TITLE 30. ENVIRONMENTAL QUALITY

PART 1. TEXAS COMMISSION ON ENVIRONMENTAL QUALITY

CHAPTER 307. TEXAS SURFACE WATER QUALITY STANDARDS

30 TAC §§307.2, 307.3, 307.6, 307.7, 307.9, 307.10

(Editor's note: In accordance with Texas Government Code, §2002.014, which permits the omission of material which is "cumbersome, expensive, or otherwise inexpedient," the figures in 30 TAC §§307.2, 307.3, 307.6, 307.7, 307.9, and 307.10 are not included in the print version of the Texas Register. The figures are available in the on-line version of the September 8, 2017, issue of the Texas Register.)

The Texas Commission on Environmental Quality (TCEQ, agency, or commission) proposes amendments to §§307.2, 307.3, 307.6, 307.7, 307.9, and 307.10.

Background and Summary of the Factual Basis for the Proposed Rules

The Federal Water Pollution Control Act, or the Clean Water Act (1972), §303 (33 United States Code, §1313), requires all states to adopt water quality standards for surface water. A water quality standard consists of the designated beneficial uses of a water body or a segment of a water body and the water quality criteria that are necessary to protect those uses. Water quality standards are the basis for establishing effluent limits in wastewater permits, setting instream water quality goals for total maximum daily loads (TMDLs), and providing water quality targets used to assess water quality monitoring data.

The states are required under the Clean Water Act to review their water quality standards at least once every three years and revise them, if appropriate. States review the standards because new scientific and technical data may be available that have a bearing on the review. Environmental changes over time may also warrant the need for a review. Where the standards do not meet established uses, they must be periodically reviewed to see if uses can be attained. Additionally, water quality standards may have been previously established for the protection and propagation of aquatic life and for recreation in and on the water without sufficient data to determine whether the uses were attainable. Finally, changes in the Texas Water Code (TWC), Clean Water Act, or regulations issued by the United States Environmental Protection Agency (EPA) may necessitate reviewing and revising standards to ensure compliance with current statutes and regulations.

Following adoption of revised Texas Surface Water Quality Standards (TSWQS) by the commission, the Governor or their designee must submit the officially adopted standards to the EPA Region 6 Administrator for review. The Regional Administrator reviews the TSWQS to determine compliance with the Clean Water Act and implementing regulations. TSWQS are not applicable to regulatory actions under the Clean Water Act until approved by the EPA.

The TSWQS were last amended in February 2014. The EPA approved a portion of the state's revised standards in September 2014.

Reviews and revisions of the TSWQS address many provisions that apply statewide, such as criteria for toxic pollutants. They also address the water quality uses and criteria that are applicable to individual water bodies. An extensive review of water quality standards for individual water bodies is often initiated when the existing standards appear to be inappropriate for water bodies that are listed as impaired under the Clean Water Act, §303(d), or that are potentially affected by permitted wastewater discharges or other permitting actions.

States may modify existing designated uses or criteria when it can be demonstrated through a use-attainability analysis (UAA) that attaining the current designated uses or criteria is not appropriate. Most changes in designated uses or criteria are based on a demonstration that natural characteristics of a water body cannot attain the currently designated uses or criteria. Natural characteristics include temperature, pH, dissolved oxygen, diversity of aquatic organisms, amount of streamflow, physical conditions such as depth, and natural background pollutant levels. Conversely, a UAA might demonstrate that the currently designated uses and criteria are appropriate, or even that they should be more stringent.

UAAs can require several years of additional sampling studies, or they may focus on a long-term evaluation of existing historical data. For UAAs on water bodies that are potentially impacted by pollutant loadings above natural background levels, sampling and evaluation are often conducted on similar but relatively unimpacted water bodies to determine reference conditions that can be applied to the water body of concern.

The focus of UAAs depends on the uses and criteria that need to be reevaluated. The applicable aquatic life use is determined by repeatedly sampling fish or invertebrates in relatively unimpacted areas and applying quantitative indices, such as indices of biotic integrity, to the sampling data of the biological communities. UAAs to assign aquatic recreational uses include assessing physical and hydrological conditions, observing existing recreation, and collecting information on current and historical recreational activities. Dissolved oxygen criteria are evaluated by monitoring dissolved oxygen over numerous (usually ten) 24-hour periods in relatively unimpacted areas. Site-specific criteria for toxic pollutants are evaluated by placing selected small aquatic organisms in water samples from the site and exposing them to different doses of the toxic pollutant of concern.

The commission is proposing editorial revisions as well as substantive changes. Editorial revisions would be adopted to improve clarity, make grammatical corrections, and renumber or re-letter subdivisions as appropriate.

Numerous revisions of toxic criteria are proposed to incorporate new data on toxicity effects. Other proposed revisions provide clarity on how water quality standards would be assessed using instream monitoring data for bacteria. Numerous revisions are also proposed for the uses and criteria of individual water bodies to incorporate new data and the results of recent UAAs.

Section by Section Discussion

§307.2, Description of Standards

The commission proposes to amend §307.2 to include language regarding temporary standards to comply with changes in federal rules listed in 40 Code of Federal Regulations (CFR) §131.14. These revisions clarify what standard applies when a criterion or designated use is not attained and cannot be attained for one or more reasons listed in 40 CFR §131.10(g) or to facilitate restoration activities. Other revisions are editorial and proposed to improve overall clarity.

§307.3, Definitions and Abbreviations

The commission proposes to amend §307.3 to add a definition for "Coastal recreation waters." Other revisions are editorial and proposed to improve overall clarity.

§307.6, Toxic Materials

The commission proposes to amend §307.6 to update references to guidance documents and sources used to calculate aquatic life and human health criteria. Other revisions are editorial and proposed to improve overall clarity.

Section 307.6(c)(1), Table 1, which lists numeric criteria for the protection of aquatic life, includes proposed revisions to the existing entry for carbaryl based on the EPA issuance of an updated national criteria document. Revisions also include the addition of acrolein to the table based on the EPA issuance of a new national criteria document.

Proposed changes to the human health criteria in §307.6(d)(1), Table 2, include the addition of the following four chemicals to the table: epichlorohydrin; ethylene glycol; 4,4'-isopropylidenediphenol; and methyl tert-butyl ether. Bioconcentration factor updates led to revisions of criteria for the following 18 noncarcinogens: anthracene; chlorobenzene; chloroform; m-dichlorobenzene; o-dichlorobenzene; 1,1-dichloroethylene; 2,4-dimethylphenol; di-n-butyl phthalate; endrin; hexachlorocyclohexane (gamma); hexachlorocyclopentadiene; methoxychlor; nitrobenzene; pentachlorobenzene; 1,2,4,5-tetrachlorobenzene; 2,4,5-TP (Silvex); 1,1,1-trichloroethane; and 2,4,5-trichlorophenol. Bioconcentration factor updates also led to revisions of criteria for the following 37 carcinogens: acrylonitrile; aldrin; benzene; benzidine; benzo(a)anthracene; benzo(a)pyrene; bis(2-chloroethyl)ether; bromodichloromethane; bromoform; carbon tetrachloride; chlordane; chrysene; 4,4'-DDD; 4,4'-DDE; 4,4'-DDT; bis(2-ethylhexyl)phthalate; chlorodibromomethane; 3,3'-dichlorobenzidine; 1,2-dichloroethane; dichloromethane; 1,2-dichloropropane; 1,3-dichloropropene; dieldrin; heptachlor; heptachlor epoxide; hexachlorobenzene; hexachlorobutadiene; hexachlorocyclohexane (alpha); hexachlorocyclohexane (beta); hexachloroethane; pentachlorophenol; 1,1,2,2-tetrachloroethane; tetrachloroethylene; toxaphene; 1,1,2-trichloroethane; trichloroethylene; and vinyl chloride. Revisions to footnotes were included to clarify what fish consumption rates were used to calculate mercury criteria and to cite the source for the new table entry for methyl tert-butyl ether.

§307.7, Site-Specific Uses and Criteria

The commission proposes an amendment to §307.7 to include an update of the saltwater single sample criterion for Enterococci from 104 per 100 milliliters (mL) to 130 per 100 mL in subsection (b)(1)(B)(i). Other revisions are editorial and proposed to improve overall clarity.

§307.9, Determination of Standards Attainment

The commission proposes an amendment to §307.9 to include basing attainment of bacteria standards in coastal recreation waters on both geometric mean and single sample criteria. Other revisions, including those regarding nutrient assessment, are editorial and proposed to improve overall clarity.

§307.10, Appendices A - G

The commission proposes an amendment to §307.10 to revise Appendices A - G. The proposed amendment to §307.10(1), Appendix A, includes the addition of a new segment, Blind Oso Bay (2486), based on the results of a UAA; changes to the footnote for the Houston Ship Channel Tidal (1006) and Houston Ship Channel/Buffalo Bayou Tidal (1007) to clarify that numerical toxic criteria applicable to sustainable fisheries apply to these segments; adding a footnote for Spring Creek (1008) to assign site-specific seasonal dissolved oxygen criteria based on the results of a UAA; adding a footnote for Mid Cibolo Creek (1913) to indicate that it is intermittent with perennial pools based on the results of a UAA; and removing the footnote for the Rio Grande Below Riverside Diversion Dam (2307) due to the removal of the Riverside Diversion Dam. The public water supply use for Cedar Bayou Above Tidal (0902) is proposed for removal due to a lack of public water supply intakes. Proposed changes also include changing the primary contact recreation use for Big Cypress Creek Below Lake Bob Sandlin (0404) to a secondary contact recreation 1 use with a corresponding change to the indicator bacteria criterion.

The following water bodies are proposed for deletion from §307.10(2), Appendix B, because they no longer qualify as sole-source drinking water supplies in accordance with TWC, §26.0286: Farmers Creek Reservoir (0210); Big Cypress Creek Below Lake O' the Pines (0402); Sabine River Above Caney Creek (0503); Sabine River Above Toledo Bend Reservoir (0505); Lower Neches Valley Authority Canal (0602); Neches River Below B.A. Steinhagen Lake (0602); Trinity River Tidal (0801); Lake Worth (0807); West Fork Trinity River Below Bridgeport Reservoir (0810); Lavon Lake (0821); Lake Grapevine (0826); Joe Pool Lake (0838); Lake Houston (1002); Brazos River Below Navasota River (1202); Lake Mexia (1210); Stillhouse Hollow Lake (1216); Leon Reservoir (1224); Waco Lake (1225); Lake Stamford (1235); White River Lake (1240); Lake Georgetown (1249); Lake Limestone (1252); Llano City Lake (1415); Brady Creek Reservoir (1416); Concho River (1421); Lake Texana (1604); Guadalupe River Below San Antonio River (1802); Guadalupe River Below San Marcos River (1803); Lake Placid (1804); Lake Wood (1804); Guadalupe River Above Canyon Lake (1806); Lower San Marcos River (1808); Upper Blanco River (1813); Medina River Below Medina Diversion Lake (1903); and Boerne Lake (1908). Additions and deletions were made to the "County" column as needed to better describe the general location of the water body.

The proposed amendment to §307.10(3), Appendix C, includes a description for a new segment, Blind Oso Bay (2486), and revisions to the description of the existing related segment, Oso Bay (2485), based on the results of a UAA. Other changes include revisions for the upper boundary for Sabine River Tidal (0501) and lower boundary for Sabine River Above Tidal (0502) based on the results of a tidal influence study. Segment description revisions are proposed for Lower Cibolo Creek (1902), Mid Cibolo Creek (1913), and Upper Cibolo Creek (1908) to better define the flow regime based on the results of a UAA. Editorial changes were made to clarify other water body descriptions.

The proposed amendment to §307.10(4), Appendix D, includes the addition of eight water bodies along with their designated aquatic life uses and dissolved oxygen criteria. Some of the additions are due to the results of receiving water assessments; however, most are the result of more extensive investigations via UAAs. All the water bodies are tributaries within the listed segment numbers as follows: Bois d'Arc Creek (0202); Catfish Creek* (0804); Elm Creek* (1803); Sandies Creek* (1803); Hurricane Levee Canal (2437); and Garcitas Creek* (2453). Water bodies added because of UAAs are indicated with an asterisk (*). UAAs also led to the revision of two existing Appendix D entries: Thompsons Creek (1242), which was given seasonal dissolved oxygen criteria, and Slaughter Creek (1427), which was divided into three entries in Appendix D to account for changing flow regimes as it passes over the Edwards Aquifer Recharge Zone and becomes intermittent. The flow regime for the existing entry for Bois d'Arc Creek (0202) was changed from perennial to intermittent with perennial pools based on U.S. Geological Survey gauge data. Editorial changes were made to correct clerical errors in water body descriptions and the dissolved oxygen criterion for Town Creek (0831), misspellings in stream names, and for overall consistency. Editorial changes to footnotes for numerous water bodies throughout Appendix D were made to improve clarity.

The proposed amendment to §307.10(5), Appendix E, includes the addition of five new site-specific copper water-effect ratios in the watersheds of segments 0601, 0820, 1008, 1014, and 2484. A site-specific water-effect ratio for aluminum is also proposed for Segment 1014 along with two site-specific water-effect ratios for zinc for segments 1006 and 1014. Some existing entries in the appendix have been reordered to arrange all table entries in numeric order by segment and then permit number.

The proposed amendment to §307.10(6), Appendix F, includes editorial changes to the opening text of the appendix and deletion of one footnote to improve clarity.

The proposed amendment to §307.10(7), Appendix G, includes changing the presumed use of primary contact recreation 1 with a corresponding criterion of 126 colonies per 100 mL to a secondary contact recreation 1 use with a corresponding criterion of 630 colonies per 100 mL for one unclassified water body in the Canadian River Basin, seven unclassified water bodies in the Red River Basin, two unclassified water bodies in the Cypress Creek Basin, five unclassified water bodies in the Sabine River Basin, three unclassified water bodies in the Neches River Basin, one unclassified water body in the Trinity River Basin, 24 unclassified water bodies in the Brazos River Basin, one unclassified water body in the Brazos Colorado Coastal Basin, and one unclassified water body in the San Antonio-Nueces Coastal Basin. These proposed changes are based on the results from recreational UAAs.

The proposed amendment to §307.10(7), Appendix G, also includes, changing the presumed use of primary contact recreation 1 with a corresponding criterion of 126 colonies per 100 mL to a secondary contact recreation 2 use with a corresponding criterion of 1030 colonies per 100 mL for six unclassified water bodies in the Brazos River Basin. Proposed changes are based on the results from recreational UAAs.

Fiscal Note: Costs to State and Local Government

Jeffrey Horvath, Analyst in the Chief Financial Officer's Division, has determined that for the first five-year period the proposed rules are in effect, no significant costs or cost savings have been identified for the agency or other units of state or local government as a result of the implementation of the proposed TSWQS.

The proposed rulemaking amends the TSWQS. The TSWQS are required by the TWC and the Clean Water Act. Revisions to the TSWQS are proposed to address new information and results from studies on the appropriate uses and criteria of individual water bodies, incorporate new scientific data on the effects of specific pollutants, and address new provisions in federal regulations and guidance of the EPA. The TWC stipulates that the TCEQ may amend the TSWQS from time to time, and the Clean Water Act directs that the TSWQS be reviewed and revised as needed every three years.

The TSWQS establish the instream water quality conditions for surface waters in the state. A water quality standard for a specific water body consists of designated beneficial uses and the water quality criteria that are necessary to protect the uses. The TSWQS are the basis for: 1) establishing discharge limits in wastewater permits; 2) setting instream water quality goals for TMDLs; and 3) providing water quality targets to assess water quality.

The proposed rulemaking includes numerous revisions of toxic criteria to incorporate new data on toxicity effects. Other revisions are proposed for the uses and criteria of individual water bodies in order to incorporate new data and the results of recent UAAs and recreational UAAs. Revisions are also made to provisions regarding temporary standards and coastal recreation waters to comply with the Clean Water Act.

For the proposed statewide aquatic life toxic criteria, three are new, one is more stringent than the current TSWQS, and none are less stringent than the current TSWQS. For the proposed statewide human health toxic criteria, nine are new, 69 are more stringent than the current TSWQS, and 24 are less stringent than the current TSWQS. Proposed site-specific aquatic life use and dissolved oxygen changes in §307.10(1) and (4), Appendices A and D, include six new water bodies. The existing entry for Slaughter Creek in §307.10(4), Appendix D, is now divided into three entries. Two of those entries have different flow regimes and therefore less stringent aquatic life and dissolved oxygen criteria than those found in the current rule. For the proposed changes to existing site-specific dissolved oxygen criteria in §307.10(1) and (4), Appendices A and D, one is more stringent and two have new footnotes with less stringent seasonal criteria. The proposed site-specific toxic criteria changes in §307.10(5), Appendix E, include eight new water bodies. No criteria changes are being made to the existing entries of §307.10(5), Appendix E., The proposed site-specific bacteria criteria to protect recreation in §307.10(7), Appendix G, include 51 new water bodies with no changes to existing criteria.

Most of the revisions of statewide toxic criteria are based on federal guidance, but the state is afforded, and during this revision has used, a measure of discretion regarding which criteria to revise. Departures from federal guidance were based on valid scientific reasons which will be provided to the EPA when the rule is submitted for federal approval.

The effects of the revised TSWQS for the TCEQ are primarily operational and procedural. The statewide monitoring and assessment of surface water quality data, and the review of wastewater permit applications, will need to incorporate the changes and additions to numerical criteria.

Some effects of the rulemaking will require procedural and operational adjustments in the TCEQ water quality management programs to accommodate the proposed revisions. These effects will tend to be higher during the first two years after TCEQ adoption and EPA approval of the TSWQS.

No additional costs are anticipated for the TCEQ to implement the revisions to the TSWQS. The incorporation of revised criteria in wastewater permits will be facilitated by concurrent revisions in the TCEQ's Procedures to Implement the Texas Surface Water Quality Standards.

Several of the proposed revisions of the site-specific criteria for individual water bodies in §307.10 are intended to address water bodies that are listed as impaired because of apparent inappropriate water quality standards. In these cases, the proposed revisions to the TSWQS can streamline the TCEQ's water quality management program by curtailing unnecessary restorative activities, such as TMDLs, for water bodies that are currently identified as being impaired and redirecting funds to water bodies where restoration activities are needed.

The proposed changes for dissolved oxygen and aquatic life criteria in §307.10(1), Appendix A, for classified water bodies, and §307.10(4), Appendix D, for unclassified water bodies, will remove two impairments from the current Texas 303(d) List of impaired waters. There are 51 proposed additions to §307.10(7), Appendix G, which designates site-specific contact recreation criteria. The changes in §307.10(7), Appendix G, will result in the removal of 50 impairments from the current Texas 303(d) List of impaired waters. Where appropriate, the removal of water bodies that are listed for dissolved oxygen impairments or contact recreation impairments also eliminates the need for a study to define a TMDL for these water bodies.

According to the agency staff on the TMDL Team, a typical TMDL costs approximately $87,000 per assessment unit (AU). If the proposed amendment delist 50 impairments or AUs, the agency may realize cost savings of approximately $1,450,000 each year for the second, third, and fourth years covered by this fiscal note due to the elimination of the need for a study to define a TMDL. The delisting of two AUs in §307.10(1) and (4), Appendices A and D, may result in additional cost savings projected to be $58,000 each year for the second, third, and fourth years for the five-year period covered by this fiscal note. These cost savings will be redirected to water bodies where restoration activities are needed.

No significant costs or cost savings have been identified for other state agencies or units of local government as a result of the implementation of the proposed TSWQS. Any potential cost increases would primarily be for certain units of state or local government that own and operate wastewater facilities that discharge into Texas water bodies who may need to perform additional monitoring and reporting or upgrade their facilities. These upgrades may range from making changes in treatment processes to renovation or construction of new wastewater treatment facilities.

The proposed amendment to §307.10(1) and (4), Appendices A and D, includes six new and four revised entries which result in dissolved oxygen criteria that are less stringent than the criteria currently being applied to these water bodies. A cost analysis did not indicate an immediate cost savings for the affected facilities.

Other State Agencies

State agencies that operate permitted domestic wastewater discharges include the Texas Department of Criminal Justice, Texas Parks and Wildlife Department, Texas Department of Transportation, and certain state universities and schools. Domestic wastewater permits are the permits that are primarily affected by the applicable dissolved oxygen criteria in the TSWQS.

In addition, the TSWQS have indirect effects on the operation of environmental programs of other state agencies. The Texas State Soil and Water Conservation Board coordinates nonpoint source programs and watershed plans related to agriculture under the Clean Water Act, §319. The location of watershed plans is affected in part by whether a water body is considered to be meeting water quality standards. Changes to the TSWQS may result in some water bodies being added or removed from the current Texas 303(d) List of impaired waters and affect priorities for watershed plans.

The Texas Water Development Board administers loans for wastewater treatment plant construction under the Clean Water Act, Title 2. The water quality standards for dissolved oxygen have a bearing on the level of wastewater treatment needed and, therefore, on the appropriate amount and priority of a loan. The proposed changes to site-specific water quality standards for dissolved oxygen can increase or decrease the required treatment levels. In rare instances, numerical toxic criteria can affect domestic wastewater permits of state agencies, but the number of affected permits cannot be predicted.

Local Governments

The TSWQS can directly affect permitted wastewater discharges in Texas. Governmental entities with permitted discharges of domestic wastewater include cities, water districts, municipal utility districts, and river authorities. A relatively small number of governmental entities have permits for industrial wastewater discharges, and these permits are primarily for: 1) discharges related to public electricity generating facilities; or 2) discharges related to salt reduction at public drinking water treatment plants.

There are approximately 2,042 domestic discharge facilities with permits issued under the Texas Pollutant Discharge Elimination System. An estimated 1,423 of these permittees are governmental entities. Permits are issued for up to a five-year period, so that approximately 284 of the permits for governmental entities are reissued each year. There are approximately 10 wastewater permits associated with electricity generation by governmental entities.

The proposed amendment applies to state, municipal, agricultural, and industrial facilities that discharge wastewater directly into bodies of water in Texas. The proposed amendment has cost implications associated with revised criteria for toxic substances to protect human health and aquatic life, revised criteria for recreational uses, and revised dissolved oxygen criteria and aquatic life uses for classified and unclassified water bodies. Cost implications are generally associated with chemical screening and monitoring and the additional treatment of wastewater which may be needed to meet the TSWQS. Dischargers may have to change or employ new wastewater treatment methods or techniques to meet the proposed TSWQS. These changes may range from developing new wastewater processes to building a new wastewater treatment facility. The costs for state agencies and municipalities affected by the proposed amendment are anticipated to be similar to those for other entities.

The proposed changes in dissolved oxygen criteria can affect local governments that operate domestic wastewater facilities. In the absence of site-specific information, unclassified perennial water bodies are assigned a presumed high aquatic life use and associated dissolved oxygen criteria. None of the proposed revisions for dissolved oxygen criteria for classified segments in §307.10(1) or (4), Appendix A or D, are anticipated to require more stringent treatment by domestic wastewater facilities.

The proposed amendment to §307.10(1) and (4), Appendices A and D, includes six new and four revised entries which result in dissolved oxygen criteria that are less stringent than the criteria currently being applied to these water bodies. Estimates were completed to determine potential savings to dischargers located in these watersheds. The analysis did not indicate an immediate cost savings for the facilities; however, there are approximately 12 domestic permittees and 14 industrial permittees which discharge directly to, or near, these water bodies. Future expansions of these facilities may be facilitated by the proposed revisions.

Public Benefits and Costs

Mr. Horvath has also determined that for each year of the first five years the proposed rules are in effect, the public benefit anticipated from enforcement of, and compliance with, the proposed rules will result in increased protection of public drinking water supplies and aquatic life resources, an improved regulatory process for permitted wastewater discharges, and potentially improved quality of the surface water resources of the state.

The proposed rules are intended to establish instream water quality standards in accordance with the TWC and will satisfy federal requirements for a triennial review of the TSWQS. In addition, the proposed site-specific standards are necessary to incorporate new water quality sampling data and establish the appropriate revisions in the rule so permit issues for specific water bodies may be resolved. The proposed changes to the TSWQS can also help streamline the TCEQ's water quality management program by curtailing unnecessary restorative activities, such as TMDLs, for water bodies that are currently identified as being impaired and redirecting funds to water bodies where restoration activities are needed.

The proposed rules are not anticipated to result in significant fiscal implications for businesses or individuals. No significant costs or cost savings have been identified for affected facilities as a result of the implementation of the proposed TSWQS.

On a statewide basis, wastewater discharge facilities monitor toxic substances to protect human health and aquatic life. There are approximately 529 wastewater permits for industrial facilities in Texas. When applying for permit renewals or amendments, industrial facilities provide substantial sampling data on a broad range of toxic pollutants that are potentially in their effluents. The screening data are evaluated to ensure compliance with the toxic criteria in the TSWQS and determine if permit limits or monitoring requirements may be required. In the proposed revisions, 70 toxic criteria become more stringent, 24 become less stringent, 215 remain unchanged, and 12 new toxic criteria are added.

It is anticipated that the majority of facilities affected by the revised toxic criteria will be industrial facilities. Although the proposed amendment includes new pollutants and various criteria changes to existing criteria, which will result in both increases and decreases in permit limits, there are no additional costs associated with facilities or the commission because the TCEQ currently screens and requires monitoring for these substances.

New site-specific metals criteria proposed for eight sites in §307.10(5), Appendix E are less stringent than the existing criteria. It is anticipated the site-specific criteria in the proposed rulemaking will avoid the imposition of inappropriately stringent criteria for a minimum of seven industrial discharge permits.

Where applicable, the costs associated with compliance with toxic standards will be determined by the size and current condition of a facility, the extent of current controls, and the nature of the wastewater and receiving waters. Because of the variability in receiving waters, the number of toxic substances, and the current condition of treatment facilities, an engineering study and design may be required to determine the extent of any facility or process changes that might be required in order to comply with the proposed requirements. This variability precludes calculation of specific costs associated with achieving proposed standards for toxic substances.

Small Business and Micro-Business Assessment

In general, no adverse fiscal implications are anticipated for small or micro-businesses due to the implementation or administration of the proposed rules for the first five-year period the proposed rules are in effect. However, some economic effects are anticipated for small businesses and micro-businesses as a result of implementing the proposed rules. Small and micro-businesses served by municipal or commercial wastewater facilities may indirectly incur increased service rates from local governments or other operators of treatment facilities that must recover increased wastewater treatment costs from their customers. Major municipal wastewater treatment systems are required by the TCEQ and EPA to establish programs that specify effluent requirements for small industries and businesses that discharge pollutants to city sewer systems. The levels of treatment required for these dischargers to sewer systems are affected by the toxic criteria in the TSWQS, since the rule determine what effluent limits are needed for a wastewater discharge. Because of the variability in treatment costs and facility characteristics and rates, the costs to customers are virtually impossible to estimate for the regulated community. However, given the limited impact of the proposed rules, if facility upgrade costs are capitalized and annualized, the effect on ratepayers should be minimal if the customer base is of a moderate size.

Small Business Regulatory Flexibility Analysis

The commission reviewed this proposed rulemaking and determined that a small business regulatory flexibility analysis is not required because the proposed rules will not adversely affect a small or micro-business in a material way for the first five years that the proposed rules are in effect and are necessary to comply with state and federal law.

Local Employment Impact Statement

The commission reviewed this proposed rulemaking and determined that a local employment impact statement is not required because the proposed rules will not adversely affect a local economy in a material way for the first five years that the proposed rules are in effect.

Draft Regulatory Impact Analysis Determination

The commission reviewed the proposed rulemaking in light of the regulatory analysis requirements of Texas Government Code, §2001.0225 and determined that the rulemaking is not subject to Texas Government Code §2001.0225 because it does not meet any of the four applicability criteria listed in Texas Government Code §2001.0225(a). According to subsection (a), §2001.0225 only applies to a major environmental rule, the result of which is to exceed a standard set by federal law, unless the rule is specifically required by state law; exceed an express requirement of state law, unless the rule is specifically required by federal law; exceed a requirement of a delegation agreement or contract between the state and an agency or representative of the federal government to implement a state and federal program; or adopt a rule solely under the general powers of the agency instead of under a specific state law. This rulemaking does not meet any of these four applicability criteria because it does not exceed a standard set by federal law; does not exceed an express requirement of state law; does not exceed a requirement of a delegation agreement or contract between the state and an agency or representative of the federal government to implement a state and federal program; and is not proposed solely under the general powers of the agency but, rather, specifically under 33 United States Code, §1313(c), which requires states to adopt water quality standards and review them at least once every three years; and TWC, §26.023, which requires the commission to set water quality standards and allows the commission to amend them. Therefore, this proposed rulemaking does not fall under any of the applicability criteria in Texas Government Code, §2001.0225.

The commission invites public comment regarding this Draft Regulatory Impact Analysis Determination. Written comments on the Draft Regulatory Impact Analysis Determination may be submitted to the contact person at the address listed under the Submittal of Comments section of this preamble.

Takings Impact Assessment

The commission evaluated this proposed rulemaking and performed an analysis of whether it constitutes a taking under Texas Government Code, Chapter 2007. The specific purpose of this rulemaking is to incorporate changes to the TSWQS deemed necessary based on the commission's triennial review of the TSWQS, which mainly consist of incorporating new data on toxicity effects and from recent UAAs and clarifying how water quality standards related to bacteria would be assessed using instream monitoring data. The proposed rulemaking would substantially advance this stated purpose by making revisions to toxic criteria, individual water bodies' uses and criteria, and bacteria standards attainment criteria in Chapter 307 of the commission's rules.

The commission's analysis indicates that Texas Government Code, Chapter 2007 does not apply to this proposed rulemaking because this is an action that is reasonably taken to fulfill an obligation mandated by federal law, which is exempt under Texas Government Code, §2007.003(b)(4). Clean Water Act, §303 requires the State of Texas to adopt water quality standards, review those standards at least once every three years, and revise the standards as necessary based on the review. TWC, §26.023 delegates the responsibility of adopting and revising the standards to the commission.

Nevertheless, the commission further evaluated this proposed rulemaking and performed an assessment of whether it constitutes a taking under Texas Government Code, Chapter 2007. Promulgation and enforcement of this proposed rulemaking would be neither a statutory nor a constitutional taking of private real property. Specifically, the proposed rules do not affect a landowner's rights in private real property because this rulemaking does not burden, restrict, or limit an owner's right to property and reduce its value by 25% or more beyond that which would otherwise exist in the absence of the rules. In other words, this rulemaking makes necessary revisions to the TSWQS without burdening, restricting, or limiting an owner's right to property and reducing its value by 25% or more. Therefore, the proposed rulemaking does not constitute a taking under Texas Government Code, Chapter 2007.

Consistency with the Coastal Management Program

The commission reviewed the proposed rulemaking and found that the proposal is subject to the Texas Coastal Management Program (CMP) in accordance with the Coastal Coordination Act, Texas Natural Resources Code, §§33.201 et seq., and therefore must be consistent with all applicable CMP goals and policies. The commission conducted a consistency determination for the proposed rules in accordance with the Coastal Coordination Act Implementation Rules, 31 Texas Administrative Code (TAC) §505.22, and found the proposed rulemaking is consistent with the applicable CMP goals and policies.

CMP goals applicable to the proposed rules include protecting, preserving, restoring, and enhancing the diversity, quality, quantity, functions, and values of coastal natural resources by establishing standards and criteria for instream water quality for Texas streams, rivers, lakes, estuaries, wetlands, and other water bodies. These proposed water quality standards and criteria will provide parameters for permitted discharges that will protect, preserve, restore, and enhance the quality, functions, and values of coastal natural resources.

CMP policies applicable to the proposed rules include 31 TAC §501.21. The proposed rulemaking will require wastewater discharge permit applicants to provide information and monitoring data to the commission so the commission may make an informed decision in authorizing a discharge permit and ensuring the authorized activities in a wastewater discharge permit comply with all applicable requirements, thus making the rulemaking consistent with the administrative policies of the CMP.

The proposed rulemaking considers information gathered through the biennial assessments of water quality in the commission's Integrated Report of Surface Water Quality to prioritize coastal waters for studies and analysis when reviewing and revising the TSWQS. The TSWQS are established to protect designated uses of coastal waters, including protecting uses for recreational purposes and propagating and protecting terrestrial and aquatic life. The proposed rulemaking is consistent with the CMP's policies for discharges of municipal and industrial wastewater to coastal waters and how they relate to specific activities and coastal natural resource areas.

Promulgation and enforcement of these proposed rules will not violate or exceed any standards identified in the applicable CMP goals and policies because the proposed rules are consistent with these CMP goals and policies, do not create or have a direct or significant adverse effect on any coastal natural resource areas, and do not create or have a direct or significant adverse effect on any coastal natural resource areas.

Written comments on the consistency of this rulemaking may be submitted to the contact person at the address listed under the Submittal of Comments section of this preamble.

Announcement of Hearing

The commission will hold a public hearing on this proposal in Austin on October 16, 2017, at 10:00 a.m. in Building E, Room 201S, at the commission's central office located at 12100 Park 35 Circle. The webcast from this hearing may be viewed at http://www.texasadmin.com/tceqs.shtml. The hearing is structured for the receipt of oral or written comments by interested persons. Individuals may present oral statements when called upon in order of registration. Open discussion will not be permitted during the hearing; however, commission staff members will be available to discuss the proposal 30 minutes prior to the hearing.

Persons who have special communication or other accommodation needs who are planning to attend the hearing should contact Sandy Wong, Office of Legal Services, at (512) 239-1802 or 1-800-RELAY-TX (TDD). Requests should be made as far in advance as possible.

Submittal of Comments

Written comments may be submitted to Ms. Kris Hogan, MC 205, Office of Legal Services, Texas Commission on Environmental Quality, P.O. Box 13087, Austin, Texas 78711-3087, or faxed to (512) 239-4808. Electronic comments may be submitted at http://www1.tceq.texas.gov/rules/ecomments/. File size restrictions may apply to comments being submitted via the eComments system. All comments should reference Rule Project Number 2016-002-307-OW. The comment period closes on October 17, 2017. Copies of the proposed rulemaking can be obtained from the commission's website at http://www.tceq.texas.gov/rules/propose_adopt.html. For further information, please contact Debbie Miller, Monitoring and Assessment Section, at (512) 239-1703.

Statutory Authority

The amendments are proposed under Texas Water Code (TWC), §5.102, which establishes the commission's general authority necessary to carry out its jurisdiction; TWC, §5.103, which establishes the commission's general authority to adopt rules; TWC, §5.105, which establishes the commission's authority to set policy by rule; TWC, §5.120, which requires the commission to administer the law so as to promote the conservation and protection of the quality of the state's environment and natural resources; TWC, §26.011, which authorizes the commission to establish the level of quality to be maintained in and control the quality of water in the state; TWC, §26.0135, which authorizes the commission to monitor and assess the water quality of each watershed and river basin in the state; TWC, §26.023, which authorizes the commission to set water quality standards for water in the state by rule; TWC, §26.027, which authorizes the commission to issue permits; and TWC, §26.121, which provides the commission's authority to prohibit unauthorized discharges; and 33 United States Code, §1313, which requires states to adopt water quality standards and review them at least once every three years.

The amendments implement TWC, §26.023.

§307.2.Description of Standards.

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

(1) Section 307.1 of this title (relating to General Policy Statement) contains the general standards policy of the commission.

(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) Section 307.3 of this title (relating to Definitions and Abbreviations) defines terms and abbreviations used in the standards.

(4) Section 307.4 of this title (relating to General Criteria) lists the general criteria that 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) Section 307.5 of this title (relating to Antidegradation) describes the antidegradation policy and implementation procedures.

(6) Section 307.6 of this title (relating to Toxic Materials) establishes criteria and control procedures for specific toxic substances and total toxicity.

(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) Section 307.8 of this title [(relating to the Application of Standards)] sets forth conditions when portions of the standards do not apply - such as in mixing zones or below critical low-flows.

(9) Section 307.9 of this title describes sampling and analytical procedures to determine standards attainment.

(10) Section 307.10 of this title (relating to Appendices A - G) lists site-specific standards and supporting information for classified segments (Appendices A and C), water bodies that are sole-source surface drinking water supplies (Appendix B), site-specific uses and criteria for unclassified water bodies (Appendix D), site-specific toxic criteria that may be derived for any water in the state (Appendix E), chlorophyll a criteria for selected reservoirs (Appendix F), and site-specific recreational uses and criteria for unclassified water bodies (Appendix G). Specific appendices are as follows:

(A) Appendix A - Site-specific Uses and Criteria for Classified Segments;

(B) Appendix B - Sole-source Surface Drinking Water Supplies;

(C) Appendix C - Segment Descriptions;

(D) Appendix D - Site-specific Uses and Criteria for Unclassified Water Bodies;

(E) Appendix E - Site-specific Toxic Criteria;

(F) Appendix F - Site-specific Nutrient Criteria for Selected Reservoirs; and

(G) Appendix G - Site-specific Recreational Uses and Criteria for Unclassified Water Bodies.

(b) Applicability. The Texas Surface Water Quality Standards apply to surface waters in the state - including wetlands.

(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) River basin waters. Surface inland waters comprising the major rivers and their tributaries, including listed impounded waters and the tidal portion of rivers to the extent that they are confined in channels.

(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) Bay waters. All tidal waters, exclusive of those included in river basin waters, coastal basin waters, and gulf waters.

(4) Gulf waters. Waters that are not included in or do not form a part of any bay or estuary but that are a part of the open waters of the Gulf of Mexico to the limit of the state's jurisdiction.

(d) Modification of standards.

(1) The commission reserves the right to amend these standards following the completion of special studies.

(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) The narrative provisions, presumed uses, 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 chapter [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 that establishes a site-specific standard requires a use-attainability analysis that demonstrates that reasonably attainable water-quality related uses are protected. Upon adoption, site-specific amendments to the standards will be listed in §307.10 of this title.

(4) Factors that may justify the development of site-specific standards are described in §307.4 and §§307.6 - 307.8 [§§307.4, 307.6, 307.7, and 307.8] of this title.

(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 or stormwater.

(A) A temporary variance is only applicable to an existing permitted discharge.

(B) A permittee may apply for a temporary variance prior to or during the permit application process. The temporary variance request must be included in a public notice during the permit application process. An opportunity for public comment is provided, and the request may be considered in any public hearing on the permit application.

(C) A temporary variance for a Texas Pollutant Discharge Elimination System permit also requires review and approval by the United States Environmental Protection Agency (EPA) during the permitting process.

(D) The permit must contain effluent limitations that protect existing uses and preclude degradation of existing water quality, and the term of the permit must not exceed three years. Effluent limitations that are needed to meet the existing standards are listed in the permit and are effective 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.

(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 chapter [title]. This extension can be approved by the commission only after a site-specific study that supports a standards change is completed and the commission agrees the completed study supports a change in the applicable standard(s).

(F) Site-specific standards that are developed under a temporary variance must be expeditiously proposed and publicly considered for adoption at the earliest opportunity.

(e) Standards implementation procedures. Provisions for implementing the water quality standards are described in a document entitled Procedures to Implement the Texas Surface Water Quality Standards (RG-194) as amended and approved by the Texas Commission on Environmental Quality and EPA.

(f) Permit schedules to meet standards. Upon permit amendment or permit renewal, the commission 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.

(g) Temporary standards. Where a criterion or designated use 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), or to facilitate restoration or reconfiguration activities that preclude the attainment of the designated use or criterion, then a temporary standard for specific water bodies or permittees may be adopted in §307.10 of this title as an alternative to changing uses. A [criterion that is established as a temporary standard must be adopted in accordance with the provisions of subsection (d)(3) of this section] temporary standard identifies the interim numerical criteria or use that applies during the existence of the temporary standard. A temporary standard must be adopted in accordance with the provisions of subsection (d)(3) of this section. Once adopted, a temporary standard is the applicable standard for the purposes of developing wastewater discharge permit limits and issuing certifications specified in the federal Clean Water Act, §401 and Chapter 279 of this title (relating to Water Quality Certification). Specific reasons and additional procedures for justifying a temporary standard are provided in the standards implementation procedures. A temporary standard must identify the water body or permittee to which [water bodies where] the temporary standard [criterion ] applies. [A temporary standard identifies the numerical criteria that 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 must be reevaluated every five years at a minimum, which may be conducted through the permit process if a triennial review of the Texas Surface Water Quality Standards has not occurred. A temporary standard expires no later than the completion of the next triennial review [revision] of the Texas Surface Water Quality Standards. When a temporary standard expires, subsequent discharge permits are issued to meet the applicable existing water quality standards. If a temporary standard is sufficiently justified in accordance with the provisions of subsection (d)(3) of this section, it can be renewed during revisions of the Texas Surface Water Quality Standards. A temporary standard cannot be established that would impair an existing use.

(h) Effective date of standards. Except as provided in 40 CFR §131.21 (EPA review and approval of water quality standards), this chapter becomes [these rules become] effective 20 days after the date the chapter is [they are] filed in the Office of the Secretary of State [office of the secretary of state]. As to actions covered by 40 CFR §131.21, the rules become effective upon approval by EPA.

(i) Effect of conflict or invalidity of rule.

(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 that can be given effect without the invalid provision or application, and to this end the provisions of this chapter are severable.

(2) To the extent of any irreconcilable conflict between provisions of this chapter and other rules of the commission, the provisions of this chapter supersede.

§307.3.Definitions and Abbreviations.

(a) Definitions. The following words and terms, when used in this chapter, have the defined meanings, unless the context clearly indicates otherwise.

(1) Acute toxicity--Toxicity that exerts a stimulus severe enough to rapidly induce an effect. The duration of exposure applicable to acute toxicity is typically 96 hours or less. Tests of total toxicity normally use lethality as the measure of acute impacts. (Direct thermal impacts are excluded from definitions of toxicity.)

(2) Ambient--Refers to the existing water quality in a particular water body.

(3) Aquatic vegetation--Refers to aquatic organisms, i.e., plant life, found in the water and includes phytoplankton; algae, both attached and floating; and vascular and nonvascular plants, both rooted and floating.

(4) Attainable use--A use that can be reasonably achieved by a water body in accordance with its physical, biological, and chemical characteristics whether it is currently meeting that use or not. Guidelines for the determination and review of attainable uses are provided in the standards implementation procedures. The designated use, existing use, or presumed use of a water body may not necessarily be the attainable use.

(5) Background--Refers to the water quality in a particular water body that would occur if that water body were relatively unaffected by human activities.

(6) Bedslope--Stream gradient, or the extent of the drop in elevation encountered as the stream flows downhill. One measure of bedslope is the elevation decline in meters over the stream distance in kilometers.

(7) Best management practices--Schedules of activities, maintenance procedures, and other management practices to prevent or reduce the pollution of water in the state from point and nonpoint sources, to the maximum extent practicable. Best management practices also include treatment requirements, operating procedures, and practices to control plant site runoff, spillage or leaks, sludge or waste disposal, or drainage from raw material storage.

(8) Bioaccumulative--Describes a chemical that is taken up by aquatic organisms from water directly or through the consumption of food containing the chemical.

(9) Bioconcentration factor--A unitless value describing the degree to which a chemical can be concentrated in the tissues of an organism in the aquatic environment and that is absorbed directly from the water. The bioconcentration factor is the ratio of a chemical's concentration in the tissue of an organism compared to that chemical's average concentration in the surrounding water.

(10) Biological integrity--The species composition, diversity, and functional organization of a community of organisms in an environment relatively unaffected by pollution.

(11) Biotic ligand model--A metal bioavailability model that uses receiving water body characteristics to develop site-specific water quality criteria.

(12) Chronic toxicity--Toxicity that continues for a long-term period after exposure to toxic substances. Chronic exposure produces sub-lethal effects, such as growth impairment and reduced reproductive success, but it may also produce lethality. The duration of exposure applicable to the most common chronic toxicity test is seven days or more.

(13) Classified--Refers to a water body that is listed and described in Appendices A and C of [Appendix A and Appendix C in] §307.10 of this title (relating to Appendices A - G). Site-specific uses and criteria for classified water bodies are listed in Appendix A of §307.10 of this title.

(14) Coastal recreation waters--Marine coastal waters including oceans, coastal estuaries, and bays designated as primary contact recreation 1 or 2. Waters upstream of an unimpaired natural connection to the open sea or tidal inland waters are not considered coastal recreation waters (e.g., tidal rivers or streams).

(15) [(14)] Commission--Texas Commission on Environmental Quality.

(16) [(15)] Criteria--Water quality conditions that are to be met in order to support and protect desired uses, i.e., existing, designated, attainable, and presumed uses.

(17) [(16)] Critical low-flow--Low-flow condition that consists of the seven-day, two-year low-flow [(7Q2 flow)] or the alternative low-flows for spring-fed streams as discussed in §307.8(a)(2) of this title (relating to Application of Standards) and below which some standards do not apply.

(18) [(17)] Designated use--A use that is assigned to specific water bodies in Appendix A, D, or G of [Appendix D, or Appendix G in] §307.10 of this title (relating to Appendices A - G). Typical uses that may be designated for specific water bodies include domestic water supply, categories of aquatic life use, recreation categories, and aquifer protection.

(19) [(18)] Discharge permit--A permit issued by the state or a federal agency to discharge treated effluent or cooling water into waters of the state.

(20) [(19)] Dry weather flows--Sustained or typical dry, warm-weather flows between rainfall events, excluding unusual antecedent conditions of drought or wet weather.

(21) [(20)] EC50--The concentration of a toxicant that produces an adverse effect on 50% of the organisms tested in a specified time period.

(22) [(21)] E. coli--Escherichia coli, a subgroup of fecal coliform bacteria that is present in the intestinal tracts and feces of warm-blooded animals. It is used as an indicator of the potential presence of pathogens.

(23) [(22)] Effluent--Wastewater discharged from any point source prior to entering a water body.

(24) [(23)] Enterococci--A subgroup of fecal streptococci bacteria (mainly Streptococcus faecalis and Streptococcus faecium that is present in the intestinal tracts and feces of warm-blooded animals. It is used as an indicator of the potential presence of pathogens.

(25) [(24)] Epilimnion--The upper mixed layer of a lake (including impoundments, ponds, and reservoirs).

(26) [(25)] Existing use--A use that is currently being supported by a specific water body or that was attained on or after November 28, 1975.

(27) [(26)] Fecal coliform--A portion of the coliform bacteria group that is present in the intestinal tracts and feces of warm-blooded animals; heat tolerant bacteria from other sources can sometimes be included. It is used as an indicator of the potential presence of pathogens.

(28) [(27)] Freshwaters--Inland waters that exhibit no measurable elevation changes due to normal tides.

(29) [(28)] Halocline--A vertical gradient in salinity under conditions of density stratification that is usually recognized as the point where salinity exhibits the greatest difference in the vertical direction.

(30) [(29)] Harmonic mean flow--A measure of mean flow in a water course that is calculated by summing the reciprocals of the individual flow measurements, dividing this sum by the number of measurements, and then calculating the reciprocal of the resulting number.

(31) [(30)] Incidental fishery--A level of fishery that applies to water bodies that are not considered to have a sustainable fishery but that have an aquatic life use of limited, intermediate, high, or exceptional.

(32) [(31)] Industrial cooling impoundment--An impoundment that is owned or operated by, or in conjunction with, the water rights permittee, and that is designed and constructed for the primary purpose of reducing the temperature and removing heat from an industrial effluent.

(33) [(32)] Industrial cooling water area--A designated area associated with a permitted wastewater discharge where numerical temperature criteria are not applicable in accordance with conditions and requirements specified in §307.4(f) of this title (relating to General Criteria) and §307.8(b) of this title (relating to Application of Standards).

(34) [(33)] Intermittent stream--A stream that has a period of zero flow for at least one week during most years. Where flow records are available, a stream with a seven-day, two-year low-flow [7Q2 flow] of less than 0.1 cubic feet per second is considered intermittent.

(35) [(34)] Intermittent stream with perennial pools--An intermittent stream that maintains persistent pools even when flow in the stream is less than 0.1 cubic feet per second.

(36) [(35)] LC50--The concentration of a toxicant that is lethal (fatal) to 50% of the organisms tested in a specified time period.

(37) [(36)] Main pool station--A monitoring station that is located in the main body of a reservoir near the dam and not located in a cove or in the riverine portion or transition zone of a reservoir.

(38) [(37)] Method detection limit--The minimum concentration of a substance that can be measured and reported with 99% confidence that the analyte concentration is greater than zero and is determined from analysis of a sample in a given matrix containing the analyte. The method detection limit [(MDL) ] is estimated in accordance with 40 Code of Federal Regulations Part 136, Appendix B.

(39) [(38)] Minimum analytical level--The lowest concentration that a particular substance can be quantitatively measured with a defined accuracy and precision level using approved analytical methods. The minimum analytical level is not the published method detection limit [MDL] for a United States Environmental Protection Agency [(EPA)]-approved analytical method that is based on laboratory analysis of the substance in reagent (distilled) water. The minimum analytical level is based on analyses of the analyte in the matrix of concern (e.g., wastewater effluents). The commission establishes general minimum analytical levels that are applicable when information on matrix-specific minimum analytical levels is unavailable.

(40) [(39)] Mixing zone--The area contiguous to a permitted discharge where mixing with receiving waters takes place and where specified criteria, as listed in §307.8(b)(1) of this title(relating to Application of Standards), can be exceeded. Acute toxicity to aquatic organisms is not allowed in a mixing zone, and chronic toxicity to aquatic organisms is not allowed beyond a mixing zone.

(41) [(40)] Noncontact recreation--Activities that do not involve a significant risk of water ingestion, such as those with limited body contact incidental to shoreline activity, including birding, hiking, and biking. Noncontact recreation use may also be assigned where primary and secondary contact recreation activities should not occur because of unsafe conditions, such as ship and barge traffic.

(42) [(41)] Nonpersistent--Describes a toxic substance that readily degrades in the aquatic environment, exhibits a half-life of less than 60 days, and does not have a tendency to accumulate in organisms.

(43) [(42)] Nutrient criteria--Numeric and narrative criteria that are established to protect surface waters from excessive growth of aquatic vegetation. Nutrient numeric criteria for reservoirs are expressed in terms of chlorophyll a concentration per unit volume as a measure of phytoplankton density.

(44) [(43)] Nutrient--A chemical constituent, most commonly a form of nitrogen or phosphorus, that in excess can contribute to the undesirable growth of aquatic vegetation and impact uses as defined in this title.

(45) [(44)] Oyster waters--Waters producing edible species of clams, oysters, or mussels.

(46) [(45)] Persistent--Describes a toxic substance that is not readily degraded and exhibits a half-life of 60 days or more in an aquatic environment.

(47) [(46)] Pollution--The alteration of the physical, thermal, chemical, or biological quality of, or the contamination of, any water in the state that renders the water harmful, detrimental, or injurious to humans, animal life, vegetation, or property or to the public health, safety, or welfare, or impairs the usefulness or the public enjoyment of the water for any lawful or reasonable purpose.

(48) [(47)] Point source--Any discernible, confined and discrete conveyance, including but not limited to any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, concentrated animal feeding operation, or vessel or other floating craft, from which pollutants or wastes are or may be discharged into or adjacent to any water in the state.

(49) [(48)] Presumed use--A use that is assigned to generic categories of water bodies (such as perennial streams). Presumed uses are superseded by designated uses for individual water bodies in Appendix A, D, or G [Appendix D, or Appendix G] of §307.10 of this title (relating to Appendices A - G).

(50) [(49)] Primary contact recreation 1--Activities that are presumed to involve a significant risk of ingestion of water (e.g., wading by children, swimming, water skiing, diving, tubing, surfing, handfishing as defined by Texas Parks and Wildlife Code, §66.115, and the following whitewater activities: kayaking, canoeing, and rafting).

(51) [(50)] Primary contact recreation 2--Water recreation activities, such as wading by children, swimming, water skiing, diving, tubing, surfing, handfishing as defined by Texas Parks and Wildlife Code, §66.115, and whitewater kayaking, canoeing, and rafting, that involve a significant risk of ingestion of water but that occur less frequently than for primary contact recreation 1 due to:

(A) physical characteristics of the water body; or

(B) limited public access.

(52) [(51)] Protection zone--Any area within the watershed of a sole-source surface drinking water supply that is:

(A) within two miles of the normal pool elevation of a body of surface water that is a sole-source surface drinking water supply;

(B) within two miles of that part of a perennial stream that is:

(i) a tributary of a sole-source surface drinking water supply; and

(ii) within three linear miles upstream of the normal pool elevation of a sole-source surface drinking water supply; or

(C) within two miles of that part of a stream that is a sole-source surface drinking water supply, extending three linear miles upstream from the water supply intake (Texas Water Code, §26.0286).

(53) [(52)] Public drinking water supply--A water body designated to provide water to a public water system as defined in Chapter 290 of this title (relating to Public Drinking Water).

(54) [(53)] Saltwater--A coastal water that has a measurable elevation change due to normal tides. In the absence of tidal information, saltwater is generally considered to be a coastal water that typically has a salinity of two parts per thousand or greater in a significant portion of the water column.

(55) [(54)] Salinity--The total dissolved solids in water after all carbonates have been converted to oxides, all bromide and iodide have been replaced by chloride, and all organic matter has been oxidized. For most purposes, salinity is considered equivalent to total dissolved salt content. Salinity is usually expressed in parts per thousand.

(56) [(55)] Seagrass propagation--A water-quality-related existing use that applies to saltwater with significant stands of submerged seagrass.

(57) [(56)] Secondary contact recreation 1--Activities that commonly occur but have limited body contact incidental to shoreline activity (e.g. fishing, canoeing, kayaking, rafting, and motor boating). These activities are presumed to pose a less significant risk of water ingestion than primary contact recreation 1 or 2 but more than secondary contact recreation 2.

(58) [(57)] Secondary contact recreation 2--Activities with limited body contact incidental to shoreline activity (e.g. fishing, canoeing, kayaking, rafting, and motor boating) that are presumed to pose a less significant risk of water ingestion than secondary contact recreation 1. These activities occur less frequently than secondary contact recreation 1 due to physical characteristics of the water body or limited public access.

(59) [(58)] Segment--A water body or portion of a water body that is individually defined and classified in Appendices A and C of §307.10 of this title (relating to Appendices A - G) in the Texas Surface Water Quality Standards. A segment is intended to have relatively homogeneous chemical, physical, and hydrological characteristics. A segment provides a basic unit for assigning site-specific standards and for applying water quality management programs of the agency. Classified segments may include streams, rivers, bays, estuaries, wetlands, lakes, or reservoirs.

(60) [(59)] Settleable solids--The volume or weight of material that settles out of a water sample in a specified period of time.

(61) [(60)] Seven-day, two-year low-flow (7Q2)--The lowest average stream flow for seven consecutive days with a recurrence interval of two years, as statistically determined from historical data. As specified in §307.8 of this title, some water quality standards do not apply at stream flows that are less than the 7Q2 flow.

(62) [(61)] Shellfish--Clams, oysters, mussels, crabs, crayfish, lobsters, and shrimp.

(63) [(62)] Sole-source surface drinking water supply--A body of surface water that is identified as a public water supply in rules adopted by the commission under Texas Water Code, §26.023 and is the sole source of supply of a public water supply system, exclusive of emergency water connections (Texas Water Code, §26.0286).

(64) [(63)] Standard Methods for the Examination of Water and Wastewater--A document describing sampling and analytical procedures that is published by the American Public Health Association, American Water Works Association, and Water Environment Federation. The most recent edition of this document is to be followed whenever its use is specified by this chapter [these rules].

(65) [(64)] Standards--Desirable uses (i.e., existing, attainable, designated, or presumed uses as defined in this section [title]) and the narrative and numerical criteria deemed necessary to protect those uses in surface waters.

(66) [(65)] Standards implementation procedures--Methods and protocols in the guidance document Procedures to Implement the Texas Surface Water Quality Standards (RG-194), as amended and approved by the commission and EPA.

(67) [(66)] Stormwater--Rainfall runoff, snow melt runoff, surface runoff, and drainage.

(68) [(67)] Stormwater discharge--A point source discharge that is composed entirely of stormwater associated with an industrial activity, a construction activity, a discharge from a municipal separate storm sewer system, or other discharge designated by the agency.

(69) [(68)] Stream order--A classification of stream size, where the smallest, unbranched tributaries of a drainage basin are designated first order streams. Where two first order streams join, a second order stream is formed; where two second order streams join, a third order stream is formed, etc. For purposes of water quality standards application, stream order is determined from United States Geological Survey topographic maps with a scale of 1:24,000.

(70) [(69)] Surface water in the state--Lakes, bays, ponds, impounding reservoirs, springs, rivers, streams, creeks, estuaries, wetlands, marshes, inlets, canals, the Gulf of Mexico inside the territorial limits of the state as defined in the Texas Water Code, §26.001, and all other bodies of surface water, natural or artificial, inland or coastal, fresh or salt, navigable or nonnavigable, and including the beds and banks of all water-courses and bodies of surface water, that are wholly or partially inside or bordering the state or subject to the jurisdiction of the state; except that waters in treatment systems that are authorized by state or federal law, regulation, or permit, and that are created for the purpose of waste treatment are not considered to be water in the state.

(71) [(70)] Sustainable Fisheries--Descriptive of water bodies that potentially have sufficient fish production or fishing activity to create significant long-term human consumption of fish. Sustainable fisheries include perennial streams and rivers with a stream order of three or greater; lakes and reservoirs greater than or equal to 150 acre-feet or 50 surface acres; all bays, estuaries, and tidal rivers. Water bodies that are presumed to have sustainable fisheries include all designated segments listed in Appendix A of §307.10 of this title (relating to Appendices A - G) unless specifically exempted.

(72) [(71)] Thalweg--The deepest portion of a stream or river channel cross-section.

(73) [(72)] Tidal--Descriptive of coastal waters that are subject to the ebb and flow of tides. For purposes of standards applicability, tidal waters are considered to be saltwater. Classified tidal waters include all bays and estuaries with a segment number that begins with 24xx, all streams with the word tidal in the segment name, and the Gulf of Mexico.

(74) [(73)] To discharge--Includes to deposit, conduct, drain, emit, throw, run, allow to seep, or otherwise release or dispose of, or to allow, permit, or suffer any of these acts or omissions.

(75) [(74)] Total dissolved solids--The amount of material (inorganic salts and small amounts of organic material) dissolved in water and commonly expressed as a concentration in terms of milligrams per liter. The term is equivalent to the term filterable residue, as used in 40 Code of Federal Regulations Part 136 and in previous editions of the publication entitled, Standard Methods for the Examination of Water and Wastewater.

(76) [(75)] Total maximum daily load (TMDL)--The total amount of a substance that a water body can assimilate and still meet the Texas Surface Water Quality Standards.

(77) [(76)] Total suspended solids--Total suspended matter in water, which is commonly expressed as a concentration in terms of milligrams per liter. The term is equivalent to nonfilterable residue, as used in 40 Code of Federal Regulations Part 136 and in previous editions of the publication entitled, Standard Methods for the Examination of Water and Wastewater.

(78) [(77)] Total toxicity--Toxicity as determined by exposing aquatic organisms to samples or dilutions of instream water or treated effluent. Also referred to as whole effluent toxicity or biomonitoring.

(79) [(78)] Toxic equivalency factor [(TEF)]--A factor to describe an order-of-magnitude consensus estimate of the toxicity of a compound relative to the toxicity of 2,3,7,8-tetraclorodibenzo-p-dioxin (2,3,7,8-TCDD). The factor is applied to transform various concentrations of dioxins and furans or dioxin-like polychlorinated biphenyls [(PCBs)] into equivalent concentrations of 2,3,7,8-TCDD, expressed as a toxic equivalency [(TEQ)].

(80) [(79)] Toxic equivalency [(TEQ)]--The sum of the products from the concentration of each dioxin and furan, or dioxin-like polychlorinated biphenyl [PCB] congener, multiplied by its respective toxic equivalency factor [TEF] to give a single 2,3,7,8-tetraclorodibenzo-p-dioxin [2,3,7,8-TCDD] equivalent.

(81) [(80)] Toxicity--The occurrence of adverse effects to living organisms due to exposure to toxic materials. Adverse effects caused by conditions of temperature and dissolved oxygen are excluded from the definition of toxicity. With respect to the provisions of §307.6(e) of this title (relating to Toxic Materials), which concerns total toxicity and biomonitoring requirements, adverse effects caused by concentrations of dissolved salts (such as sodium, potassium, calcium, chloride, carbonate) in source waters are excluded from the definition of toxicity. Source water is defined as surface water or groundwater that is used as a public water supply or industrial water supply (including a cooling-water supply). Source water does not include brine water that is produced during the extraction of oil and gas, or other sources of brine water that are substantially uncharacteristic of surface waters in the area of discharge. In addition, adverse effects caused by concentrations of dissolved salts that are added to source water by industrial processes are not excluded from the requirements of §307.6(e) of this title, except as specifically noted in §307.6(e)(2)(B) of this title, which concerns requirements for toxicity testing of 100% effluent. This definition of toxicity does not affect the standards for dissolved salts in this chapter other than §307.6(e) of this title. The standards implementation procedures contain provisions to protect surface waters from adverse effects of dissolved salts and methods to address the effects of dissolved salts on total toxicity tests.

(82) [(81)] Toxicity biomonitoring--The process or act of determining total toxicity. Documents that describe procedures for toxicity biomonitoring are cited in §307.6 of this title (relating to Toxic Materials). Also referred to simply as biomonitoring.

(83) [(82)] Water-effect ratio (WER)--The WER is calculated as the toxic concentration (LC50) of a substance in water at a particular site, divided by the toxic concentration of that substance as reported in laboratory dilution water. The WER can be used to establish site-specific acute and chronic criteria to protect aquatic life. The site-specific criterion is equal to the WER times the statewide aquatic life criterion in §307.6(c) of this title.

(84) [(83)] Water quality management program--The agency's overall program for attaining and maintaining water quality consistent with state standards, as authorized under the Texas Water Code, the Texas Administrative Code, and the Clean Water Act, §§106, 205(j), 208, 303(e) and 314 (33 United States Code, §§1251 et seq.).

(85) [(84)] Wetland--An area (including a swamp, marsh, bog, prairie pothole, or similar area) having a predominance of hydric soils that are inundated or saturated by surface or groundwater at a frequency and duration sufficient to support and that under normal circumstances supports the growth and regeneration of hydrophytic vegetation. The term "hydric soil" means soil that, in its undrained condition, is saturated, flooded, or ponded long enough during a growing season to develop an anaerobic condition that supports the growth and regeneration of hydrophytic vegetation. The term "hydrophytic vegetation" means a plant growing in: water or a substrate that is at least periodically deficient in oxygen during a growing season as a result of excessive water content. The term "wetland" does not include irrigated acreage used as farmland; a man-made wetland of less than one acre; or a man-made wetland where construction or creation commenced on or after August 28, 1989, and that was not constructed with wetland creation as a stated objective, including but not limited to an impoundment made for the purpose of soil and water conservation that has been approved or requested by soil and water conservation districts. If this definition of wetland conflicts with the federal definition in any manner, the federal definition prevails.

(86) [(85)] Wetland water quality functions--Attributes of wetlands that protect and maintain the quality of water in the state, which include stormwater storage and retention and the moderation of extreme water level fluctuations; shoreline protection against erosion through the dissipation of wave energy and water velocity, and anchoring of sediments; habitat for aquatic life; and removal, transformation, and retention of nutrients and toxic substances.

(87) [(86)] Zone of initial dilution--The small area at the immediate point of a permitted discharge where initial dilution with receiving waters occurs and that may not meet certain criteria applicable to the receiving water. A zone of initial dilution is substantially smaller than a mixing zone.

(b) Abbreviations. The following abbreviations apply to this chapter:

(1) ALU--aquatic life use.

(2) AP--aquifer protection.

(3) AS--agricultural water supply.

(4) ASTER--Assessment Tools for the Evaluation of Risk.

(5) BCF--bioconcentration factor.

(6) CASRN--Chemical Abstracts Service Registry number.

(7) CFR--Code of Federal Regulations.

(8) cfs--cubic feet per second.

(9) Cl-1--chloride.

(10) CR--county road.

(11) DO--dissolved oxygen.

(12) E--exceptional aquatic life use.

(13) EPA--United States Environmental Protection Agency.

(14) degrees F--degrees [Degree(s)] Fahrenheit.

(15) FM--Farm to Market Road.

(16) ft3/s--cubic feet per second.

(17) H--high aquatic life use.

(18) HEAST--Health Effects Assessment Summary Tables.

(19) I--intermediate aquatic life use.

(20) BWC--International Boundary and Water Commission.

(21) IH--Interstate Highway.

(22) [(21)] IRIS--Integrated Risk Information System.

(23) [(22)] IS--industrial water supply.

(24) [(23)] km--kilometer.

(25) [(24)] L--limited aquatic life use.

(26) [(25)] M--minimal aquatic life use.

(27) [(26)] m--multiplier.

(28) [(27)] m/km--meters per kilometer.

(29) [(28)] MCL--maximum contaminant level (for public drinking water supplies).

(30) [(29)] MDL--method detection limit.

(31) [(30)] mg/L--milligrams per liter.

(32) [(31)] mi--mile.

(33) [(32)] mL--milliliter.

(34) [(33)] N--navigation.

(35) [(34)] NCR--noncontact recreation.

(36) [(35)] O--oyster waters.

(37) [(36)] PCR--primary contact recreation.

(38) [(37)] PS--public water supply.

(39) [(38)] RfD--reference dose.

(40) [(39)] RR--ranch road.

(41) [(40)] 7Q2--seven-day, two-year low-flow.

(42) [(41)] SCR--secondary contact recreation.

(43) [(42)] SH--state highway.

(44) [(43)] SO4-2 --sulfate.

(45) [(44)] SU--standard units.

(46) [(45)] TCEQ--Texas Commission on Environmental Quality.

(47) [(46)] TDS--total dissolved solids.

(48) [(47)] TEF--toxic equivalency factor.

(49) [(48)] TMDL--total maximum daily load.

(50) [(49)] TPDES--Texas Pollutant Discharge Elimination System.

(51) [(50)] TRE--toxicity reduction evaluation.

(52) [(51)] TSS--total suspended solids.

(53) [(52)] US--United States.

(54) [(53)] USFDA--United States Food and Drug Administration.

(55) [(54)] USGS--United States Geological Survey.

(56) [(55)] WER--Water-effect ratio.

(57) [(56)] WF--waterfowl habitat.

(58) [(57)] WQM--water quality management.

(59) [(58)] µg/L--micrograms per liter.

(60) [(59)] ZID--zone of initial dilution

§307.6.Toxic Materials.

(a) Application. The toxic criteria set forth in this section apply to surface water in the state and specifically apply to substances attributed to waste discharges or human activity. With the exception of numeric human health criteria, toxic criteria do not apply to those instances where surface water, solely as a result of natural phenomena, exhibit characteristics beyond the limits established by this section. Standards and procedures set forth in this section are applied in accordance with §307.8 of this title (relating to Application of Standards) and §307.9 of this title (relating to Determination of Standards Attainment).

(b) General provisions.

(1) Water in the state must not be acutely toxic to aquatic life in accordance with §307.8 of this title.

(2) Water in the state with designated or existing aquatic life uses of limited or greater must not be chronically toxic to aquatic life, in accordance with §307.8 of this title.

(3) Water in the state must be maintained to preclude adverse toxic effects on human health resulting from contact recreation, consumption of aquatic organisms, consumption of drinking water or any combination of the three. Water in the state with sustainable fisheries or public drinking water supply uses must not exceed applicable human health toxic criteria, in accordance with subsection (d) of this section and §307.8 of this title.

(4) Water in the state must be maintained to preclude adverse toxic effects on aquatic life, terrestrial life, livestock, or domestic animals, resulting from contact, consumption of aquatic organisms, consumption of water, or any combination of the three.

(c) Specific numerical aquatic life criteria.

(1) Numerical criteria are established in Table 1 of this paragraph for those specific toxic substances where adequate toxicity information is available and that have the potential for exerting adverse impacts on water in the state.

Figure: 30 TAC §307.6(c)(1) (.pdf)

[Figure: 30 TAC §307.6(c)(1)]

(2) Numerical criteria are based on ambient water quality criteria documents published by the EPA [United States Environmental Protection Agency (EPA)]. EPA guidance criteria have been appropriately recalculated to eliminate the effects of toxicity data for aquatic organisms that are not native to Texas, in accordance with procedures in the EPA guidance documents [document] entitled Guidelines for Deriving Numerical Site-specific Water Quality Criteria (EPA 600/3-84-099) and Revised Deletion Process for the Site-Specific Recalculation Procedure for Aquatic Life Criteria (EPA-823-R-13-001). [Appendix B of the EPA draft guidance document entitled Interim Guidance on the Determination and Use of Water-Effect Ratios for Metals (EPA-823-B-94-001).] Additional EPA guidelines that may be used to establish aquatic life criteria are detailed in the guidance documents.

(3) Specific numerical acute aquatic life criteria are applied as 24-hour averages, and specific numerical chronic aquatic life criteria are applied as seven-day averages.

(4) Ammonia and chlorine toxicity are addressed by total toxicity (biomonitoring) requirements in subsection (e) of this section.

(5) Specific numerical aquatic life criteria for metals and metalloids in Table 1 of paragraph (1) of this subsection apply to dissolved concentrations where noted. Dissolved concentrations can be estimated by filtration of samples prior to analysis, or by converting from total recoverable measurements in accordance with procedures approved by the commission in the standards implementation procedures (RG-194) as amended. Specific numerical aquatic life criteria for non-metallic substances in Table 1 of paragraph (1) of this subsection apply to total recoverable concentrations unless otherwise noted.

(6) Specific numerical acute criteria for toxic substances are applicable to all water in the state except for small zones of initial dilution (ZIDs) at discharge points. Acute criteria may be exceeded within a ZID and below extremely low streamflow conditions (one-fourth of critical low-flow conditions) in accordance with §307.8 of this title. There must be no lethality to aquatic organisms that move through a ZID, and the sizes of ZIDs are limited in accordance with §307.8 of this title. Specific numerical chronic criteria are applicable to all water in the state with designated or existing aquatic life uses of limited or greater, except inside mixing zones and below critical low-flow conditions, in accordance with §307.8 of this title.

(7) For toxic materials where specific numerical criteria are not listed in Table 1 of paragraph (1) of this subsection, the appropriate criteria for aquatic life protection may be derived in accordance with current EPA guidelines for deriving site-specific water quality criteria. When insufficient data are available to use EPA guidelines, the following provisions are applied in accordance with this section and §307.8 of this title. The LC50 data used in the subsequent calculations are typically obtained from traditional laboratory studies; however, if LC50 data are unavailable or incomplete, other methodologies (such as quantitative structure-activity relationships) may be used:

(A) acute criteria are calculated as 0.3 of the LC50 of the most sensitive aquatic species; LC50 x (0.3) = acute criteria;

(B) concentrations of nonpersistent toxic materials must not exceed concentrations that are chronically toxic as determined from appropriate chronic toxicity data obtained in accordance with procedures in the EPA guidance document entitled Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Life and Their Uses (EPA 822-R-85-100) or calculated as 0.1 of acute LC50 values to the most sensitive aquatic species; LC50 x (0.1) = chronic criteria;

(C) concentrations of persistent toxic materials that do not bioaccumulate shall not exceed concentrations that are chronically toxic as determined from appropriate chronic toxicity data obtained in accordance with procedures in the EPA guidance document entitled Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Life and Their Uses (EPA 822-R-85-100) or calculated as 0.05 of LC50 values to the most sensitive aquatic species; LC50 x (0.05) = chronic criteria; and

(D) concentrations of toxic materials that bioaccumulate must not exceed concentrations that are chronically toxic as determined from appropriate chronic toxicity data obtained in accordance with procedures in the EPA guidance document entitled Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Life and Their Uses (EPA 822-R-85-100) or calculated as 0.01 of LC50 values to the most sensitive aquatic species; LC50 x (0.01) = chronic criteria.

(8) For toxic substances where the relationship of toxicity is defined as a function of pH or hardness, numerical criteria are presented as an equation based on this relationship. Site-specific values for each segment are given in the standards implementation procedures (RG-194) as amended.

(9) Criteria for most metals are multiplied by a water-effect ratio (WER) in order to incorporate the effects of local water chemistry on toxicity. The WER is assumed to be equal to one except where sufficient site-specific data are available to determine the WER for a particular water body or portion of a water body. A WER is only applicable to those portions of a water body that are adequately addressed by site-specific data. WERs that have been determined for particular water bodies are listed in Appendix E of §307.10 of this title (relating to Appendices A - G) when standards are revised. A site-specific WER that affects an effluent limitation in a wastewater discharge permit, and that has not been incorporated into Appendix E of §307.10 of this title, must be noted in a public notice during the permit application process. An opportunity for public comment must be provided, and the WER may be considered in any public hearing on the permit application.

(10) Freshwater copper aquatic-life criteria include a multiplier (m) to incorporate effects of local water chemistry on toxicity. This multiplier may be based on either a WER or a biotic ligand model. The multiplier is assumed to be equal to one except where sufficient site-specific data are available to determine the multiplier for a particular water body or portion of a water body. The multiplier is only applicable to those portions of a water body that are adequately addressed by site-specific data. As multipliers are determined for particular water bodies they are listed in Appendix E of §307.10 of this title when standards are revised. A site-specific multiplier that affects an effluent limitation in a wastewater discharge permit, and that has not been incorporated into Appendix E of §307.10 of this title, is noted in a public notice during the permit application process. An opportunity for public comment must be provided, and the multiplier may be considered in any public hearing on the permit application.

(11) Additional site-specific factors may indicate that the numerical criteria listed in Table 1 of paragraph (1) of this subsection are inappropriate for a particular water body. These factors are applied as a site-specific standards modification in accordance with §307.2(d) of this title (relating to Description of Standards). The application of a site-specific standard must not impair an existing, attainable, or designated use. Factors that may justify a temporary variance or site-specific standards amendment include the following:

(A) background concentrations of specific toxics of concern in receiving waters, sediment, or indigenous biota;

(B) persistence and degradation rate of specific toxic materials;

(C) synergistic, additive, or antagonistic interactions of toxic substances with other toxic or nontoxic materials;

(D) measurements of total effluent toxicity;

(E) indigenous aquatic organisms, which may have different responses to particular toxic materials;

(F) technological or economic limits of treatability for specific toxic materials;

(G) bioavailability of specific toxic substances of concern, as determined by WER tests or other analyses approved by the commission; and

(H) new information concerning the toxicity of a particular substance.

(d) Specific numerical human health criteria.

(1) Numerical human health criteria are established in Table 2 of this paragraph.

Figure: 30 TAC §307.6(d)(1) (.pdf)

[Figure: 30 TAC §307.6(d)(1)]

(2) Categories of human health criteria:

(A) concentration criteria to prevent contamination of drinking water, fish, and other aquatic life to ensure that they are safe for human consumption. These criteria apply to surface waters that are designated or used for public drinking water supplies, including all water bodies identified as having a public drinking water supply use in Appendix A of §307.10 of this title [this chapter] or as a sole-source surface drinking water supply in Appendix B of §307.10 of this title [this chapter]. (Column A in Table 2 of paragraph (1) of this subsection);

(B) concentration criteria to prevent contamination of fish and other aquatic life to ensure that they are safe for human consumption. These criteria apply to surface waters that have sustainable fisheries and that are not designated or used for public water supply or as a sole-source surface drinking water supply (Column B in Table 2 of paragraph (1) of this subsection);

(3) Specific assumptions and procedures (except where noted in Table 2 of paragraph (1) of this subsection).

(A) Sources for the toxicity factors to calculate criteria were derived from EPA's Integrated Risk Information System (IRIS); EPA's National Recommended Water Quality Criteria: 2002, Human Health Criteria Calculation Matrix (EPA-822-R-02-012); EPA inputs for calculating the 2015 updated national recommended human health criteria; EPA Health Effects Assessment Summary Tables (HEAST); Assessment Tools for the Evaluation of Risk (ASTER); EPA's QSAR Toxicity Estimation Software Tool, version 4.1; and the computer program, CLOGP3.

(B) For known or suspected carcinogens (as identified in EPA's IRIS database), an incremental cancer risk level of 10-5 (1 in 100,000) was used to derive criteria. An RfD (reference dose) was determined for carcinogens [noncarcinogens] and noncarcinogens [for carcinogens] where the EPA has not derived cancer slope factors.

(C) Consumption rates of fish and shellfish were estimated as 17.5 grams per person per day, unless otherwise specified in Table 2 of paragraph (1) of this subsection.

(D) Drinking water consumption rates were estimated as 2.0 liters per person per day.

(E) For carcinogens, a body-weight scaling factor of 3/4 power was used to convert data on laboratory test animals to human scale. Reported weights of laboratory test animals are used, and an average weight of 70 kilograms is assumed for humans.

(F) Childhood exposure was considered for all noncarcinogens. Consumption rates for fish and shellfish were estimated as 5.6 grams per child per day, and drinking water consumption rates were estimated as 0.64 liters per child per day. A child body weight was estimated at 15 kilograms. Both the water consumption rate and body weight are age-adjusted for a six-year-old child. The consumption rate for fish and shellfish for children is from Table 10-61 of EPA's 1997 Exposure Factors Handbook (EPA/600/P-95/002Fa-c).

(G) Numerical human health criteria were derived in accordance with the general procedures and calculations in the EPA guidance documents entitled Technical Support Document for Water Quality-based Toxics Control (EPA/505/2-90-001); Guidance Manual for Assessing Human Health Risks from Chemically Contaminated Fish and Shellfish (EPA/503/8-89-002); and Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health (2000) (EPA-822-B-00-004).

(H) If a calculated criterion to prevent contamination of drinking water and fish to ensure they are safe for human consumption (Column A in Table 2 of paragraph (1) of this subsection) was greater than the applicable maximum contaminant level (MCL) in Chapter 290 of this title (relating to Public Drinking Water), then the MCL was used as the criterion.

(I) If the concentration of a substance in fish tissue used for these calculations was greater than the applicable United States Food and Drug Administration Action Level for edible fish and shellfish tissue, then the acceptable concentration in fish tissue was lowered to the Action Level for calculation of criteria.

(4) Human health criteria for additional toxic materials are adopted by the commission as appropriate.

(5) Specific human health concentration criteria for water are applicable to water in the state that has sustainable fisheries or designation or use as a public drinking water supply or as a sole-source drinking water supply except within mixing zones and below stream flow conditions as specified in §307.8 of this title. The following waters are considered to have sustainable fisheries:

(A) all designated segments listed in Appendix A of §307.10 of this title, unless specifically exempted;

(B) perennial streams and rivers with a stream order of three or greater, as defined in §307.3 of this title (relating to Definitions and Abbreviations);

(C) lakes and reservoirs greater than or equal to 150 acre-feet or 50 surface acres;

(D) all bays, estuaries, and tidal rivers; and

(E) any other waters that potentially have sufficient fish production or fishing activity to create significant long-term human consumption of fish.

(6) Waters that are not considered to have a sustainable fishery, but that have an aquatic life use of limited or greater, are considered to have an incidental fishery. Consumption rates assumed for incidental fishery waters are 1.75 grams per person per day. Therefore, numerical criteria applicable to incidental fishery waters are ten times the criteria listed in Column B in [of] Table 2 of paragraph (1) of this subsection.

(7) Specific human health criteria are applied as long term average exposure criteria designed to protect populations over a life time. Attainment measures for human health are addressed in §307.9 of this title.

(8) For toxic materials of concern where specific human health criteria are not listed in Table 2 of paragraph (1) of this subsection, the following provisions apply:

(A) For known or suspected carcinogens (as identified in EPA's IRIS database), a cancer risk of 10-5 (1 in 100,000) is applied to the most recent numerical criteria adopted by the EPA and published in the Federal Register. If an MCL or equivalent agency guideline for protection of drinking water sources is less than the resulting criterion, then the MCL applies to public drinking water supplies in accordance with paragraph (3)(H) of this subsection.

(B) For toxic materials not defined as carcinogens, the most recent numerical criteria adopted by the EPA and published in the Federal Register are applicable. If an MCL or equivalent agency guideline for protection of drinking water sources is less than the resulting criterion, then the MCL applies to public drinking water supplies in accordance with paragraph (3)(H) of this subsection.

(C) In the absence of available criteria, numerical criteria may be derived from technically valid information and calculated in accordance with the provisions of paragraph (3) of this subsection.

(9) Numerical criteria for bioconcentratable pollutants are derived in accordance with the general procedures in the EPA guidance document entitled Assessment and Control of Bioconcentratable Contaminants in Surface Water (March 1991). The commission may develop discharge permit limits in accordance with the provisions of this section.

(10) Numerical human health criteria are expressed as total recoverable concentrations for nonmetals and selenium and as dissolved concentrations for other metals and metalloids.

(11) Additional site-specific factors may indicate that the numerical human health criteria listed in Table 2 of paragraph (1) of this subsection are inappropriate for a particular water body. These factors are applied as a site-specific standards modification in accordance with §307.2(d) of this title. The application of site-specific criteria must not impair an existing, attainable, presumed, or designated use or affect human health. Factors that may justify a temporary variance or site-specific standards amendment include the following:

(A) background concentrations of specific toxics of concern in receiving waters, sediment, or indigenous biota;

(B) persistence and degradation rate of specific toxic materials;

(C) synergistic or antagonistic interactions of toxic substances with other toxic or nontoxic materials;

(D) technological or economic limits of treatability for specific toxic materials;

(E) bioavailability of specific toxic substances of concern;

(F) local water chemistry and other site-specific conditions that may alter the bioconcentration, bioaccumulation, or toxicity of specific toxic substances;

(G) site-specific differences in the bioaccumulation responses of indigenous, edible aquatic organisms to specific toxic materials;

(H) local differences in consumption patterns of fish and shellfish or drinking water, but only if any changes in assumed consumption rates are protective of the local population that frequently consumes fish, shellfish, or drinking water from a particular water body; and

(I) new information concerning the toxicity of a particular substance.

(e) Total toxicity.

(1) Total (whole-effluent) toxicity of permitted discharges, as determined from biomonitoring of effluent samples at appropriate dilutions, must be sufficiently controlled to preclude acute total toxicity in all water in the state with the exception of small ZIDs at discharge points and at extremely low streamflow conditions (one-fourth of critical low-flow conditions) in accordance with §307.8 of this title. Acute total toxicity levels may be exceeded in a ZID, but there must be no significant lethality to aquatic organisms that move through a ZID, and the sizes of ZIDs are limited in accordance with §307.8 of this title. Chronic total toxicity, as determined from biomonitoring of effluent samples at appropriate dilutions, must be sufficiently controlled to preclude chronic toxicity in all water in the state with an existing or designated aquatic life use of limited or greater except in mixing zones at discharge points and at flows less than critical low-flows, in accordance with §307.8 of this title. Chronic toxicity levels may be exceeded in a mixing zone, but there must be no significant sublethal toxicity to aquatic organisms that move through the mixing zone.

(2) General provisions for controlling total toxicity.

(A) Dischargers whose effluent has a significant potential for exerting toxicity in receiving waters as described in the Procedures to Implement the Texas Surface Water Quality Standards (RG-194) as amended are required to conduct whole effluent toxicity biomonitoring at appropriate dilutions.

(B) In addition to the other requirements of this section, the effluent of discharges to water in the state must not be acutely toxic to sensitive species of aquatic life, as demonstrated by effluent toxicity tests. Toxicity testing for this purpose is conducted on samples of 100% effluent, and the criterion for acute toxicity is mortality of 50% or more of the test organisms after 24 hours of exposure. This provision does not apply to mortality that is a result of an excess, deficiency, or imbalance of dissolved inorganic salts (such as sodium, calcium, potassium, chloride, or carbonate) that are in the effluent and are not listed in Table 1 of [in] subsection (c)(1) of this section or that are in source waters.

(C) The latest revisions of the following EPA publications provide methods for appropriate biomonitoring procedures: Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms, Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms, Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Marine and Estuarine Organisms, and the Technical Support Document for Water Quality-based Toxics Control. The use of other procedures approved by the agency and the EPA is also acceptable. Toxicity tests must be conducted using representative, sensitive aquatic organisms as approved by the agency, and any such testing must adequately determine if toxicity standards are being attained.

(D) If toxicity biomonitoring results indicate that a discharge is not sufficiently controlled to preclude acute or chronic toxicity as described in this subsection, then the permittee will be required to eliminate sources of toxicity and may be required to conduct a toxicity reduction evaluation (TRE) in accordance with the permitting procedures of the commission. In accordance with the standards implementation procedures (RG-194), permits are amended to include appropriate provisions to eliminate toxicity. Such provisions may include total toxicity limits, chemical-specific limits, best management practices, or other actions (such as moving a discharge location) designed to reduce or eliminate toxicity. Where sufficient to attain and maintain applicable numeric and narrative state water quality standards, a chemical-specific limit, best management practices, or other actions designed to reduce or eliminate toxicity rather than a total toxicity limit may be established in the permit. Where conditions may be necessary to prevent or reduce effluent toxicity, permits must include a reasonable schedule for achieving compliance with such additional conditions.

(E) Discharge permit limits based on total toxicity may be established in consideration of site-specific factors, but the application of such factors must not result in impairment of an existing, attainable, presumed, or designated use. These factors are applied as a site-specific standards modification in accordance with §307.2(d) of this title. A demonstration that uses are protected may consist of additional effluent toxicity testing, instream monitoring requirements, or other necessary information as determined by the agency. Factors that may justify a temporary variance or site-specific standards amendment include the following:

(i) background toxicity of receiving waters;

(ii) persistence and degradation rate of principal toxic materials that are contributing to the total toxicity of the discharge;

(iii) site-specific variables that may alter the impact of toxicity in the discharge;

(iv) indigenous aquatic organisms, that may have different levels of sensitivity than the species used for total toxicity testing; and

(v) technological, economic, or legal limits of treatability or control for specific toxic material.

§307.7.Site-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 130 [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 §307.3 of this title (relating to Definitions and Abbreviations) [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 EPA documents entitled Recreational Water Quality Criteria (EPA-820-F-12-058) and Ambient Water Quality Criteria for Bacteria - 1986 (EPA 440/5-84-002). [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, Subchapter B 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.

Figure: 30 TAC §307.7(b)(3)(A)(i) (.pdf)

[Figure: 30 TAC §307.7(b)(3)(A)(i)]

(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 US [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 of this clause, 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 Table 3 of 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.

Figure: 30 TAC §307.7(b)(3)(A)(ii) (.pdf)

[Figure: 30 TAC §307.7(b)(3)(A)(ii)]

(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.

(iii) Oyster waters should be maintained so that concentrations of toxic materials do not cause edible species of clams, oysters, and mussels to exceed accepted guidelines for the protection of public health. Guidelines are provided by the United States Food and Drug Administration Action Levels for molluscan shellfish, but additional information related to human health protection may also be considered in determining acceptable toxic concentrations.

(4) Additional criteria.

(A) Chemical parameters. Site-specific criteria for chloride, sulfate, and total dissolved solids are established as averages over an annual period for either a single sampling point or multiple sampling points.

(B) pH. Site-specific numerical criteria for pH are established as absolute minima and maxima.

(C) Temperature. Site-specific temperature criteria are established as absolute maxima.

(D) Toxic materials. Criteria for toxic materials are established in §307.6 of this title (relating to Toxic Materials).

(E) Nutrient criteria. Numeric and narrative criteria to preclude excessive growth of aquatic vegetation are intended to protect multiple uses such as primary, secondary, and noncontact recreation, aquatic life, and public water supplies. Nutrient numeric criteria for specific reservoirs, expressed as concentrations of chlorophyll a in water, are listed in Appendix F of §307.10 of this title.

(5) Additional uses. Other basic uses, such as navigation, agricultural water supply, industrial water supply, seagrass propagation, and wetland water quality functions must be maintained and protected for all water in the state where these uses can be achieved.

§307.9.Determination of Standards Attainment.

(a) General standards attainment sampling and assessment procedures. The procedures listed in this section are solely for the purposes of assessing water quality monitoring data to determine if water quality standards are attained in individual water bodies. Unless otherwise stated in this chapter, additional details concerning sampling procedures for the measurement, collection, preservation and laboratory analysis of water quality samples are provided in the Texas Commission on Environmental Quality (TCEQ) Surface Water Quality Monitoring Procedures, Volume 1: Physical and Chemical Monitoring Methods (RG-415) as amended, the most recently published edition of the book entitled Standard Methods for the Examination of Water and Wastewater, 40 Code of Federal Regulations (CFR) Part 136, or other reliable sources acceptable to the commission. Laboratory accreditation requirements are specified in Chapter 25 of this title (relating to Environmental Testing Laboratory Accreditation and Certification). Unless otherwise stated in this chapter, additional details concerning how sampling data are evaluated to assess standards compliance are provided in the TCEQ Guidance for Assessing and Reporting Surface Water Quality in Texas as amended.

(b) Samples to determine standards attainment are collected at locations approved by the commission. Samples collected at non-approved locations may be accepted at the discretion of the commission. Samples to determine standards attainment in ambient water must be representative in terms of location, seasonal variations, and hydrologic conditions. Locations must be typical of significant areas of a water body. Temporal sampling must be sufficient to appropriately address seasonal variations of concern. Sample results that are used to assess standards attainment must not include samples that are collected during extreme hydrologic conditions such as high-flows and flooding immediately after heavy rains. Further guidance on representative sampling, both spatially, temporally, and hydrologically, can be found in the TCEQ Surface Water Quality Monitoring Procedures, Volume 1: Physical and Chemical Monitoring Methods (RG-415), Surface Water Quality Monitoring Procedures, Volume 2: Methods for Collecting and Analyzing Biological Assemblage and Habitat (RG-416), and the TCEQ Guidance for Assessing and Reporting Surface Water Quality in Texas as amended.

(c) Collection and preservation of water samples.

(1) For the purposes of assessing standards attainment, samples are collected and preserved in accordance with procedures set forth in the most recently published edition of the book entitled Standard Methods for the Examination of Water and Wastewater, the TCEQ Surface Water Quality Monitoring Procedures, Volume 1: Physical and Chemical Monitoring Methods (RG-415) as amended, 40 CFR Part 136, or other reliable procedures acceptable to the commission.

(2) Bacterial and temperature determinations must be conducted on samples or measurements taken at or near the surface in accordance with the TCEQ Surface Water Quality Monitoring Procedures, Volume 1: Physical and Chemical Monitoring Methods (RG-415) as amended. Depth collection procedures for chloride, sulfate, total dissolved solids, dissolved oxygen, chlorophyll a, and pH to determine standards attainment may vary depending on the water body being sampled. Standards for chloride, sulfate, total dissolved solids, dissolved oxygen, chlorophyll a, pH are applicable to the mixed surface layer, but a single sample taken near the surface normally provides an adequate representation of these parameters. When the water column is entirely mixed according to determinations described in TCEQ Guidance for Assessing and Reporting Surface Water Quality in Texas as amended, standards may apply to any sample taken in the water column for parameters indicated in this section.

(3) For toxic materials, numerical aquatic life criteria are applicable to water samples collected at any depth. Numerical human health criteria are applicable to the average (arithmetic) concentration from the surface to the bottom. For the purposes of standards attainment for aquatic life protection and human health protection, samples that are collected at approximately one foot below the water surface are acceptable for assessing standards attainment of numerical criteria.

(d) Sample analysis.

(1) Numerical criteria. Procedures for laboratory analysis must be in accordance with the most recently published edition of the book entitled Standard Methods for the Examination of Water and Wastewater, the TCEQ [Texas] Surface Water Quality Monitoring Procedures, Volume 1: Physical and Chemical Monitoring Methods (RG-415) as amended, 40 CFR Part 136, or other reliable procedures acceptable to the commission, and in accordance with Chapter 25 of this title.

(2) Radioactivity. Measurements must be made on filtered samples to determine radioactivity associated with dissolved minerals in accordance with current analytical methodology approved by the EPA [United States Environmental Protection Agency (EPA)].

(3) Toxicity. Bioassay techniques must be selected as testing situations dictate but are generally conducted using representative sensitive organisms in accordance with §307.6 of this title (relating to Toxic Materials).

(e) Sampling periodicity and evaluation.

(1) Chloride, sulfate, total dissolved solids. Standards attainment determinations to demonstrate compliance with the annual average may be based on the long term mean in accordance with TCEQ Guidance for Assessing and Reporting Surface Water Quality in Texas as amended. Results from all monitoring stations within the segment are used to allow for reasonable parametric gradients. Total dissolved solids determinations may be based on measurements of specific conductance.

(2) Radioactivity. The impact of radioactive sources on surface waters must be evaluated in accordance with Chapter 336 of this title (relating to Radioactive Substance Rules), and in accordance with Chapter 290 of this title (relating to Public Drinking Water).

(3) Bacteria. [Standards attainment must be based on a long-term geometric mean of applicable samples in accordance with TCEQ Guidance for Assessing and Reporting Surface Water Quality in Texas as amended, and data are evaluated in accordance with the provisions of §307.7(b)(1) of this title (relating to Site-Specific Uses and Criteria). Determination of attainment may account for statistical variability to reduce uncertainty in evaluations in accordance with TCEQ Guidance for Assessing and Reporting Surface Water Quality in Texas as amended. Samples may be evaluated with the single sample maximum criterion for purposes of swimmer safety notification programs and wastewater permit compliance.]

(A) For coastal recreation waters, as defined in §307.3 of this title (relating to Definitions and Abbreviations), standards attainment must be based on a geometric mean and a single sample maximum. Data are evaluated in accordance with §307.7(b)(1) of this title (relating to Site-Specific Uses and Criteria).

(B) For inland waters (tidal rivers, high saline inland waters, and freshwater), and other non-coastal recreation waters, standards attainment must be based on a long-term geometric mean of applicable samples in accordance with the TCEQ's Guidance for Assessing and Reporting Surface Water Quality in Texas as amended. Data are evaluated in accordance with §307.7(b)(1) of this title.

(C) Samples may be evaluated with the single sample maximum criterion for the purposes of swimmer safety notification programs and wastewater permit compliance.

(D) Determination of attainment may account for statistical variability to reduce uncertainty in evaluations in accordance with the TCEQ's Guidance for Assessing and Reporting Surface Water Quality in Texas.

(4) Toxic materials. Standards attainment must be evaluated in accordance with §307.6 of this title, and in accordance with §307.8 of this title (relating to Application of Standards). To protect aquatic life, specific numerical acute toxic criteria are applied as 24-hour averages, and specific numerical chronic toxic criteria are applied as seven-day averages. Human health criteria are applied as long-term average exposure criteria designed to protect populations over a life time. Standards attainment for acute and chronic toxic criteria for aquatic life and human health criteria must be in accordance with the TCEQ Guidance for Assessing and Reporting Surface Water Quality in Texas as amended. Standards attainment for human health criteria must be based on the mean of samples collected in accordance with the TCEQ Guidance for Assessing and Reporting Surface Water Quality in Texas as amended.

(5) Temperature and pH. Standards attainment must be in accordance with the TCEQ Guidance for Assessing and Reporting Surface Water Quality in Texas as amended.

(6) Dissolved oxygen.

(A) Criteria for daily (24-hour) average concentrations must be compared to a time-weighted average of measurements taken over a 24-hour period in accordance with TCEQ Guidance for Assessing and Reporting Surface Water Quality in Texas as amended.

(B) Criteria for minimum concentrations must be compared to individual measurements in accordance with TCEQ Guidance for Assessing and Reporting Surface Water Quality in Texas as amended. When data are collected over a 24-hour period, the lowest measurement observed during that 24-hour period is compared to the applicable minimum criterion.

(7) Assessment of chlorophyll a criteria in reservoirs. Procedures to determine standards attainment for chlorophyll a criteria in reservoirs must be in accordance with the TCEQ Guidance for Assessing and Reporting Surface Water Quality in Texas as amended, including the evaluation of multiple uses as indicated in §307.7(b)(4) of this title. Chlorophyll a criteria in individual reservoirs are found in Appendix F of §307.10 of this title (relating to Appendices A - G). The data for the assessment must be collected at the sampling stations used for calculating the criteria, as listed in Appendix F of §307.10 of this title, or from comparable stations in the main pool of the reservoir. Assessment values indicated in the TCEQ Guidance for Assessing and Reporting Surface Water Quality in Texas are to be used for assessment purposes only and are not to be used as water quality-based effluent limits in wastewater discharge permits for wastewater permitting. [ Chlorophyll a in reservoirs. Standards attainment must be based on the long term median of chlorophyll a measurements in accordance with TCEQ Guidance for Assessing and Reporting Surface Water Quality in Texas as amended. Medians are compared to the chlorophyll a criteria for individual reservoirs in Appendix F of §307.10 of this title (relating to Appendices A - G). The data for the assessment must be collected at the sampling stations used for calculating the criteria, as listed in Appendix F of §307.10 of this title, or from comparable stations in the main pool of the reservoir.]

(8) Site-specific criteria for aquatic recreation (geometric mean), total dissolved solids, chloride, and sulfate as established in Appendix A of §307.10 of this title, and human health criteria as established in Table 2 of §307.6(d)(1) of this title do not apply in the following stream types and flow conditions:

(A) perennial streams when flows are below 0.1 cubic feet per second;

(B) intermittent streams when less than 20% of the stream bed of a 500 meter sampling reach is covered by pools; or when extremely dry conditions are indicated by comparable observations of flow severity.

(f) Biological integrity. Biological integrity, which is an essential component of the aquatic life categories defined in §307.7(b)(3) of this title [(relating to Site-Specific Uses and Criteria)], is assessed by sampling the aquatic community. Attainment of biological integrity is assessed by indices of biotic integrity that are described in the TCEQ Surface Water Quality Monitoring Procedures, Volume 2: Methods for Collecting and Analyzing Biological Assemblage and Habitat Data (RG-416) as amended. Determination of attainment may account for statistical variability to reduce uncertainty in evaluations in accordance with TCEQ Guidance for Assessing and Reporting Surface Water Quality in Texas as amended. Primary criteria associated with assessing the attainment of aquatic life uses are indices of biotic integrity and criteria for dissolved oxygen. When the appropriate aquatic life use as determined by the use-attainability study is less stringent than the presumed high use, then the appropriate aquatic life use and dissolved oxygen criteria are listed in Appendix D of §307.10 of this title after approval by EPA.

(g) Additional parameters. Assessment of narrative criteria parameters must be performed in accordance with the TCEQ Guidance for Assessing and Reporting Surface Water Quality in Texas as amended.

§307.10.Appendices A - G.

The following appendices are integral components of this chapter of the Texas Surface Water Quality Standards.

(1) Appendix A - Site-specific Uses and Criteria for Classified Segments:

Figure: 30 TAC §307.10(1) (.pdf)

[Figure: 30 TAC §307.10(1)]

(2) Appendix B - Sole-source Surface Drinking Water Supplies:

Figure: 30 TAC §307.10(2) (.pdf)

[Figure: 30 TAC §307.10(2)]

(3) Appendix C - Segment Descriptions:

Figure: 30 TAC §307.10(3) (.pdf)

[Figure: 30 TAC §307.10(3)]

(4) Appendix D - Site-specific Uses and Criteria for Unclassified Water Bodies:

Figure: 30 TAC §307.10(4) (.pdf)

[Figure: 30 TAC §307.10(4)]

(5) Appendix E - Site-specific Toxic Criteria:

Figure: 30 TAC §307.10(5) (.pdf)

[Figure: 30 TAC §307.10(5)]

(6) Appendix F - Site-specific Nutrient Criteria for Selected Reservoirs:

Figure: 30 TAC §307.10(6) (.pdf)

[Figure: 30 TAC §307.10(6)]

(7) Appendix G - Site-specific Recreational Uses and Criteria for Unclassified Water Bodies:

Figure: 30 TAC §307.10(7) (.pdf)

[Figure: 30 TAC §307.10(7)]

The agency certifies that legal counsel has reviewed the proposal and found it to be within the state agency's legal authority to adopt.

Filed with the Office of the Secretary of State on August 25, 2017.

TRD-201703349

Robert Martinez

Director, Environmental Law Division

Texas Commission on Environmental Quality

Earliest possible date of adoption: October 8, 2017

For further information, please call: (512) 239-6812