Department Of Health Tests Water Quality From Memorial Day To Labor Day


The Anne Arundel County Department of Health’s goal is to reduce the risk of exposure and incidence of disease where bacteria levels are above the U.S. Environmental Protection Agency’s (EPA) acceptable standard for direct water contact or where a public health risk, such as a wastewater spill, exists. Anne Arundel County has more than 534 miles of linear coastline, and county residents and visitors enjoy the recreational use of its many waterways. Swimming in rivers, creeks and other natural waters has the potential for risk due to bacteria, viruses and other harmful microorganisms that exist in natural water bodies. Safety precautions are important because disease-causing microorganisms, such as Mycobacterium marinum or Vibrio vulnificus, can enter the body through open cuts, scrapes and wounds.

From Memorial Day to Labor Day, the Anne Arundel County Department of Health takes samples from more than 80 county beaches where people swim or engage in activities that may result in ingestion of recreational water. The water is tested for enterococci, bacteria that come from the intestines of all warm-blooded animals and are associated with fecal contamination. Enterococci are used to indicate water quality trends in recreational water. Results are updated weekly, biweekly or monthly based on the EPA’s criteria of location, use, ecological factors, pollution sources and risk of contamination. Many factors can affect readings. Rainwater runoff, waterfowl and tidal action can cause high results that nature will fix in a day or two.

Water Quality, Health Risks, And Swimming Or Fishing In Anne Arundel County

After rainfall, all Anne Arundel County beaches are under a no swimming and no direct water contact advisory for 48 hours due to predicted elevated bacteria levels. Do not swim until 48 hours after rainfall or until the water clears.

Under Maryland regulations, the Anne Arundel County Department of Health conducts water quality sampling at community bathing beaches along area creeks and rivers from Memorial Day to Labor Day. The water bodies are tested for levels of enterococci bacteria. Below are the most commonly asked questions about the Department of Health’s water quality sampling and recreational use of natural water.

How does the department determine which bodies of water to monitor?

The Department of Health follows criteria issued by the State of Maryland and the U.S. Environmental Protection Agency (EPA). The EPA criteria are for recreational water bodies that are deep enough for most people to swim with their entire body underwater.

What are enterococci?

Enterococci are bacteria found in the intestines of all warm-blooded animals, including humans. Because the bacteria are always present in animal and human waste and are easy to detect, they are used as indicators of water quality conditions. Enterococci are in food, water and soils, but they cannot become airborne. The EPA recommends using enterococci levels to measure bacterial contamination in recreational water.

What does monitoring for enterococci in water samples show?

Enterococci results are most useful for watching long-term trends in water quality. Results are collected over several weeks and then evaluated. Since many factors can affect readings, single-sample results may be misleading. Rainwater runoff, waterfowl and tidal action can cause high results that nature will fix in a day or two. If sample results remain high over time, the department will look to identify the source of pollution.

What causes the Department of Health to issue an advisory recommending against swimming and other direct water contact in a certain area?

Swimming in natural water bodies poses certain risks. If enterococci counts exceed the acceptable level or when a sewage spill impacts a waterway, a human health risk exists. The Department of Health will issue an advisory against swimming and other direct water contact activities. There are no restrictions on boating, crabbing or fishing.

When will the Department of Health lift an advisory?

The advisory will remain in effect until test results show enterococci counts are within acceptable levels. The acceptable level for bodies of water sampled is 104 MPN (Most Probable Number of) colonies of organisms per 100 milliliters of water.

What health risks are associated with swimming and other direct water contact?

Natural water bodies can contain bacteria, viruses or other harmful microorganisms. Common problems associated with swimming in contaminated water are ear, eye and skin infections. Diarrhea and other water-related illnesses can occur from accidentally swallowing contaminated water. Disease-causing microorganisms, such as Mycobacterium marinum, can also enter the body through cuts and scrapes.

What are Mycobacterium marinum and Vibrio vulnificus?

Mycobacterium marinum is a bacterium most commonly found in fresh or saltwater that may cause infections in fish and people. It is a natural part of the ecosystem of the Chesapeake Bay and its tributaries and also exists in other water bodies worldwide. In humans, it can cause skin and joint infections.

Water-related infections can also be caused by Vibrio vulnificus, a bacterium found in saltwater.

What precautions should I take before swimming in area creeks and rivers?

After rainfall, all Anne Arundel County beaches are under a no swimming and no direct water contact advisory for 48 hours due to predicted elevated bacteria levels. Do not swim until 48 hours or until the water clears. Never swim near storm drains. Look for trash and other signs of pollution, such as oil slicks or scum on the water. These kinds of pollutants may indicate the presence of disease-causing microorganisms that may also have washed into the water. Do not swim with dead fish or other dead animals. Don’t swim if you have an ear infection, perforated eardrum, open cuts or skin lesions. Exercise caution if you have immunity problems.

What should I do after coming in contact with natural bodies of water?

Wash well with soap and warm, clean water as soon as possible.

How can I prevent illnesses when crabbing and fishing?

Assure proper bandaging and care of wounds or abrasions. Wear sturdy gloves if you will have contact with water and sharp objects (fish fins and scales, boating equipment, etc.). Keep hands as clean as you can. Waterless hand cleansers kill many germs and are easier on the skin than constant handwashing.

Is it OK to eat crabs and fish from an area that is closed to swimming?

Because cooking kills bacteria, it’s acceptable to eat crabs and fish taken from these areas provided they are handled properly. Fish should be kept in a cool place or on ice and then cooked thoroughly. Live crabs should be thoroughly cooked. Cooked fish and crabs should not come back into contact with any surfaces or containers where they were kept uncooked.

You should not eat any filter-feeding shellfish, such as oysters or mussels, taken from water contaminated by sewage. They feed by drawing water through a membrane and trapping food for digestion. Therefore, they draw contaminated water through the flesh that you’ll end up eating – this is particularly dangerous if consumed raw because of the disease-causing bacteria associated with sewage. Organisms like viruses (especially hepatitis A and norovirus) are trapped in the flesh of the shellfish and are not killed by the normal cooking process.

What should I do if I have symptoms of a recreational water illness?

If you have symptoms of a gastrointestinal, skin, ear or other infection, consult your doctor for immediate treatment. Let your doctor know that you have had contact or suspected contact with contaminated water.

How can I get information about the water at my favorite Anne Arundel County beach?

From Memorial Day to Labor Day, the Anne Arundel County Department of Health provides water sampling results on this website and on a 24-hour information line (410-222-7999). Both the website and phone line provide reports on emergency closings of local waterways year-round. The Department of Health offers email alerts of recreational waterway advisories and closings. To sign up for these alerts, visit, or receive text messages and tweets by following the Department on Twitter @AAHealth_Water.


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