Coliform bacteria occur naturally in animal feces (e.g., humans, fish, and livestock), as well as stormwater runoff, soils and vegetation. By themselves, these microscopic organisms are considered harmless and often aid in digestion and vitamin synthesis in the body.
However, high numbers of coliform bacteria in the water may indicate the presence of potentially harmful microorganisms, including Salmonella, Shigella and Vibrio cholera, viruses such as infectious hepatitis, and others that may lead to outbreaks of diarrhea and gastro-urinary infections.
While there is increasing controversy about coliform as an accurate indicator of health concerns, it remains the most common gauge used to indicate whether a water body is safe for swimming. The state's saltwater beaches are sampled weekly for fecal coliform (a sub-group of total coliform, indicating human or animal fecal contamination) and enterococci (present in the intestines of all warm-blooded animals), a more reliable measure of water quality because it survives longer in water. County health departments issue health advisories or warnings based on these standards, although the link between exposure to these organisms and public health risk remains unclear.
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Contact your county public health department for a list of designated swimming areas and monitoring criteria. Apply common-sense guidelines in areas not covered by the county public health deparment.
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Be aware that rivers, streams and canals are more prone to pollution than larger bodies of water that may be safer because of dilution.
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Avoid swimming immediately after it rains, near stormwater outfalls or in stormwater ponds where pollutants concentrate.
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Children, pregnant women, and people with compromised immune systems (such as those living with AIDS, organ transplant recipients, or those receiving certain types of chemotherapy) are more prone to illness if infected.
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People with liver or kidney conditions, or open wounds or abrasions, should avoid salt water and promptly seek medical attention if exposure leads to an infection.
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Avoid swimming in lakes where septic tanks are present during flooding because pollution from septic drain fields may spill over.
The threat of bacterial contamination is one of the reasons some coastal areas are closed to shellfish harvesting, but closures are based on state presumption of contamination rather than actual monitoring. For additional information on shellfish harvesting, visit the Florida Department of Agriculture and Consumer Services webpage devoted to
Shellfish Harvesting Management.