TR-530 Expansion and Evaluation of the Texas Bacterial Source Tracking Program (FY18-FY19)

Authors: Anna Gitter, Lucas Gregory, Brian Hux, John Boswell, Terry Gentry, Carlos Monserrat, Elizabeth Casarez, Kristina Mena

The 2018 Texas Integrated Report of Surface Water Quality identified 250 waterbodies as being impaired due to excessive bacteria in Texas. To identify bacterial sources and help address these impairments, Texas established the Bacterial Source Tracking (BST) Program in 2006. To support the maintenance, expansion, and use of the Texas BST Library and other BST tools, the Texas Water Resources Institute (TWRI), University of Texas Health Science Center at Houston School of Public Health, El Paso Campus, Environmental Microbiology Laboratory (UTSPH EP), and the Texas A&M AgriLife Research, Department of Soil and Crop Sciences (SCSC) collaborated with the Texas State Soil and Water Conservation Board (TSSWCB) to 1) expand the Texas Escherichia coli (E. coli) BST Library through known source sample collection in the Mission and Aransas river watersheds; 2) support BST efforts in the Mission and Aransas river watersheds; 3) evaluate and refine the Texas E. coli BST Library by assessing geographic and temporal stability, composition, average rates of correct classification, diversity of source isolates of the updated library, and working to develop/refine source-specific PCR markers; and 4) provide outreach regarding BST. Major findings from the project included:

  • The current version of the Texas E. coli BST Library now contains 1,912 isolates from 1,653 known source fecal samples retrieved from 4,301 individual known source samples in over 20 watersheds. An additional 30 isolates from the Mission and Aransas Rivers were added to the BST Library.
  • BST analysis in the Mission & Aransas watersheds indicate that wildlife (non-avian and avian) are the leading contributors of E. coli in the two individual watersheds, followed by domestic animals and humans.
  • Analysis of the Texas E. coli BST Library and qPCR markers identified: 1) the need for continued evaluation of geographic impacts on source identification as the statewide library continues to expand and 2) potential application of new human-specific qPCR markers for future BST projects in Texas.
  • Outreach of the BST Program resulted in:
    • Three conferences and five meetings where BST Program results were shared with the public.
    • The Texas BST Program website was updated as part of the Texas Water Resources Institute’s overall website redesign.
    • The BST Program had 385 visits.