Water Quality > Water Quality Monitoring > TMDL

TOTAL MAXIMUM DAILY LOAD (TMDL)

The TMDL is the amount of a pollutant a stream can assimilate and still meet State water quality standards. The Federal Clean Water Act requires that TMDLs be developed on all waterbodies that are impaired (listed on the EPA 303(d) list). Once TMDLs are established for a stream, steps can be taken (rigorous wastewater permit limits, abatement of storm water runoff, utilization of best management practices, etc.) to bring pollutants below a level, that will allow the stream to meet the Texas State Water Quality Standards.

There are currently three TMDL development projects in the San Antonio River Basin. The project titles are: Salado Creek - Dissolved Oxygen, San Antonio River Basin and Leon River – Bacteria, and South Central Texas – Bacteria and Dissolved Oxygen.

The Salado Creek – Dissolved Oxygen TMDL has been completed by the San Antonio River Authority and James Miertschin and Associates. The report has been accepted by the Texas Commission on Environmental Quality (TCEQ). The TCEQ has held public meetings, and has submitted the project to the EPA for approval for this project.

James Miertschin and Associates is heading a study of affected streams and development of a TMDL if necessary for the San Antonio River Basin and Leon River for Bacteria. This project includes the following streams in the San Antonio River Basin:

• Segment 1901—Lower San Antonio River
• Segment 1903—Medina River below Medina Lake Diversion Dam
• Segment 1910—Salado Creek
• Segment 1910A—Walzem Creek
• Segment 1911—Upper San Antonio River

SARA’s project, Bacteriological Assessment of the Lower San Antonio River, will provide additional data for this TMDL development study. SARA is a stakeholder and hosted the 2002 stakeholder meeting for this project.

Texas A&M University at Corpus Christi has signed a contract to study affected streams and develop a TMDL if necessary for South Central Texas for Bacteria and Dissolved Oxygen. This project includes the following streams in the San Antonio River Basin:

• Segment 1906—Lower Leon Creek
• Segment 1908—Upper Cibolo Creek (Dissolved Oxygen Only)
• Segment 1913—Mid Cibolo Creek (Dissolved Oxygen Only)

SARA has provided laboratory support for this project. SARA is a stakeholder and hosted the 2002 stakeholder meeting.

Total Maximum Daily Load Implementation in the Upper San Antonio River, Salado Creek and Walzem Creek

The Upper San Antonio River (segment 1911), Salado Creek (segment 1910), and Walzem Creek (segment 1910A) have been identified as not meeting the Texas Commission on Environmental Quality (TCEQ) State Stream Standard for bacteria. The Environmental Protection Agency requires that a Total Maximum Daily Load Implementation Plan (IP) be developed to address the bacteria water quality impairments identified. The TCEQ has partnered with the San Antonio River Authority to develop an IP for the Upper San Antonio River, Salado Creek, and Walzem Creek. The IP will identify best management practices to abate or control non-point sources of bacteria and develop a timeline for implementation. The IP will include information, input and planning from the Bexar Regional Watershed Management program partners, area stakeholders and the public.

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