Floodway Chemical, Pesticide Contamination below Levels of Health Concern
Detailed analysis of the May 24 limited sampling of floodwaters in the Birds Point-New Madrid Floodway in southeast Missouri found contamination at levels typically found in the Mississippi River in nine samples of collected water. The samples are also below levels of health concern for those involved with continuing cleanup activities. Previous results had indicated the presence of E. coli bacteria, however it was detected well below Missouri’s official standard for fishing, wading and boating activities.
EPA crews on May 24, conducted surface water sampling at six locations within the floodway and three outside the floodway to determine if any threats might be present for emergency response workers who could come into contact with the floodwaters.
“Public health and the health of emergency responders are always critical issues in any flood response,” said EPA Region 7 Administrator Karl Brooks. “While the levels found were below health concerns, we still recommend the use of appropriate personal protection equipment for the public and workers who may contact floodwater.”
EPA’s surface water samples were analyzed for organophosphorus pesticides, triazine herbicides, total metals including aluminum, perchlorate, total petroleum hydrocarbons (TPH), gasoline range organics (GRO), and TPH-diesel range organics.
Levels of metals found in surface waters were consistent with those found in the Mississippi River and were below health- based limits. Of the organic compounds analyzed, only perchlorate and two herbicides (atrazine and metolachlor) were actually detected above the detection limits of the instruments used by the laboratory.
Metolachlor was found at three locations, slightly above the detection limit of 0.2 micrograms per liter (ug/L), ranging from 0.21 to 0.26 ug/L. Atrazine was found in all nine samples, and ranged from 0.38 to 1.1 ug/L. Both of these are below EPA's respective drinking water Maximum Contaminant Level (MCL) or Health Advisory (HA) level. These levels are used as conservative health-protective screening values for incidental ingestion of water. The data are also consistent with concentrations found upstream in the Mississippi River throughout the year by the U.S. Geological Survey at their water quality monitoring station in Thebes, Missouri.
Perchlorate was found at three of nine locations sampled at levels ranging from 10.6-11.9 ug/L. This falls below the existing EPA interim health assessment value for perchlorate of 15 ug/L. Perchlorate is both a naturally occurring and man-made chemical that is used to produce rocket fuel, fireworks, flares and explosives. Perchlorate can also be present in bleach and in some fertilizers.
The primary concern regarding activities in receding floodwaters continues to be the potential presence of bacteria. EPA continues to advise citizens to avoid contact with floodwaters, if possible. Harmful bacteria in the water can cause symptoms such as stomach ache, fever, vomiting and diarrhea. Persons exposed to fecal coliform can become ill if they have an open cut, wound or scrape that comes into contact with contaminated water. Symptoms include fever, redness and swelling at the site of an open wound. If these symptoms occur, a doctor should be consulted.
Normally, the Missouri Department of Natural Resources (MDNR) is responsible for water quality testing in the state. However, due to extraordinary circumstances related to responding to the Mississippi River flooding, EPA offered its assistance to the state to conduct this round of limited sampling.
The U.S. Geological Survey is also conducting water quality sampling within the floodway.
EPA involvement in the floodway began in mid-April when the Agency assisted MDNR and bulk fuel suppliers to contact farmers and agricultural operators within the floodway and remove threatened petroleum tanks and small amounts of hazardous materials, prior to the opening of the floodway by the U.S. Army Corps of Engineers.