Challenges include the ability to identify suitable markers. Both library-dependent and library-independent methods require thorough validation." (Soule, Loge, and Gay, 2007) Challenges are stated to be inclusive of "....the ability to identify suitable markers. Both library-dependent and library-independent methods require thorough validation." (Soule, Loge, and Gay, 2007) it is stated that no matter which method is appointed for MST there are two basic and inherent assumptions to the effectiveness of these methods which include: (1) Host-specificity exists and is detectable; and (2) the proportion of any given marker is constant in the environment: (a) No differential loss; (b) No significant environmental replication; and - No significant environmental reservoirs. (Soule, Loge, and Gay, 2007)
Background on TMDL Including Components and Calculation and Various Environmental Issues Needing Considerations in Calculating TMDL
The work of Hagedorn (2001) entitled: "Bacterial Source Tracking Methodology (BST) (2001) Crop and Soil Environmental News March update states that BST is needed in every TMDL project "that contains impairments due to fecal bacteria." (Hagedorn, 2001) it is reported that a TMDL project was performed by Federal and state on the Cottonwood Creek watershed in Idaho, "without including a source-tracking component. At public meetings regulatory officials reported that, based on professional judgment, livestock was a major contributor to fecal pollution in the watershed. After ranchers raised serious objections to this conclusion, the conclusion was changed to indicate that wildlife (probably elk) were the major fecal contributors to the impaired stream. This is an example of what can happen when BST is not used. Actual results from employing BST should be used in place of opinion whenever possible. " (Hagedorn, 2001) the literature on BST, according to Hagedorn (2001) reveals that "there is one non-molecular method and three molecular methods, as well as three polymerase chain reaction methods to choose from among. The non-molecular method is stated to be 'antibiotic resistance analysis (ARA)' and the three molecular methods are stated to include: (1) ribotyping (RT); (2) pulsed-field gel electrophoresis (PFGE); or (3) polymerase chain reaction (PCR). It is related: "While procedures for RT and PFGE are relatively similar in studies that have used them, there are several substantially different variations in reported PCR methods. Also, other non-molecular methods such as carbon source utilization (BIOLOG System) and cell wall analysis of fatty acid methyl esters (FAME, Sherlock-MIDI System) should be available in the near future." (Hagedorn, 2001) Hagedorn (2001) holds that needed are the following in this area of study: (1) Needed are comparative method studies in which a collection of 'known source isolates' is utilized by various investigators through the BST method of their own choice in building libraries; (2) Data analysis of libraries where the statistical methodologies allow suitable comparisons of correct classification rates between methods to be made; (3) Studies on shared stream samples to determine how similar the identified sources and proportionality of those sources are for different BST methods. Geographic evaluation to determine if there are limitations within any of the BST methods. Developing the known source isolate collection from different regions should be appropriate to provide an answer; and (4) Stability evaluations where known source isolates are collected over some multi-year time frame and added to the libraries to determine the impact of time on results obtained with the different BST methods. (Hagedorn, 2001) the National Water Program a partnership of the USDA, CSREES & the Land Grant System states that 'Bacterial Source Tracking (BST) is being examined by CSREES and the Land Grant System. BST is stated to be a relatively new methodology for determining sources of fecal bacteria in water samples. Identification of these sources assist in the formulation of plans for reduction of pollution specifically in regards to minimizing bacterial and pathogenic pollution and ensuring safety of the supplies of drinking water. Accomplishments in this area are stated to include those related as follows: (1) University of Georgia researchers made the determination that "geographically-limited host origins for BST may not be universally applicable" (the National Water Program, 2008) (2) an Oregon State University Study reported by Field (2003) states findings that most of the tested sites in the Tillamook watershed were "heavily impacted by ruminant rather than fecal pollution (the National Water Program, 2008); and (3) Managers will be better able to target pollution prevention measures. Fifty strains of Enterococcus bacteria have been isolated for the construction of four BST libraries at Washington State University. (the National Water Program, 2008)
SUMMARY & CONCLUSION
It is clear that 'Bacterial Source Tracking in measurement of the TMDL is effective and efficient although it is not well researched at this juncture however, thus far uses of BST in measuring the TMDL of fecal coliform shows great promise for reduction of water fecal pollution levels through tracking and targeting host animals and location sites of the pollutants. There are still problems in that the host origins for BST due to geographical limitations may not be universally applicable. More research is needed and reported in the literature to be forthcoming in the near future.
Kern, J., et al. (2002) Bacterial Source Tracking in the Total Maximum Daily Load (TMDL) Process. American Society of Agriculture and Biological Engineers. Environmental regulations Proceedings of the March 11-13 2002 Conference, Fort Worth, Texas.
Bacterial Source Tracking (BST) CREES Southern Regional Water Quality Program. The University of Georgia. Online available at http://pubs.caes.uga.edu/caespubs/pubs/PDF/B1242-7.pdf.
Bernstein, Brock B, Griffith, J.F., and Weisberg, S.B. (2002) Microbiological Source Tracking Workshop: Workgroup Findings and Recommendations. Online available at: ftp://ftp.sccwrp.org/pub/download/DOCUMENTS/TechnicalReports/363_mst_workshop_document.pdf
Soule, Marilyn, Loge, Frank and Gay, John (2007) Microarray Lab - Microbial Source Tracking, Department of Veterinary Microbiology and Pathology (VMP) Washington State University. Online available at http://www.vetmed.wsu.edu/research_vmp/MicroArrayLab/Webpages/MST.asp
Hagedorn, Charles (2001) Bacterial Source Tracking Methodology (BST): Update as of March 20021. Virginia Cooperative Extension. Virginia Tech University. Crop and Soil Environmental News, March 20001.
Edelson, Jonathan (2005) Statement of Issues and Justification October 1, 2005 to September 30, 2010. S1022: Basic and Applied Aspects of Bacterial Source Tracking: Statement of Issues and Justification. SAAESD (nd) Online available at http://nimss.umd.edu/homepages/home.cfm?trackID=6536
National Water Program (2008) Source Water Assessment - Drinking Water & Human Health. USDA-CSREES National Research…