Understanding the origin of fecal pollution is essential in assessing potential health risks as well as for determining the actions necessary to remediate the quality of waters contaminated by fecal matter. As a result, microbial source tracking (MST) has emerged as a field that has evolved and diversified rapidly since the first approaches were described only a decade ago. In response to the emergence of MST, there have been three large multi-laboratory method comparison studies (two in the US and one in Europe), plus numerous workshops, book chapters, and review articles dedicated to...