Purpose: This study evaluated the microbial quality of surface agricultural water used in pre-harvest production on the Eastern Shore of Virginia.
Methods: Water samples (1 L) from 20 agricultural ponds were collected during the 2015 growing season (n=200). Total aerobic bacteria, total coliforms, and generic Escherichia coli were enumerated for each sample. Population levels of each microorganism were calculated in log CFU/100 ml. Samples were also enriched for Salmonella. Environmental and meteorological factors were analyzed for their association with the detection of a Salmonella-positive water sample.
Results: Currently, 17 of the 20 ponds met the FSMA-Produce Safety Rule standards for surface agricultural water. Three ponds did not meet the standards because the statistical threshold value exceeded 410 CFU/100 ml of generic E. coli. Salmonella was detected in 19% of water samples (38/200). Interestingly, 17 of the 20 ponds were Salmonella-positive at least once during the growing season. Total aerobic bacteria, total coliforms, and generic E. coli levels were not associated with the detection of Salmonella in water samples. Furthermore, farm was significantly associated with the likelihood of detection of Salmonella.
Significance: Minimal data exists on surface water metrics in Virginia. Our findings provide crucial data that will assist growers with science-based evaluation of their water and implementation of strategies that reduce the likelihood of produce contamination.