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INVESTIGATION AND EVALUATION OF CRYPTOSPORIDIUM AND GIARDIA IN COMBINED SEWER OVERFLOW (CSO) AND STORMWATER RUNOFF
Citation:
ARNONE, R., M. BORST, AND JOYCE M. WALLING. INVESTIGATION AND EVALUATION OF CRYPTOSPORIDIUM AND GIARDIA IN COMBINED SEWER OVERFLOW (CSO) AND STORMWATER RUNOFF. Presented at World Water and Environmental Resources Congress, Anchorage, AL, May 15 - 19, 2005.
Impact/Purpose:
To inform the public
Description:
Since the first identified Cryptosporidium outbreaks occurred in the 1980s and the massive 1993 Milwaukee, Wisconsin outbreak affected more than 400,000 people (Fox & Lytle 1996), the concern over the public health risks related to protozoan pathogens Cryptosporidium and Giardia has grown. Both organisms are recognized causative agents of gastrointestinal illnesses linked to the consumption of contaminated surface or groundwater. This study, part of a planned series to estimate the urban contribution to the total Cryptosporidium and Giardia load to surface waters, focused on combined sewer overflow (CSO) and stormwater. Limited data had been available for assessing the loads of these two pathogens in CSOs. CSO samples were collected from six outfalls in five municipalities in the U.S. and analyzed using a modified U.S. EPA Method 1623 that addressed the high solids content of CSO. Results showed that CSO from urban areas was not a significant contributor of Cryptosporidium to surface waters; it was found to be a Giardia source. Stormwater samples were collected from three stormwater outfalls. Each outfall was sampled during two separate rain events. Sample locations were chosen based on United States Geological Society (USGS) land use/land cover classifications. Cryptosporidium was found in small quantities at 50% of the locations, and Giardia was significantly found at 75% of the locations.