Bacteria Testing Data

Below is enterococci data reported by Hood College (Frederick County), Harford Community College, and Howard Community College. Learn more about this project.


Red values = counts greater than 61 cfu/100 ml in fresh water. At the time of sampling the site was not healthy for "moderate" bathing use, according to EPA standards. Readings above 151 cfu are not suitable for any bathing or "full body contact." More on the EPA standards.
Light blue background = .5 inches or more of rainfall at least 24 hours before collecting water samples
Lavender background = .5 inches or more of rainfall at least 48 hours before collecting water samples


Enterococci are bacteria that are found in the GI tract of warm-blooded animals, which includes all birds and mammals. Their presence in surface water indicates recent contamination with fecal waste. Counts are expressed as cfu or colony-forming units. Counts greater than 61 cfu/100 ml in fresh water indicate conditions not suitable for recreational use by the U.S. Environmental Protection Agency (EPA). Water samples were taken within 24 hours of a rainstorm of .5 inches or more. Exact rainfall amounts on individual sampling days are available. All samples tested at biology laboratories of partner colleges. None of the laboratories is certified by the EPA for bacteria testing.

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