NEWS FROM THE DELAWARE DEPARTMENT OF NATURAL RESOURCES, DEPARTMENT OF AGRICULTURE AND DEPARTMENT OF HEALTH AND SOCIAL SERVICES, DIVISION OF PUBLIC HEALTH

June 25, 2009
Vol. 39, No. 282

Contact: Robin Tyler, DNREC Division of Water Resources, (302) 739-9942; or Melinda Carl, DNREC Public Affairs, (302) 739-9902; Anne Fitzgerald, Department of Agriculture, (302) 698-4520; and Jennifer Wooleyhand, Division of Public Health, Department of Health and Social Services, (302) 744-4704

    Water advisories to be posted for blue-green algae at lakes and ponds
                                     Committee recommends common-sense guidelines for annual occurrence
 
DOVER – A team of scientists, biologists and managers from the Department of Natural Resources and Environmental Control, the Department of Health and Social Services, Division of Public Health and the Department of Agriculture have developed a water advisory sign that will be displayed at selected state and municipal lakes and ponds throughout Delaware to alert the public to the presence of blue-green algae and its possible harmful effects on people and animals.

States ranging from Massachusetts to Washington and Wisconsin have developed or are developing guidance for the public who may recreate in fresh water bodies.  Blue-green algae – also known as cyanobacteria – are naturally occurring microscopic organisms that increase in density or “bloom” under certain environmental conditions, most commonly, an oversupply of nutrients combined with warm water temperatures. 

The blue-green algal blooms can form dense mats that appear most often as thick green, white or reddish-brown scum on the surface of the water. The blooms or dense mats can cover entire areas of a pond or only certain portions such as along the shoreline. When the algal blooms die and decay, the water can appear multi-colored and mistaken for a paint spill. 

As noted in DNREC’s 2006 news release, blue-green algal blooms occur annually throughout Delaware on ponds and lakes of all sizes and some tidal freshwaters. They begin forming during summer and are often particularly vigorous in early autumn.  

Certain strains of blue-green algae can produce toxins and the incidence of this occurrence is unpredictable. Although there have been no reported cases of human or animal illness in Delaware associated with exposure to blue-green algae, the inter-agency team was formed to review the scientific knowledge of the state’s recreational lakes and ponds and develop educational water advisories as a common-sense, precautionary measure for the public.

The best precaution is to avoid contact or exposure to water with blue-green algal blooms or scum and if contact is unavoidable or accidental, to wash thoroughly after contact.  Recreational activities that may inadvertently result in swallowing or inhaling droplets of water from areas of scum should be avoided.  

Health effects to humans from skin contact can include rashes, hives and blisters, especially on lips and under swimsuits. Less frequent reactions reported nationally in individuals who have inhaled or swallowed water containing high concentrations of blue-green algae include, from inhalation: runny eyes and nose, sore throat, asthma-like symptoms or allergic reactions.  If swallowed, reactions could include: diarrhea and vomiting, liver toxicity, kidney toxicity and neurotoxicity.

Pets may have the same adverse reactions as humans and should be washed or rinsed off after contact with the water.

Toxins from blue-green algae have been documented in waters in other parts of the country where the algae is not visible or in full bloom. The problem is global as well as local and is being addressed in many other countries as scientific knowledge and data related to the algae’s capabilities to form toxins increases.

DNREC’s 2006 news release regarding blue-green algae was issued during a blue-green algal bloom on Silver Lake in Dover, which lingered for weeks and gave the water the characteristic “pea green” color after forming a scum on portions of the lake’s surface. The high coloration caused some residents to report a suspected paint spill.

Since then, laboratory results from a single day sampling during a bloom indicated elevated levels of the blue-green algal toxin in laboratory results. Although a sample taken the following day showed no elevated levels of the toxin and, as noted above, no human or pet illnesses associated with the blue-green algae have been reported in Delaware, the team was constituted to address potential health effects.

In Delaware, as elsewhere, dense blue-green algae blooms also contribute to lowered levels of dissolved oxygen, which can lead to fish kills.  Information on how to help reduce algal blooms in waterways, a list of lakes and ponds where signs will be posted, and answers to frequently asked questions about blue-green algae can be found at www.wr.dnrec.delaware.gov.

                    Blue-Green Algae in Delaware Freshwaters
                                                                         FACT SHEET

Blue-green algae, also known as Cyanobacteria, occur naturally in freshwaters worldwide and are found each year throughout Delaware on ponds and lakes of all sizes and in some tidal fresh waters.

During summer and into early fall blue-green algae give many ponds a “murky” appearance and sometimes form a “paint-like” scum on the water surface that is commonly referred to as “pond scum.” The water and scum are typically pea-green in color but can also exhibit combinations of several colors including blue-green, white, brown and red.  A “swampy” odor can be present.

Some blue-green algae in Delaware ponds can produce toxins. Toxins are chemical compounds. They are produced by the algal cell and, if contacted or swallowed, can be harmful to people and animals. Blue-green algae may not always be producing toxin even if they have the capability to do so.  It is not possible to know if algae are producing toxins without laboratory tests. It is also not possible to predict when algae will produce toxins.  Because of this, ponds, lakes and tidal fresh waters that show signs of blue-green algae should be approached with care.

No cases of human or animal illness associated with blue-green algae exposure have ever been reported in Delaware; however all waters that have algae should be treated with caution, particularly waters that have scum.

For Humans and Animals, contact with water containing blue-green algal toxins may result in health problems that include:

• Skin rashes, hives or blisters

• Irritation of eyes and nose, sore throat, and breathing problems

• Stomach cramps, diarrhea, vomiting, headache, fever, muscle weakness. In extreme cases, pneumonia, liver damage, and kidney failure have been reported.

 Use common sense when near ponds, lakes and other freshwater bodies and please follow this advice:

• Do not swallow water from any waterway.

• Do not swim, water ski, play, or wade in areas of scum.

• Avoid scum while boating.

• Avoid exposure to water with blue-green algae scum or wear gloves, if unavoidable.

• Avoid blue-green algae areas, especially if you suffer from asthma, hay fever or allergies.

• Do not let pets or livestock drink or get into water where scum is present.

• Do not feed waterfowl in or near scum areas.

• Do not cook or wash food in pond water.

• Clean fish properly and follow fish consumption advisories listed on DNREC’s website, www.dnrec.delaware.gov/fw/Fisheries.advisories.htm.

If you or your pet is exposed to blue-green algae scum:

• Wash thoroughly to remove all traces of scum.

• If you or your pet becomes ill after contact with pond water, call your family doctor or veterinarian.

For more information, visit www.dnrec.delaware.gov/wr/