From 2000 to 2002 researchers at the State of North Carolina Department of Health and Human Services, Raleigh, N.C., conducted a study in eastern North Carolina to assess the extent to which bacteria, antibiotics-resistant bacteria, antibiotic residues and nitrates are released from animal-feeding operations into groundwater aquifers and drinking-water supplies.
This study was done after extensive flooding occurred in eastern North Carolina in September 1999 due to Hurricane Floyd.
The results of the study showed that E. coli and Enterococci (enteric indicator bacteria) were present in groundwater on or near two swine farms in eastern North Carolina that have conventional anaerobic lagoon and sprayfield land application systems for swine waste management, as well as an alternative technology of compacting the swine waste solids and land—applying them as biosolids.
Multidrug-resistant E. coli and Enterococci were detected in groundwater on or near two swine farms in eastern North Carolina.
This study also detected elevated concentrations of nitrogen nutrients in the groundwater near swine farms.
Antibiotic residue analysis indicated that antibiotics were detectable in swine wastes and in some groundwater and surface-water samples at the swine farm testing sites, but rarely or not at all at the non-swine farm sites.
Overall, the data from this study show that the current practices at the two swine farms that were studied are negatively impacting groundwater by the introduction of fecal bacteria and elevated levels of nitrogenous nutrients.