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INVESTIGATION AND EVALUATION OF CRYPTOSPORIDIUM AND GIARDIA IN COMBINED SEWER OVERFLOW (CSO) AND STORMWATER RUNOFF
Citation:
Arnone*, R D., M Borst*, AND J. F. Walling. INVESTIGATION AND EVALUATION OF CRYPTOSPORIDIUM AND GIARDIA IN COMBINED SEWER OVERFLOW (CSO) AND STORMWATER RUNOFF. Presented at World Water & Environmental Resources Congress, Anchorage, AK, 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, WI outbreak affected more than 400,000 people, 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. In this study the urban contribution of Cryptosporidium and Giardia from 10 distinct CSO and stormwater locations was estimated. These data are useful for drinking water plants located downstream of CSO and stormwater discharges. EPA Method 1623 was used for stormwater analysis, and a modification of this method was used for CSO analysis. Several indicator organisms and physical parameters were measured to further describe the sample and to determine possible correlations with these protozoa. In addition, the method variability and cyst/oocyst recoveries were determined. Results show CSO and stormwater runoff from urban areas were not a significant source of Cryptosporidium to surface waters. Giardia was found in significant numbers in CSO, and also found, but to a lesser extent, in urban stormwater runoff. A meaningful correlation was not found between concentrations of indicator organisms and the two protozoa.