Click on “Download PDF” for the PDF version or on the title for the HTML version.

If you are not an ASABE member or if your employer has not arranged for access to the full-text, Click here for options.

Federal regulations require that Total Maximum Daily Loads(TMDLs) be conducted to restore impaired uses on waterbodies not attaining water quality standards. Addressing bacteria related water quality impairments involves identification and quantification of potential sources. DNA based source tracking tools have the potential to greatly enhance the source assessment phases of this process. The Texas Commission on Environmental Quality Studies have conducted several studies throughout Texas using several different library based methods. . The studies employed libraries ranging from1,058 to more than 120,500 isolates. The number of classification categories ranged from 6 to 21. The studies produced unknown classification rates ranging from 10% to 46.25%.. Rates of correct classification ranged from 9%-100% across all of the watersheds and methods. The results from these studies indicate that additional refinement is necessary before the methods are used in TMDL development with any certainty. The use of broad categories, large libraries and multiple methods could possibly enhance the performance of this tool for TMDL development. However, microbial source tracking tools should be utilized in concert with other methods to fully characterize sources for the development of effective restoration plans.