Little is known about the environmental contamination risks associated with agricultural uses of antibiotics or the risks for spread of resistant organisms from agricultural sites to humans. Cephalosporin resistant CMY-2 E. coli have been identified in food animals and humans from Iowa. Preliminary studies suggest that waterborne transfer may play a role in transmission of this resistance. Sixty Iowa surface waterways will be sampled monthly and E. coli expressing CMY-2 will be identified. The associations between upstream agricultural, water treatment or industrial facilities and the effects of rainfall, temperature and stream flow will be analyzed. Sites repeatedly contaminated with CMY-2 E.coli will be intensively studied to pinpoint possible sites of contamination. Candidate contaminating facilities will be identified, and ground water, fecal waste and soil contamination will be analyzed. Studies will utilize microbiology, molecular epidemiology and molecular analyses to understand the epidemiology of CMY-2 E. coli in surface waterways.