Section 307.4 - General Criteria(a) Application. The general criteria set forth in this section apply to surface water in the state and specifically apply to substances attributed to waste discharges or human activities. General criteria do not apply to those instances when surface water, as a result of natural phenomena, exhibit characteristics beyond the limits established by this section. General criteria are superseded by specific exemptions stated in this section or in § 307.8 of this title (relating to the Application of Standards), or by site-specific water quality standards for classified segments. Provisions of the general criteria remain in effect in mixing zones or below critical low-flow conditions unless specifically exempted in § 307.8 of this title.(b) Aesthetic parameters. (1) Concentrations of taste and odor producing substances must not interfere with the production of potable water by reasonable water treatment methods, impart unpalatable flavor to food fish including shellfish, result in offensive odors arising from the waters, or otherwise interfere with the reasonable use of the water in the state.(2) Surface water must be essentially free of floating debris and suspended solids that are conducive to producing adverse responses in aquatic organisms or putrescible sludge deposits or sediment layers that adversely affect benthic biota or any lawful uses.(3) Surface waters must be essentially free of settleable solids conducive to changes in flow characteristics of stream channels or the untimely filling of surface water in the state. This provision does not prohibit dredge and fill activities that are permitted in accordance with the Federal Clean Water Act.(4) Surface waters must be maintained in an aesthetically attractive condition.(5) Waste discharges must not cause substantial and persistent changes from ambient conditions of turbidity or color.(6) No foaming or frothing of a persistent nature is permissible.(7) Surface waters must be maintained so that oil, grease, or related residue do not produce a visible film or sheen of oil or globules of grease on the surface or coat the banks or bottoms of the watercourse; or cause toxicity to man, aquatic life, or terrestrial life in accordance with subsection (d) of this section.(8) There shall be no discharge of visible pre-production plastic. For the purposes of this paragraph, visible means able to be seen by the naked eye without special equipment. This prohibition applies to individual and general TPDES permit authorizations held by plastic manufacturers, formers/molders, and facilities that otherwise handle pre-production plastic. Facilities that handle pre-production plastic must implement best management practices as defined in §307.3(a)(7) to eliminate discharges of visible pre-production plastic in stormwater through the implementation of control measures such as the following, where determined feasible (list not exclusive): minimizing spills, cleaning up spills promptly and thoroughly, sweeping and/or vacuuming thoroughly, and pellet capturing.(c) Radiological substances. Radioactive materials must not be discharged in excess of the amount regulated by Chapter 336 of this title (relating to Radioactive Substance Rules).(d) Toxic substances. Surface waters must not be toxic to man from ingestion of water, consumption of aquatic organisms, or contact with the skin, or to terrestrial or aquatic life. Additional requirements and criteria for toxic substances are specified in § 307.6 of this title (relating to Toxic Materials). Criteria to protect aquatic life from acute toxicity apply to all surface waters in the state except as specified in § 307.8(a)(3) of this title. Criteria to protect aquatic life from chronic toxicity apply to surface waters with an aquatic life use of limited, intermediate, high, or exceptional as designated in § 307.10 of this title (relating to Appendices A - G) or as determined on a case-by-case basis in accordance with subsection (l) of this section. Toxic criteria to protect human health for consumption of fish apply to waters with a sustainable or incidental fishery, as described in § 307.6(d) of this title. Additional criteria apply to water in the state with a public drinking water supply use, as described in § 307.6(d) of this title. The general provisions of this subsection do not change specific provisions in § 307.8 of this title for applying toxic criteria.(e) Nutrients. Nutrients from permitted discharges or other controllable sources must not cause excessive growth of aquatic vegetation that impairs an existing, designated, presumed, or attainable use. Site-specific nutrient criteria, nutrient permit limitations, or separate rules to control nutrients in individual watersheds are established where appropriate after notice and opportunity for public participation and proper hearing. Site-specific numeric criteria related to chlorophyll a are listed in Appendix F of § 307.10 of this title.(f) Temperature. Consistent with § 307.1 of this title (relating to General Policy Statement) and in accordance with state water rights permits, temperature in industrial cooling impoundments, industrial cooling water areas, and all other surface water in the state must be maintained so as to not interfere with the reasonable use of such waters. Numerical temperature criteria have not been specifically established for industrial cooling impoundments, which in most areas of the state contribute to water conservation and water quality objectives. In addition, numerical criteria for temperature are not applicable in designated industrial cooling water areas, as defined in § 307.3 of this title (relating to Definitions and Abbreviations). The horizontal boundaries of an industrial cooling water area must be defined in the applicable wastewater permit. The following temperature criteria, expressed as a maximum temperature differential (rise over ambient) are established except for industrial cooling impoundments, temperature elevations due to discharges of treated domestic (sanitary) effluent, and temperature elevations within designated mixing zones or industrial cooling water areas. The maximum temperature differentials are: (1) freshwater streams: 5 degrees Fahrenheit (degrees F);(2) freshwater lakes and impoundments: 3 degrees F; and(3) tidal river reaches, bay, and gulf waters: 4 degrees F in fall, winter, and spring, and 1.5 degrees F in summer (June, July, and August).(4) Additional temperature criteria (expressed as maximum temperatures) for classified segments are specified in Appendix A of § 307.10 of this title. These criteria are not applicable within industrial cooling water areas.(g) Salinity.(1) Concentrations and the relative ratios of dissolved minerals such as chloride, sulfate, and total dissolved solids must be maintained such that existing, designated, presumed, and attainable uses are not impaired.(2) Criteria for chloride, sulfate, and total dissolved solids for classified freshwater segments are specified in Appendix A of § 307.10 of this title.(3) Salinity gradients in estuaries must be maintained to support attainable estuarine dependent aquatic life uses. Numerical salinity criteria for Texas estuaries have not been established because of the high natural variability of salinity in estuarine systems, and because long-term studies by state agencies to assess estuarine salinities are still ongoing. Absence of numerical criteria must not preclude evaluations and regulatory actions based on estuarine salinity, and careful consideration must be given to all activities that may detrimentally affect salinity gradients.(h) Aquatic life uses and dissolved oxygen. (1) Dissolved oxygen concentrations must be sufficient to support existing, designated, presumed, and attainable aquatic life uses. Aquatic-life use categories and corresponding dissolved oxygen criteria are described in § 307.7(b)(3) of this title (relating to Site-Specific Uses and Criteria).(2) Aquatic life use categories and dissolved oxygen criteria for classified segments are specified in Appendix A of § 307.10 of this title. Aquatic life use categories and dissolved oxygen criteria for other specific water bodies are specified in Appendix D of § 307.10 of this title. Where justified by sufficient site-specific information, dissolved oxygen criteria that differ from § 307.7(b)(3) of this title may be adopted for a particular water body in § 307.10 of this title.(3) Perennial streams, rivers, lakes, bays, estuaries, and other appropriate perennial waters that are not specifically listed in Appendix A or D of § 307.10 of this title are presumed to have a high aquatic life use and corresponding dissolved oxygen criteria. Applicable dissolved oxygen criteria are described in § 307.7(b)(3)(A) of this title. Higher uses are protected where they are attainable.(4) When water is present in the streambed of intermittent streams, a 24-hour dissolved oxygen mean of at least 2.0 mg/L and 24-hour minimum dissolved oxygen concentration of 1.5 mg/L must be maintained. Intermittent streams that are not specifically listed in Appendix A or D of § 307.10 of this title are considered to have a minimal aquatic life use except as indicated below in this subsection. For intermittent streams with seasonal aquatic life uses, dissolved oxygen concentrations commensurate with the aquatic life uses must be maintained during the seasons when the aquatic life uses occur. Unclassified intermittent streams with perennial pools are presumed to have a limited aquatic life use and corresponding dissolved oxygen criteria. Higher uses are protected where they are attainable.(i) Aquatic life uses and habitat. Vegetative and physical components of the aquatic environment must be maintained or mitigated to protect aquatic life uses. Procedures to protect habitat in permits for dredge and fill are specified in Federal Clean Water Act, §404 and in Chapter 279 of this title (relating to Water Quality Certification).(j) Aquatic recreation. (1) Existing, designated, presumed, and attainable uses of aquatic recreation must be maintained, as determined by criteria that indicate the potential presence of pathogens. Categories of recreation and applicable criteria are established in § 307.7(b)(1) of this title.(2) Recreational use categories and criteria for classified segments are specified in Appendix A of § 307.10 of this title. Site-specific recreational use categories and criteria for selected unclassified water bodies are specified in Appendix G of § 307.10 of this title. Where justified by sufficient site-specific information, recreational uses and criteria that differ from § 307.7(b)(1) of this title may be adopted for a particular water body in § 307.10 of this title. For water bodies not specifically listed in Appendix A or Appendix G of § 307.10 of this title, the following recreational uses are presumed to apply.(A) Primary contact recreation 1. Primary contact recreation 1 is presumed for lakes, reservoirs, and tidal water bodies. Primary contact recreation 1 is presumed to apply to intermittent streams, intermittent streams with perennial pools, nontidal wetlands, and perennial freshwater streams and rivers, except where site-specific information indicates that recreational activities that involve a significant risk of ingestion have little to no likelihood of occurring, in accordance with subparagraph (C) of this paragraph.(B) Primary contact recreation 2. No water body is presumed to have a use of primary contact recreation 2. This use is applicable when designated for an individual water body as listed in Appendix A or G in § 307.10 of this title. Primary contact recreation 2 applies to water bodies where water recreation activities that involve a significant risk of ingestion of water occur, but less frequently than for primary contact recreation 1 due to:(i) physical characteristics of the water body; or(ii) limited public access.(C) Secondary contact recreation 1. Secondary contact recreation 1 applies to water bodies where water recreation can occur, but the nature of the recreation does not involve a significant risk of ingestion. Secondary contact recreation 1 applies to intermittent and perennial freshwaters where site-specific information demonstrates that primary contact recreation 1 or 2 have little to no likelihood of occurring. At a minimum, the following characteristics must be demonstrated for a presumed use of secondary contact recreation 1 to apply:(i) during dry weather flows, the average depth at the thalweg (mid-channel) is less than 0.5 meters and there are not substantial pools with a depth of 1 meter or greater; and(ii) there are no existing recreational activities that create a significant risk of ingestion or uses for primary contact recreation 1 or 2.(D) Secondary contact recreation 2. Secondary contact recreation 2 applies to water bodies where water recreation activities do not involve a significant risk of water ingestion and where activities occur less frequently than for secondary contact recreation 1 due to physical characteristics of the water body or limited public access. No water body is presumed to have a use of secondary contact recreation 2. This use is applicable when designated for an individual water body as listed in Appendix A or G in § 307.10 of this title.(E) Noncontact recreation. Noncontact recreation applies to water bodies where recreation activities do not involve a significant risk of water ingestion and where primary and secondary contact recreation uses should not occur because of unsafe conditions. No water body is presumed to have a use of noncontact recreation. This use is applicable when designated for an individual water body as listed in Appendix A or G in § 307.10 of this title.(3) Assigning recreational uses to an unclassified water body.(A) Applying presumed uses. Recreational uses and associated numerical criteria are assigned to an unclassified water body in accordance with the presumed uses and guidelines established in paragraph (2) of this subsection. To assign uses other than primary contact recreation 1, a reasonable level of inquiry is conducted to determine if a different presumed use is appropriate for a particular water body. A reasonable level of inquiry includes review of available relevant information or completed site surveys.(B) Assigning presumed uses. Presumed uses of primary contact recreation 1 and secondary contact recreation 1 can be assigned to an individual water body for regulatory action without individually designating the recreational use and criteria in Appendix G in § 307.10 of this title. Regulatory action may include issuing Texas Pollutant Discharge Elimination System permits, revising the list of impaired water bodies under federal Clean Water Act, §303(d), or setting and implementing a total maximum daily load. The presumed secondary contact recreation 1 use is included in the public notice of a regulatory action that could affect recreational water quality, and the assigned recreational uses are subject to applicable public comment and approval by the United States Environmental Protection Agency (EPA). For tracking purposes, presumed recreational uses that have been determined to be less stringent than primary contact recreation 1 are noted in a publicly available list such as the EPA's Water Quality Standards Repository prior to a water quality standards revision. Presumed uses that have been determined for particular water bodies are listed in Appendix G in § 307.10 of this title when the water quality standards are revised.(C) Assigning a use less stringent than presumed use. A recreational use that is less stringent than the applicable presumed use can only be assigned to an individual water body for a regulatory action after that use is approved by the EPA and designated in Appendix A or G in § 307.10 of this title. Support for designating a use less stringent than an applicable presumed use requires a use-attainability analysis (UAA). 40 Code of Federal Regulations §131.10(g) lists six reasons for a change in use in a water body. At least one of these reasons must be included in the UAA.(k) Antidegradation. Nothing in this section is intended to be construed or otherwise used to supersede the requirements of § 307.5 of this title (relating to Antidegradation).(l) Assessment of unclassified waters for aquatic life uses. Waters that are not specifically listed in Appendices A or D of § 307.10 of this title are assigned the specific uses that are attainable or characteristic of those waters. Upon administrative or regulatory action by the commission that affects a particular unclassified water body, the characteristics of the affected water body must be reviewed by the commission to determine which aquatic life uses are appropriate. Additional uses so determined must be indicated in public notices for discharge applications. Uses that are not applicable throughout the year in a particular unclassified water body are assigned and protected for the seasons where such uses are attainable. Initial determinations of use are considered preliminary, and in no way preclude redeterminations of use in public hearings conducted under the provisions of the Texas Water Code. For unclassified waters where the presumed minimum uses or criteria specified in this section are inappropriate, site-specific standards may be developed in accordance with § 307.2(d) of this title (relating to Description of Standards). Uses and criteria are assigned in accordance with this section and with § 307.7(b)(3) of this title. Procedures for assigning uses and criteria are described in the standards implementation procedures.(m) pH. Consistent with § 307.1 of this title, pH levels in all surface water in the state must be maintained so as to not interfere with the reasonable use of such waters.30 Tex. Admin. Code § 307.4
The provisions of this §307.4 adopted to be effective July 10, 1991, 16 TexReg 3400; amended to be effective July 13, 1995, 20 TexReg 4701; amended to be effective April 30, 1997, 22 TexReg 3712; amended to be effective August 17, 2000, 25 TexReg 7722; amended to be effective July 22, 2010, 35 TexReg 6294; amended to be effective March 6, 2014, 39 TexReg 1450; Amended by Texas Register, Volume 47, Number 38, September 23, 2022, TexReg 6216, eff. 9/29/2022