Leon Creek, Segment 1906 TMDL For dissolved Oxygen and Bacteria Impairments

The draft 2008 TCEQ 303(d) List (March 19, 2008) identified several assessment units in the Lower Leon Creek as being impaired based on the state’s contact recreation (bacteria) and high aquatic life (dissolved oxygen) use criterion. In response to these conditions, the TCEQ Total Maximum Daily Load Program in partnership with the San Antonio River Authority (SARA)initiated a project to verify depressed dissolved oxygen and develop information necessary to support a bacterial (E. coli) Total Maximum Daily Load (TMDL) in the Lower Leon Creek, Segment 1906. The specific objectives of the Leon Creek Segment 1906 TMDL for Dissolved Oxygen and Bacteria Impairments, TCEQ contract number 582-8-80193 were to: (1) Collect targeted 24 hour dissolved oxygen data in order to verify the water quality impairment and overall organic loading; (2) Collect targeted bacterial data in order to establish source of impairment and over loading; (3) Conduct modeling and assessment activities required to allocate loading; (4) Provide technical assistance to the TCEQ in the evaluation of actions necessary to achieve the recommended loading allocations, and; (5) Document, compile, and summarize technical analyses in reports to the TCEQ. There were two phases to this project; Phase I addressed dissolved oxygen deficiencies in Leon Creek, Phase II addressed excessive bacteria concentrations.