Two men rush into Lake Michigan for Milwaukee’s annual polar bear plunge. Image: Wikimedia Commons
By Talitha Tukura Pam
Polar bear plungers beware: Researchers in Canada report that feces in snowmelt pollute the Great Lakes.
Runoff from snow and snowmelt could be a significant nonpoint source of fecal contamination and threaten the health of winter sports enthusiasts, according to a study published early this year in the Journal of Great Lakes Research and produced by researchers at Canada’s Water and Science Directorate.
The lakes are used for winter recreation and in the spring leading up to swimming season. There is usually no water quality monitoring for recreational waters in the winter despite the growing popularity of winter sports and recreation, the study reported. Participants in polar bear plunges and winter swimming, surfing and sailboarding are at risk of infection if they ingest contaminated water.
The new findings show it is especially important for beach managers and enthusiasts to know the microbial water quality conditions at their beaches, even in the winter, the study said.
The researchers found that fecal contamination and associated pathogens can persist for months in snow as cold as 14 degrees Fahrenheit.
E. coli is a bacteria found in the digestive systems of warm-blooded mammals and birds. Health authorities look for it to determine the presence of human and other waste.
“The presence of E. coli in surface water is an indicator of pollution by feces,” said Joan Rose, a professor of water microbiology at Michigan State University and an international expert in water quality and public health safety. “If ingested, it can make you sick. If pathogens are present, there is fear of an outbreak. Our goal is to keep fecal contamination down and keep E. coli out of drinking water and food.”
The Center for Disease Control states that E. coli also indicates the potential for other pathogens that can be the source of large outbreaks of disease, including cholera, dysentery, giardia, diarrhea, urinary tract infections, respiratory illness and pneumonia.
“Fecal contamination of snow is from various sources ranging from manure, sewage, livestock waste and droppings from pets like dogs,” said Molly Rippke, an aquatic biologist specialist for the Michigan Department of Environmental Quality.
Waterfowl and migratory birds may also contribute to direct fecal deposition in snow and during ice formation in water along beaches and in lakes, the report said.
“However, wildlife isn’t as much of a problem as human sewage, domesticated animals, agriculture and agricultural cattle, sheep, pigs and chickens,” Rose said. “Ultimately, our goal is to prevent pollution and to ensure that animal and human feces are adequately treated before disposed of.”
Preventing contamination is not easy.
“We recommend that farmers incorporate manure into the soil within 24 hours, or prior to a heavy rainfall whichever comes first,” Rippke said.
In colder climates, runoff from snow contributes to elevated levels of fecal contamination to impacted waters, potentially increasing E. coli concentration by as much as 100-fold, the study reported. This high level is likely due to an accumulation of fecal contamination in snow which is preserved by the cold. During ice melt, trapped pathogens flow into adjacent water.
The research also says that climate change means that people may increasingly use the water recreationally in the winter and early spring. The extended persistence of pathogens may present an increased risk of exposure to the public.
“Climate change is also a driver for increased rainfall and flooding, so there is a risk of water-borne diseases,” Rose said. “What we don’t know is if E. coli will present that potential.”
The Natural Resource Defense Council reports that between 1992 and 2010, Michigan had 184,923 days of beach closure or advisories because of contamination.
The research showed that the highest E. coli concentration occurs in May. This high level is usually the lead up to the spring opening of the swimming season.