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Fact Sheet 2010–3068

Occurrence of Escherichia coli in the Cuyahoga River in the Cuyahoga Valley National Park, Ohio

By Amie M.G. Brady and Meg B. Plona

Why is Escherichia Coli Important?

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There are several measures of the “cleanliness” of a natural body of water, including concentrations of indicator bacteria, anthropogenic chemicals (chemicals derived from human activities), and nutrients, such as nitrogen and phosphorous. Escherichia coli (E. coli) is a bacterium that lives in the intestinal tract of warm-blooded animals, such as humans, deer, cows, and dogs. Most strains of E. coli are not harmful and are in fact beneficial to humans by aiding in the digestive process. A few strains, such as the O157 strain, produce toxins that can cause gastrointestinal illness, but occurrence of toxic strains in the environment is not common. E. coli is considered a good indicator bacterium because its occurrence in the environment indicates the presence of fecal contamination and therefore the possible presence of pathogenic organisms associated with feces.

The U.S. Environmental Protection Agency (USEPA) recommends using measurements of E. coli to monitor freshwaters and set criteria for the concentration of bacteria that can be present in the water with minimal adverse human-health effects. Typically, a State’s waters are assigned a recreational-use designation, such as bathing, primary-contact, or secondary contact waters, which is used to set the State’s water-quality standards based on the USEPA criteria. The Cuyahoga River in the Cuyahoga Valley National Park is designated for primary-contact recreation; therefore, when concentrations of E. coli exceed 298 CFU/100mL, the river would be considered potentially unsafe for recreation.

First posted November 18, 2010

For additional information contact:
U.S. Geological Survey
Ohio Water Science Center
6480 Doubletree Avenue
Columbus, Ohio 43229-1111

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Suggested citation:

Brady, A.M.G., and Plona, M.B., 2010, Occurrence of Escherichia coli in the Cuyahoga River in the Cuyahoga Valley National Park, Ohio: U.S. Geological Survey Fact Sheet 2010–3068, 4 p. (Also available at



Why is Escherichia coli Important?

How is Escherichia coli Detected in Water Samples?

Has Escherichia coli Been Detected in the Cuyahoga River in the Cuyahoga Valley National Park?

How Can Models Be Used to Determine When Water in the Cuyahoga Valley National Park
Is Unsafe for Recreation?

Where Can I Find More information?
References Cited

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