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An Introduction to the Texas Surface Water Quality Standards

A summary that includes the federal and state regulatory authority that allows the state to write the standards, a summary of the different sections of the rule, and how water bodies are divided throughout the state.


The Texas Surface Water Quality Standards establish explicit goals for the quality of streams, rivers, lakes, and bays throughout the state. The Standards are developed to maintain the quality of surface waters in Texas so that it supports public health and enjoyment and protects aquatic life, consistent with the sustainable economic development of the state.

Water quality standards identify appropriate uses for the state’s surface waters, including aquatic life, recreation, and sources of public water supply (or drinking water). The criteria for evaluating support of those uses include dissolved oxygen, temperature, pH, dissolved minerals, toxic substances, and bacteria. Statewide standards may be revised on a site-specific basis when sufficient information is available.

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Standards Are State Rules

The Texas Surface Water Quality Standards are codified in Title 30, Chapter 307 of the Texas Administrative CodeExit the TCEQ . The Standards are written by the TCEQ under the authority of the Clean Water ActExit the TCEQ and the Texas Water CodeExit the TCEQ (Scroll down to Chapter 26 and select Section 26.023.)The Texas Surface Water Quality Standards are effective for Clean Water Act purposes when they are approved by EPA.

One important section of the standards is the General Criteria (307.4Exit the TCEQ ). The general criteria are narrative, and apply to all waters in the state. They address pollutants for which there are no specific numerical criteria and specify procedures for developing site-specific standards for small unclassified water bodies.

The Antidegradation Policy (307.5Exit the TCEQ ) establishes additional protection for water bodies that are defined in the standards as being of intermediate, high, or exceptional quality. Specific numerical criteria (307.6Exit the TCEQ ) for 42 toxic pollutants (expressed as maximum instream concentrations) protect aquatic life. Human consumption of fish and drinking water is protected by numerical criteria for 100 toxic pollutants. Section 307.6 also addresses biomonitoring, which involves exposing selected aquatic organisms to samples of a discharge effluent. Any significant toxicity observed during biomonitoring must then be evaluated and resolved.

Appropriate numerical criteria needed to support various water-quality related uses are defined in Section 307.7Exit the TCEQ . Conditions under which portions of the standards do not apply are noted in Section 307.8Exit the TCEQ . Sampling and analytical procedures to assess standards attainment are described in Section 307.9Exit the TCEQ . Site-specific standards for designated water bodies are individually listed in Section 307.10Exit the TCEQ (Appendices A, C, D, E, F, and G). Sole-source surface water drinking supplies are listed in Appendix B.

The water quality segments listed in 307.10 are divisions of major river basins, bays, and estuaries. All water bodies in the state have been divided into segments based on regional hydrologic and geologic diversity, which are referred to as classified or designated segments. Segments are listed and defined in Appendices A and C of the Texas Surface Water Quality Standards.

The Water Quality Standards are applied to permits as discussed in the Implementation Procedures.

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Public Participation

The public may participate in the development and implementation of the Standards through the Surface Water Quality Standards Advisory Work Group (SWQSAWG).

The work group’s guidance is sought on various topics, including nutrient criteria development and application, changes to toxic criteria per EPA criteria updates, implementation of EPA’s guidance on recreational indicators and uses, and site-specific criteria changes to classified and unclassified water bodies.

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For More Information

See contact information for a TCEQ staff member who specializes in the area related to your question.

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