F.A.Q.’s
Q. Why are beaches tested?
Simply put, to protect the public health. The beach water samples are analyzed for "indicator" organisms, which of themselves are not harmful, but indicate the potential for the presence of human pathogens. A human pathogen is an organism or virus that is capable of producing an illness in a human host.
Q. What are these "indicator" organisms?
Indicator organisms, as their name implies, are used to "indicate" the presence of conditions which have the potential to cause illness. Through various studies conducted by Environmental Protection Agency (USEPA) and others, it has been determined that certain levels of some indicator organisms in bathing beach waters represent a threat to the public health. The indicator organisms assayed for in bathing beach samples that we collect are bacteria called enterococci and E. coli. Enterococcus has proven the most useful bacterial indicator for determining the extent of fecal contamination in marine recreational waters, while E. coli have proven most useful in freshwater situations. An important thing to remember regarding indicator organisms is that, of themselves, they may not be harmful. Rather,
since these organisms are found in the intestine of many warm-blooded animals, their presence suggests that other harmful organisms and viruses also in the intestine of warm-blooded animals (including humans) may be present. If these harmful organisms and viruses (called pathogens) are present and are inadvertently ingested while swimming, they may cause a variety of diseases. The good news is that the most common illness is a mild gastroenteritis with flu-like symptomology. But even the milder diseases can be problematic to immune-compromised people.
Q. How do these organisms and pathogens get into the bathing water?
Runoff from rain events is the dominant cause for elevated indicator bacteria levels. Runoff carries pollutants from roads and other paved surfaces directly to the surface water of beaches. Other possible causes are animal waste from pets as well as wild animals. Common waste observed on beaches can be from dogs, fox, seals, seagulls, ducks and geese. Most warm-blooded animals carry the same indicator bacterium used to classify recreational waters.
Q. Do boats affect samples taken at bathing beaches?
Sanitary wastes from marine craft has been increasingly eliminated as a potential threat to our bathing beaches for two reasons. Foremost, many marinas now have pumpout facilities for their visitors (often at no cost), and secondly, if a boat does discharge sanitary waste, it is required that it do so at least 3 miles offshore, where dilution rates are very high.
Q. How is it determined whether or not a beach is to be closed?
When a sample is taken for a marine beach, the water is brought back to the laboratory and tested for the presence of the indicator organism enterococci. It takes 24 hours to determine if enterococci are present in the sample. The maximum allowable number of enterococci colony forming units per 100ml sample are 104. If a sample exceeds this limit, the beach must be closed and resampled.
Running averages (geometric means) are kept at all bathing beach sites as well.
Q. How long are beaches closed if high levels of bacteria are detected?
In the event a sample has a bacteria level above the standard listed above a resample of the bathing water will be conducted as soon as possible, and the beach will be reopened when test results show acceptable bacteria levels. The tides and currents in open waters act to disperse contaminants. Generally the level of the indicator bacteria is reduced within twenty-four hours after the conclusion of the rainfall, typically after one full tide cycle. Unfortunately the laboratory analysis of a sample does not provide instantaneous results. There is a 24-hour incubation period for all samples. Therefore it is common for a closure to last for a day or two to ensure public health and safety.
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