The facts on foam in the Finger Lakes

Questions and concerns about the foam streaking the waters and accumulating on the shoreline of Owasco Lake have been on the rise lately. People ask what the foam is, some thinking it is soap bubbles or phosphate residue. In fact, it is neither of these, but instead a complex mixture of natural and manmade compounds mixing with air and water to create sudsy white foam.

Foam is not a new phenomenon. It is formed by a natural process that occurs when organisms such as algae, plants and aquatic animals die. As they decompose, they release chemicals called polysaccharides, a type of surfactant, into the water, reducing its surface tension. Wind, currents and boat activity mix air into the surfactant-rich water, producing foam.

Foam becomes concerning, however, when manmade chemicals, invasive species and cyanobacteria (harmful algal blooms) are added to the mix. Research conducted by the Canandaigua Lake Watershed Association and Global Aquatic Research on Canandaigua Lake has discovered that lake foam can concentrate pollutants from the lake water.

GAR and CLWA samples were analyzed to attempt to determine the source of the lake foam. The studies revealed that the source of the foam comes from within the lake, and that the foam itself is not made up of invasive mussel proteins. But as we will see below, invasive mussels do play a role in foam production.

Further study indicated that the polysaccharides in Canandaigua Lake foam are chemically similar to phytoplankton in the lake. Mycrocystis cyanobacteria make up much of this phytoplankton during HAB season.

Researchers have found that when cyanobacteria bloom, they release polysaccharides outside of their cells to create large colonies. Called exopolysaccarides, or EPSs, these surfactants change the surface chemistry of the lake.

Invasive mussels like zebra and quagga filter plankton, the microscopic plants and animals in the lake, but the mussels don’t filter microcystis cyanobacteria, or HABs. Instead, they rerelease the cyanobacteria cells, concentrating them in the water. In addition, when feeding on HABs, the mussels produce a polysaccharide-rich mucus, adding to the mycrocystin-produced EPSs. Together, the surfactant EPSs accumulate on the surface of the lake water and mix with air to produce foam.

Although research is still ongoing, the Canandaigua Lake study has found that lake foam can concentrate pollutants at much higher levels than those in the surrounding lake water. Microcystin toxins in foam have sometimes been higher than the New York State Department of Health’s recreational limit, while nearby water had much lower levels.

In 2023, the CLWA was awarded a grant by Freshwater Future to expand its research into lake foam. Partnering with GAR and Binghamton University, they investigated the presence and concentration of PFAS in lake water and lake foam. PFAS have been connected to increased risks of a variety of human diseases. They found that levels of PFAS in lake water were low, at 5.4 parts per trillion, while levels in foam samples had 70 times that concentration, measuring between 381 and 387 parts per trillion. Seven PFAS were detected in surrounding lake water, while 13 compounds were found in the foam samples, with the concentration of six exceeding reporting limits. Foam samples also contained high levels of related PFOS and PFCAS, which were not detected in the lake water.

These studies indicate that lake foam has the potential to accumulate chemicals and toxins at greater concentrations than surrounding lake water. It is recommended that people and their pets avoid contact with lake foam, and wash thoroughly if exposed to it. For more information, check out the EPA website.

With reports of increased lake foam throughout the Finger Lakes, Global Aquatic Research is planning further studies on Keuka, Owasco, Skaneateles and Seneca lakes this fall. You can help GAR by reporting foam sitings. Google the Global Aquatic Research Finger Lakes Foam Reporting Tool.

Nancy Hart is a member of the board of directors of the Owasco Watershed Lake Association.

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