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Beaches and Bacteria (January 2014 Update of an August 2004 Virginia Water Central Article)

—By Jackie McGeehan, Alan Raflo, and Julia Sherry; cartoon by George Wills.

[This article updates a previous version published in the August 2004 issue of Virginia Water Central, the newsletter of the Virginia Water Resources Research Center  (available online at  That article was written as part of a Virginia Tech English Department internship by Ms. McGeehan in summer 2004.  The authors thank Julie Jordan, formerly of the Virginia Tech Biological Systems Engineering Department, and Michele Monti, formerly of the Virginia Department of Health, for reviewing the original article.  Thanks to Charles Hagedorn of the Virginia Tech Crop and Soil Environmental Sciences Department for his assistance with the updated version.  The Virginia Water Resources Research Center takes responsibility for any errors that may remain.  All Web sites mentioned were functional as of January 29, 2014, and were re-checked November 16, 2017.

“Bacterial contamination clears at Fairview Beach,” Fredericksburg Free Lance-Star, September 20, 2006.

“High bacteria levels found off Hilton Beach,” Daily Press, July 20, 2009.

“Health Advisory Issued for Ocean View Beaches,” Associated Press, as published in Virginian-Pilot, June 11, 2013.

If you live near Virginia’s coastal waters, you may have seen these recent headlines, or you may even have been one of the beach-goers who were told, “Enjoy the sun, but the water is off- limits.”

The cause of the beach advisories in the three articles mentioned above was bacteria: certain kinds used to indicate fecal pollution were found at levels above the state’s legal maximums. Elevated bacteria levels are also the cause of a large percentage of advisories nationwide. This article, therefore, is designed to help Virginians be more informed about the causes of beach closures, the regulations and legislation behind them, and the role of bacteria in beach water-quality monitoring.


Issuing a Beach Advisory or Closure

The difference between a beach advisory and closure is that an advisory recommends people stay out of the water while a closure seeks to prohibit anyone from entering the water until the water is safe. An advisory might also recommend special precautions to reduce possible illness, such as showering immediately after exposure or avoiding contact with open cuts/wounds.

How do the people responsible for beach closures or advisories make a decision about what is “safe”? Generally, the basis for such a decision is whether or not the coastal waters in question meet a state’s water-quality standards. Under the Clean Water Act, the U.S. Environmental Protection Agency (EPA) requires each state to set water-quality standards; in Virginia, the State Water Control Board, assisted by the staff of the Department of Environmental Quality (DEQ), is responsible for promulgating regulations that establish water-quality standards.

A water-quality standard for a given body of water identifies the designated uses that the body of water is intended to provide. In Virginia, according to the DEQ (“Designated Uses,” online at, “All…waters are designated for the following uses: recreational uses, e.g., swimming and boating; the propagation and growth of a balanced, indigenous population of aquatic life, including game fish, which might reasonably be expected to inhabit them; wildlife; and the production of edible and marketable natural resources, e.g., fish and shellfish.” Many water bodies also have a designated use as a public water supply.

A water-quality standard also identifies specific indicators, known as criteria, which are measured or otherwise assessed to determine whether the water body will support its designated uses. The DEQ describes criteria as “general narrative statements that describe good water quality and specific numerical concentrations that are known to protect aquatic life and human health.” Water-quality criteria in Virginia address, for example, the minimum amount of dissolved oxygen allowed, the minimum and maximum temperature allowed, and the maximum level of bacteria allowed. (The section below, “Elevated Bacteria,” will discuss Virginia’s bacteria standards more specifically).

Typically, beach advisories and closures are issued when the water at the beach fails to meet one or more state standards, and often the bacterial standard is the issue. In Virginia, the state government is responsible for monitoring and testing state waters, and beach monitoring for bacteria has been delegated to local offices of the Virginia Department of Health (VDH).  According to “Frequently Asked Questions/VDH-Issued Swimming Advisories,” on the VDH’s beach monitoring Web site at, several public-notification methods may be used to issue a swimming advisory: posting an advisory sign in plain view at the swimming location, issuing a local press release, and publishing swimming advisories at coastal public beaches on the VDH Web site. Swimming advisories are lifted when additional sampling demonstrates that bacteria levels are below the state standard levels.

National and Regional Beach Closure and Advisory Statistics

Every year the Natural Resources Defense Council (NRDC) releases a report compiling federal and state data on beach closures and advisories. The 2013 edition of this report, titled “Testing the Waters: A Guide to Water Quality at Vacation Beaches,” is available online at The 2013 report covered conditions in 2012 at 3,673 beaches or beach segments—in 30 states—at which water quality is monitored at least once a week (in most cases) and reported to public agencies. In 2012, elevated bacteria levels were one of the leading causes of swimming-beach closures and advisories both nationally (83 percent) and in the state (100 percent). According to NRDC reports on data from 2007 to 2011, 2012 was not an unusual year; the national percentages of advisories due to bacteria ranged from 68% to 75% and the state percentage was 100% every year. Other main reasons for beach advisories nationally in those years included preemptive closures for rainfall events expected to carry pollution into coastal waters, known sewage spills, algal blooms, and chemical spills.

Elevated Bacteria

As noted above, high levels of bacteria cause of a large percentage of beach closures and advisories, both nationwide and in Virginia. Three types of bacteria are monitored in various water-quality standards: fecal coliform bacteria, Escherichia coli (E. coli), or enterococci bacteria (please see the following box for more details on these kinds of bacteria). These are indicator organisms: they do not cause disease but indicate fecal contamination by human or animal waste, which may contain other, disease-causing (or pathogenic) organisms, including other bacteria, viruses, single-celled animals (Protozoa), fungi, and parasites. (Some varieties of E. coli do cause human illness, but different strains are used as indicator organisms.) Using actual pathogens as indicator organisms would pose a contamination risk for laboratory personnel; instead, labs test for non-pathogenic indicator organisms that are easier and safer to monitor.

Indicator Bacteria

Fecal Coliform Bacteria

Refers to a group of many different species of bacteria most (but not all) of which live in the intestines of warm-blooded animals (mammals and birds).

Escherichia coli (E. coli)

A single species (but with many varieties, or strains) within the fecal coliform group; found only within the intestines of warm-blooded animals. Most strains of E. coli do not cause illness, but shiga-toxin producing strains, such as 0157:H7 produces a toxin and can cause serious illness.


A group of species within the larger group known as fecal streptococci bacteria, which typically inhabit the intestines of warm-blooded animals; normally enterococci are found only in humans. Because enterococci can survive in salt water, they are useful as an indicator of contamination of marine waters. Some species can cause infection of the urinary tract, wounds, or bloodstream.


U.S. Department of Health and Human Services/Centers for Disease Control, “E. Coli, Escherichia coli,”, accessed October 30, 2013; and online articles on enterococci, accessed October 30, 2013.
U.S. Environmental Protection Agency, Volunteer Stream Monitoring: A Methods Manual (EPA 841-B-97-003), 1997, pp. 180—181.

The EPA, in the Beaches Environmental Assessment and Coastal Health (BEACH) Act of 2000, stipulates that states must use enterococci as indicator bacteria for marine and transitional waters, whereas freshwater sources may be tested for either E. coli or enterococci.  According to the EPA, E. coli and enterococci are considered to have a higher degree of association with outbreaks of certain diseases than fecal coliforms.  They were recommended as the basis for bacterial water quality standards in the EPA’s 1986 “Ambient Water Quality Criteria for Bacteria” document.  EPA information on beaches is available online at; water-quality criteria for bacteria is available online at

Since April 2004, under The BEACH Act, states have had to comply with the EPA bacterial requirements established in 1986. The BEACH Act redefined coastal waters to include the Great Lakes and marine coastal waters (including estuaries) designated by states under the Clean Water Act for swimming, bathing, surfing, or similar water-contact activities. The definition excludes any location upstream of the mouth of a river. The EPA provides grants, authorized under the BEACH Act, to help states meet the Act’s tougher monitoring requirements. In addition, the Clean Beaches Plan of 2004 provided grants, technical expertise, and scientific studies to “help state, tribal, and local beach managers strengthen their [beach water-quality monitoring] programs… to achieve two major goals: promote recreational water quality programs nationwide and create scientific improvements that support timely recreational water monitoring and reporting.” (As of 11/16/17, the Clean Beaches Plan of 2004 was not readily available online at

When water-containing bacteria is sampled and processed appropriately in a laboratory, bacterial colonies will form on special growth plates. Bacterial standards typically refer to the number of bacterial colony-forming units, or CFUs, found in a sample of water. In Virginia, two measurements are regulated and monitored: 1) the number of CFUs in any single sample; and 2) the geometric mean of a minimum of four weekly samples during any calendar month.  (A geometric mean is nth root of the product of n numbers.  For example, the geometric mean of 2, 4, and 8 [n = 3] would be the cube root of 64 [2 x 4 x 8] or 4; the geometric mean of 8, 8, and 8 would be 8.)  The instantaneous standard is the maximum number of bacteria colonies allowed in any single sample, whereas the geometric mean standard is the upper limit allowed for a minimum of four weekly samples taken during any calendar month. The geometric mean standard is lower than the instantaneous standard (regulations allow occasional high levels but aim for a lower level over time).

Virginia’s bacteria standards are shown in Table 1, compared to EPA criteria. As the table shows, Virginia’s standards are in compliance with the BEACH Act. These standards are part of regulations published in January 2011; the regulations are in 9 VAC 25-260 of the Virginia Administrative Code.  Note that the bacteria group enterococci are used as the indicator bacteria in Virginia’s marine waters, while E. coli is used as the indicator in fresh water.  Numbers before the slash are the maximum-allowable instantaneous levels; numbers after the slash are the maximum-allowable geometric means (all values in colony-forming units).

Table 1. U.S. EPA Criteria and Virginia Standards (Instantaneous and Geometric Mean) for E. coli and Enterococci Bacteria in Surface Waters



Fresh Water


Marine Water


E. coli =


Enterococci =


E. coli = Not applicable.

Enterococci =



E. coli =


Enterococci =


* All values in the table are in colony-forming units per 100 milliliters of water. Numbers before the slash are the maximum-allowable instantaneous levels; numbers after the slash are the maximum-allowable geometric means.
Sources: U.S. EPA, Implementation Guidance for Ambient Water Quality Criteria for Bacteria, May 2002 Draft, p. 81; and Virginia Administrative Code, 9 VAC 25-260-170 (January 11, 2011).

Finding a Source

If a coastal water source consistently fails to support its designated uses (by exceeding its instantaneous standard or geometric mean), it can be categorized as “impaired” in the state’s biennial water quality report to the U.S. EPA. This can lead to a “total maximum daily load” (TMDL) process. This extensive and costly process determines a maximum amount of pollutant that a water body can receive and still meet state standards. The next step is to reduce the current amount of that pollutant in the water. In cases of bacterial pollution, it is often important to identify the source of fecal matter contributing the bacteria.

A set of technologies to do just that is collectively called microbial source tracking (sometimes referred to as bacterial source tracking). The varied diets of humans, wildlife, and livestock result in different communities of intestinal bacteria. These differences make it possible, with DNA-based techniques that are source specific, to distinguish what kind of animal the bacteria in a sample (or series of samples) formerly inhabited.

If one knows the general source of the bacteria that is impairing a coastal water body, it’s then possible to focus on land uses or other activities that may be causing the contamination. For example, if the contamination is from human sources, the focus might be on malfunctioning septic systems, sewer-line leaks, boat discharges, or wastewater treatment system overflows. If the source were domestic animals, the focus might be on educating pet owners to clean up their pets’ waste or on restricting pets from beach areas. If the source were livestock or wildlife, the focus might be on better ways to manage stormwater runoff in the watershed.


Elevated bacteria are one of the most common reasons for health officials to issue a beach closure or advisory. Closures and advisories occur infrequently in Virginia, but even an occasional situation can have important social and economic consequences. Beach water-quality monitoring allows us to identify the days when bacteria get the beach to themselves.


Natural Resources Defense Council, “Testing the Waters, 2013. A Guide to Water Quality at Vacation Beaches,”, accessed Nov. 17, 2017.

U.S. Environmental Protection Agency, “Clean Beaches Plan – 2004,” accessed at, October 30, 2013.  [Link no longer provides ready access to the document, as of 11/16/17.]

U. S. Environmental Protection Agency, “National Coastal Condition Report III,” Dec. 2008.  Available online at, accessed October 23, 2013.

U. S. Environmental Protection Agency.  “Draft National Coastal Condition Report IV,” Sept. 2012.  Accessed online at, October 23, 2013.

U. S. Environmental Protection Agency.  “Ambient Water Quality Criteria for Bacteria – 1986,”  Jan. 1986.  Updated information available online at, as of 11/17/17.

U. S. Environmental Protection Agency.  “Bacterial Water Quality Standards for Recreational Waters (Freshwater and Marine Waters) Status Report June 2003.”  Originally accessed October 2013; available online at this link, as of 11/16/17.

U. S. Environmental Protection Agency. “Implementation Guidance for Ambient Water Quality Criteria for Bacteria (EPA-823-B-02-003),” May 2002 draft.

U.S. Environmental Protection Agency.  “Volunteer Stream Monitoring: A Methods Manual,” (EPA 841-B-97-003), 1997.

Virginia Department of Environmental Quality.  “Designated Uses.”  Online at, accessed Oct 23, 2013.

Virginia Department of Environmental Quality, “Water Quality Criteria,”, accessed Oct 23, 2013.

Virginia Department of Health.  “Beach Monitoring,” online at, last accessed 11/16/17.

Virginia Department of Health.  “FAQ’s- VDH Swimming Advisory,”, last accessed 11/16/17.

Other Sources of Beach and Coastal Information

The “Healthy Swimming” page from the U. S. Department of Health and Human Services’ Centers for Disease Control is located online at

The Web site for the Virginia Department of Environmental Quality’s Coastal Zone Management Program is The program publishes Virginia Coastal Management twice a year (available online). For more information about the program: phone (804) 698-4320.

3 responses to “Beaches and Bacteria (January 2014 Update of an August 2004 Virginia Water Central Article)”

  1. […] article was updated in January 2014 and is available at….  It was first published by the Virginia Water Resources Research Center in Virginia Water Central […]

  2. […] article was updated in January 2014 and is available at….  It was first published by the Virginia Water Resources Research Center in Virginia Water Central […]

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