Source Molecular Shares MST Guidelines to Indiana Stormwater Managers

Source Molecular Corporation discussed MST guidelines at the 2018 Annual Conference hosted by the Indiana Association for Floodplain and Stormwater Management (INAFSM) from September 5 to 7, 2018, at Old National Events Plaza in Evansville, where it was both speaker and exhibitor.

Source Molecular’s Project Manager James Herrin gave a presentation entitled, “Evidence-based Guidelines for Microbial Source Tracking Projects,” under the MS4 track. The conference also had a Floodplain Track, Stormwater Track, Technical Track and Plenary Sessions.

Mr. Herrin noted there is increasing pressure to keep the waters clean from pollutants. But an analysis of federal compliance data commissioned by an environmental group showed that 17 major industrial facilities in Colorado discharged pollutants such as E. coli bacteria that exceeded the legal limits a total of 241 times in an 18-month period. According to the analysis, Colorado had the fourth-highest number of higher-than-permitted releases per industrial facility in the country. State regulators are taking action against the violators.

Available tools to address bacteria impairment include legacy testing such as fecal indicator bacteria (FIB) and field observations. But these tools are ineffective and subjective. According to Mr. Herrin, DNA-based microbial source tracking (MST) provides a set of methods to identify sources of contamination. MST is useful in monitoring receiving waters by locating aging infrastructure in urban watershed. It is also helpful in monitoring outfall discharges to determine which outfall needs to be prioritized. MST can also monitor receiving waters for multiple sources.

In explaining the MST guidelines, Mr. Herrin cited case studies that used MST to evaluate an Illicit Discharge Detection and Elimination (IDDE) program of a Municipal Separate Storm Sewer Systems (MS4); plan best management practice (BMP) and remediation; monitor the effectiveness of a BMP; and demonstrate Natural Source Exclusion. A copy of Mr. Herrin’s presentation is available here. For additional information, contact Mr. Herrin at

The IAFSM members include federal, state, and local agency staff, engineers, consultants, planners, elected officials, members of academia, students, and floodplain residents. Among others, the association aims to keep individuals concerned with proper floodplain and stormwater management well informed through educational and professional seminars.