1. (a) Contents of the Texas Surface Water Quality Standards.

   1. (1) Section 307.1 of this title (relating to General Policy Statement) contains the general standards policy of the commission.
   2. (2) This section lists the major sections of the standards, defines basin classification categories, describes justifications for standards modifications, and provides the effective dates of the rules.
   3. (3) Section 307.3 of this title (relating to Definitions and Abbreviations) defines terms and abbreviations used in the standards.
   4. (4) Section 307.4 of this title (relating to General Criteria) lists the general criteria, which are applicable to all surface waters of the state unless specifically excepted in §307.8 of this title (relating to Application of Standards) or §307.9 of this title (relating to Determination of Standards Attainment).
   5. (5) Section 307.5 of this title (relating to Antidegradation) describes the antidegradation policy and implementation procedures.
   6. (6) Section 307.6 of this title (relating to Toxic Materials) establishes criteria and control procedures for specific toxic substances and total toxicity.
   7. (7) Section 307.7 of this title (relating to Site-specific Uses and Criteria) defines appropriate water uses and supporting criteria for site-specific standards.
   8. (8) Section 307.8 of this title sets forth conditions under which portions of the standards do not apply--such as in mixing zones or below critical low-flows.
   9. (9) Section 307.9 of this title describes sampling and analytical procedures to determine standards attainment.

   10. (10) Section 307.10 of this title (relating to Appendices A - E) lists site-specific standards and supporting information for classified segments (Appendices A - C), partially classified water bodies (Appendix D), and site-specific criteria that may be derived for any water in the state (Appendix E). Specific appendices are as follows:

       1. (A) Appendix A--Water Uses and Numerical Criteria;
       2. (B) Appendix B--Low-Flow Criteria;
       3. (C) Appendix C--Segment Descriptions;
       4. (D) Appendix D--Site-specific Receiving Water Assessments; and
       5. (E) Appendix E--Site-specific Criteria.
2. (b) Applicability. The Texas Surface Water Quality Standards apply to surface waters in the state--including wetlands.

3. (c) Classification of surface waters. The major surface waters of the state are classified as segments for purposes of water quality management and designation of site-specific standards. Classified segments are aggregated by basin, and basins are categorized as follows:

   1. (1) River basin waters. Surface inland waters comprising the major rivers, their tributaries, including listed impounded waters, and the tidal portion of rivers to the extent that they are confined in channels.
   2. (2) Coastal basin waters. Surface inland waters, including listed impounded waters but exclusive of paragraph (1) of this subsection, discharging, flowing, or otherwise communicating with bays or the gulf, including the tidal portion of streams to the extent that they are confined in channels.
   3. (3) Bay waters. All tidal waters, exclusive of those included in river basin waters, coastal basin waters, and gulf waters.
   4. (4) Gulf waters. Waters which are not included in or do not form a part of any bay or estuary but which are a part of the open waters of the Gulf of Mexico to the limit of the state's jurisdiction.

4. (d) Modification of standards.

   1. (1) The commission reserves the right to amend these standards following the completion of special studies.
   2. (2) Any errors in water quality standards resulting from clerical errors or errors in data may be corrected by the commission through amendment of the affected standards. Water quality standards not affected by such clerical errors or errors in data remain valid until changed by the commission.
   3. (3) The narrative provisions, designated uses, and numerical criteria of the Texas Surface Water Quality Standards may be amended for a specific water body to account for local conditions. A site-specific standard is an explicit amendment to this title, Chapter 307 (Texas Surface Water Quality Standards), and adoption of a site-specific standard requires the procedures for public notice and hearing established under the Texas Water Code, §26.024 and §26.025. An amendment which establishes a site-specific standard will require a use-attainability analysis which demonstrates that reasonably attainable water-quality related uses will be protected. Upon adoption, site-specific amendments to the standards will be listed in §307.10 of this title.
   4. (4) Factors which may justify the development of site-specific standards are described in §§307.4, 307.6, 307.7, and 307.8 of this title.

   5. (5) Temporary variance. When scientific information indicates that a site-specific standards amendment is justified, the commission may allow a corresponding temporary variance to the water quality standards in a permit for a discharge of wastewater.

      1. (A) A temporary variance is only applicable to an existing discharge.
      2. (B) A permittee may apply for a temporary variance prior to or during the permit application process. The temporary variance request shall be included in a public notice during the permit application process. An opportunity for public comment will be provided, and the request may be considered in any public hearing on the permit application.
      3. (C) A temporary variance for a TPDES permit will also require review and approval by the EPA during the permitting process.
      4. (D) The permit shall contain effluent limitations that protect existing uses and preclude degradation of existing water quality, and the term of the permit shall not exceed three years. Effluent limitations that are needed to meet the existing standards will be listed in the permit and will go into effect immediately as final permit effluent limitations in the succeeding permit, unless the permittee fulfills the requirements of the conditions for the variance in the permit.
      5. (E) When the permittee has complied with the terms of the conditions in the temporary variance, then the succeeding permit may include a permit schedule to meet standards in accordance with subsection (f) of this section. The succeeding permit may also extend the temporary variance in accordance with subsection (f) of this section in order to allow additional time for a site-specific standard to be adopted in this title. This extension can be approved by the commission only after a site-specific study that supports a standards change has been completed and the commission agrees the completed study supports a change in the applicable standard(s).
      6. (F) Site-specific standards which are developed under a temporary variance will be expeditiously proposed and publicly considered for adoption at the earliest opportunity.
5. (e) Implementation procedures. Provisions for implementing the water quality standards are described in a document entitled Procedures to Implement the Texas Surface Water Quality Standards.
6. (f) Permit schedules to meet standards. Upon permit amendment or permit renewal, the executive director or commission, as appropriate, may establish interim effluent limitations to allow a permittee time to modify effluent quality in order to attain final effluent limitations. The duration of any interim effluent limitations may not be longer than three years from the effective date of the permit issuance, except in accordance with a temporary variance as described in subsection (d)(5) of this section.
7. (g) Temporary standards. Where a criterion is not attained and cannot be attained for one or more of the reasons listed in 40 Code of Federal Regulations (CFR) §131.10(g), then a temporary standard for specific water bodies may be adopted in §307.10 of this title as an alternative to changing uses. A criterion which is established as a temporary standard must be adopted in accordance with the provisions of subsection (d)(3) of this section. Specific reasons and additional procedures for justifying a temporary standard are provided in the standards implementation procedures. A temporary standard shall identify the water body or water bodies where the criterion applies. A temporary standard will identify the numerical criteria that will apply during the existence of the temporary standard. A temporary standard does not exempt any discharge from compliance with applicable technology-based effluent limits. A temporary standard shall expire no later than the completion of the next triennial revision of the Texas Surface Water Quality Standards. When a temporary standard expires, subsequent discharge permits will be issued to meet the applicable existing water quality standards. If a temporary standard is sufficiently justified in accordance with the provisions of subsection (b)(3) of this section, it can be renewed during revisions of the Texas Surface Water Quality Standards. A temporary standard cannot be established which would impair an existing use.
8. (h) Effective date of standards. Except as provided in 40 CFR §131.21 (EPA review and approval of water quality standards), these rules shall become effective 20 days after the date on which they are filed in the office of the secretary of state. As to actions covered by 40 CFR §131.21, the rules shall become effective upon approval by EPA.

9. (i) Effect of conflict or invalidity of rule.

   1. (1) If any provision of this chapter or its application to any person or circumstances is held invalid, the invalidity does not affect other provisions or applications of the provisions contained in this chapter which can be given effect without the invalid provision or application, and to this end the provisions of this chapter are severable.
   2. (2) To the extent of any irreconcilable conflict between provisions of this chapter and other rules of the commission, the provisions of this chapter shall supersede.

Source Note:The provisions of this §307.2 adopted to be effective July 10, 1991, 16 TexReg 3400; amended to be effective July 13, 1995, 20 TexReg 4701; amended to be effective August 17, 2000, 25 TexReg 7722.