Purpose: To evaluate SNIW sources for the presence of generic E. coli and compare the GM and STV from these sites to FSMA standards.
Methods: Surface and nontraditional irrigation water (100ml) from 12 sites (n=51) in the Mid-Atlantic was collected and filtered for enumeration of E. coli by standard membrane filtration (EPA Method 1604). Water from 8 surface water sites, 3 reclaimed wastewater sites, and a produce processing facility were evaluated on up to 6 different dates (Sept–Dec 2016). E. coli was quantified on MI agar, and GM and STV were calculated from all available data.
Results: E. coli levels below 126 CFU/100ml were found in 47% of water samples analyzed. Of the 12 sites analyzed, 7 had a GM above the 126 CFU/100ml FSMA threshold. The FSMA STV of 410 CFU E. coli /100ml was exceeded in 10/12 sites examined. Of all surface and nontraditional water sources tested, only 2 sites, both reclaimed wastewater, had E. coli levels below GM and STV thresholds. Overall, samples collected from river water and vegetable processing sites contained higher levels of E. coli, while reclaimed wastewater (chlorinated before sampling) and pond water contained lower levels of E. coli.
Significance: Many surface and nontraditional irrigation water sources in the Mid-Atlantic analyzed from Sept–Dec 2016 would require mitigation before use as irrigation water for fresh produce crops to comply with FSMA standards.