# 40 CFR 131.14 (up to date as of 9/19/2023) > Briefs, arguments, decisions, and more. URL: https://www.frixlaw.com/law-library/documents/tribal%3Aseneca_nation%3Aff6f818edc7caa5e ## Record - **Collection:** Tribal code - **Document type:** Tribal code ## Text 40 CFR 131.14 (up to date as of 9/19/2023) Water quality standards variances. 40 CFR 131.14 (Sept. 19, 2023) This content is from the eCFR and is authoritative but unofficial. Title 40 —Protection of Environment Chapter I —Environmental Protection Agency Subchapter D —Water Programs Part 131 —Water Quality Standards Subpart B —Establishment of Water Quality Standards Authority: 33 U.S.C. 1251 et seq. Source: 48 FR 51405, Nov. 8, 1983, unless otherwise noted. § 131.14 Water quality standards variances. States may adopt WQS variances, as defined in § 131.3(o). Such a WQS variance is subject to the provisions of this section and public participation requirements at § 131.20(b). A WQS variance is a water quality standard subject to EPA review and approval or disapproval. (a) Applicability. (1) A WQS variance may be adopted for a permittee(s) or water body/waterbody segment(s), but only applies to the permittee(s) or water body/waterbody segment(s) specified in the WQS variance. (2) Where a State adopts a WQS variance, the State must retain, in its standards, the underlying designated use and criterion addressed by the WQS variance, unless the State adopts and EPA approves a revision to the underlying designated use and criterion consistent with §§ 131.10 and 131.11. All other applicable standards not specifically addressed by the WQS variance remain applicable. (3) A WQS variance, once adopted by the State and approved by EPA, shall be the applicable standard for purposes of the Act under § 131.21(d) through (e), for the following limited purposes. An approved WQS variance applies for the purposes of developing NPDES permit limits and requirements under 301(b)(1)(C), where appropriate, consistent with paragraph (a)(1) of this section. States and other certifying entities may also use an approved WQS variance when issuing certifications under section 401 of the Act. (4) A State may not adopt WQS variances if the designated use and criterion addressed by the WQS variance can be achieved by implementing technology-based effluent limits required under sections 301(b) and 306 of the Act. (b) Requirements for Submission to EPA. (1) A WQS variance must include: (i) Identification of the pollutant(s) or water quality parameter(s), and the water body/waterbody segment(s) to which the WQS variance applies. Discharger(s)-specific WQS variances must also identify the permittee(s) subject to the WQS variance. (ii) The requirements that apply throughout the term of the WQS variance. The requirements shall represent the highest attainable condition of the water body or waterbody segment applicable throughout the term of the WQS variance based on the documentation required in (b)(2) of this section. The requirements shall not result in any lowering of the currently attained ambient 40 CFR 131.14(b)(1)(ii) (enhanced display) page 1 of 3 40 CFR 131.14 (up to date as of 9/19/2023) Water quality standards variances. 40 CFR 131.14(b)(1)(ii)(A) water quality, unless a WQS variance is necessary for restoration activities, consistent with paragraph (b)(2)(i)(A)(2) of this section. The State must specify the highest attainable condition of the water body or waterbody segment as a quantifiable expression that is one of the following: (A) For discharger(s)-specific WQS variances: (1) The highest attainable interim criterion; or (2) The interim effluent condition that reflects the greatest pollutant reduction achievable; or (3) If no additional feasible pollutant control technology can be identified, the interim criterion or interim effluent condition that reflects the greatest pollutant reduction achievable with the pollutant control technologies installed at the time the State adopts the WQS variance, and the adoption and implementation of a Pollutant Minimization Program. (B) For WQS variances applicable to a water body or waterbody segment: (1) The highest attainable interim use and interim criterion; or (2) If no additional feasible pollutant control technology can be identified, the interim use and interim criterion that reflect the greatest pollutant reduction achievable with the pollutant control technologies installed at the time the State adopts the WQS variance, and the adoption and implementation of a Pollutant Minimization Program. (iii) A statement providing that the requirements of the WQS variance are either the highest attainable condition identified at the time of the adoption of the WQS variance, or the highest attainable condition later identified during any reevaluation consistent with paragraph (b)(1)(v) of this section, whichever is more stringent. (iv) The term of the WQS variance, expressed as an interval of time from the date of EPA approval or a specific date. The term of the WQS variance must only be as long as necessary to achieve the highest attainable condition and consistent with the demonstration provided in paragraph (b)(2) of this section. The State may adopt a subsequent WQS variance consistent with this section. (v) For a WQS variance with a term greater than five years, a specified frequency to reevaluate the highest attainable condition using all existing and readily available information and a provision specifying how the State intends to obtain public input on the reevaluation. Such reevaluations must occur no less frequently than every five years after EPA approval of the WQS variance and the results of such reevaluation must be submitted to EPA within 30 days of completion of the reevaluation. (vi) A provision that the WQS variance will no longer be the applicable water quality standard for purposes of the Act if the State does not conduct a reevaluation consistent with the frequency specified in the WQS variance or the results are not submitted to EPA as required by (b)(1)(v) of this section. (2) The supporting documentation must include: (i) Documentation demonstrating the need for a WQS variance. 40 CFR 131.14(b)(2)(i) (enhanced display) page 2 of 3 40 CFR 131.14 (up to date as of 9/19/2023) Water quality standards variances. 40 CFR 131.14(b)(2)(i)(A) (A) For a WQS variance to a use specified in section 101(a)(2) of the Act or a sub-category of such a use, the State must demonstrate that attaining the designated use and criterion is not feasible throughout the term of the WQS variance because: (1) One of the factors listed in § 131.10(g) is met, or (2) Actions necessary to facilitate lake, wetland, or stream restoration through dam removal or other significant reconfiguration activities preclude attainment of the designated use and criterion while the actions are being implemented. (B) For a WQS variance to a non-101(a)(2) use, the State must submit documentation justifying how its consideration of the use and value of the water for those uses listed in § 131.10(a) appropriately supports the WQS variance and term. A demonstration consistent with paragraph (b)(2)(i)(A) of this section may be used to satisfy this requirement. (ii) Documentation demonstrating that the term of the WQS variance is only as long as necessary to achieve the highest attainable condition. Such documentation must justify the term of the WQS variance by describing the pollutant control activities to achieve the highest attainable condition, including those activities identified through a Pollutant Minimization Program, which serve as milestones for the WQS variance. (iii) In addition to paragraphs (b)(2)(i) and (ii) of this section, for a WQS variance that applies to a water body or waterbody segment: (A) Identification and documentation of any cost-effective and reasonable best management practices for nonpoint source controls related to the pollutant(s) or water quality parameter(s) and water body or waterbody segment(s) specified in the WQS variance that could be implemented to make progress towards attaining the underlying designated use and criterion. A State must provide public notice and comment for any such documentation. (B) Any subsequent WQS variance for a water body or waterbody segment must include documentation of whether and to what extent best management practices for nonpoint source controls were implemented to address the pollutant(s) or water quality parameter(s) subject to the WQS variance and the water quality progress achieved. (c) Implementing WQS variances in NPDES permits. A WQS variance serves as the applicable water quality standard for implementing NPDES permitting requirements pursuant to § 122.44(d) of this chapter for the term of the WQS variance. Any limitations and requirements necessary to implement the WQS variance shall be included as enforceable conditions of the NPDES permit for the permittee(s) subject to the WQS variance. [80 FR 51048, Aug. 21, 2015] 40 CFR 131.14(c) (enhanced display) page 3 of 3 Appendix B to Part 132, Title 40 (up to date as of 2/01/2024) Great Lakes Water Quality Initiative Appendix B to Part 132, Title 40 (Feb. 1, 2024) This content is from the eCFR and is authoritative but unofficial. Title 40 —Protection of Environment Chapter I —Environmental Protection Agency Subchapter D —Water Programs Part 132 —Water Quality Guidance for the Great Lakes System Authority: 33 U.S.C. 1251 et seq. Source: 60 FR 15387, Mar. 23, 1995, unless otherwise noted. Appendix B to Part 132—Great Lakes Water Quality Initiative Methodology for Deriving Bioaccumulation Factors Great Lakes States and Tribes shall adopt provisions consistent with (as protective as) this appendix. I. Introduction A. The purpose of this methodology is to describe procedures for deriving bioaccumulation factors (BAFs) to be used in the calculation of Great Lakes Water Quality Guidance (Guidance) human health Tier I criteria and Tier II values and wildlife Tier I criteria. A subset of the human health BAFs are also used to identify the chemicals that are considered bioaccumulative chemicals of concern (BCCs). B. Bioaccumulation reflects uptake of a substance by aquatic organisms exposed to the substance through all routes (i.e., ambient water and food), as would occur in nature. Bioconcentration reflects uptake of a substance by aquatic organisms exposed to the substance only through the ambient water. Both BAFs and bioconcentration factors (BCFs) are proportionality constants that describe the relationship between the concentration of a substance in aquatic organisms and its concentration in the ambient water. For the Guidance in this part, BAFs, rather than BCFs, are used to calculate Tier I criteria for human health and wildlife and Tier II values for human health because they better account for the total exposure of aquatic organisms to chemicals. C. For organic chemicals, baseline BAFs can be derived using four methods. Measured baseline BAFs are derived from field-measured BAFs; predicted baseline BAFs are derived using biota-sediment accumulation factors (BSAFs) or are derived by multiplying a laboratory-measured or predicted BCF by a food-chain multiplier (FCM). The lipid content of the aquatic organisms is used to account for partitioning of organic chemicals within organisms so that data from different tissues and species can be integrated. In addition, the baseline BAF is based on the concentration of freely dissolved organic chemicals in the ambient water to facilitate extrapolation from one water to another. D. For inorganic chemicals, baseline BAFs can be derived using two of the four methods. Baseline BAFs are derived using either field-measured BAFs or by multiplying laboratory-measured BCFs by a FCM. For inorganic chemicals, BAFs are assumed to equal BCFs (i.e., the FCM is 1.0), unless chemicalspecific biomagnification data support using a FCM other than 1.0. E. Because both humans and wildlife consume fish from both trophic levels 3 and 4, two baseline BAFs are needed to calculate either a human health criterion or value or a wildlife criterion for a chemical. When appropriate, ingestion through consumption of invertebrates, plants, mammals, and birds in the diet of wildlife species to be protected may be taken into account. 40 CFR Appendix-B-to-Part-132 I.E. (enhanced display) page 1 of 13 Appendix B to Part 132, Title 40 (up to date as of 2/01/2024) Great Lakes Water Quality Initiative 40 CFR Appendix-B-to-Part-132 II. “Baseline BAF” II. Definitions Baseline BAF. For organic chemicals, a BAF that is based on the concentration of freely dissolved chemical in the ambient water and takes into account the partitioning of the chemical within the organism; for inorganic chemicals, a BAF that is based on the wet weight of the tissue. Baseline BCF. For organic chemicals, a BCF that is based on the concentration of freely dissolved chemical in the ambient water and takes into account the partitioning of the chemical within the organism; for inorganic chemicals, a BCF that is based on the wet weight of the tissue. Bioaccumulation. The net accumulation of a substance by an organism as a result of uptake from all environmental sources. Bioaccumulation factor (BAF). The ratio (in L/kg) of a substance's concentration in tissue of an aquatic organism to its concentration in the ambient water, in situations where both the organism and its food are exposed to and the ratio does not change substantially over time. Bioconcentration. The net accumulation of a substance by an aquatic organism as a result of uptake directly from the ambient water through gill membranes or other external body surfaces. Bioconcentration factor (BCF). The ratio (in L/kg) of a substance's concentration in tissue of an aquatic organism to its concentration in the ambient water, in situations where the organism is exposed through the water only and the ratio does not change substantially over time. Biota-sediment accumulation factor (BSAF). The ratio (in kg of organic carbon/kg of lipid) of a substance's lipid-normalized concentration in tissue of an aquatic organism to its organic carbon-normalized concentration in surface sediment, in situations where the ratio does not change substantially over time, both the organism and its food are exposed, and the surface sediment is representative of average surface sediment in the vicinity of the organism. Depuration. The loss of a substance from an organism as a result of any active or passive process. Food-chain multiplier (FCM). The ratio of a BAF to an appropriate BCF. Octanol-water partition coefficient (KOW). The ration of the concentration of a substance in the n-octanol phase to its concentration in the aqueous phase in an equilibrated two-phase octanol-water system. For log KOW, the log of the octanol-water partition coefficient is a base 10 logarithm. Uptake. Acquisition of a substance from the environment by an organism as a result of any active or passive process. III. Review and Selection of Data A. Data Sources. Measured BAFs, BSAFs and BCFs are assembled from available sources including the following: 1. EPA Ambient Water Quality Criteria documents issued after January 1, 1980. 2. Published scientific literature. 3. Reports issued by EPA or other reliable sources. 4. Unpublished data. 40 CFR Appendix-B-to-Part-132 III.A.4. (enhanced display) page 2 of 13 Appendix B to Part 132, Title 40 (up to date as of 2/01/2024) Great Lakes Water Quality Initiative 40 CFR Appendix-B-to-Part-132 III.B. One useful source of references is the Aquatic Toxicity Information Retrieval (AQUIRE) database. B. C. D. Field-Measured BAFs. The following procedural and quality assurance requirements shall be met for field-measured BAFs: 1. The field studies used shall be limited to those conducted in the Great Lakes System with fish at or near the top of the aquatic food chain (i.e., in trophic levels 3 and/or 4). 2. The trophic level of the fish species shall be determined. 3. The site of the field study should not be so unique that the BAF cannot be extrapolated to other locations where the criteria and values will apply. 4. For organic chemicals, the percent lipid shall be either measured or reliably estimated for the tissue used in the determination of the BAF. 5. The concentration of the chemical in the water shall be measured in a way that can be related to particulate organic carbon (POC) and/or dissolved organic carbon (DOC) and should be relatively constant during the steady-state time period. 6. For organic chemicals with log KOW greater than four, the concentrations of POC and DOC in the ambient water shall be either measured or reliably estimated. 7. For inorganic and organic chemicals, BAFs shall be used only if they are expressed on a wet weight basis; BAFs reported on a dry weight basis cannot be converted to wet weight unless a conversion factor is measured or reliably estimated for the tissue used in the determination of the BAF. Field-Measured BSAFs. The following procedural and quality assurance requirements shall be met for field-measured BSAFs: 1. The field studies used shall be limited to those conducted in the Great Lakes System with fish at or near the top of the aquatic food chain (i.e., in trophic levels 3 and/or 4). 2. Samples of surface sediments (0–1 cm is ideal) shall be from locations in which there is net deposition of fine sediment and is representative of average surface sediment in the vicinity of the organism. 3. The KOW s used shall be acceptable quality as described in section III.F below. 4. The site of the field study should not be so unique that the resulting BAF cannot be extrapolated to other locations where the criteria and values will apply. 5. The tropic level of the fish species shall be determined. 6. The percent lipid shall be either measured or reliably estimated for the tissue used in the determination of the BAF. Laboratory-Measured BCFs. The following procedural and quality assurance requirements shall be met for laboratory-measured BCFs: 1. The test organism shall not be diseased, unhealthy, or adversely affected by the concentration of the chemical. 40 CFR Appendix-B-to-Part-132 III.D.1. (enhanced display) page 3 of 13 Appendix B to Part 132, Title 40 (up to date as of 2/01/2024) Great Lakes Water Quality Initiative 40 CFR Appendix-B-to-Part-132 III.D.2. 2. The total concentration of the chemical in the water shall be measured and should be relatively constant during the steady-state time period. 3. The organisms shall be exposed to the chemical using a flow-through or renewal procedure. 4. For organic chemicals, the percent lipid shall be either measured or reliably estimated for the tissue used in the determination of the BCF. 5. For organic chemicals with log KOW greater than four, the concentrations of POC and DOC in the test solution shall be either measured or reliably estimated. 6. Laboratory-measured BCFs should be determined using fish species, but BCFs determined with molluscs and other invertebrates may be used with caution. For example, because invertebrates metabolize some chemicals less efficiently than vertebrates, a baseline BCF determined for such a chemical using invertebrates is expected to be higher than a comparable baseline BCF determined using fish. 7. If laboratory-measured BCFs increase or decrease as the concentration of the chemical increases in the test solutions in a bioconcentration test, the BCF measured at the lowest test concentration that is above concentrations existing in the control water shall be used (i.e., a BCF should be calculated from a control treatment). The concentrations of an inorganic chemical in a bioconcentration test should be greater than normal background levels and greater than levels required for normal nutrition of the test species if the chemical is a micronutrient, but below levels that adversely affect the species. Bioaccumulation of an inorganic chemical might be overestimated if concentrations are at or below normal background levels due to, for example, nutritional requirements of the test organisms. 8. For inorganic and organic chemicals, BCFs shall be used only if they are expressed on a wet weight basis. BCFs reported on a dry weight basis cannot be converted to wet weight unless a conversion factor is measured or reliably estimated for the tissue used in the determination of the BAF. 9. BCFs for organic chemicals may be based on measurement or radioactivity only when the BCF is intended to include metabolites or when there is confidence that there is no interference due to metabolites. 10. The calculation of the BCF must appropriately address growth dilution. 11. Other aspects of the methodology used should be similar to those described by ASTM (1990). E. Predicted BCFs. The following procedural and quality assurance requirements shall be met for predicted BCFs: 1. The KOW used shall be of acceptable quality as described in section III.F below. 2. The predicted baseline BCF shall be calculated using the equation: predicted baseline BCF = KOW where: KOW = octanol-water partition coefficient. F. Octanol-Water Partition Coefficient (K OW). 40 CFR Appendix-B-to-Part-132 III.F. (enhanced display) page 4 of 13 Appendix B to Part 132, Title 40 (up to date as of 2/01/2024) Great Lakes Water Quality Initiative 1. 40 CFR Appendix-B-to-Part-132 III.F.1. The value of KOW used for an organic chemical shall be determined by giving priority to the experimental and computational techniques used as follows: Log KOW <4: Priority Technique 1 Slow-stir. 1 Generator-column. 1 Shake-flask. 2 Reverse-phase liquid chromatography on C18 chromatography packing with extrapolation to zero percent solvent. 3 Reverse-phase liquid chromatography on C18 chromatography packing without extrapolation to zero percent solvent. 4 Calculated by the CLOGP program. Log KOW >4: Priority 2. Technique 1 Slow Stir. 1 Generator-column. 2 Reverse-phase liquid chromatography on C18 chromatography packing with extrapolation to zero percent solvent. 3 Reverse-phase liquid chromatography on C18 chromatography packing without extrapolation to zero percent solvent. 4 Shake-flask. 5 Calculated by the CLOGP program. The CLOGP program is a computer program available from Pomona College. A value of KOW that seems to be different from the others should be considered an outlier and not used. The value of KOW used for an organic chemical shall be the geometric mean of the available KOW s with highest priority or can be calculated from the arithmetic mean of the available log KOW with the highest priority. Because it is an intermediate value in the derivation of a BAF, the value used for the KOW of a chemical should not be rounded to fewer than three significant digits and a value for log KOW should not be rounded to fewer than three significant digits after the decimal point. G. This methodology provides overall guidance for the derivation of BAFs, but it cannot cover all the decisions that must be made in the review and selection of acceptable data. Professional judgment is required throughout the process. A degree of uncertainty is associated with the determination of any BAF, BSAF, BCF or KOW. The amount of uncertainty in a baseline BAF depends on both the quality of data available and the method used to derive the BAF. H. Hereinafter in this methodology, the terms BAF, BSAF, BCF and KOW refer to ones that are consistent with the procedural and quality assurance requirements given above. IV. Four Methods for Deriving Baseline BAFs 40 CFR Appendix-B-to-Part-132 III.H. (enhanced display) page 5 of 13 Appendix B to Part 132, Title 40 (up to date as of 2/01/2024) Great Lakes Water Quality Initiative 40 CFR Appendix-B-to-Part-132 IV.A. Baseline BAFs shall be derived using the following four methods, which are listed from most preferred to least preferred: A. A measured baseline BAF for an organic or inorganic chemical derived from a field study of acceptable quality. B. A predicted baseline BAF for an organic chemical derived using field-measured BSAFs of acceptable quality. C. A predicted baseline BAF for an organic or inorganic chemical derived from a BCF measured in a laboratory study of acceptable quality and a FCM. D. A predicted baseline BAF for an organic chemical derived from a KOW of acceptable quality and a FCM. For comparative purposes, baseline BAFs should be derived for each chemical by as many of the four methods as available data allow. V. Calculation of Baseline BAFs for Organic Chemicals A. Lipid Normalization. 1. It is assumed that BAFs and BCFs for organic chemicals can be extrapolated on the basis of percent lipid from one tissue to another and from one aquatic species to another in most cases. 2. Because BAFs and BCFs for organic chemicals are related to the percent lipid, it does not make any difference whether the tissue sample is whole body or edible portion, but both the BAF (or BCF) and the percent lipid must be determined for the same tissue. The percent lipid of the tissue should be measured during the BAF or BCF study, but in some cases it can be reliably estimated from measurements on tissue from other organisms. If percent lipid is not reported for the test organisms in the original study, it may be obtained from the author; or, in the case of a laboratory study, lipid data for the same or a comparable laboratory population of test organisms that were used in the original study may be used. 3. The lipid-normalized concentration, Cl, of a chemical in tissue is defined using the following equation: Where: CB = concentration of the organic chemical in the tissue of aquatic biota (either whole organism or specified tissue) (µg/g). fl = fraction of the tissue that is lipid. B. Bioavailability. By definition, baseline BAFs and BCFs for organic chemicals, whether measured or predicted are based on the concentration of the chemical that is freely dissolved in the ambient water in order to account for bioavailability. For the purposes of this Guidance in this part, the relationship between the total concentration of the chemical in the water (i.e., that which is freely 40 CFR Appendix-B-to-Part-132 V.B. (enhanced display) page 6 of 13 Appendix B to Part 132, Title 40 (up to date as of 2/01/2024) Great Lakes Water Quality Initiative 40 CFR Appendix-B-to-Part-132 V.C. dissolved plus that which is sorbed to particulate organic carbon or to dissolved organic carbon) to the freely dissolved concentration of the chemical in the ambient water shall be calculated using the following equation: Where: Cfdw = freely dissolved concentration of the organic chemical in the ambient water; Ctw = total concentration of the organic chemical in the ambient water; ffd = fraction of the total chemical in the ambient water that is freely dissolved. The fraction of the total chemical in the ambient water that is freely dissolved, ffd, shall be calculated using the following equation: Where: DOC = concentration of dissolved organic carbon, kg of dissolved organic carbon/L of water. KOW = octanol-water partition coefficient of the chemical. POC = concentration of particulate organic carbon, kg of particulate organic carbon/L of water. C. Food-Chain Multiplier. In the absence of a field-measured BAF or a predicted BAF derived from a BSAF, a FCM shall be used to calculate the baseline BAF for trophic levels 3 and 4 from a laboratorymeasured or predicted BCF. For an organic chemical, the FCM used shall be derived from Table B–1 using the chemical's log KOW and linear interpolation. A FCM greater than 1.0 applies to most organic chemicals with a log KOW of four or more. The trophic level used shall take into account the age or size of the fish species consumed by the human, avian or mammalian predator because, for some species of fish, the young are in trophic level 3 whereas the adults are in trophic level 4. D. Calculation of a Baseline BAF from a Field-Measured BAF. A baseline BAF shall be calculated from a field-measured BAF of acceptable quality using the following equation: Where: BAFtT = BAF based on total concentration in tissue and water. fl = fraction of the tissue that is lipid. 40 CFR Appendix-B-to-Part-132 V.D. (enhanced display) page 7 of 13 Appendix B to Part 132, Title 40 (up to date as of 2/01/2024) Great Lakes Water Quality Initiative 40 CFR Appendix-B-to-Part-132 V.E. ffd = fraction of the total chemical that is freely dissolved in the ambient water. The trophic level to which the baseline BAF applies is the same as the trophic level of the organisms used in the determination of the field-measured BAF. For each trophic level, a species mean measured baseline BAF shall be calculated as the geometric mean if more than one measured baseline BAF is available for a given species. For each trophic level, the geometric mean of the species mean measured baseline BAFs shall be calculated. If a baseline BAF based on a measured BAF is available for either trophic level 3 or 4, but not both, a measured baseline BAF for the other trophic level shall be calculated using the ratio of the FCMs that are obtained by linear interpolation from Table B–1 for the chemical. E. Calculation of a Baseline BAF from a Field-Measured BSAF. 1. A baseline BAF for organic chemical “i” shall be calculated from a field-measured BSAF of acceptable quality using the following equation: Where: (BSAF)i = BSAF for chemical “i”. (BSAF)r = BSAF for the reference chemical “r”. (KOW)i = octanol-water partition coefficient for chemical “i”. (KOW)r = octanol-water partition coefficient for the reference chemical “r”. 2. A BSAF shall be calculated using the following equation: Where: Ct = the lipid-normalized concentration of the chemical in tissue. CSOC = the organic carbon-normalized concentration of the chemical in sediment. 3. The organic carbon-normalized concentration of a chemical in sediment, CSOC, shall be calculated using the following equation: Where: CS = concentration of chemical in sediment (µg/g sediment). fOC = fraction of the sediment that is organic carbon. 40 CFR Appendix-B-to-Part-132 V.E.3. (enhanced display) page 8 of 13 Appendix B to Part 132, Title 40 (up to date as of 2/01/2024) Great Lakes Water Quality Initiative F. 40 CFR Appendix-B-to-Part-132 V.E.4. 4. Predicting BAFs from BSAFs requires data from a steady-state (or near steady-state) condition between sediment and ambient water for both a reference chemical “r” with a field-measured BAFl fd and other chemicals “n = i” for which BSAFs are to be determined. 5. The trophic level to which the baseline BAF applies is the same as the trophic level of the organisms used in the determination of the BSAF. For each trophic level, a species mean baseline BAF shall be calculated as the geometric mean if more than one baseline BAF is predicted from BSAFs for a given species. For each trophic level, the geometric mean of the species mean baseline BAFs derived using BSAFs shall be calculated. 6. If a baseline BAF based on a measured BSAF is available for either trophic level 3 or 4, but not both, a baseline BAF for the other trophic level shall be calculated using the ratio of the FCMs that are obtained by linear interpolation from Table B–1 for the chemical. Calculation of a Baseline BAF from a Laboratory-Measured BCF. A baseline BAF for trophic level 3 and a baseline BAF for trophic level 4 shall be calculated from a laboratory-measured BCF of acceptable quality and a FCM using the following equation: Where: BCFtT = BCF based on total concentration in tissue and water. fl = fraction of the tissue that is lipid. ffd = fraction of the total chemical in the test water that is freely dissolved. FCM = the food-chain multiplier obtained from Table B–1 by linear interpolation for trophic level 3 or 4, as necessary. For each trophic level, a species mean baseline BAF shall be calculated as the geometric mean if more than one baseline BAF is predicted from laboratory-measured BCFs for a given species. For each trophic level, the geometric mean of the species mean baseline BAFs based on laboratory-measured BCFs shall be calculated. G. Calculation of a Baseline BAF from an Octanol-Water Partition Coefficient. A baseline BAF for trophic level 3 and a baseline BAF for trophic level 4 shall be calculated from a KOW of acceptable quality and a FCM using the following equation: Baseline BAF = (FCM) (predicted baseline BCF) = (FCM) (KOW) Where: FCM = the food-chain multiplier obtained from Table B–1 by linear interpolation for trophic level 3 or 4, as necessary. KOW = octanol-water partition coefficient. 40 CFR Appendix-B-to-Part-132 V.G. (enhanced display) page 9 of 13 Appendix B to Part 132, Title 40 (up to date as of 2/01/2024) Great Lakes Water Quality Initiative 40 CFR Appendix-B-to-Part-132 VI.A. VI. Human Health and Wildlife BAFs for Organic Chemicals A. To calculate human health and wildlife BAFs for an organic chemical, the KOW of the chemical shall be used with a POC concentration of 0.00000004 kg/L and a DOC concentration of 0.000002 kg/L to yield the fraction freely dissolved: B. The human health BAFs for an organic chemical shall be calculated using the following equations: For trophic level 3: For trophic level 4: Where: 0.0182 and 0.0310 are the standardized fraction lipid values for trophic levels 3 and 4, respectively, that are used to derive human health criteria and values for the GLI. C. The wildlife BAFs for an organic chemical shall be calculated using the following equations: For trophic level 3: For trophic level 4: Where: 0.0646 and 0.1031 are the standardized fraction lipid values for trophic levels 3 and 4, respectively, that are used to derive wildlife criteria for the GLI. 40 CFR Appendix-B-to-Part-132 VI.C. (enhanced display) page 10 of 13 Appendix B to Part 132, Title 40 (up to date as of 2/01/2024) Great Lakes Water Quality Initiative 40 CFR Appendix-B-to-Part-132 VII.A. VII. Human Health and Wildlife BAFs for Inorganic Chemicals A. For inorganic chemicals, the baseline BAFs for trophic levels 3 and 4 are both assumed to equal the BCF determined for the chemical with fish, i.e., the FCM is assumed to be 1 for both trophic levels 3 and 4. However, a FCM greater than 1 might be applicable to some metals, such as mercury, if, for example, an organometallic form of the metal biomagnifies. B. BAFs for Human Health Criteria and Values. 1. Measured BAFs and BCFs used to determine human health BAFs for inorganic chemicals shall be based on edible tissue (e.g., muscle) of freshwater fish unless it is demonstrated that wholebody BAFs or BCFs are similar to edible-tissue BAFs or BCFs. BCFs and BAFs based on measurements of aquatic plants and invertebrates should not be used in the derivation of human health criteria and values. 2. If one or more field-measured baseline BAFs for an inorganic chemical are available from studies conducted in the Great Lakes System with the muscle of fish: 3. C. a. For each trophic level, a species mean measured baseline BAF shall be calculated as the geometric mean if more than one measured BAF is available for a given species; and b. For each trophic level, the geometric mean of the species mean measured baseline BAFs shall be used as the human health BAF for that chemical. If an acceptable measured baseline BAF is not available for an inorganic chemical and one or more acceptable edible-portion laboratory-measured BCFs are available for the chemical, a predicted baseline BAF shall be calculated by multiplying the geometric mean of the BCFs times a FCM. The FCM will be 1.0 unless chemical-specific biomagnification data support using a multiplier other than 1.0. The predicted baseline BAF shall be used as the human health BAF for that chemical. BAFs for Wildlife Criteria. 1. Measured BAFs and BCFs used to determine wildlife BAFs for inorganic chemicals shall be based on whole-body freshwater fish and invertebrate data unless it is demonstrated that edible-tissue BAFs or BCFs are similar to whole-body BAFs or BCFs. 2. If one or more field-measured baseline BAFs for an inorganic chemical are available from studies conducted in the Great Lakes System with whole body of fish or invertebrates: 3. a. For each trophic level, a species mean measured baseline BAF shall be calculated as the geometric mean if more than one measured BAF is available for a given species. b. For each trophic level, the geometric mean of the species mean measured baseline BAFs shall be used as the wildlife BAF for that chemical. If an acceptable measured baseline BAF is not available for an inorganic chemical and one or more acceptable whole-body laboratory-measured BCFs are available for the chemical, a predicted baseline BAF shall be calculated by multiplying the geometric mean of the BCFs times a FCM. The FCM will be 1.0 unless chemical-specific biomagnification data support using a multiplier other than 1.0. The predicted baseline BAF shall be used as the wildlife BAF for that chemical. 40 CFR Appendix-B-to-Part-132 VII.C.3. (enhanced display) page 11 of 13 Appendix B to Part 132, Title 40 (up to date as of 2/01/2024) Great Lakes Water Quality Initiative 40 CFR Appendix-B-to-Part-132 VII.C.3. VIII. Final Review For both organic and inorganic chemicals, human health and wildlife BAFs for both trophic levels shall be reviewed for consistency with all available data concerning the bioaccumulation, bioconcentration, and metabolism of the chemical. For example, information concerning octanol-water partitioning, molecular size, or other physicochemical properties that might enhance or inhibit bioaccumulation should be considered for organic chemicals. BAFs derived in accordance with this methodology should be modified if changes are justified by available data. IX. Literature Cited ASTM. 1990. Standard Practice for Conducting Bioconcentration Tests with Fishes and Saltwater Bivalve Molluscs. Standard E 1022. American Society for Testing and Materials, Philadelphia, PA. Table B–1—Food-Chain Multipliers for Trophic Levels 2, 3 & 4 Log KOW Trophic1 level 3 Trophic level 2 Trophic level 4 2.0 1.000 1.005 1.000 2.5 1.000 1.010 1.002 3.0 1.000 1.028 1.007 3.1 1.000 1.034 1.007 3.2 1.000 1.042 1.009 3.3 1.000 1.053 1.012 3.4 1.000 1.067 1.014 3.5 1.000 1.083 1.019 3.6 1.000 1.103 1.023 3.7 1.000 1.128 1.033 3.8 1.000 1.161 1.042 3.9 1.000 1.202 1.054 4.0 1.000 1.253 1.072 4.1 1.000 1.315 1.096 4.2 1.000 1.380 1.130 4.3 1.000 1.491 1.178 4.4 1.000 1.614 1.242 4.5 1.000 1.766 1.334 4.6 1.000 1.950 1.459 4.7 1.000 2.175 1.633 4.8 1.000 2.452 1.871 4.9 1.000 2.780 2.193 5.0 1.000 3.181 2.612 5.1 1.000 3.643 3.162 5.2 1.000 4.188 3.873 5.3 1.000 4.803 4.742 40 CFR Appendix-B-to-Part-132 VII.C.3. (enhanced display) page 12 of 13 Appendix B to Part 132, Title 40 (up to date as of 2/01/2024) Great Lakes Water Quality Initiative Log KOW 40 CFR Appendix-B-to-Part-132 VII.C.3. Trophic1 level 3 Trophic level 2 Trophic level 4 5.4 1.000 5.502 5.821 5.5 1.000 6.266 7.079 5.6 1.000 7.096 8.551 5.7 1.000 7.962 10.209 5.8 1.000 8.841 12.050 5.9 1.000 9.716 13.964 6.0 1.000 10.556 15.996 6.1 1.000 11.337 17.783 6.2 1.000 12.064 19.907 6.3 1.000 12.691 21.677 6.4 1.000 13.228 23.281 6.5 1.000 13.662 24.604 6.6 1.000 13.980 25.645 6.7 1.000 14.223 26.363 6.8 1.000 14.355 26.669 6.9 1.000 14.388 26.669 7.0 1.000 14.305 26.242 7.1 1.000 14.142 25.468 7.2 1.000 13.852 24.322 7.3 1.000 13.474 22.856 7.4 1.000 12.987 21.038 7.5 1.000 12.517 18.967 7.6 1.000 11.708 16.749 7.7 1.000 10.914 14.388 7.8 1.000 10.069 12.050 7.9 1.000 9.162 9.840 8.0 1.000 8.222 7.798 8.1 1.000 7.278 6.012 8.2 1.000 6.361 4.519 8.3 1.000 5.489 3.311 8.4 1.000 4.683 2.371 8.5 1.000 3.949 1.663 8.6 1.000 3.296 1.146 8.7 1.000 2.732 0.778 8.8 1.000 2.246 0.521 8.9 1.000 1.837 0.345 9.0 1.000 1.493 0.226 1 The FCMs for trophic level 3 are the geometric mean of the FCMs for sculpin and alewife. 40 CFR Appendix-B-to-Part-132 VII.C.3. (enhanced display) page 13 of 13 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures Appendix F to Part 132, Title 40 (Sept. 19, 2023) This content is from the eCFR and is authoritative but unofficial. Title 40 —Protection of Environment Chapter I —Environmental Protection Agency Subchapter D —Water Programs Part 132 —Water Quality Guidance for the Great Lakes System Authority: 33 U.S.C. 1251 et seq. Source: 60 FR 15387, Mar. 23, 1995, unless otherwise noted. Appendix F to Part 132—Great Lakes Water Quality Initiative Implementation Procedures Procedure 1: Site-specific Modifications to Criteria and Values Great Lakes States and Tribes shall adopt provisions consistent with (as protective as) this procedure. A. Requirements for Site-specific Modifications to Criteria and Values. Criteria and values may be modified on a site-specific basis to reflect local environmental conditions as restricted by the following provisions. Any such modifications must be protective of designated uses and aquatic life, wildlife or human health and be submitted to EPA for approval. In addition, any site-specific modifications that result in less stringent criteria must be based on a sound scientific rationale and shall not be likely to jeopardize the continued existence of endangered or threatened species listed or proposed under section 4 of the Endangered Species Act (ESA) or result in the destruction or adverse modification of such species' critical habitat. More stringent modifications shall be developed to protect endangered or threatened species listed or proposed under section 4 of the ESA, where such modifications are necessary to ensure that water quality is not likely to jeopardize the continued existence of such species or result in the destruction or adverse modification of such species' critical habitat. More stringent modifications may also be developed to protect candidate (C1) species being considered by the U.S. Fish and Wildlife Service (FWS) for listing under section 4 of the ESA, where such modifications are necessary to protect such species. 1. Aquatic Life. a. Aquatic life criteria or values may be modified on a site-specific basis to provide an additional level of protection, pursuant to authority reserved to the States and Tribes under Clean Water Act (CWA) section 510. Guidance on developing site-specific criteria in these instances is provided in Chapter 3 of the U.S. EPA Water Quality Standards Handbook, Second Edition—Revised (1994). b. Less stringent site-specific modifications to chronic or acute aquatic life criteria or values may be developed when: i. The local water quality characteristics such as Ph, hardness, temperature, color, etc., alter the biological availability or toxicity of a pollutant; or ii. The sensitivity of the aquatic organisms species that “occur at the site” differs from the species actually tested in developing the criteria. The phrase “occur at the site” includes the species, genera, families, orders, classes, and phyla that: are usually present at the site; are present at the site only seasonally due to migration; are present intermittently 40 CFR Appendix-F-to-Part-132 “” 1.b.ii. (enhanced display) page 1 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures 40 CFR Appendix-F-to-Part-132 “” 1.c. because they periodically return to or extend their ranges into the site; were present at the site in the past, are not currently present at the site due to degraded conditions, and are expected to return to the site when conditions improve; are present in nearby bodies of water, are not currently present at the site due to degraded conditions, and are expected to be present at the site when conditions improve. The taxa that “occur at the site” cannot be determined merely by sampling downstream and/or upstream of the site at one point in time. “Occur at the site” does not include taxa that were once present at the site but cannot exist at the site now due to permanent physical alteration of the habitat at the site resulting, for example, from dams, etc. c. Less stringent modifications also may be developed to acute and chronic aquatic life criteria or values to reflect local physical and hydrological conditions. Guidance on developing site-specific criteria is provided in Chapter 3 of the U.S. EPA Water Quality Standards Handbook, Second Edition—Revised (1994). d. 2. Any modifications to protect threatened or endangered aquatic species required by procedure 1.A of this appendix may be accomplished using either of the two following procedures: i. If the Species Mean Acute Value (SMAV) for a listed or proposed species, or for a surrogate of such species, is lower than the calculated Final Acute Value (FAV), such lower SMAV may be used instead of the calculated FAV in developing site-specific modified criteria; or, ii. The site-specific criteria may be calculated using the recalculation procedure for sitespecific modifications described in Chapter 3 of the U.S. EPA Water Quality Standards Handbook, Second Edition—Revised (1994). Wildlife. a. Wildlife water quality criteria may be modified on a site-specific basis to provide an additional level of protection, pursuant to authority reserved to the States and Tribes under CWA section 510. b. Less stringent site-specific modifications to wildlife water quality criteria may be developed when a site-specific bioaccumulation factor (BAF) is derived which is lower than the systemwide BAF derived under appendix B of this part. The modification must consider both the mobility of prey organisms and wildlife populations in defining the site for which criteria are developed. In addition, there must be a showing that: c. i. Any increased uptake of the toxicant by prey species utilizing the site will not cause adverse effects in wildlife populations; and ii. Wildlife populations utilizing the site or downstream waters will continue to be fully protected. Any modification to protect endangered or threatened wildlife species required by procedure 1.A of this appendix must consider both the mobility of prey organisms and wildlife populations in defining the site for which criteria are developed, and may be accomplished by using the following recommended method. 40 CFR Appendix-F-to-Part-132 “” 2.c. (enhanced display) page 2 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures 40 CFR Appendix-F-to-Part-132 “” 2.c.i. i. The methodology presented in appendix D to part 132 is used, substituting appropriate species-specific toxicological, epidemiological, or exposure information, including changes to the BAF; ii. An interspecies uncertainty factor of 1 should be used where epidemiological data are available for the species in question. If necessary, species-specific exposure parameters can be derived as presented in appendix D of this part; iii. An intraspecies uncertainty factor (to account for protection of individuals within a wildlife population) should be applied in the denominator of the effect part of the wildlife equation in appendix D of this part in a manner consistent with the other uncertainty factors described in appendix D of this part; and iv. The resulting wildlife value for the species in question should be compared to the two class-specific wildlife values which were previously calculated, and the lowest of the three shall be selected as the site-specific modification. Note: Further discussion on the use of this methodology may be found in the Great Lakes Water Quality Initiative Technical Support Document for Wildlife Criteria. 3. BAFs. a. BAFs may be modified on a site-specific basis to larger values, pursuant to the authority reserved to the States and Tribes under CWA section 510, where reliable data show that local bioaccumulation is greater than the system-wide value. b. BAFs may be modified on a site-specific basis to lower values, where scientifically defensible, if: i. The fraction of the total chemical that is freely dissolved in the ambient water is different than that used to derive the system-wide BAFs (i.e., the concentrations of particulate organic carbon and the dissolved organic carbon are different than those used to derive the system-wide BAFs); ii. Input parameters of the Gobas model, such as the structure of the aquatic food web and the disequilibrium constant, are different at the site than those used to derive the systemwide BAFs; iii. The percent lipid of aquatic organisms that are consumed and occur at the site is different than that used to derive the system-wide BAFs; or iv. Site-specific field-measured BAFs or biota-sediment accumulation factor (BSAFs) are determined. If site-specific BAFs are derived, they shall be derived using the methodology in appendix B of this part. c. 4. Any more stringent modifications to protect threatened or endangered species required by procedure 1.A of this appendix shall be derived using procedures set forth in the methodology in appendix B of this part. Human Health. 40 CFR Appendix-F-to-Part-132 “” 4. (enhanced display) page 3 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures 40 CFR Appendix-F-to-Part-132 “” 4.a. a. Human health criteria or values may be modified on a site-specific basis to provide an additional level of protection, pursuant to authority reserved to the States and Tribes under CWA section 510. Human health criteria or values shall be modified on a site-specific basis to provide additional protection appropriate for highly exposed subpopulations. b. Less stringent site-specific modifications to human health criteria or values may be developed when: i. local fish consumption rates are lower than the rate used in deriving human health criteria or values under appendix C of this part; and/or ii. a site-specific BAF is derived which is lower than that used in deriving human health criteria or values under appendix C of this part. B. Notification Requirements. When a State proposes a site-specific modification to a criterion or value as allowed in section 4.A above, the State should notify the other Great Lakes States of such a proposal and, for less stringent criteria, supply appropriate justification. C. References. U.S. EPA. 1984. Water Quality Standards Handbook—Revised. Chapter 3 and Appendices. U.S. Environmental Protection Agency, Office of Water Resource Center (RC–4100), 1200 Pennsylvania Ave., NW., Washington, DC 20960. Procedure 2: Variances from Water Quality Standards for Point Sources The Great Lakes States or Tribes may adopt water quality standards (WQS) variance procedures and may grant WQS variances for point sources pursuant to such procedures. Variance procedures shall be consistent with (as protective as) the provisions in this procedure. A. Applicability. A State or Tribe may grant a variance to a WQS which is the basis of a water quality-based effluent limitation included in a National Pollutant Discharge Elimination System (NPDES) permit. A WQS variance applies only to the permittee requesting the variance and only to the pollutant or pollutants specified in the variance. A variance does not affect, or require the State or Tribe to modify, the corresponding water quality standard for the waterbody as a whole. 1. This provision shall not apply to new Great Lakes dischargers or recommencing dischargers. 2. A variance to a water quality standard shall not be granted that would likely jeopardize the continued existence of any endangered or threatened species listed under Section 4 of the Endangered Species Act (ESA) or result in the destruction or adverse modification of such species' critical habitat. 3. A WQS variance shall not be granted if standards will be attained by implementing effluent limits required under sections 301(b) and 306 of the Clean Water Act (CWA) and by the permittee implementing costeffective and reasonable best management practices for nonpoint source control. B. Maximum Timeframe for Variances. A WQS variance shall not exceed five years or the term of the NPDES permit, whichever is less. A State or Tribe shall review, and modify as necessary, WQS variances as part of each water quality standards review pursuant to section 303(c) of the CWA. 40 CFR Appendix-F-to-Part-132 3.B. (enhanced display) page 4 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures C. Conditions to Grant a Variance. A variance may be granted if: 1. 2. D. E. 40 CFR Appendix-F-to-Part-132 3.C. The permittee demonstrates to the State or Tribe that attaining the WQS is not feasible because: a. Naturally occurring pollutant concentrations prevent the attainment of the WQS; b. Natural, ephemeral, intermittent or low flow conditions or water levels prevent the attainment of the WQS, unless these conditions may be compensated for by the discharge of sufficient volume of effluent to enable WQS to be met without violating State or Tribal water conservation requirements; c. Human-caused conditions or sources of pollution prevent the attainment of the WQS and cannot be remedied, or would cause more environmental damage to correct than to leave in place; d. Dams, diversions or other types of hydrologic modifications preclude the attainment of the WQS, and it is not feasible to restore the waterbody to its original condition or to operate such modification in a way that would result in the attainment of the WQS; e. Physical conditions related to the natural features of the waterbody, such as the lack of a proper substrate cover, flow, depth, pools, riffles, and the like, unrelated to chemical water quality, preclude attainment of WQS; or f. Controls more stringent than those required by sections 301(b) and 306 of the CWA would result in substantial and widespread economic and social impact. In addition to the requirements of C.1, above, the permittee shall also: a. Show that the variance requested conforms to the requirements of the State's or Tribe's antidegradation procedures; and b. Characterize the extent of any increased risk to human health and the environment associated with granting the variance compared with compliance with WQS absent the variance, such that the State or Tribe is able to conclude that any such increased risk is consistent with the protection of the public health, safety and welfare. Submittal of Variance Application. The permittee shall submit an application for a variance to the regulatory authority issuing the permit. The application shall include: 1. All relevant information demonstrating that attaining the WQS is not feasible based on one or more of the conditions in section C.1 of this procedure; and, 2. All relevant information demonstrating compliance with the conditions in section C.2 of this procedure. Public Notice of Preliminary Decision. Upon receipt of a complete application for a variance, and upon making a preliminary decision regarding the variance, the State or Tribe shall public notice the request and preliminary decision for public comment pursuant to the regulatory authority's Administrative Procedures Act and shall notify the other Great Lakes States and Tribes of the preliminary decision. This public notice requirement may be satisfied by including the supporting information for the variance and the preliminary decision in the public notice of a draft NPDES permit. 40 CFR Appendix-F-to-Part-132 3.E. (enhanced display) page 5 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures F. 40 CFR Appendix-F-to-Part-132 3.F. Final Decision on Variance Request. The State or Tribe shall issue a final decision on the variance request within 90 days of the expiration of the public comment period required in section E of this procedure. If all or part of the variance is approved by the State or Tribe, the decision shall include all permit conditions needed to implement those parts of the variance so approved. Such permit conditions shall, at a minimum, require: 1. Compliance with an initial effluent limitation which, at the time the variance is granted, represents the level currently achievable by the permittee, and which is no less stringent than that achieved under the previous permit; 2. That reasonable progress be made toward attaining the water quality standards for the waterbody as a whole through appropriate conditions; 3. When the duration of a variance is shorter than the duration of a permit, compliance with an effluent limitation sufficient to meet the underlying water quality standard, upon the expiration of said variance; and 4. A provision that allows the permitting authority to reopen and modify the permit based on any State or Tribal triennial water quality standards revisions to the variance. The State shall deny a variance request if the permittee fails to make the demonstrations required under section C of this procedure. G. Incorporating Variance into Permit. The State or Tribe shall establish and incorporate into the permittee's NPDES permit all conditions needed to implement the variance as determined in section F of this procedure. H. Renewal of Variance. A variance may be renewed, subject to the requirements of sections A through G of this procedure. As part of any renewal application, the permittee shall again demonstrate that attaining WQS is not feasible based on the requirements of section C of this procedure. The permittee's application shall also contain information concerning its compliance with the conditions incorporated into its permit as part of the original variance pursuant to sections F and G of this procedure. Renewal of a variance may be denied if the permittee did not comply with the conditions of the original variance. I. EPA Approval. All variances and supporting information shall be submitted by the State or Tribe to the appropriate EPA regional office and shall include: J. 1. Relevant permittee applications pursuant to section D of this procedure; 2. Public comments and records of any public hearings pursuant to section E of this procedure; 3. The final decision pursuant to section F of this procedure; and, 4. NPDES permits issued pursuant to section G of this procedure. 5. Items required by sections I.1 through I.3. of this procedure shall be submitted by the State within 30 days of the date of the final variance decision. The item required by section I.4 of this procedure shall be submitted in accordance with the State or Tribe Memorandum of Agreement with the Regional Administrator pursuant to 40 CFR 123.24. 6. EPA shall review the State or Tribe submittal for compliance with the CWA pursuant to 40 CFR 123.44, and 40 CFR 131.21. State WQS Revisions. All variances shall be appended to the State or Tribe WQS rules. 40 CFR Appendix-F-to-Part-132 3.J. (enhanced display) page 6 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures 40 CFR Appendix-F-to-Part-132 A. Procedure 3: Total Maximum Daily Loads, Wasteload Allocations for Point Sources, Load Allocations for Nonpoint Sources, Wasteload Allocations in the Absence of a TMDL, and Preliminary Wasteload Allocations for Purposes of Determining the Need for Water Quality Based Effluent Limits The Great Lakes States and Tribes shall adopt provisions consistent with (as protective as) this procedure 3 for the purpose of developing Total Maximum Daily Loads (TMDLs), Wasteload Allocations (WLAs) in the Absence of TMDLs, and Preliminary Wasteload Allocations for Purposes of Determining the Need for Water Quality Based Effluent Limits (WQBELs), except as specifically provided. A. Where a State or Tribe develops an assessment and remediation plan that the State or Tribe certifies meets the requirements of sections B through F of this procedure and public participation requirements applicable to TMDLs, and that has been approved by EPA as meeting those requirements under 40 CFR 130.6, the assessment and remediation plan may be used in lieu of a TMDL for purposes of appendix F to part 132. Assessment and remediation plans under this procedure may include, but are not limited to, Lakewide Management Plans, Remedial Action Plans, and State Water Quality Management Plans. Also, any part of an assessment and remediation plan that also satisfies one or more requirements under Clean Water Act (CWA) section 303(d) or implementing regulations may be incorporated by reference into a TMDL as appropriate. Assessment and remediation plans under this section should be tailored to the level of detail and magnitude for the watershed and pollutant being assessed. B. General Conditions of Application. Except as provided in § 132.4, the following are conditions applicable to establishing TMDLs for all pollutants and pollutant parameters in the Great Lakes System, with the exception of whole effluent toxicity, unless otherwise provided in procedure 6 of appendix F. Where specified, these conditions also apply to wasteload allocations (WLAs) calculated in the absence of TMDLs and to preliminary WLAs for purposes of determining the needs for WQBELs under procedure 5 of appendix F. 1. TMDLs Required. TMDLs shall, at a minimum, be established in accordance with the listing and priority setting process established in section 303(d) of the CWA and at 40 CFR 130.7. Where water quality standards cannot be attained immediately, TMDLs must reflect reasonable assurances that water quality standards will be attained in a reasonable period of time. Some TMDLs may be based on attaining water quality standards over a period of time, with specific controls on individual sources being implemented in stages. Determining the reasonable period of time in which water quality standards will be met is a casespecific determination considering a number of factors including, but not limited to: receiving water characteristics; persistence, behavior and ubiquity of pollutants of concern; type of remediation activities necessary; available regulatory and non-regulatory controls; and individual State or Tribal requirements for attainment of water quality standards. 2. Attainment of Water Quality Standards. A TMDL must ensure attainment of applicable water quality standards, including all numeric and narrative criteria, Tier I criteria, and Tier II values for each pollutant or pollutants for which a TMDL is established. 3. TMDL Allocations. 40 CFR Appendix-F-to-Part-132 3. (enhanced display) page 7 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures 40 CFR Appendix-F-to-Part-132 3.a. a. TMDLs shall include WLAs for point sources and load allocations (LAs) for nonpoint sources, including natural background, such that the sum of these allocations is not greater than the loading capacity of the water for the pollutant(s) addressed by the TMDL, minus the sum of a specified margin of safety (MOS) and any capacity reserved for future growth. b. Nonpoint source LAs shall be based on: i. Existing pollutant loadings if changes in loadings are not reasonably anticipated to occur; ii. Increases in pollutant loadings that are reasonably anticipated to occur; iii. Anticipated decreases in pollutant loadings if such decreased loadings are technically feasible and are reasonably anticipated to occur within a reasonable time period as a result of implementation of best management practices or other load reduction measures. In determining whether anticipated decreases in pollutant loadings are technically feasible and can reasonably be expected to occur within a reasonable period of time, technical and institutional factors shall be considered. These decisions are case-specific and should reflect the particular TMDL under consideration. c. WLAs. The portion of the loading capacity not assigned to nonpoint sources including background, or to an MOS, or reserved for future growth is allocated to point sources. Upon reissuance, NPDES permits for these point sources must include effluent limitations consistent with WLAs in EPAapproved or EPA-established TMDLs. d. Monitoring. For LAs established on the basis of subsection b.iii above, monitoring data shall be collected and analyzed in order to validate the TMDL's assumptions, to varify anticipated load reductions, to evaluate the effectiveness of controls being used to implement the TMDL, and to revise the WLAs and LAs as necessary to ensure that water quality standards will be achieved within the time-period established in the TMDL. 4. WLA Values. If separate EPA-approved or EPA-established TMDLs are prepared for different segments of the same watershed, and the separate TMDLs each include WLAs for the same pollutant for one or more of the same point sources, then WQBELs for that pollutant for the point source(s) shall be consistent with the most stringent of those WLAs in order to ensure attainment of all applicable water quality standards. 5. Margin of Safety (MOS). Each TMDL shall include a MOS sufficient to account for technical uncertainties in establishing the TMDL and shall describe the manner in which the MOS is determined and incorporated into the TMDL. The MOS may be provided by leaving a portion of the loading capacity unallocated or by using conservative modeling assumptions to establish WLAs and LAs. If a portion of the loading capacity is left unallocated to provide a MOS, the amount left unallocated shall be described. If conservative modeling assumptions are relied on to provide a MOS, the specific assumptions providing the MOS shall be identified. 6. More Stringent Requirements. States and Tribes may exercise authority reserved to them under section 510 of the CWA to develop more stringent TMDLs (including WLAs and LAs) than are required herein, provided that all LAs in such TMDLs reflect actual nonpoint source loads or those loads that can reasonably be expected to occur within a reasonable time-period as a result of implementing nonpoint source controls. 40 CFR Appendix-F-to-Part-132 6. (enhanced display) page 8 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures 40 CFR Appendix-F-to-Part-132 7. 7. Accumulation in Sediments. TMDLs shall reflect, where appropriate and where sufficient data are available, contributions to the water column from sediments inside and outside of any applicable mixing zones. TMDLs shall be sufficiently stringent so as to prevent accumulation of the pollutant of concern in sediments to levels injurious to designated or existing uses, human health, wildlife and aquatic life. 8. Wet Weather Events. Notwithstanding the exception provided for the establishment of controls on wet weather point sources in § 132.4(e)(1), TMDLs shall reflect, where appropriate and where sufficient data are available, discharges resulting from wet weather events. This procedure does not provide specific procedures for considering discharges resulting from wet weather events. However, some of the provisions of procedure 3 may be deemed appropriate for considering wet weather events on a case-bycase basis. 9. Background Concentration of Pollutants. The representative background concentration of pollutants shall be established in accordance with this subsection to develop TMDLs, WLAs calculated in the absence of a TMDL, or preliminary WLAs for purposes of determining the need for WQBELs under procedure 5 of appendix F. Background loadings may be accounted for in a TMDL through an allocation to a single “background” category or through individual allocations to the various background sources. a. Definition of Background. “Background” represents all loadings that: (1) flow from upstream waters into the specified watershed, waterbody or waterbody segment for which a TMDL, WLA in the absence of a TMDL or preliminary WLA for the purpose of determining the need for a WQBEL is being developed; (2) enter the specified watershed, waterbody or waterbody segment through atmospheric deposition or sediment release or resuspension; or (3) occur within the watershed, waterbody or waterbody segment as a result of chemical reactions. b. Data considerations. When determining what available data are acceptable for use in calculating background, the State or Tribe should use best professional judgment, including consideration of the sampling location and the reliability of the data through comparison to reported analytical detection levels and quantification levels. When data in more than one of the data sets or categories described in section B.9.c.i through B.9.c.iii below exist, best professional judgment should be used to select the one data set that most accurately reflects or estimates background concentrations. Pollutant degradation and transport information may be considered when utilizing pollutant loading data. c. Calculation requirements. Except as provided below, the representative background concentration for a pollutant in the specified watershed, waterbody or waterbody segment shall be established on a case-by-case basis as the geometric mean of: d. i. Acceptable available water column data; or ii. Water column concentrations estimated through use of acceptable available caged or resident fish tissue data; or iii. Water column concentrations estimated through use of acceptable available or projected pollutant loading data. Detection considerations. i. Commonly accepted statistical techniques shall be used to evaluate data sets consisting of values both above and below the detection level. 40 CFR Appendix-F-to-Part-132 9.d.i. (enhanced display) page 9 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures ii. 40 CFR Appendix-F-to-Part-132 9.d.ii. When all of the acceptable available data in a data set or category, such as water column, caged or resident fish tissue or pollutant loading data, are below the level of detection for a pollutant, then all the data for that pollutant in that data set shall be assumed to be zero. 10. Effluent Flow. If WLAs are expressed as concentrations of pollutants, the TMDL shall also indicate the point source effluent flows assumed in the analyses. Mass loading limitations established in NPDES permits must be consistent with both the WLA and assumed effluent flows used in establishing the TMDL. 11. Reserved Allocations. TMDLs may include reserved allocations of loading capacity to accommodate future growth and additional sources. Where such reserved allocations are not included in a TMDL, any increased loadings of the pollutant for which the TMDL was developed that are due to a new or expanded discharge shall not be allowed unless the TMDL is revised in accordance with these proceudres to include an allocation for the new or expanded discharge. C. Mixing Zones for Bioaccumulative Chemicals of Concern (BCCs). The following requirements shall be applied in establishing TMDLs, WLAs in the absence of TMDLs, and preliminary WLAs for purposes of determining the need for WQBELs under procedure 5 of appendix F, for BCCs: 1. There shall be no mixing zones available for new discharges of BCCs to the Great Lakes System. WLAs established through TMDLs, WLAs in the absence of TMDLs, and preliminary WLAs for purposes of determining the need for WQBELs for new discharges of BCCs shall be set no higher than the most stringent applicable water quality criteria or values for the BCCs in question. This prohibition takes effect for a Great Lakes State or Tribe on the date EPA approves the State's or Tribe's submission of such prohibition or publishes a notice under 40 CFR 132.5(f) identifying that prohibition as applying to discharges within the State or Federal Tribal reservation. 2. For purposes of section C of procedure 3 of appendix F, new discharges are defined as: (1) A “discharge of pollutants” (as defined in 40 CFR 122.2) to the Great Lakes System from a building, structure, facility, or installation, the construction of which commences after the date the prohibition in section C.1 takes effect in that State or Tribe; (2) a new discharge from an existing Great Lakes discharger that commences after the date the prohibition in section C.1 takes effect in that State or Tribe; or (3) an expanded discharge from an existing Great Lakes discharger that commences after the date the prohibition in section C.1 takes effect in that State or Tribe, except for those expanded discharges resulting from changes in loadings of any BCC within the existing capacity and processes (e.g., normal operational variability, changes in intake water pollutants, increasing the production hours of the facility or adding additional shifts, or increasing the rate of production), and that are covered by the existing applicable control document. Not included within the definition of “new discharge” are new or expanded discharges of BCCs from a publicly owned treatment works (POTW as defined at 40 CFR 122.2) when such discharges are necessary to prevent a public health threat to the community (e.g., a situation where a community with failing septic systems is connected to a POTW to avert a potential public health threat from these failing systems). These and all other discharges of BCCs are defined as existing discharges. 3. Up until November 15, 2010, mixing zones for BCCs may be allowed for existing discharges to the Great Lakes System pursuant to the procedures specified in sections D and E of this procedure. 40 CFR Appendix-F-to-Part-132 3. (enhanced display) page 10 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures 40 CFR Appendix-F-to-Part-132 4. 4. Except as provided in sections C.5 and C.6 of this procedure, permits issued on or after this provision takes effect in a Great Lakes State or Tribe shall not authorize mixing zones for existing discharges of BCCs to the Great Lakes System after November 15, 2010. After November 15, 2010, WLAs established through TMDLs, WLAs established in the absence of TMDLs, and preliminary WLAs for purposes of determining the need for WQBELs under procedure 5 of appendix F for existing discharges of BCCs to the Great Lakes System shall be equal to the most stringent applicable water quality criteria or values for the BCCs in question. 5. Exception for Water Conservation. Great Lakes States and Tribes may grant mixing zones for any existing discharge of BCCs to the Great Lakes System beyond the date specified in section C.4 of this procedure where it can be demonstrated, on a case-by-case basis, that failure to grant a mixing zone would preclude water conservation measures that would lead to overall load reductions in BCCs, even though higher concentrations of BCCs occur in the effluent. Such mixing zones must also be consistent with sections D and E of this procedure. 6. Exception for Technical and Economic Considerations. Great Lakes States and Tribes may grant mixing zones beyond the date specified in section C.4 of this procedure for any existing discharge of a BCC to the Great Lakes System upon the request of a discharger, subject to sections C.6.a through C.6.c below. a. b. The State or Tribe must determine that: i. The discharger is in compliance with and will continue to implement, for the BCC in question, all applicable requirements of Clean Water Act sections 118, 301, 302, 303, 304, 306, 307, 401, and 402, including existing National Pollutant Discharge Elimination System (NPDES) water-quality based effluent limitations; and ii. The discharger has reduced and will continue to reduce the loading of the BCC for which a mixing zone is requested to the maximum extent possible, such that any additional controls or pollution prevention measures to reduce or ultimately eliminate the BCC discharge would result in unreasonable economic effects on the discharger or the affected community because the controls or measures are not feasible or cost-effective. Any mixing zone established pursuant to this section shall: i. Not result in any less stringent limitations than those existing prior to November 13, 2000; ii. Be no larger than necessary to account for the technical constraints and economic effects identified pursuant to paragraph C.6.a.ii above; iii. Meet all applicable acute and chronic aquatic life, wildlife and human health criteria and values within and at the edge of the mixing zone or be consistent with the applicable TMDL or assessment and remediation plan authorized under procedure 3.A. iv. Be accompanied, as appropriate, by a permit condition requiring the discharger to implement an ambient monitoring plan to ensure compliance with water quality standards and consistency with any applicable TMDL or such other strategy consistent with Section A of this procedure, including the evaluation of alternative means for reducing the BCC from other sources in the watershed; and v. Be limited to one permit term unless the permitting authority makes a new determination in accordance with this section for each successive permit application in which a mixing zone for the BCC is sought. 40 CFR Appendix-F-to-Part-132 6.b.v. (enhanced display) page 11 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures c. 7. 40 CFR Appendix-F-to-Part-132 6.c. For each draft NPDES permit that would allow a mixing zone for one or more BCCs after November 15, 2010, the fact sheet or statement of basis for the draft permit that is required to be made available through public notice under 40 CFR 124.6(e) shall: i. Specify the mixing provisions used in calculating the permit limits; and ii. Identify each BCC for which a mixing zone is proposed. Any mixing zone authorized under sections C.3, C.5 or C.6 must be consistent with sections D and E of this procedure, as applicable. D. Deriving TMDLs, WLAs, and LAs for Point and Nonpoint Sources: WLAs in the Absence of a TMDL; and Preliminary WLAs for Purposes of Determining the Need for WQBELs for OWGL. This section addresses conditions for deriving TMDLs for Open Waters of the Great Lakes (OWGL), inland lakes and other waters of the Great Lakes System with no appreciable flow relative to their volumes. State and Tribal procedures to derive TMDLs under this section must be consistent with (as protective as) the general conditions in section B of this procedure, CWA section 303(d), existing regulations (40 CFR 130.7), section C of this procedure, and sections D.1. through D.4 below. State and Tribal procedures to derive WLAs calculated in the absence of a TMDL and preliminary WLAs for purposes of determining the need for WQBELs under procedure 5 of appendix F must be consistent with sections B.9, C.1, C3 through C.6, and D. 1 through D.4 of this procedure. 1. Individual point source WLAs and preliminary WLAs for purposes of determining the need for WQBELs under procedure 5 of appendix F shall assume no greater dilution than one part effluent to 10 parts receiving water for implementation of numeric and narrative chronic criteria and values (including, but not limited to human cancer criteria, human cancer values, human noncancer values, human noncancer criteria, wildlife criteria, and chronic aquatic life criteria and values) unless an alternative mixing zone is demonstrated as appropriate in a mixing zone demonstration conducted pursuant to section F of this procedure. In no case shall a mixing zone be granted that exceeds the area where discharge-induced mixing occurs. 2. Appropriate mixing zone assumptions to be used in calculating load allocations for nonpoint sources shall be determined, consistent with applicable State or Tribal requirements, on a case-by-case basis. 3. WLAs and preliminary WLAs based on acute aquatic life criteria or values shall not exceed the Final Acute Value (FAV), unless a mixing zone demonstration is conducted and approved pursuant to section F of this procedure. If mixing zones from two or more proximate sources interact or overlap, the combined effect must be evaluated to ensure that applicable criteria and values will be met in the area where acute mixing zones overlap. 4. In no case shall a mixing zone be granted that would likely jeopardize the continued existence of any endangered or threatened species listed under section 4 of the ESA or result in the destruction or adverse modification of such species' critical habitat. E. Deriving TMDLs, WLAs, and LAs for Point and Nonpoint Sources; WLAs in the Absence of a TMDL; and Preliminary WLAs for the Purposes of Determining the Need for WQBELs for Great Lakes Systems Tributaries and Connecting Channels. This section describes conditions for deriving TMDLs for tributaries and connecting channels of the Great Lakes System that exhibit appreciable flows relative to their volumes. State and Tribal procedures to derive TMDLs must be consistent with the general conditions listed in section B of this procedure, section C of this procedure, existing TMDL regulations (40 CFR 130.7) and specific conditions E.1 through E.5. State and Tribal procedures to 40 CFR Appendix-F-to-Part-132 4. (enhanced display) page 12 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures 40 CFR Appendix-F-to-Part-132 1. derive WLAs calculated in the absence of a TMDL, and preliminary WLAs for purposes of determining reasonable potential under procedure 5 of this appendix for discharges to tributaries and connecting channels must be consistent with sections B.9, C.1, C.3 through C.6, and E.1 through E.5 of this procedure. 1. Stream Design. These design flows must be used unless data exist to demonstrate that an alternative stream design flow is appropriate for stream-specific and pollutant-specific conditions. For purposes of calculating a TMDL, WLAs in the absence of a TMDL, or preliminary WLAs for the purposes of determining reasonable potential under procedure 5 of this appendix, using a steady-state model, the stream design flows shall be: a. The 7-day, 10-year stream design flow (7Q10), or the 4-day, 3-year biologically-based stream design flow for chronic aquatic life criteria or values; b. The 1-day, 10-year stream design flow (1Q10), for acute aquatic life criteria or values; c. The harmonic mean flow for human health criteria or values; d. The 90-day, 10-year flow (90Q10) for wildlife criteria. e. TMDLs, WLAs in the absence of TMDLs, and preliminary WLAs for the purpose of determining the need for WQBELs calculated using dynamic modelling do not need to incorporate the stream design flows specified in sections E.1.a through E.1.d of this procedure. 2. Loading Capacity. The loading capacity is the greatest amount of loading that a water can receive without violating water quality standards. The loading capacity is initially calculated at the farthest downstream location in the watershed drainage basin. The maximum allowable loading consistent with the attainment of each applicable numeric criterion or value for a given pollutant is determined by multiplying the applicable criterion or value by the flow at the farthest downstream location in the tributary basin at the design flow condition described above. This loading is then compared to the loadings at sites within the basin to assure that applicable numeric criteria or values for a given pollutant are not exceeded at all applicable sites. The lowest load is then selected as the loading capacity. 3. Polluant Degradation. TMDLs, WLAs in the absence of a TMDL and preliminary WLAs for purposes of determining the need for WQBELs under procedure 5 of appendix F shall be based on the assumption that a pollutant does not degrade. However, the regulatory authority may take into account degradation of the pollutant if each of the following conditions are met. 4. a. Scientifically valid field studies or other relevant information demonstrate that degradation of the pollutant is expected to occur under the full range of environmental conditions expected to be encountered; b. Scientifically valid field studies or other relevant information address other factors that affect the level of pollutants in the water column including, but not limited to, resuspension of sediments, chemical speciation, and biological and chemical transformation. Acute Aquatic Life Criteria and Values. WLAs and LAs established in a TMDL, WLAs in the absence of a TMDL, and preliminary WLAs for the purpose of determining the need for WQBELs based on acute aquatic life criteria or values shall not exceed the FAV, unless a mixing zone demonstration is completed and approved pursuant to section F of this procedure. If mixing zones from two or more proximate sources interact or overlap, the combined effect must be evaluated to ensure that applicable criteria and values will be met in the area where any applicable acute mixing zones overlap. This acute WLA review shall include, but not be limited to, consideration of: 40 CFR Appendix-F-to-Part-132 4. (enhanced display) page 13 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures 40 CFR Appendix-F-to-Part-132 4.a. a. The expected dilution under all effluent flow and concentration conditions at stream design flow; b. Maintenance of a zone of passage for aquatic organisms; and c. Protection of critical aquatic habitat. In no case shall a permitting authority grant a mixing zone that would likely jeopardize the continued existence of any endangered or threatened species listed under section 4 of the ESA or result in the destruction or adverse modification of such species' critical habitat. 5. Chronic Mixing Zones. WLAs and LAs established in a TMDL, WLAs in the absence of a TMDL, and preliminary WLAs for the purposes of determining the need for WQBELs for protection of aquatic life, wildlife and human health from chronic effects shall be calculated using a dilution fraction no greater than 25 percent of the stream design flow unless a mixing zone demonstration pursuant to section F of this procedure is conducted and approved. A demonstration for a larger mixing zone may be provided, if approved and implemented in accordance with section F of this procedure. In no case shall a permitting authority grant a mixing zone that would likely jeopardize the continued existence of any endangered or threatened species listed under section 4 of the ESA or result in the destruction or adverse modification of such species' critical habitat. F. Mixing Zone Demonstration Requirements. 1. For purposes of establishing a mixing zone other than as specified in sections D and E above, a mixing zone demonstration must: a. Describe the amount of dilution occurring at the boundaries of the proposed mixing zone and the size, shape, and location of the area of mixing, including the manner in which diffusion and dispersion occur; b. For sources discharging to the open waters of the Great Lakes (OWGLs), define the location at which discharge-induced mixing ceases; c. Document the substrate character and geomorphology within the mixing zone; d. Show that the mixing zone does not interfere with or block passage of fish or aquatic life; e. Show that the mixing zone will be allowed only to the extent that the level of the pollutant permitted in the waterbody would not likely jeopardize the continued existence of any endangered or threatened species listed under section 4 of the ESA or result in the destruction or adverse modification of such species' critical habitat; f. Show that the mixing zone does not extend to drinking water intakes; g. Show that the mixing zone would not otherwise interfere with the designated or existing uses of the receiving water or downstream waters; h. Document background water quality concentrations; i. Show that the mixing zone does not promote undesirable aquatic life or result in a dominance of nuisance species; and j. Provide that by allowing additional mixing/dilution: 40 CFR Appendix-F-to-Part-132 1.j. (enhanced display) page 14 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures 2. 40 CFR Appendix-F-to-Part-132 1.j.i. i. Substances will not settle to form objectionable deposits; ii. Floating debris, oil, scum, and other matter in concentrations that form nuisances will not be produced; and iii. Objectionable color, odor, taste or turbidity will not be produced. In addition, the mixing zone demonstration shall address the following factors: a. Whether or not adjacent mixing zones overlap; b. Whether organisms would be attracted to the area of mixing as a result of the effluent character; and c. Whether the habitat supports endemic or naturally occurring species. 3. The mixing zone demonstration must be submitted to EPA for approval. Following approval of a mixing zone demonstration consistent with sections F.1 and F.2, adjustment to the dilution ratio specified in section D.1 of this procedure shall be limited to the dilution available in the area where discharger-induced mixing occurs. 4. The mixing zone demonstration shall be based on the assumption that a pollutant does not degrade within the proposed mixing zone, unless: a. Scientifically valid field studies or other relevant information demonstrate that degradation of the pollutant is expected to occur under the full range of environmental conditions expected to be encountered; and b. Scientifically valid field studies or other relevant information address other factors that affect the level of pollutants in the water column including, but not limited to, resuspension of sediments, chemical speciation, and biological and chemical transformation. Procedure 4: Additivity The Great Lakes States and Tribes shall adopt additivity provisions consistent with (as protective as) this procedure. A. The Great Lakes States and Tribes shall adopt provisions to protect human health from the potential adverse additive effects from both the noncarcinogenic and carcinogenic components of chemical mixtures in effluents. For the chlorinated dibenzo-p-dioxins (CDDs) and chlorinated dibenzofurans (CDFs) listed in Table 1, potential adverse additive effects in effluents shall be accounted for in accordance with section B of this procedure. B. Toxicity Equivalency Factors (TEFs)/Bioaccumulation Equivalency Factors (BEFs). 1. The TEFs in Table 1 and BEFs in Table 2 shall be used when calculating a 2,3,7,8-TCDD toxicity equivalence concentration in effluent to be used when implementing both human health noncancer and cancer criteria. The chemical concentration of each CDDs and CDFs in effluent shall be converted to a 2,3,7,8-TCDD toxicity equivalence concentration in effluent by (a) multiplying the chemical concentration of each CDDs and CDFs in the effluent by the appropriate TEF in Table 1 below, 40 CFR Appendix-F-to-Part-132 B.1.(a) (enhanced display) page 15 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures 40 CFR Appendix-F-to-Part-132 B.1.(b) (b) multiplying each product from step (a) by the BEF for each CDDs and CDFs in Table 2 below, and (c) adding all final products from step (b). The equation for calculating the 2,3,7,8-TCDD toxicity equivalence concentration in effluent is: where: (TEC)tcdd = 2,3,7,8-TCDD toxicity equivalence concentration in effluent (C)x = concentration of total chemical x in effluent (TEF)x = TCDD toxicity equivalency factor for x (BEF)x = TCDD bioaccumulation equivalency factor for x 2. The 2,3,7,8-TCDD toxicity equivalence concentration in effluent shall be used when developing waste load allocations under procedure 3, preliminary waste load allocations for purposes of determining reasonable potential under procedure 5, and for purposes of establishing effluent quality limits under procedure 5. 40 CFR Appendix-F-to-Part-132 B.2. (enhanced display) page 16 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures 40 CFR Appendix-F-to-Part-132 B.2. Table 1—Toxicity Equivalency Factors for CDDs and CDFs Congener TEF 2,3,7,8-TCDD 1.0 1,2,3,7,8-PeCDD 0.5 1,2,3,4,7,8-HxCDD 0.1 1,2,3,6,7,8-HxCDD 0.1 1,2,3,7,8,9-HxCDD 0.1 1,2,3,4,6,7,8-HpCDD 0.01 OCDD 0.001 2,3,7,8-TCDF 0.1 1,2,3,7,8-PeCDF 0.05 2,3,4,7,8-PeCDF 0.5 1,2,3,4,7,8-HxCDF 0.1 1,2,3,6,7,8-HxCDF 0.1 2,3,4,6,7,8-HxCDF 0.1 1,2,3,7,8,9-HxCDF 0.1 1,2,3,4,6,7,8-HpCDF 0.01 1,2,3,4,7,8,9-HpCDF 0.01 OCDF 0.001 Table 2—Bioaccumulation Equivalency Factors for CDDs and CDFs Congener BEF 2,3,7,8-TCDD 1.0 1,2,3,7,8-PeCDD 0.9 1,2,3,4,7,8-HxCDD 0.3 1,2,3,6,7,8-HxCDD 0.1 1,2,3,7,8,9-HxCDD 0.1 1,2,3,4,6,7,8-HpCDD 0.05 OCDD 0.01 2,3,7,8-TCDF 0.8 1,2,3,7,8-PeCDF 0.2 2,3,4,7,8-PeCDF 1.6 1,2,3,4,7,8-HxCDF 0.08 1,2,3,6,7,8-HxCDF 0.2 2,3,4,6,7,8-HxCDF 0.7 1,2,3,7,8,9-HxCDF 0.6 1,2,3,4,6,7,8-HpCDF 0.01 1,2,3,4,7,8,9-HpCDF 0.4 OCDF 0.02 40 CFR Appendix-F-to-Part-132 B.2. (enhanced display) page 17 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures 40 CFR Appendix-F-to-Part-132 A. Procedure 5: Reasonable Potential To Exceed Water Quality Standards Great Lakes States and Tribes shall adopt provisions consistent with (as protective as) this procedure. If a permitting authority determines that a pollutant is or may be discharged into the Great Lakes System at a level which will cause, have the reasonable potential to cause, or contribute to an excursion above any Tier I criterion or Tier II value, the permitting authority shall incorporate a water quality-based effluent limitation (WQBEL) in an NPDES permit for the discharge of that pollutant. When facility-specific effluent monitoring data are available, the permitting authority shall make this determination by developing preliminary effluent limitations (PEL) and comparing those effluent limitations to the projected effluent quality (PEQ) of the discharge in accordance with the following procedures. In all cases, the permitting authority shall use any valid, relevant, representative information that indicates a reasonable potential to exceed any Tier I criterion or Tier II value. A. B. Developing Preliminary Effluent Limitations on the Discharge of a Pollutant From a Point Source. 1. The permitting authority shall develop preliminary wasteload allocations (WLAs) for the discharge of the pollutant from the point source to protect human health, wildlife, acute aquatic life, and chronic aquatic life, based upon any existing Tier I criteria. Where there is no Tier I criterion nor sufficient data to calculate a Tier I criterion, the permitting authority shall calculate a Tier II value for such pollutant for the protection of human health, and aquatic life and the preliminary WLAs shall be based upon such values. Where there is insufficient data to calculate a Tier II value, the permitting authority shall apply the procedure set forth in section C of this procedure to determine whether data must be generated to calculate a Tier II value. 2. The following provisions in procedure 3 of appendix F shall be used as the basis for determining preliminary WLAs in accordance with section 1 of this procedure: procedure 3.B.9, Background Concentrations of Pollutants; procedure 3.C, Mixing Zones for Bioaccumulative Chemicals of Concern (BCCs), procedures 3.C.1, and 3.C.3 through 3.C.6; procedure 3.D, Deriving TMDLs for Discharges to Lakes (when the receiving water is an open water of the Great Lakes (OWGL), an inland lake or other water of the Great Lakes System with no appreciable flow relative to its volume); procedure 3.E, Deriving TMDLs, WLAs and Preliminary WLAs, and load allocations (LAs) for Discharges to Great Lakes System Tributaries (when the receiving water is a tributary or connecting channel of the Great Lakes that exhibits appreciable flow relative to its volume); and procedure 3.F, Mixing Zone Demonstration Requirements. 3. The permitting authority shall develop PELs consistent with the preliminary WLAs developed pursuant to sections A.1 and A.2 of this procedure, and in accordance with existing State or Tribal procedures for converting WLAs into WQBELs. At a minimum: a. The PELs based upon criteria and values for the protection of human health and wildlife shall be expressed as monthly limitations; b. The PELs based upon criteria and values for the protection of aquatic life from chronic effects shall be expressed as either monthly limitations or weekly limitations; and c. The PELs based upon the criteria and values for the protection of aquatic life from acute effects shall be expressed as daily limitations. Determining Reasonable Potential Using Effluent Pollutant Concentration Data. 40 CFR Appendix-F-to-Part-132 B. (enhanced display) page 18 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures 40 CFR Appendix-F-to-Part-132 B.1. If representative, facility-specific effluent monitoring data samples are available for a pollutant discharged from a point source to the waters of the Great Lakes System, the permitting authority shall apply the following procedures: C. 1. The permitting authority shall specify the PEQ as the 95 percent confidence level of the 95th percentile based on a log-normal distribution of the effluent concentration; or the maximum observed effluent concentration, whichever is greater. In calculating the PEQ, the permitting authority shall identify the number of effluent samples and the coefficient of variation of the effluent data, obtain the appropriate multiplying factor from Table 1 of procedure 6 of appendix F, and multiply the maximum effluent concentration by that factor. The coefficient of variation of the effluent data shall be calculated as the ratio of the standard deviation of the effluent data divided by the arithmetic average of the effluent data, except that where there are fewer than ten effluent concentration data points the coefficient of variation shall be specified as 0.6. If the PEQ exceeds any of the PELs developed in accordance with section A.3 of this procedure, the permitting authority shall establish a WQBEL in a NPDES permit for such pollutant. 2. In lieu of following the procedures under section B.1 of this procedure, the permitting authority may apply procedures consistent with the following: a. The permitting authority shall specify the PEQ as the 95th percentile of the distribution of the projected population of daily values of the facility-specific effluent monitoring data projected using a scientifically defensible statistical method that accounts for and captures the long-term daily variability of the effluent quality, accounts for limitations associated with sparse data sets and, unless otherwise shown by the effluent data set, assumes a lognormal distribution of the facility-specific effluent data. If the PEQ exceeds the PEL based on the criteria and values for the protection of aquatic life from acute effects developed in accordance with section A.3 of this procedure, the permitting authority shall establish a WQBEL in an NPDES permit for such pollutant; b. The permitting authority shall calculate the PEQ as the 95th percentile of the distribution of the projected population of monthly averages of the facility-specific effluent monitoring data using a scientifically defensible statistical method that accounts for and captures the long-term variability of the monthly average effluent quality, accounts for limitations associated with sparse data sets and, unless otherwise shown by the effluent data set, assumes a lognormal distribution of the facility-specific effluent data. If the PEQ exceeds the PEL based on criteria and values for the protection of aquatic life from chronic effects, human health or wildlife developed in accordance with section A.3 of this procedure, the permitting authority shall establish a WQBEL in an NPDES permit for such pollutant; and c. The permitting authority shall calculate the PEQ as the 95th percentile of the distribution of the projected population of weekly averages of the facility-specific effluent monitoring data using a scientifically defensible statistical method that accounts for and captures the long-term variability of the weekly average effluent quality, accounts for limitations associated with sparse data sets and, unless otherwise shown by the effluent data set, assumes a lognormal distribution of the facility-specific effluent data. If the PEQ exceeds the PEL based on criteria and values to protect aquatic life from chronic effects developed in accordance with section A.3 of this procedure, the permitting authority shall establish a WQBEL in an NPDES permit for such pollutant. Developing Necessary Data to Calculate Tier II Values Where Such Data Does Not Currently Exist. 40 CFR Appendix-F-to-Part-132 C. (enhanced display) page 19 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures 1. 2. 3. 40 CFR Appendix-F-to-Part-132 C.1. Except as provided in sections C.2, C.4, or D of this procedure, for each pollutant listed in Table 6 of part 132 that a permittee reports as known or believed to be present in its effluent, and for which pollutant data sufficient to calculate Tier II values for non-cancer human health, acute aquatic life and chronic aquatic life do not exist, the permitting authority shall take the following actions: a. The permitting authority shall use all available, relevant information, including Quantitative Structure Activity Relationship information and other relevant toxicity information, to estimate ambient screening values for such pollutant which will protect humans from health effects other than cancer, and aquatic life from acute and chronic effects. b. Using the procedures specified in sections A.1 and A.2 of this procedure, the permitting authority shall develop preliminary WLAs for the discharge of the pollutant from the point source to protect human health, acute aquatic life, and chronic aquatic life, based upon the estimated ambient screening values. c. The permitting authority shall develop PELs in accordance with section A.3 of this procedure, which are consistent with the preliminary WLAs developed in accordance with section C.1.b of this procedure. d. The permitting authority shall compare the PEQ developed according to the procedures set forth in section B of this procedure to the PELs developed in accordance with section C.1.c of this procedure. If the PEQ exceeds any of the PELs, the permitting authority shall generate or require the permittee to generate the data necessary to derive Tier II values for noncancer human health, acute aquatic life and chronic aquatic life. e. The data generated in accordance with section C.1.d of this procedure shall be used in calculating Tier II values as required under section A.1 of this procedure. The calculated Tier II value shall be used in calculating the preliminary WLA and PEL under section A of this procedure, for purposes of determining whether a WQBEL must be included in the permit. If the permitting authority finds that the PEQ exceeds the calculated PEL, a WQBEL for the pollutant or a permit limit on an indicator parameter consistent with 40 CFR 122.44(d)(1)(vi)(C) must be included in the permit. With the exception of bioaccumulative chemicals of concern (BCCs), a permitting authority is not required to apply the procedures set forth in section C.1 of this procedure or include WQBELs to protect aquatic life for any pollutant listed in Table 6 of part 132 discharged by an existing point source into the Great Lakes System, if: a. There is insufficient data to calculate a Tier I criterion or Tier II value for aquatic life for such pollutant; b. The permittee has demonstrated through a biological assessment that there are no acute or chronic effects on aquatic life in the receiving water; and c. The permittee has demonstrated in accordance with procedure 6 of this appendix that the whole effluent does not exhibit acute or chronic toxicity. Nothing in sections C.1 or C.2 of this procedure shall preclude or deny the right of a permitting authority to: a. Determine, in the absence of the data necessary to derive a Tier II value, that the discharge of the pollutant will cause, have the reasonable potential to cause, or contribute to an excursion above a narrative criterion for water quality; and 40 CFR Appendix-F-to-Part-132 C.3.a. (enhanced display) page 20 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures b. 4. D. 40 CFR Appendix-F-to-Part-132 C.3.b. Incorporate a WQBEL for the pollutant into an NPDES permit. If the permitting authority develops a WQBEL consistent with section C.3 of this procedure, and the permitting authority demonstrates that the WQBEL developed under section C.3 of this procedure is at least as stringent as a WQBEL that would have been based upon the Tier II value or values for that pollutant, the permitting authority shall not be obligated to generate or require the permittee to generate the data necessary to derive a Tier II value or values for that pollutant. Consideration of Intake Pollutants in Determining Reasonable Potential. 1. 2. General. a. Any procedures adopted by a State or Tribe for considering intake pollutants in water qualitybased permitting shall be consistent with this section and section E. b. The determinations under this section and section E shall be made on a pollutant-by-pollutant, outfall-by-outfall, basis. c. This section and section E apply only in the absence of a TMDL applicable to the discharge prepared by the State or Tribe and approved by EPA, or prepared by EPA pursuant to 40 CFR 130.7(d), or in the absence of an assessment and remediation plan submitted and approved in accordance with procedure 3.A. of appendix F. This section and section E do not alter the permitting authority's obligation under 40 CFR 122.44(d)(vii)(B) to develop effluent limitations consistent with the assumptions and requirements of any available WLA for the discharge, which is part of a TMDL prepared by the State or Tribe and approved by EPA pursuant to 40 CFR 130.7, or prepared by EPA pursuant to 40 CFR 130.7(d). Definition of Same Body of Water. a. This definition applies to this section and section E of this procedure. b. An intake pollutant is considered to be from the same body of water as the discharge if the permitting authority finds that the intake pollutant would have reached the vicinity of the outfall point in the receiving water within a reasonable period had it not been removed by the permittee. This finding may be deemed established if: i. The background concentration of the pollutant in the receiving water (excluding any amount of the pollutant in the facility's discharge) is similar to that in the intake water; ii. There is a direct hydrological connection between the intake and discharge points; and iii. Water quality characteristics (e.g., temperature, Ph, hardness) are similar in the intake and receiving waters. c. The permitting authority may also consider other site-specific factors relevant to the transport and fate of the pollutant to make the finding in a particular case that a pollutant would or would not have reached the vicinity of the outfall point in the receiving water within a reasonable period had it not been removed by the permittee. d. An intake pollutant from groundwater may be considered to be from the same body of water if the permitting authority determines that the pollutant would have reached the vicinity of the outfall point in the receiving water within a reasonable period had it not been removed by the 40 CFR Appendix-F-to-Part-132 D.2.d. (enhanced display) page 21 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures 40 CFR Appendix-F-to-Part-132 D.2.e. permittee, except that such a pollutant is not from the same body of water if the groundwater contains the pollutant partially or entirely due to human activity, such as industrial, commercial, or municipal operations, disposed actions, or treatment processes. e. 3. An intake pollutant is the amount of a pollutant that is present in waters of the United States (including groundwater as provided in section D.2.d of this procedure) at the time it is withdrawn from such waters by the discharger or other facility (e.g., public water supply) supplying the discharger with intake water. Reasonable Potential Determination. a. The permitting authority may use the procedure described in this section of procedure 5 in lieu of procedures 5.A through C provided the conditions specified below are met. b. The permitting authority may determine that there is no reasonable potential for the discharge of an identified intake pollutant or pollutant parameter to cause or contribute to an excursion above a narrative or numeric water quality criterion within an applicable water quality standard where a discharger demonstrates to the satisfaction of the permitting authority (based upon information provided in the permit application or other information deemed necessary by the permitting authority) that: c. i. The facility withdraws 100 percent of the intake water containing the pollutant from the same body of water into which the discharge is made; ii. The facility does not contribute any additional mass of the identified intake pollutant to its wastewater; iii. The facility does not alter the identified intake pollutant chemically or physically in a manner that would cause adverse water quality impacts to occur that would not occur if the pollutants were left in-stream; iv. The facility does not increase the identified intake pollutant concentration, as defined by the permitting authority, at the edge of the mixing zone, or at the point of discharge if a mixing zone is not allowed, as compared to the pollutant concentration in the intake water, unless the increased concentration does not cause or contribute to an excursion above an applicable water quality standard; and v. The timing and location of the discharge would not cause adverse water quality impacts to occur that would not occur if the identified intake pollutant were left in-stream. Upon a finding under section D.3.b of this procedure that a pollutant in the discharge does not cause, have the reasonable potential to cause, or contribute to an excursion above an applicable water quality standard, the permitting authority is not required to include a WQBEL for the identified intake pollutant in the facility's permit, provided: i. The NPDES permit fact sheet or statement of basis includes a specific determination that there is no reasonable potential for the discharge of an identified intake pollutant to cause or contribute to an excursion above an applicable narrative or numeric water quality criterion and references appropriate supporting documentation included in the administrative record; 40 CFR Appendix-F-to-Part-132 D.3.c.i. (enhanced display) page 22 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures d. E. 40 CFR Appendix-F-to-Part-132 D.3.c.ii. ii. The permit requires all influent, effluent, and ambient monitoring necessary to demonstrate that the conditions in section D.3.b of this procedure are maintained during the permit term; and iii. The permit contains a reopener clause authorizing modification or revocation and reissuance of the permit if new information indicates changes in the conditions in section D.3.b of this procedure. Absent a finding under section D.3.b of this procedure that a pollutant in the discharge does not cause, have the reasonable potential to cause, or contribute to an excursion above an applicable water quality standard, the permitting authority shall use the procedures under sections 5.A through C of this procedure to determine whether a discharge causes, has the reasonable potential to cause, or contribute to an excursion above an applicable narrative or numeric water quality criterion. Consideration of Intake Pollutants in Establishing WQBELs. 1. General. This section applies only when the concentration of the pollutant of concern upstream of the discharge (as determined using the provisions in procedure 3.B.9 of appendix F) exceeds the most stringent applicable water quality criterion for that pollutant. 2. The requirements of sections D.1–D.2 of this procedure shall also apply to this section. 3. Intake Pollutants from the Same Body of Water. 4. a. In cases where a facility meets the conditions in sections D.3.b.i and D.3.b.iii through D.3.b.v of this procedure, the permitting authority may establish effluent limitations allowing the facility to discharge a mass and concentration of the pollutant that are no greater than the mass and concentration of the pollutant identified in the facility's intake water (“no net addition limitations”). The permit shall specify how compliance with mass and concentration limitations shall be assessed. No permit may authorize “no net addition limitations” which are effective after March 23, 2007. After that date, WQBELs shall be established in accordance with procedure 5.F.2 of appendix F. b. Where proper operation and maintenance of a facility's treatment system results in removal of a pollutant, the permitting authority may establish limitations that reflect the lower mass and/or concentration of the pollutant achieved by such treatment, taking into account the feasibility of establishing such limits. c. For pollutants contained in intake water provided by a water system, the concentration of the intake pollutant shall be determined at the point where the raw water supply is removed from the same body of water, except that it shall be the point where the water enters the water supplier's distribution system where the water treatment system removes any of the identified pollutants from the raw water supply. Mass shall be determined by multiplying the concentration of the pollutant determined in accordance with this paragraph by the volume of the facility's intake flow received from the water system. Intake Pollutants from a Different Body of Water. Where the pollutant in a facility's discharge originates from a water of the United States that is not the same body of water as the receiving water (as determined in accordance with section D.2 of this procedure), WQBELs shall be established based upon the most stringent applicable water quality criterion for that pollutant. 40 CFR Appendix-F-to-Part-132 E.4. (enhanced display) page 23 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) Great Lakes Water Quality Initiative Implementation Procedures 5. F. 40 CFR Appendix-F-to-Part-132 E.5. Multiple Sources of Intake Pollutants. Where a facility discharges intake pollutants that originate in part from the same body of water, and in part from a different body of water, the permitting authority may apply the procedures of sections E.3 and E.4 of this procedure to derive an effluent limitation reflecting the flow-weighted average of each source of the pollutant, provided that adequate monitoring to determine compliance can be established and is included in the permit. Other Applicable Conditions. 1. In addition to the above procedures, effluent limitations shall be established to comply with all other applicable State, Tribal and Federal laws and regulations, including technology-based requirements and antidegradation policies. 2. Once the permitting authority has determined in accordance with this procedure that a WQBEL must be included in an NPDES permit, the permitting authority shall: a. Rely upon the WLA established for the point source either as part of any TMDL prepared under procedure 3 of this appendix and approved by EPA pursuant to 40 CFR 130.7, or as part of an assessment and remediation plan developed and approved in accordance with procedure 3.A of this appendix, or, in the absence of such TMDL or plan, calculate WLAs for the protection of acute and chronic aquatic life, wildlife and human health consistent with the provisions referenced in section A.1 of this procedure for developing preliminary wasteload allocations, and b. Develop effluent limitations consistent with these WLAs in accordance with existing State or Tribal procedures for converting WLAs into WQBELs. 3. When determining whether WQBELs are necessary, information from chemical-specific, whole effluent toxicity and biological assessments shall be considered independently. 4. If the geometric mean of a pollutant in fish tissue samples collected from a waterbody exceeds the tissue basis of a Tier I criterion or Tier II value, after consideration of the variability of the pollutant's bioconcentration and bioaccumulation in fish, each facility that discharges detectable levels of such pollutant to that water has the reasonable potential to cause or contribute to an excursion above a Tier I criteria or a Tier II value and the permitting authority shall establish a WQBEL for such pollutant in the NPDES permit for such facility. Procedure 6: Whole Effluent Toxicity Requirements The Great Lakes States and Tribes shall adopt provisions consistent with (as protective as) procedure 6 of appendix F of part 132. The following definitions apply to this part: Acute toxic unit (TUa ). 100/LC50 where the LC50 is expressed as a percent effluent in the test medium of an acute whole effluent toxicity (WET) test that is statistically or graphically estimated to be lethal to 50 percent of the test organisms. Chronic toxic unit (TUc ). 100/NOEC or 100/IC25, where the NOEC and IC25 are expressed as a percent effluent in the test medium. 40 CFR Appendix-F-to-Part-132 “Chronic toxic unit (TUc” (enhanced display) page 24 of 33 Appendix F to Part 132, Title 40 (up to date as of 9/19/2023) 40 CFR Appendix-F-to-Part-132 “Inhibition concentration 25 Great Lakes Water Quality Initiative Implementation Procedures (IC25” Inhibition concentration 25 (IC25 ). The toxicant concentration that would cause a 25 percent reduction in a nonquantal biological measurement for the test population. For example, the IC25 is the concentration of toxicant that would cause a 25 percent reduction in mean young per female or in growth for the test population. No observed effect concen [Text truncated at 120,000 characters. The full text is on the page linked above.] --- Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/tribal%3Aseneca_nation%3Aff6f818edc7caa5e. Public record. Not legal advice.