DNREC monitors waterbodies commonly used for swimming and other recreational activities by testing for Enterococcus bacteria, a harmless bacteria found in the intestines of warm-blooded animals (including humans). While Enterococcus doesn’t cause illnesses, it serves as an indicator for pathogens, harmful bacteria and viruses that are also found in the intestine.

For more information, please contact the DNREC Shellfish and Recreational Water Programs, at 302-739-9939.

Primary Sources of Illness

Sources of these pathogens may include humans, wildlife, pets and livestock. They can enter our waters through rainfall runoff and stormwater pipes, malfunctioning septic systems and human waste from boats and swimmers.

Illness risk is generally higher after rainfall because pathogens are washed into the water. It is also higher in waters that do not have a lot of flow and are not regularly flushed out by tides.

The pathogens that may cause illnesses from recreational activities in natural waterbodies are generally the same as those that cause foodborne illnesses, such as Norovirus and Salmonella.

Illness may be contracted through accidentally swallowing small amounts of water during recreational activities, so these pathogens are generally not of concern if a person’s head is not submerged under the water. Symptoms of illness may include nausea, diarrhea, abdominal cramps and sometimes fever.

At-Risk Groups

Like the risk of foodborne illness, the risk of illness from recreational activities in natural waters is most significant for at-risk groups. These include small children, senior citizens and people with certain medical conditions or a weakened immune system.

If you are unsure whether you are in the at-risk group, please consult your doctor. In people not in the at-risk group, illness occurs rarely and is generally mild.

Individuals considered at-risk include small children, senior citizens and people with certain health conditions including:

If you are unsure whether you are in the at-risk group, please consult your doctor.

Other Sources of Illness

There are other potential sources of illness or health effects from recreation in natural waters.

In Saltwater

Vibrio bacteria is a naturally occurring bacteria that may cause infections of skin cuts or wounds, particularly in at-risk groups.

Because Vibrio is part of the normal ecosystem and does not originate from intestines, it is not indicated by Enterococcus. Recreational water advisories are not issued for Vibrio since it is naturally present in all saltwater or brackish water.

Seabather’s Eruption (sometimes incorrectly referred to as sea lice) is an itchy rash caused by contact with jellyfish larvae, especially when the larvae are trapped between a bathing suit and the skin.

In Freshwater

Naegleria fowleri is an amoeba that may enter the nose and cause a brain infection. Cases are rare (about ten per year in the US) but are almost always fatal.

No cases have been reported in Delaware, as the amoeba prefers warmer waters and so is more common in southern states.

Blue-green algae blooms, which have the appearance of pond scum, may release toxins that are harmful to humans and animals. No illnesses have been reported in Delaware.

In Saltwater and Freshwater

Swimmer’s Itch is a skin rash caused by an allergic reaction to a microscopic parasite that infests some birds and mammals. Because humans are not a good host for this parasite, the rash resolves itself in time, and most cases do not require medical attention.

Protect Yourself and Others

Tips for Protecting Your Own Health

• Take a shower after recreating. 
• Wash hands before handling food. 
• Know that illness is higher after rainfall and with submersion of the head. 
• Take care to avoid sustaining a skin cut or wound while recreating. 
• Wear water shoes. 
• Wear gloves when fishing or crabbing. 
• If you cut yourself, leave the water, clean it and seek immediate medical attention if any symptoms develop. 

Tips on Keeping Our Beaches Clean

• Pick up pet waste and dispose of it properly. 
• Use designated restrooms and dispose of diapers properly. 
• Do not attract birds by feeding them. 
• Do not discharge untreated human waste from boats in any Delaware waters. 

Safety of Fish or Shellfish from Waters Under a Recreational Water Advisory

Fishing and consumption of wild-caught fish and shellfish are not affected by recreational water advisories. Pathogens are killed by cooking.

DNREC monitors the presence of chemical contaminants in the edible flesh of finfish and shellfish in Delaware waters. They issue periodic fish consumption advisories, in coordination with the Department of Health and Social Services (DHSS), to guide anglers on the amount of fish they can safely consume from specific water bodies to increase risk awareness.

The DNREC Shellfish Program offers information on shellfish safety.

Related Topics:  assessment, illness, monitoring, recreational, watershed stewardship