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TITLE 30ENVIRONMENTAL QUALITY
PART 1TEXAS COMMISSION ON ENVIRONMENTAL QUALITY
CHAPTER 307TEXAS SURFACE WATER QUALITY STANDARDS
RULE §307.7Site-Specific Uses and Criteria

(a) Uses and numerical criteria are established on a site-specific basis in Appendices A, B, D, E, F, and G of §307.10 of this title (relating to Appendices A - G). Site-specific uses and numerical criteria may also be applied to unclassified waters in accordance with §307.4 of this title (relating to General Criteria) and §307.5(c) of this title (relating to Antidegradation). Site-specific criteria apply specifically to substances attributed to waste discharges or human activity. Site-specific criteria do not apply to those instances when surface waters exceed criteria due to natural phenomena. The application of site-specific uses and criteria is described in §307.8 of this title (relating to the Application of Standards) and §307.9 of this title (relating to the Determination of Standards Attainment).

(b) Appropriate uses and criteria for site-specific standards are defined as follows.

  (1) Recreation. Recreational use consists of five categories--primary contact recreation 1, primary contact recreation 2, secondary contact recreation 1, secondary contact recreation 2, and noncontact recreation waters. Classified segments are designated for primary contact recreation 1 unless sufficient site-specific information demonstrates that elevated concentrations of indicator bacteria frequently occur due to sources of pollution that cannot be reasonably controlled by existing regulations, wildlife sources of bacteria are unavoidably high and there is limited aquatic recreational potential, or primary or secondary contact recreation is considered unsafe for other reasons such as ship or barge traffic. In a classified segment where contact recreation is considered unsafe for reasons unrelated to water quality, a designated use of noncontact recreation may be assigned either noncontact recreation criteria or criteria normally associated with primary contact recreation. A designation of primary or secondary contact recreation is not a guarantee that the water so designated is completely free of disease-causing organisms. Indicator bacteria, although not generally pathogenic, are indicative of potential contamination by feces of warm blooded animals. Recreational criteria are based on these indicator bacteria rather than direct measurements of pathogens. Criteria are expressed as the number of bacteria per 100 milliliters mL of water (in terms of colony forming units, most probable number, or other applicable reporting measures). Even where the concentration of indicator bacteria is less than the criteria for primary or secondary contact recreation, there is still some risk of contracting waterborne diseases. Additional guidelines on minimum data requirements and procedures for evaluating standards attainment are specified in the TCEQ Guidance for Assessing and Reporting Surface Water Quality in Texas, as amended.

    (A) Freshwater

      (i) Primary contact recreation 1. The geometric mean criterion for E. coli is 126 per 100 mL. In addition, the single sample criterion for E. coli is 399 per 100 mL.

      (ii) Primary contact recreation 2. The geometric mean criterion for E. coli is 206 per 100 mL.

      (iii) Secondary contact recreation 1. The geometric mean criterion for E. coli is 630 per 100 mL.

      (iv) Secondary contact recreation 2. The geometric mean criterion for E. coli is 1,030 per 100 mL.

      (v) Noncontact recreation. The geometric mean criterion for E. coli is 2,060 per 100 mL.

      (vi) For high saline inland water bodies where Enterococci is the designated recreational indicator in Appendix A of §307.10 of this title, Enterococci is the applicable recreational indicator for instream bacteria sampling at all times for the classified water body and for the unclassified water bodies that are within the watershed of that classified segment, unless it is demonstrated that an unclassified water body is not high saline. E. coli is the applicable recreational indicator for instream bacteria sampling at all times for unclassified water bodies where conductivity values indicate that the water bodies are not high saline. For high saline inland waters with primary contact recreation 1, the geometric mean criterion for Enterococci is 33 per 100 mL and the single sample criterion is 78 per 100 mL. For high saline inland waters with secondary contact recreation 1, the geometric mean criterion for Enterococci is 165 per 100 mL. For high saline inland waters with secondary contact recreation 2, the geometric mean criterion for Enterococci is 270 per 100 mL. For high saline inland water bodies with noncontact recreation, the geometric mean criterion for Enterococci is 540 per 100 mL.

    (B) Saltwater.

      (i) Primary contact recreation 1. The geometric mean criterion for Enterococci is 35 per 100 mL. In addition, the single sample criterion for Enterococci is 104 per 100 mL.

      (ii) Secondary contact recreation 1. A secondary contact recreation 1 use for tidal streams and rivers can be established on a site-specific basis in §307.10 of this title if justified by a use-attainability analysis and the water body is not a coastal recreation water as defined in the Beaches Environmental Assessment and Coastal Health Act of 2000 (BEACH Act). The geometric mean criterion for Enterococci is 175 per 100 mL.

      (iii) Noncontact recreation. A noncontact recreation use for tidal streams and rivers can be established on a site-specific basis in §307.10 of this title if justified by a use-attainability analysis and the water body is not a coastal recreation water as defined in the BEACH Act. The geometric mean criterion for Enterococci is 350 per 100 mL.

    (C) Swimming advisory programs. For areas where local jurisdictions or private property owners voluntarily provide public notice or closure based on water quality, the use of any single-sample or short-term indicators of recreational suitability are selected at the discretion of the local managers of aquatic recreation. Guidance for single-sample bacterial indicators is available in the United States Environmental Protection Agency (EPA) document entitled Ambient Water Quality Criteria for Bacteria - 1986. Other short-term indicators to assess water quality suitability for recreation - such as measures of streamflow, turbidity, or rainfall - may also be appropriate.

  (2) Domestic water supply.

    (A) Use categories. Domestic water supply consists of three use subcategories - public water supply, sole-source surface drinking water supply, and aquifer protection.

      (i) Public water supply. Segments designated for public water supply are those known to be used or exhibit characteristics that would allow them to be used as the supply source for public water systems as defined by Chapter 290 of this title (relating to Public Drinking Water).

      (ii) Sole-source surface drinking water supplies and their protection zones. Water bodies that are sole-source surface drinking water supplies are listed in Appendix B of §307.10 of this title. Sole-source surface drinking water supplies and their protection zones are addressed in Chapter 321 of this title (relating to Subchapter B: Concentrated Animal Feeding Operations).

      (iii) Aquifer protection. Segments designated for aquifer protection are capable of recharging the Edwards Aquifer. The principal purpose of this use designation is to protect the quality of water infiltrating into and recharging the aquifer. The designation for aquifer protection applies only to those portions of the segments so designated that are on the recharge zone, transition zone, or contributing zone as defined in Chapter 213 of this title (relating to the Edwards Aquifer). Chapter 213 of this title establishes provisions for activities in the watersheds of segments that are designated for aquifer protection.

    (B) Use criteria. The following use criteria apply to all domestic water supply use subcategories.

      (i) Radioactivity associated with dissolved minerals in the freshwater portions of river basin and coastal basin waters should not exceed levels established by drinking water standards as specified in Chapter 290 of this title unless the conditions are of natural origin.

      (ii) Surface waters utilized for domestic water supply must not exceed toxic material concentrations that prevent them from being treated by conventional surface water treatment to meet drinking water standards as specified in Chapter 290 of this title.

      (iii) Chemical and microbiological quality of surface waters used for domestic water supply should conform to drinking water standards as specified in Chapter 290 of this title.

  (3) Aquatic life. The establishment of numerical criteria for aquatic life is highly dependent on desired use, sensitivities of aquatic communities, and local physical and chemical characteristics. Six subcategories of aquatic life use are established. They include minimal, limited, intermediate, high, and exceptional aquatic life and oyster waters. Aquatic life use subcategories designated for segments listed in Appendix A of §307.10 of this title recognize the natural variability of aquatic community requirements and local environmental conditions.

    (A) Dissolved oxygen.

      (i) The characteristics and associated dissolved oxygen criteria for limited, intermediate, high, and exceptional aquatic life use subcategories are indicated in Table 3 of this clause. This table also includes dissolved oxygen criteria for a minimal aquatic life use subcategory that applies to intermittent streams without perennial pools as indicated in §307.4(h)(4) of this title.

Attached Graphic

      (ii) Critical low-flow values associated with the bedslopes and dissolved oxygen criteria in Table 4 of this clause apply to streams that have limited, intermediate, high, or exceptional aquatic life uses and to streams that are specifically listed in Appendix A or D of §307.10 of this title. The critical low-flow values in Table 4 of this clause apply to streams in Texas that are east of a line defined by Interstate Highways 35 and 35W from the Red River to the community of Moore in Frio County, and by United States Highway 57 from the community of Moore to the Rio Grande. Table 4 of this clause does not apply where specifically superseded by the equation that is listed in footnote 3 in the Cypress Creek Basin in Appendix A and in footnote 2 in Appendix D of §307.10 of this title. The critical low-flow values in Table 4 of this clause (at the appropriate stream bedslope) are utilized as headwater flows when the flows are larger than applicable seven-day, two-year low-flows in order to determine discharge effluent limits necessary to achieve dissolved oxygen criteria. For streams that have bedslopes less than the minimum bedslopes in Table 4, the flows listed for the minimum bedslope of 0.1 meters per kilometer (m/km) are applicable. For streams that have bedslopes greater than the maximum bedslope in Table 4 of this clause, the flows listed for the maximum bedslope of 2.4 m/km are applicable. The required effluent limits are those necessary to achieve each level of dissolved oxygen (as defined in clause (i) of this subparagraph, Table 3) at or below an assigned, designated, or presumed aquatic life use. Presumed aquatic life uses must be in accordance with those required by §307.4(h) of this title. The critical low-flow values in Table 4 of this clause do not apply to tidal streams.

Attached Graphic

      (iii) The critical low-flow values in Table 4 of clause (ii) of this subparagraph for limited, intermediate, high, and exceptional aquatic life uses are based upon data from the commission's least impacted stream study (Texas Aquatic Ecoregion Project). Results of this study indicate a strong dependent relationship for average summertime background dissolved oxygen concentrations and several hydrologic and physical stream characteristics - particularly bedslope (stream gradient) and stream flow. The critical low-flow values in Table 4 of clause (ii) of this subparagraph are derived from a multiple regression equation for the eastern portion of Texas as defined in clause (ii) of this subparagraph. Further explanation of the development of the regression equation and its application are contained in the standards implementation procedures as amended.

      (iv) The critical low-flow values in Table 4 of clause (ii) of this subparagraph may be adjusted based on site-specific data relating dissolved oxygen concentrations to factors such as flow, temperature, or hydraulic conditions in accordance with the standards implementation procedures as amended. Site-specific, critical low-flow values require approval by the commission. The EPA must review any site-specific, critical low-flow values that could affect permits or other regulatory actions that are subject to approval by EPA. Critical low-flow values that have been determined for particular streams are listed in the standards implementation procedures.

    (B) Oyster waters.

      (i) A 1,000 foot buffer zone, measured from the shoreline at ordinary high tide, is established for all bay and gulf waters except those contained in river or coastal basins as defined in §307.2 of this title (relating to Description of Standards). Recreational criteria for indicator bacteria, as specified in §307.7(b)(1) of this title (relating to Site-Specific Uses and Criteria), are applicable within buffer zones.

      (ii) The criteria for median fecal coliform concentration in bay and gulf waters, exclusive of buffer zones, are 14 colonies per 100 mL with not more than 10% of all samples exceeding 43 colonies per 100 mL.

Cont'd...

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