Water quality has been a concern for numerous stakeholders and has been monitored for many decades; in particular since the enactment of the Clean Water Act in 1972. However, more than 30 years after the Clean Water Act was implemented, a significant fraction of US rivers, lakes, and estuaries continue to be classified as failing to meet their designated use due to high levels of fecal bacteria (US EPA 2005). As a consequence, protection from fecal contamination is one of the most important and difficult challenges facing environmental scientists, regulators, and communities trying to safeguard public water supplies as well as waters used for recreation (primary and secondary contact). Traditional water quality monitoring has helped improve water sanitation to protect public health but has also led to economic losses due to closures of recreational beaches, lakes and rivers. Additionally, solutions to contamination are not always readily apparent and easily identifiable. The ability to discriminate between sources of fecal contamination is necessary for a more defined evaluation of human health risks and to make waters safe for human use.
The potential sources of fecal contamination causing these impairments can be classified into two groups: point sources that are easily identifiable (e.g., raw and treated sewage and combined sewer overflows) and non-point sources that are diffuse in the environment and may be difficult to identify (e.g., agriculture, forestry, wild-life, and urban runoff). Understanding the origin of fecal contamination is paramount in assessing associated health risks as well as identifying the actions necessary to remedy the problem (Scott et al. 2002). As a result, numerous methods have been developed to identify fecal contamination as well as differentiate between these sources of pollution. Accurately identifying these sources can help to facilitate the elimination of waterborne microbial disease as a leading threat to public health.