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Home > Resources & Publications > Newsletters & Magazines > Chenier Ecology > 2007 > 09-07

Resources & Publications:  Chenier Ecology

September 2007

The reason for health closures is the occurrence of high fecal coliform counts during high flow episodes of the Calcasieu River. Fecal coliform is a bacterium found in the intestines of warm blooded animals – birds and mammals, including humans. Fecal coliform is monitored as an indicator species. It is assumed that if it is present, other human pathogens and bacterium such as hepatitis, vibrio, cholera, etc. may also be present.

Fecal coliform bacteria can live for up to 48 hours outside of the gut of warm blooded animals. When river flows are heavy, water carrying fecal coliform and potentially other pathogens reaches the harvest area alive. A study completed in the early 1990s by the Louisiana Department of Public Health correlated fecal coliform counts on Calcasieu Lake and West Cove oyster harvest areas with the Calcasieu River stage at Kinder. When the river stage at Kinder reaches 13.5 feet, fecal coliform numbers on the Lower Calcasieu management area pose a health threat. A health threat is posed for the West Cove management area when the Kinder station reaches seven feet. Harvesters monitoring the status of openings can call (800) 256-2775.

The mechanism by which fecal coliform enters our waterways is through runoff during heavy rainfall. This is called non-point source pollution, which is very diffuse and hard to identify. The concern over fecal coliform in our waterways can be divided into two sources; those coming from human activities, and naturally occurring sources (birds and animals). During winter months, water draining through marshes surrounding Calcasieu Lake picks up fecal coliform from large waterfowl populations overwintering and from furbearers and other animals. Normally, these wastes are assimilated in the marsh ecosystem and reduced to usable nutrients and organic matter. But, in heavy rain and in cooler seasons, it is flushed out before being metabolized or reduced.

Runoff from rural and urban areas picks up fecal coliform from faulty or overloaded sewer treatment systems. Both residential and municipal sewer treatment plants are designed to reduce sewage and bacteria through biological and mechanical treatment. But heavy rainfall runoff overloads the systems and water flushes untreated waste out and eventually into the river. Improperly maintained home sewage treatment units also contribute to untreated waste entering the river.

Oysters are filter feeders and readily pick up bacteria and pathogens when actively feeding. The major concern with oysters is caused by the raw consumption of oysters and thereby increasing the risk of also consuming live bacteria and pathogens.

According to the U.S. Food and Drug Administration, approximately 20 million Americans eat raw oysters; however the risk is not the same for everyone. People with certain health conditions such as diabetes, immune disorders, stomach problems, liver disorders or disease and those on long-term steroid use have an increased risk of becoming ill from eating raw oysters. People within these categories or those wanting to reduce their risk and still enjoy oysters are encouraged to consume only fully cooked oysters.

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