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An Overview of Microbial Source Tracking

Maintaining and improving water quality for drinking, human recreation, and agriculture are imperative to protect public health. Watershed-based approaches for protecting source water have become an important tool in the management of water resources in the United States. Microbial source tracking (MST) methods that identifY the source of pollution have been suggested as one of the tools for source water protection and watershed management. MST methods are mainly categorized by scientific approach and include host-specific indicator methods, phenotypic methods, molecular-based methods, and chemical indicator methods. The objective of this research was to evaluate the state of MST tool development and application. To achieve this goal, a literature review ofMST methods was conducted to investigate the state of research, knowledge and current trends. Each method reviewed was assessed as to method maturity, source specificity of data, cost, time for analysis, and other considerations. A utility survey was conducted to assess the state of awareness and implementation of MST among drinking water utilities in the United States. The results of the literature review and method evaluations indicated that there is no single universal method applicable to track all types of microbial contamination. Depending on the pollution problems, types of potential sources, and watershed characteristics, different methods can be more appropriately applied. Once chosen, MST methods can provide scientific evidence as to the identity of pollution sources. This allows water professionals to develop appropriate management and remediation strategies towards the offending pollution. Results of the utility survey indicated that MST is an emerging tool among drinking water utilities. At present, the state of MST development as a tool is still between the laboratory research and field application levels. In order to progress to the practical application stage, continuing studies to increase confidence in method reliability and feasibility are required.