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Developing TMDL Projects

Information for contractors and other organizations that develop TMDLs in Texas.

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The goal of a TMDL is to restore the full use of a water body that has limited quality in relation to one or more of its uses. The TMDL defines an environmental target by determining the extent to which a certain pollutant must be reduced in order to attain and maintain the affected use. Based on this environmental target, the state helps stakeholders develop an implementation plan to mitigate sources of pollution within the watershed and restore full use of the water body.

TCEQ and the Texas State Soil and Water Conservation Board (TSSWCB) work closely on the preparation and approval of TMDLs when one or more of the sources of pollution are from agriculture or silviculture. A Memorandum of Agreement between TCEQ and TSSWCB provides the framework for collaboration between the two agencies to develop and implement TMDLs. For additional information or questions about TMDLs managed by TSSWCB, see TSSWCB’s TMDL Program webpage.

For a summary of TCEQ’s approach to defining and managing the quality of surface waters in Texas, see Preserving and Improving Water Quality. Additionally, you can read Texas Surface Water Quality: What Is It, and How Is It Measured? for a brief overview of water quality standards and the criteria by TCEQ evaluates their attainment.

Hydrography Information

You can review Hydrography Data and Map-Based Viewers for statewide, map-based viewers for surface water information. You will also find links to GIS data for stream segments, Level 4 ecoregions, and other data layers for use in ArcGIS.

Guidance for Project Leaders

A lead organization accepts primary responsibility for guiding a TMDL project. Often, TCEQ is the lead organization. However, TSSWCB, other state agencies, consultants, universities, river authorities, communities, or private consortiums may lead the development of TMDLs. Ultimately, TCEQ is responsible for ensuring that all TMDLs developed for Texas water bodies conform with state and federal law; therefore, TCEQ participates in all TMDL projects, regardless of who leads them.

The June 1999 guidance for the state's TMDL program is no longer applicable to TCEQ's TMDL projects. Guides and procedures provided on this webpage supersede all similar topics addressed in the June 1999 publication. For guidance on topics not addressed on this webpage, please contact the TMDL Program at or 512-239-6682.

Collecting Data

Data must be collected and managed under TCEQ guidelines and procedures for collecting quality-assured data. See the Quality Assurance and Monitoring Procedures for Surface Water Quality Monitoring.

Managing Data

Guidance, forms, and contact information for people who monitor and manage surface water quality are provided at Managing Surface Water Quality Data.

Quality Assurance

Quality assurance project plans (QAPPs) or quality assurance plans (QAPs) are required for most TMDL projects. For more information, contact your TCEQ project manager on the TMDL Team. 

The Environmental Protection Agency (EPA) provides guidance for quality management on their website. All approved TCEQ QAPPs are consistent with EPA guidance. 

See TSSWCB’s Environmental Data Quality Management  webpage for their quality assurance documents.

Federal Regulations and EPA Guidance

U.S. EPA administers the federal TMDL program.

Contact the TMDL Program

To contact the TMDL program, or call us at 512-239-6682.

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