Pahl, Donna MarieMicrobial water quality standards exist to prevent food safety outbreaks due to the use of agricultural water, although little is known about how the levels the fecal indicator organisms in water relate to the counts on the tomato fruit surface. This study used fecal indicator organisms commonly used in microbial water quality standards (Enterobacteriaceae, total coliforms, fecal coliforms, and <italic>E. coli</italic>) to monitor the water quality of surface ponds, a groundwater source, and the phyllosphere of treated grape tomatoes over two growing seasons. Water source and date caused a significant difference in the counts of fecal indicator organisms. Variability in bacterial counts was found in the surface water sources over the course of the season, partially explained by environmental variables such as water temperature, pH, precipitation, and air temperature. The microbial counts on the surfaces of the tomato fruit did not reflect the water treatments applied to the plants.ThesisPlant SciencescoliformE. coliEnterobacteriaceaeGood Agricultural PracticespetrifilmsSolanum lycopersicum