E.Coli
Understanding E. coli: What It Is and Why It Matters
When you hear the term E. coli, if you’re like most people, your mind probably goes to thoughts of food poisoning and contaminated lettuce. But
June 3, 2024
Bacteria in the Water
The health of our rivers is critical for environmental sustainability, preservation of wildlife, and clean water protection. River health is determined based on water quality monitoring efforts. Water quality data are utilized to identify and quantify contamination/impairments, inform protection and management strategies, and verify and evaluate management efforts.
Bacteria threaten our waterways and pose health risks to swimmers. Waterborne pathogens (bacteria capable of causing disease in humans) have been known to cause Salmonellosis, Legionnaires’ disease, Dysentery, and other stomach, respiratory, skin, and brain effects. Bacteria sources may include sewage, urban runoff, agricultural runoff, or industrial waste. When these bacteria flow into our beaches and rivers they can pose serious health risks.
Recreational waters are threatened by fecal contamination from urban and agricultural drainage that may contain human pathogens associated with gastrointestinal and respiratory illness. Many recreational beaches and rivers around the United States are monitored for fecal contamination, which indicates a threat to human health. According to the Center for Disease Control, the top causes of recreational water illnesses are human pathogens that can be monitored via E. coli sampling.
Unfortunately, the state of TN performs very little E. coli sampling particularly in our highly recreated rivers (i.e. >500,000 visit the Harpeth River State Parks annually) and none of these sampling efforts are paired with predictive modeling, which provides the general public “early warning” notice if waters may be unsafe to swim based on levels of E. coli. Harpeth Conservancy (HC) strives to mitigate this problem through our Citizen Water Quality Monitoring Program that regularly monitors water quality in Middle Tennessee rivers through our network of citizen scientists. During the 2023 sampling season (May-September), this program focuses on regular sampling of E. coli at highly recreated sections of the Harpeth River, Richland Creek, Mill Creek, Browns Creek, Whites Creek, Cumberland River, and Piney River and pair those data with predictive models that will provide the public with an “early warning” when levels of E. coli are elevated and likely unsafe to be in contact with. This real-time public safety advisory system will launch in 2023 as TN Water Watch. Stay tuned!
Harpeth Conservancy E. coli Modeling Study
The Basics of Predicting E. coli Levels Using a Model
Efforts to monitor recreational waters for fecal contamination have shifted away from culturing pathogen indicator organisms, such as E. coli, to developing real-time predictive models. Culturing E. coli requires 18 to 24 hours to complete; thus, “do NOT swim advisories” are based on previous day measurements– this traditional approach under-performs compared to predictive models. Predictive models, such as a multiple linear regression analysis can utilize a variety of water quality and environmental parameters to correlate elevated levels of E. coli with certain environmental conditions (see graphic to right).
Model Details
The health of our rivers is integral to environmental sustainability, protection of wildlife, and clean water, and subsequently the health of residents that depend on the use of the water. River health is determined by monitoring various factors of water quality, such as temperature, precipitation, dissolved oxygen and other particles, and concentration of microbial life and contaminants. Water quality data are utilized to identify and quantify contamination/impairments, inform protection and management strategies, and verify and evaluate management efforts.
Among all the factors affecting water quality, harmful microbials such as bacteria threaten our waterways and pose health risks to swimmers, kayakers, and recreational fishers. Waterborne pathogens (bacteria capable of causing disease in humans) have been known to cause Salmonellosis, Legionnaires’ disease, Dysentery, and other stomach, respiratory, skin, and brain effects. Bacteria sources may include sewage, urban runoff, agricultural runoff, or industrial waste. When these bacteria flow into our beaches and rivers they can pose serious health risks.
Recreational waters are threatened by fecal contamination from urban and agricultural drainage that may contain human pathogens associated with gastrointestinal and respiratory illness. Many recreational rivers are monitored for fecal contamination, arousing threat to human health. According to the data from Center for Disease Control, human pathogens are one of the top causes of recreational water illness, which can be indexed with measurements of E. coli level in the water.
Unfortunately, there is very little E. coli sampling work being done, particularly in our highly recreational rivers (i.e. >500,000 visit the Harpeth River State Parks annually) and none of these sampling efforts are paired with predictive modeling, which provides the general public “early warning” notice if waters may be unsafe to swim based on levels of E. coli. Typically, water samples must be processed in a lab environment and take up to a couple of days to acquire E. coli levels, which is inadequate for informing recreational use to people that the water from two days ago was a health hazard.
Fortunately, it is possible to develop a framework model using past sample data in conjunction with live data from environmental monitors such as live water quality and weather data to predict the level of harmful bacteria in the water.
Why are we concerned about E. coli?
Previous incidents investigated by Tennessee of Department of Environment and Conservation (TDEC)
In 2014, TDEC investigated an uncommon waterborne salmonellosis outbreak. There was one risk factor in common to many of the cases — having enjoyed water recreation at a splash pad. The investigation lead to a state survey of water quality and patron behaviors at splash pads.
In July 2017, TDEC investigated a large outbreak of legionellosis linked to a hotel in Western Tennessee. A total of 92 ill people were identified and ill people were more likely to have spent time in or around the aquatics area (outdoor pool, hot tub). Water testing of the aquatics area identified the Legionella bacteria was present.
In 2018, TDEC investigated a large outbreak involving multiple pathogens was investigated at an outdoor adventure company in Eastern Tennessee. Visitors to the facility had drank water from an untreated well and later become ill. Testing of the water identified E. coli and coliforms, which indicated contamination.
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