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Snell: The autumn foam phenomenon on Owasco Lake
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Snell: The autumn foam phenomenon on Owasco Lake

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Owasco Lake displays a variety of seasonal water quality indicators that include an abundance of cyanobacteria during warm temperatures that occur during the late summer months, as well as the more common presence of lake foam during the transition into autumn. During late summer and autumn months, lake foam can accumulate along the shorelines of the Finger Lakes and meander on the water surface in long streaks called "windrows" that move in sync with wind and wave currents. On any given autumn day, across the 11 square miles of surface area of Owasco Lake, miles of white sudsy windrows can be seen in the lake and along sections of the 22 miles of shoreline.

Concerns about lake foam on Owasco Lake are often expressed by vigilant residents, and appreciated. At first glance, the foam appears to look identical to detergent or soap suds, which can lead to the suspicion that a nearby source such as a car wash, laundromat, industrial business, farm or residential septic system is to blame for discharging cleaning products into the lake. However, a closer inspection of the lake foam often reveals distinct differences in composition from synthetic foams, predominantly odor and feel. Lake foams tend to emit an “earthy” scent and are not filmy, while synthetic detergents are typically injected with and smell of perfumes, and feel filmy to the touch.

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The autumn foam phenomenon is certainly not unique to Owasco Lake. The Finger Lakes, including Canandaigua Lake, experience similar occurrences and subsequent public concerns. In late 2019, the Canandaigua Lake Watershed Association embarked on a mission to address concerns and explore the source of the foam. The association contracted with Global Aquatic Research and initiated a robust, phased effort to draw foam samples from the lake and analyze chemical characteristics through advanced laboratory techniques.

The results of this initial analysis by GAR were released earlier this year, and provided analysis of lake foam composition, including the ingredients and conditions necessary for its development. According to the GAR analysis, the chemical “signatures” in the Canandaigua Lake foam suggest the origin is from within the lake itself, and has direct and indirect relationships to water quality. Foam occurs naturally in lakes when the top layer of water is stirred by wind and waves, which mixes air and “foaming agents.” The foaming agents are primarily chains of organic sugars or carbohydrates known as polysaccharides, as well as oils or surfactants from decomposing organic matter. These compounds are not very water-soluble and tend to ride along the water surface. Depending on wind direction and wave action, windrows of foam can form and migrate to the shoreline, where they accumulate into larger areas of dense surface foam.

So, why are areas and streaks of foam larger in some lakes and locations than others? The GAR research on Canandaigua Lake determined a plausible explanation for this question, which may also prove an indicator of lake health and changes that occur throughout Canandaigua Lake, as well as other Finger Lakes, including Owasco Lake. Through their microanalysis, GAR has identified phytoplankton, including cyanobacteria (as well as cyanobacteria in its toxic form that constitutes harmful algal blooms) as a direct source of foam-creating polysaccharides found in Canandaigua Lake. They concluded, “cyanobacteria release polysaccharides outside of their cells in order to create large colonies and to regulate their environment. These ‘exopolysaccharides’ or ‘EPSs’ are produced in large quantities during phytoplankton blooms and change the chemistry of the surface of the lake.” Their analysis indicates a correlation between cyanobacteria and lake foam. From these results, parallels can be drawn that would suggest that ingredients that create foam on Canandaigua Lake closely resemble those in other Finger Lakes, such as Owasco Lake. The scientific research community has demonstrated that cyanobacteria blooms and a growing abundance of aquatic plants are manifested by an imbalance in nutrient levels within the lake ecology. New research on lake foam chemistry and its relationship with levels of cyanobacteria suggest that lake foam may be yet another manifestation of nutrient enrichment of Owasco Lake.

Owasco Lake is a critical resource on which the community depends. Progressing efforts to reduce nutrient transport from watersheds to adjacent waterways will help reduce nutrient enrichment of freshwater lakes and target reductions in the occurrences of HABs and lake foam. Conscious efforts to use less commercial lawn fertilizers, plant trees and shrubs along the shoreline and streams, stabilize soils, and expand the use of best practices in all corners of the watershed will help preserve high levels of water quality for Owasco Lake.

Andrew “Drew” Snell is a specialist with the Owasco Lake Watershed Inspection and Protection Division. For more information, visit


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One warm summer’s day in 1974, when I was a college kid interning as a cub reporter at what was then known as the Auburn Citizen-Advertiser, I left the paper’s new building on Dill Street in downtown Auburn and walked three blocks to the City Hall on South Street to cover a meeting of the City Council — or, to be technically accurate, the Auburn Urban Renewal Agency, or AURA, which was an offshoot of the council.

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