Beach Water Quality Testing


The Village continues to be committed to mitigating potential health risks associated with high bacteria levels on beaches. The recent swimming advisories issued by the Florida Department of Health (FDOH) for several beach areas within Key Biscayne have concerned Village residents and visitors. These swimming advisories were issued for Crandon Park North, Crandon Park South and Key Biscayne Beach. After routine weekly beach water sampling, results showed the presence of enterococci bacteria above acceptable levels for recreational beaches in early September 2018.

The Florida Department of Health (FDOH) currently conducts weekly beach water sampling at the following four (4) locations:

    1. Crandon Park North
    2. Crandon Park South
    3. Key Biscayne Beach Club
    4. Bill Baggs Cape Florida State Park

The Key Biscayne Community Foundation has added another resource for Village residents and visitors using our beaches. Supplemental beach water samples will be collected weekly for testing. An independent laboratory collected samples at Crandon Park North, Key Biscayne Beach Park and within a Village bayside location on Thursday, September 13, 2018 for beach water quality testing. Testing to see if enterococci are present is underway. The independent laboratory also is conducting microbial source tracking on the three samples. This test takes analysis a step further by identifying detectable levels of specific DNA fragments that indicate the presence of the particular bacterial/viral/parasitic strain associated with the DNA of specific sources.

For more information regarding the methodology and frequency of FDOH’s routine weekly beach water sampling, testing locations and how to obtain their beach water sampling results, see below.

Florida Department of Health Beach Water Sampling Program

Lab tests conducted on water samples collected weekly by the FDOH from the four Key Biscayne ocean beach locations look for the presence of enterococci bacteria (FDOH Florida Healthy Beaches Program, 2018). The presence of enterococci is used as a saltwater quality indicator on the recommendation of the U.S. Environmental Protection Agency (USEPA; EPA, 2015).

If enterococci are present above a certain number after a 24-hour incubation period, FDOH staff returns to the same location to take another sample. If the results are again above the threshold for recreational water quality, the FDOH is required by law to issue a Swimming Advisory to the municipality in the vicinity of the beach.

Florida Healthy Beaches Program testing result categories as reported by the Miami-Dade County FDOH are:

  • Good = 0-35.4 enterococci per 100 milliliters of marine water
  • Moderate = 35.5-70.4 enterococci per 100 milliliters of marine water
  • Poor = 70.5 or greater enterococci per 100 milliliters of marine water

This process is codified in State of Florida Statute 514.023 Sampling of beach waters; and public bathing places; health advisories. This means the FDOH, including its County offices, have the jurisdiction to issue beach swimming advisories (Florida Statutes, 2018).

What Do Enterococci Levels Tell Us About Water Quality and Safety?

Statewide beach water quality tests look for enterococci because these bacteria are a indicator for other harmful bacteria associated with the human intestinal tract. (Herrin, 2018). It is these other bacteria that can make people sick. However, “enterococci have a greater correlation with swimming-associated gastrointestinal illness in both marine and fresh waters than other bacterial indicator organisms, and are less likely to "die off" in saltwater” and “it is difficult to test waters for every possible type of disease-causing bacteria” (USEPA, 2015).

The presence of enterococci does not mean that the water is contaminated with human sewage. According to Boehm and Sassubre (2014), “The use of enterococci as indicators of human fecal pollution or contamination can be problematic, however, because enterococci are also found in animal feces and on plants.” Enterococci species are found in the guts of mammals and birds as well as in soils, land and marine plants and beach sand. It is possible that some of the bacteria are associated with the decay of sargassum seaweed that has accumulated in large amounts in recent months.


Additional sampling and testing (“source tracking”) is required to identify the sources of enterococci (e.g., human, bird) in beach water samples. These analyses look for bacteroides shown to be closely associated with certain mammals and birds and generally take longer than the 24-hour FDOH analyses (Herrin, 2018).


If the FDOH issues a beach advisory, it is required by law to notify the local office of the Florida Department of Environmental Protection (DEP) who “shall promptly investigate wastewater treatment facilities within 1 mile of the affected beach waters … to determine if a facility experienced an incident that may have contributed to the contamination …” (Florida Statutes, 2018).

How to Find Water Sampling Info for Key Biscayne

The Florida Healthy Beaches Program webpage allows users to search for beach sampling info by County (note: Dade is used instead of Miami-Dade) and then by beach sampling location from a table or via a Google map of the area of interest. Blue symbols on the map represent each sampling location. A mouseover of the symbol gives the location name, last sample date, whether an advisory is active, and a link to view samples.

Follow this link for data for Cape Florida Park, Crandon Park South and Crandon Park North on page 1 of 5 for Dade sampling locations. Follow this link for Key Biscayne Beach (the Beach Club) on page 2. Click on “View Samples” to see the sampling and analytical result history for each location.



Boehm A.B. and Sassoubre L.M. 2014 Feb 5. Enterococci as Indicators of Environmental Fecal Contamination. In: Gilmore MS, Clewell DB, Ike Y, et al., editors. Enterococci: From Commensals to Leading Causes of Drug Resistant Infection [Internet]. Boston: Massachusetts Eye and Ear Infirmary; 2014-. Available from:


Florida Department of Health, 2018. Florida Healthy Beaches Program

Florida Statutes, 2018. Chapter 514.023 Sampling of beach waters; and public bathing places; health advisories

Herrin, J., 2018. Personal Communication, Source Molecular Laboratories (September 12-13, 2018).


US Environmental Protection Agency, 2015. Recreational Water Quality Criteria, OFFICE OF WATER 820-F-12-058 (PDF)



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