmental Assistance Center at or 800-662-9278.

If you find pollution and believe it is human-induced, please report it to the State of Michigan’s Pollution Emergency Alerting System (PEAS) hotline at (800) 292-4706.