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New Hampshire Department of Environmental Services
PUBLIC GOVERNMENT BUSINESS A to Z LIST

Frequently Asked Questions
Advisories
 
  • How often are public beaches inspected?
    Both public coastal and freshwater beaches are monitored from approximately Memorial Day to Labor Day. Sixteen coastal beaches are inspected once or twice a week depending on visitor frequency. For example, the beach usage at Hampton Beach State Park warrants a higher monitoring frequency than some of the smaller and less visited coastal beaches. Over 160 inland freshwater beaches are sampled once per month. Local municipalities that have their own programs, such as Salem, Manchester, Laconia and Amherst, sample more frequently.
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  • What does it mean if I see a green DES sign at a beach?
    A green sign indicates that the particular beach or section of beach is monitored during the swim season by the DES Beach Program for bacteria levels. The bacteria level in the water collected during the most recent inspection are not elevated above the state bacteria standards.
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  • What does it mean if I see a yellow DES sign at a beach?
    A yellow sign indicates an advisory has been issued for the beach or section of beach due to levels of bacteria above the state standard. Contact with the water is not recommended. When fecal bacteria levels are elevated, more disease-causing organisms are likely to be in the water.
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  • What does it mean if I see a red DES sign at a beach?
    A red sign indicates an advisory has been issued for the beach or section of beach due to elevated amounts of cyanobacteria (formerly known as blue-green algae) have been found at the beach or section of beach. Signs are available free of charge for beaches participating in the DES Beach Inspection Program.
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  • What causes high bacteria levels?
    There are many potential causes of elevated bacteria levels in lakes, ponds, and the ocean. Runoff from precipitation events can carry a variety of contaminants into the water, including animal waste, pollutants and excess nutrients from lawns. In addition to runoff, the other common causes of high bacteria levels are failing septic systems, animal waste on a beach or in the water (typically from birds), leaking baby diapers, and individuals swimming during an illness.
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  • Why do you monitor for Escherichia coli (E. coli) or Enterococci?
    There are numerous diseases that can be transmitted via water, such as cholera, typhoid and dysentery. It is difficult to test waters for every possible type of disease-causing bacterium, so E. coli and Enterococci are used as indicator organisms. These numbers signify, on a statistical basis, the likelihood of contracting a disease by recreating in or consuming water at a certain concentration of bacteria. E. coli is sampled across the nation as a freshwater indicator. Enterococci are bacteria more persistent than E. coli in saltwater and used as an indicator of coastal water quality.
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  • Why is there an advisory for one side of the beach and not the other?
    Occasionally on a very large beach (such as Wellington State Park, which is over 1,300 feet long) there will be an advisory for only one side or section. This is because the beach is so long that it is possible to have one end with elevated bacteria levels and the other end to be considered under safe levels with little threat of being contaminated. This is a very rare situation, and generally, if one portion of a beach has an elevated level of bacteria the entire beach will be placed under an advisory.
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  • What is Escherichia coli?
    E. coli is a common form of coliform bacteria that is found in the large intestines of humans and other warm-blooded animals. It is used as an indicator organism since it is easily cultured, and if present in elevated amounts, indicates that fecal matter is present in the water. If fecal matter is in the water, then other disease-causing bacteria may also be present..
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  • What is the state E. coli standard for freshwater beaches?
    The state E. coli standard is at freshwater swimming beaches is 88 counts/100 ml of water in one sample or a geometric mean of 47 counts/100 ml of water in at least three samples over a 60-day period. Geometric means are used instead of an average to summarize bacteria concentrations. A geometric mean tends to dampen the effect of very high or low values, which might bias the results if an average were calculated. This is helpful when analyzing bacteria concentrations, because levels may vary anywhere from 10 to 10,000 over a short period. A geometric mean is The nth root of a product of n values. For three results collected from a beach over 60 days, the geometric mean would be the 3rd root of the value of all three numbers multiplied together.
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  • When is an advisory issued for a freshwater beach?
    When either two or more samples taken at a beach exceed the standard or when one sample exceeds 158 counts/100 ml, a beach advisory is issued. At that time, beach managers are notified, notices are posted on the DES beach inspection website, and managers post signs at beach entrances to warn the public of the potential health threat posed by water contact at the beach. Freshwater beaches are resampled within 24 hours of an elevated bacteria result. Beach advisories remain in effect until subsequent beach sampling reflects results below the state standard.
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  • What is Enterococci?
    Enterococci are bacteria more persistent than E. coli in saltwater and used as an indicator of coastal water quality. Enterococci are a form of fecal streptococci and, if present, indicate fecal material from warm blooded animals is present in water.
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  • What is the state Enterococci standard for tidal swimming beaches?
    The state Enterococci standard at tidal swimming waters is 104 counts/100 ml of water in one sample or a geometric mean of 35 counts/100 ml of water in at least three samples over a 60-day period.
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  • When is an advisory issued for a coastal beach?
    When either two or more samples taken at a beach exceed the standard or when one sample exceeds 174 counts/100 ml, a beach advisory is issued. At that time, beach managers are notified, notices are posted on the DES beach inspection website, and managers post signs at beach entrances to warn the public of the potential health threat posed by water contact at the beach. Coastal beaches are resampled within 24 hours of an elevated bacteria result. Beach advisories remain in effect until subsequent beach samplings reflect results below the state standard.
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  • What are cyanobacteria?
    Cyanobacteria are bacterial microorganisms that photosynthesize and are found naturally in lakes and ponds. They are not a type of fecal bacteria. When there are excess nutrients in the water due to fertilizer and other contaminants, cyanobacteria can appear at high concentrations in the form of a bloom. A bloom can appear as a blue-green scum or as dispersed cells floating either on the surface or in the water column.

    Cyanobacteria (formerly called blue-green algae) are present in all lakes around the world and it is true that some species of cyanobacteria produce toxins. However, it is usually only when a visible bloom of cyanobacteria is present that these toxins pose a threat to animal or human health. The DES recommendation is to avoid swimming and other contact with any area of water experiencing a visible bloom, as ingestion of the bloom/scum is one of our primary concerns. Due to the nature of cyanobacteria it can be very frustrating to track a bloom. This is because it may be visible in one area in the morning, but in a few hours it can appear to have vanished or dispersed by wind, current and/or rain.

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  • When is an advisory issued for cyanobacteria?
    Collected materials are microscopically analyzed at the DES Limnology Center. The microscopic evaluation is to protect public health and serves only as a precautionary measure for short term exposure to cyanobacteria and is notmeant to indicate potential toxicity. An advisory will be issued if more than 50 percent of the total cell count in a sample are identified as cyanobacteria.

    Any advisories that are issued by the DES Beach Inspection Program are followed up with additional inspections until the violating parameter is below the state standard. Water samples are collected weekly at the designated beach after an advisory is issued for cyanobacteria.

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  • Why is the beach area not closed by the State when levels of bacteria are above the State standard?
    The NH Department of Environmental Services will post an advisory for a beach that has bacteria levels above the state standard. It is at the discretion of the beach manager, town officials, or recreation director whether to close a beach swimming area or not. Often there are other recreation options within a beach area that do not involve water contact. If a beach with an advisory remains open, it will be posted with signs to inform the public about the high bacteria levels in the water and possible health effects of water contact. Visitors may then make their own informed decision.
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NH Department of Environmental Services | 29 Hazen Drive | PO Box 95 | Concord, NH 03302-0095
(603) 271-3503 | TDD Access: Relay NH 1-800-735-2964 | Hours: M-F, 8am-4pm

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