Microbial Source Tracking Removes Waterbody From 303(d) List

A study published in the Water Research journal showed how microbial source tracking was instrumental in removing a waterbody from the 303(d) impaired water body list by the Florida Department of Environmental Protection.

MST test results were used as evidence to show that the fecal bacteria found in the waterbody did not come from humans but it came from birds.

Researchers were studying a watershed managed for wildlife conservation in central Florida. Water samples at the site consistently showed high bacteria levels, more than state regulatory guidelines for fecal coliforms. It was suspected that the bacteria came from sewage contamination. However, MST results showed that birds were actually the major contributor and the sewage markers were attributed to cross-reaction with deer feces.

The management organization was able to obtain natural source exclusion (NSE) status due to the MST results. According to the study, achieving NSE status can be cost-effective because management organizations may not be required to implement remediation practices or develop Total Maximum Daily Load (TMDL) programs.

“To the best of our knowledge, this is the first peer-reviewed publication that demonstrates natural source exclusion in a watershed that would have had to develop a TMDL plan. We demonstrated that wild birds, but not sewage, contributed substantially to FIB levels in this stream,” Dr. Valerie J. Harwood, Professor the University of South Florida, told an email forum. Dr. Harwood is one of the authors of the article titled, “Determination of wild animal sources of fecal indicator bacteria by microbial source tracking (MST) influences regulatory decisions.”

Source Molecular Corporation’s Chief Executive Officer Mauricio Larenas also pointed out that the study affirms that MST does save management organizations time, money and effort in fixing sites believed to be impaired with human waste, which poses the greatest threat to public health. Mr. Larenas and the Source Molecular team have been going from state to state to conduct workshops and speak at water quality conferences on how MST can be used for effective investigations of bacteria impairment.

Researchers also stated that: “Overall, our results lend credence to the growing body of evidence that using culture-based methods for FIB [fecal indicator bacteria] alone provides an incomplete indication of microbial water quality and human health risk (Harwood et al., 2005; Schoen et al., 2011; Kirs et al., 2017).”

Source Molecular’s laboratory is the world’s only ISO-accredited MST laboratory. It passed the stringent quality guidelines and demonstrated that it performs the highest standards in its Test Method 3-QPCR for Microbial Source Tracking on water, filters, and DNA samples.