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EVALUATING CRYPTOSPORIDIUM AND GIARDIA IN STORMWATER AS A THREAT TO DRINKING WATER SUPPLIES
Citation:
Arnone*, R D., M Borst*, D. Szaro, I. Katz, AND R. Sykes. EVALUATING CRYPTOSPORIDIUM AND GIARDIA IN STORMWATER AS A THREAT TO DRINKING WATER SUPPLIES. Presented at Watershed Management Conference 2005, Williamsburg, VA, July 19 - 22, 2005.
Impact/Purpose:
To inform the public.
Description:
Since the first identified Cryptosporidium outbreak in the United Kingdom in 1983, the
pathogens Cryptosporidium and Giardia have become the subject of growing local, state, and
national concern. Both organisms have been the causative agent of many gastrointestinal
illnesses from the consumption of contaminated surface or ground water in the United
States within the last decade. Outbreaks attributed to cryptosporidiosis have occurred in
Texas, Pennsylvania, and Georgia. One of the most famous is the massive Milwaukee,
Wisconsin outbreak of 1993 that affected over 400,000 people.
The purpose of this project is to determine the concentrations of Cryptosporidium and Giardia in stormwater runoff. The results of this study will contribute to the ability in estimating the amount of Cryptosporidium and Giardia from stormwater discharges to receiving waters. A secondary objective is to determine the method variability and cyst/oocyst recoveries when analyzing stormwater. Four stormwater outfall sites will be sampled and analyzed for Cryptosporidium and Giardia during two storm events. Sample locations are classified by the United States Geological Survey (USGS) as high density residential (65% impervious), low density residential (17% impervious), landscaped/commercial and industrial (85% impervious) where approximately 15% of the total area is vegetated, and wooded area with nearly 100% pervious landcover.
This cooperative effort between the Office of Research and Development and EPA Region 2 will determine the detection frequency and concentration of Cryptosporidium and Giardia in stormwater. This data is useful to drinking water treatment plants located downstream of where stormwater discharges occur during times of wet weather. This is crucial in determining the potential concentration of these parasites in treatment plant intake. U.S. EPA Method 1623 is used for Cryptosporidium and Giardia analysis. Six indicator organisms (total coliform, fecal coliform, E. coli, Enterococcus, fecal streptococcus, Clostridium perfringens), and several physical and chemical parameters are being analyzed in unison to further describe the sample.