Presented below are water quality standards that are in effect for Clean    Water Act purposes.    EPA is posting these standards as a convenience to users and has made    a reasonable effort to assure their accuracy. Additionally, EPA has made  a reasonable effort to identify parts of the standards that are not  approved, disapproved, or are otherwise not in effect for Clean Water  Act purposes. April 4, 2022 Article 2. Water Quality Standards Effective February 1, 2022 The attached Water Quality Standards for the State of Indiana are effective for Clean Water Act purposes, with the following exceptions: • EPA disapproved the variance provision at 327 IAC 2-1.5-17(b) o Federal Great Lakes Guidance provisions contained at 40 CFR 132, Appendix F, Procedure II, Section C, paragraph 1 are effective for CWA purposes • The WQS variance for H.D. Wood Ditch and Mud Creek at 327 IAC 2-1.5-17(i) expired on October 14, 2014. EPA approved a subsequent variance for the discharger on September 28, 2021 that is not reflected in the attached WQS. o The current variance includes updated interim limits of 1,024 mg/L (daily maximum) and 745 mg/L (monthly average) and expires on May 31, 2025 ARTICLE 2. WATER QUALITY STANDARDS Rule 1. Water Quality Standards Applicable to All State Waters Except Waters of the State Within the Great Lakes System 327 IAC 2-1-1 Applicability of rule Authority: IC 13-14-8; IC 13-14-9; IC 13-18-3 Affected: IC 13-18-4 Sec. 1. The water quality standards established by this rule shall apply to all waters of the state except waters of the state within the Great Lakes system regulated under 327 IAC 2-1.5. (Water Pollution Control Division; 327 IAC 2-1-1; filed Sep 24, 1987, 3:00 p.m.: 11 IR 579; filed Feb 1, 1990, 4:30 p.m.: 13 IR 1018; filed Jan 14, 1997, 12:00 p.m.: 20 IR 1347) 327 IAC 2-1-1.5 Water quality goals Authority: IC 13-14-8; IC 13-18-4 Affected: IC 13-30-2-1 Sec. 1.5. The goal of the state is to restore and maintain the chemical, physical, and biological integrity of the waters of the state. In furtherance of this primary goal: (1) it is the public policy of the state that the discharge of toxic substances in toxic amounts be prohibited; and (2) it is the public policy of the state that the discharge of persistent and bioconcentrating toxic substances be reduced or eliminated. (Water Pollution Control Division; 327 IAC 2-1-1.5; filed Feb 1, 1990, 4:30 p.m.: 13 IR 1018) 327 IAC 2-1-2 Maintenance of surface water quality standards (Repealed) Sec. 2. (Repealed by Water Pollution Control Division; filed May 29, 2012, 3:19 p.m.: 20120627-IR-327080764FRA) 327 IAC 2-1-3 Surface water use designations; multiple uses Authority: IC 13-14-8; IC 13-14-9; IC 13-18-3 Affected: IC 13-18-4 Sec. 3. (a) The following water uses are designated by the environmental rules board: (1) Except as provided in subsection (c), surface waters of the state are designated for full body contact recreation as provided in section 6(d) of this rule. (2) All waters, except as described in subdivision (5), will be capable of supporting: (A) a well-balanced, warm water aquatic community; and (B) where natural temperatures will permit, put-and-take trout fishing. All waters capable of supporting the natural reproduction of trout as of February 17, 1977, shall be so maintained. (3) All waters that are used for public or industrial water supply must meet the standards for those uses at the points where the water is withdrawn. This use designation and its corresponding water quality standards are not to be construed as imposing a user restriction on those exercising or desiring to exercise the use. (4) All waters that are used for agricultural purposes must, as a minimum, meet the standards established in section 6(a) of this rule. (5) All waters in which naturally poor physical characteristics (including lack of sufficient flow), naturally poor chemical quality, or irreversible man-induced conditions, which came into existence before January 1, 1983, and having been established by use attainability analysis, public comment period, and hearing: (A) may qualify to be classified for limited use; and (B) must be evaluated for restoration and upgrading at each triennial review of this rule. Specific waters of the state designated for limited use are listed in section 11(a) of this rule. (b) Where multiple uses have been designated for a body of water, the most protective of all simultaneously applicable standards will apply. Indiana Administrative Code Page 1 WATER QUALITY STANDARDS (c) A CSO wet weather limited use designation is established as a subcategory of the recreational use designation established under subsection (a). This subcategory shall be applied in accordance with section 3.1 of this rule. (Water Pollution Control Division; 327 IAC 2-1-3; filed Sep 24, 1987, 3:00 p.m.: 11 IR 580; filed Feb 1, 1990, 4:30 p.m.: 13 IR 1019; filed Jan 14, 1997, 12:00 p.m.: 20 IR 1348; filed Sep 6, 2007, 12:25 p.m.: 20071003-IR-327050218FRA; filed Nov 10, 2014, 1:51 p.m.: 20141210-IR- 327130290FRA) 327 IAC 2-1-3.1 CSO wet weather limited use designation Authority: IC 13-14-8; IC 13-14-9; IC 13-18-3-2.5 Affected: IC 13-14-2-6; IC 13-14-9-14; IC 13-18-4 Sec. 3.1. (a) The combined sewer overflow (CSO) wet weather limited use subcategory established under section 3 of this rule applies only to waters receiving wet weather discharges from combined sewer overflows that are listed in 327 IAC 2-1.1. (b) To receive consideration for the CSO wet weather limited use subcategory designation, a CSO community must do the following: (1) Perform a use attainability analysis (UAA) to change the recreational designated use of the waterbody or waterbodies receiving the wet weather discharges from combined sewer overflows. (2) Submit the UAA to the department for approval. (3) Submit a long term control plan (LTCP) consistent with the application of the CSO wet weather limited use subcategory to the department for approval. (c) The LTCP submitted to the department must: (1) specify the water quality-based requirements that will apply to combined sewer overflows under subsection (h) if the waterbody or waterbodies receiving the wet weather overflows are redesignated to the CSO wet weather limited use subcategory; and (2) meet the requirements of Section 402(q) of the Clean Water Act*. (d) The department shall: (1) review the UAA concurrently with the LTCP if they are submitted concurrently; and (2) use the LTCP to satisfy the requirements of the UAA, to the extent possible. (e) Upon approval of a UAA, the department shall begin a rulemaking under IC 13-14-9-14 to amend the designated use to a CSO wet weather limited use designation. The rulemaking may commence before full implementation of the approved LTCP. (f) Upon completion of the rulemaking required under subsection (e), the department shall submit the amended recreational use designation and the supporting UAA to the U.S. EPA for approval. (g) Upon U.S. EPA's approval of the use designation change for the waterbody or waterbodies receiving wet weather overflows from a CSO community, the department shall modify the NPDES permit holder's permit to incorporate the CSO wet weather limited use designation and the approved LTCP into the permit. (h) The water quality-based requirements for the CSO wet weather limited use designation must: (1) be determined by the approved LTCP for the combined sewer system; (2) be consistent with the Clean Water Act; and (3) remain in effect during the time and to the physical extent that the recreational use designation that applied to the waters immediately before the application to the waters of the CSO wet weather limited use subcategory is not attained but for not more than four (4) days after the date the overflow discharge ends. *This document is incorporated by reference. Copies may be obtained from the Government Publishing Office, www.gpo.gov, or are available for review at the Indiana Department of Environmental Management, Office of Legal Counsel, Indiana Government Center North, Thirteenth Floor, 100 North Senate Avenue, Indianapolis, Indiana 46204. (Water Pollution Control Division; 327 IAC 2-1-3.1; filed Sep 6, 2007, 12:25 p.m.: 20071003-IR-327050218FRA; filed Apr 27, 2020, 8:57 a.m.: 20200506-IR-327190510FRA, eff Apr 27, 2020, see Executive Order 20-15, posted at 20200422-IR-GOV200234EOA; filed Feb 21, 2022, 10:07 a.m.: 20220323- IR-327210164FRA) 327 IAC 2-1-4 Mixing zone guidelines Authority: IC 13-14-8; IC 13-18-3 Affected: IC 13-18-4 Indiana Administrative Code Page 2 WATER QUALITY STANDARDS Sec. 4. (a) All surface water quality standards in this rule, except those provided in section 6(a)(1) of this rule, are to be applied at a point outside of the mixing zone to allow for a reasonable admixture of waste effluents with the receiving waters. (b) Due to varying physical, chemical, and biological conditions, no universal mixing zone may be prescribed. The commissioner shall determine the mixing zone upon application by the discharger. The applicability of the guideline set forth in subsection (c) will be on a case-by-case basis and any application to the commissioner shall contain the following information: (1) The dilution ratio. (2) The physical, chemical, and biological characteristics of the receiving body of water. (3) The physical, chemical, and biological characteristics of the waste effluent. (4) The present and anticipated uses of the receiving body of water. (5) The measured or anticipated effect of the discharge on the quality of the receiving body of water. (6) The existence of and impact upon any spawning or nursery areas of any indigenous aquatic species. (7) Any obstruction of migratory routes of any indigenous aquatic species. (8) The synergistic effects of overlapping mixing zones or the aggregate effects of adjacent mixing zones. (c) The mixing zone should be limited to no more than one-fourth (1/4) (twenty-five percent (25%)) of the cross-sectional area and/or volume of flow of the stream, leaving at least three-fourths (3/4) (seventy-five percent (75%)) free as a zone of passage for aquatic biota nor should it extend over one-half (1/2) (fifty percent (50%)) of the width of the stream. (d) Based on consideration of aquatic life or human health effects, the commissioner may deny a mixing zone for a discharge or certain substances in a discharge. (e) Notwithstanding other subsections of this section, no mixing zone shall be allowed for discharges to lakes except for those consisting entirely of noncontact cooling water which meet the requirements set forth in Section 316(a) of the Federal Water Pollution Control Act of 1972. (Water Pollution Control Division; 327 IAC 2-1-4; filed Sep 24, 1987, 3:00 p.m.: 11 IR 580; filed Feb 1, 1990, 4:30 p.m.: 13 IR 1020) 327 IAC 2-1-5 Exception to quality standards applicability Authority: IC 13-14-9; IC 13-18-3-2 Affected: IC 13-14-8 Sec. 5. All surface water quality standards in section 6 of this rule, except those provided in section 6(a)(1) of this rule, will cease to be applicable when the stream flows are less than the average minimum seven (7) consecutive day low flow that occurs once in ten (10) years. This determination will be made using Low-Flow Characteristics of Indiana Streams, 1996, United States Department of the Interior, Geological Survey, or any additional information compiled on a comparable basis. (Water Pollution Control Division; 327 IAC 2-1-5; filed Sep 24, 1987, 3:00 p.m.: 11 IR 581; filed Feb 1, 1990, 4:30 p.m.: 13 IR 1020; filed Feb 14, 2005, 10:05 a.m.: 28 IR 2047) 327 IAC 2-1-6 Minimum surface water quality criteria Authority: IC 13-14-8-2; IC 13-14-8-3; IC 13-18-4-3 Affected: IC 13-11-2-258; IC 13-18-4; IC 13-30-2-1; IC 14-22-9 Sec. 6. (a) The following are minimum surface water quality conditions: (1) All surface waters, including waters within a mixing zone, must be free from substances, materials, floating debris, oil, or scum attributable to municipal, industrial, agricultural, and other land use practices, or other discharges that do any of the following: (A) Settle to form putrescent or otherwise objectionable deposits. (B) Occur in amounts sufficient to be unsightly or deleterious. (C) Produce: (i) color; (ii) visible oil sheen; (iii) odor; or (iv) other conditions; to an extent that creates a nuisance. Indiana Administrative Code Page 3 WATER QUALITY STANDARDS (D) Occur in concentrations or combinations that will cause or contribute to the growth of aquatic plants or algae to a degree as to: (i) create a nuisance; (ii) be unsightly; or (iii) otherwise impair the designated uses of the surface waters. (E) Occur in amounts sufficient to be acutely toxic to, or to otherwise severely injure or kill, aquatic life, other animals, plants, or humans. To ensure protection of aquatic life, concentrations of toxic substances must not exceed the final acute value (FAV = 2 (AAC)) in the undiluted discharge or the acute aquatic criterion (AAC) outside the zone of initial dilution or, if applicable, the zone of discharge-induced mixing. The following apply where applicable: (i) For certain substances, an AAC is specified in: (AA) subdivision (3), Table 6-1, which incorporates subdivision (5), Table 6-2; and (BB) subdivision (6). (ii) An AAC may be calculated by the commissioner using the procedures in section 8.2 of this rule for substances for which an AAC is not specified in: (AA) subdivision (3), Table 6-1, which incorporates subdivision (5), Table 6-2; or (BB) subdivision (6). (iii) The AAC determined under item (i) or (ii) may be modified on a site-specific basis to reflect local conditions in accordance with section 8.9 of this rule. (F) Clause (E) does not apply to the chemical control of plants and animals when that control is performed in compliance with approval conditions specified by the Indiana department of natural resources as provided by IC 14-22-9. (2) All surface waters outside of mixing zones must be free of substances in concentrations that, on the basis of available scientific data, are believed to be sufficient to injure, be chronically toxic to, or be carcinogenic, mutagenic, or teratogenic to humans, animals, aquatic life, or plants. The requirements to ensure protection against the adverse effects identified in this subdivision are as follows: (A) A toxic substance or pollutant must not be present in surface waters outside of mixing zones in concentrations that exceed the most stringent of the following continuous criterion concentrations (CCCs): (i) A chronic aquatic criterion (CAC) to protect aquatic life from chronic toxic effects. (ii) A terrestrial life cycle safe concentration (TLSC) to protect terrestrial organisms from toxic effects that may result from the consumption of aquatic organisms or water from the waterbody. (iii) A human life cycle safe concentration (HLSC) to protect human health from toxic effects that may result from the consumption of aquatic organisms or drinking water from the waterbody. (iv) For carcinogenic substances, a criterion to protect human health from unacceptable cancer risk of greater than one (1) additional occurrence of cancer per one hundred thousand (100,000) population. (B) For certain substances, one (1) or more of the CCCs identified in clause (A) are specified in: (i) subdivision (3), Table 6-1, which incorporates subdivision (5), Table 6-2; (ii) subdivision (4)(A), Table 6-1a; (iii) subdivision (4)(B), Table 6-1b; (iv) subdivision (6); and (v) subdivision (7), Table 6-4. (C) Criterion or criteria may be calculated by the commissioner using the corresponding procedures prescribed by sections 8.3 through 8.6 of this rule for substances for which a CCC identified in clause (A) is not specified in: (i) subdivision (3), Table 6-1, which incorporates subdivision (5), Table 6-2; (ii) subdivision (4)(A), Table 6-1a; (iii) subdivision (4)(B), Table 6-1b; (iv) subdivision (6); or (v) subdivision (7), Table 6-4. (D) A CCC determined under clause (B)(i), (B)(iv), (B)(v), or (C) may be modified on a site-specific basis to reflect local conditions in accordance with section 8.9 of this rule. (E) The CAC and TLSC for a substance apply in all surface waters outside of a mixing zone for a discharge of that substance. Indiana Administrative Code Page 4 WATER QUALITY STANDARDS (F) In surface waters where a public water system intake is not present or is unaffected by the discharge of a substance, the HLSC and the carcinogenic criterion for that substance based on consumption of organisms from the waterbody and only incidental ingestion of water apply to all surface waters outside of the mixing zone for a discharge of that substance. (G) In surface waters where a public water system intake is present, the HLSC and the carcinogenic criterion for a substance based on consumption of organisms and potable water from the waterbody apply at the point of the public water system intake. (3) Surface water quality criteria for the protection of aquatic life for specific substances are as follows: Table 6-1 Surface Water Quality Criteria for the Protection of Aquatic Life CAS Substances Acute Aquatic AAC Conversion Chronic Aquatic CAC Conversion Number Criteria (AAC) Factors (CF) Criteria (CAC) (4- Factors (CF) (Maximum) (µg/l) Day Average) (ìg/l) Metals 7440382 Arsenic[1] WER(340)(CF) 1.000 WER(150)(CF) 1.000 7440439 Cadmium[1][2] WER (e(0.9789[lnH]- 1.136672- WER (e(0.7977[lnH]-3.909)) 1.101672- 3.866))(CF) [lnH]0.041838 (CF) [lnH]0.041838 16065831 Chromium (III)[1][2] WER 0.316 WER 0.860 (e(0.819[lnH]+3.7256))(CF) (e(0.819[lnH]+0.6848))(CF) 18540299 Chromium (VI)[1] WER(16)(CF) 0.982 WER(11)(CF) 0.962 7440508 Copper[1][2] WER (e(0.9422[lnH]- 0.960 WER (e(0.8545[lnH]-1.465)) 0.960 1.464))(CF) (CF) 7439921 Lead[1][2] WER (e(1.273[lnH]- 1.46203- WER (e(1.273[lnH]-4.705)) 1.46203- 1.460))(CF) [lnH]0.145712 (CF) [lnH]0.145712 7439976 Mercury[3][4] 2.4 NA 0.012 NA 7440020 Nickel[1][2] WER 0.998 WER 0.997 (e(0.846[lnH]+2.255))(CF) (e(0.846[lnH]+0.0584))(CF) 7440224 Silver[1][2][5] WER (e(1.72[lnH]- 0.85 6.59)/2)(CF) 7440666 Zinc[1][2] WER 0.978 WER (e(0.8473[lnH]+0.884)) 0.986 (e(0.8473[lnH]+0.884))(CF) (CF) Organics 309002 Aldrin[4][5] 1.5 NA NA 57749 Chlordane[4][5] 1.2 NA 0.0043 NA 2921882 Chlorpyrifos 0.083 NA 0.041 NA 50293 DDT[4][5] 0.55 NA 0.0010 NA 60571 Dieldrin[4][5] 1.3 NA 0.0019 NA Endosulfan[5] 0.11 NA 0.056 NA 72208 Endrin[4][5] 0.09 NA 0.0023 NA 76448 Heptachlor[4][5] 0.26 NA 0.0038 NA 58899 Gamma HCH 1.0 NA 0.080 NA (Lindane)[4][5] 56382 Parathion 0.065 NA 0.013 NA 87865 Pentachlorophenol e(1.005[pH]-4.830) NA e(1.005[pH]-5.290) NA Polychlorinated NA 0.014 NA Biphenyls (PCBs)[4] 8001352 Toxaphene[4] 0.73 NA 0.0002 NA Other Substances Indiana Administrative Code Page 5 WATER QUALITY STANDARDS 7782505 Chlorine (Total 19 NA 11 NA Residual) 7782505 Chlorine 200 NA (intermittent, total residual)[6] 57125 Cyanide (free) 22 NA 5.2 NA Selenium CAC are specified in subdivision (4). Chloride AAC and CAC are specified in subdivision (6). [1]Aquatic life criteria for these metals are expressed as a dissolved concentration and are calculated using the water-effect ratio (WER) and the specified conversion factor (CF). The AAC and CAC for a dissolved metal are calculated by multiplying the WER by the criterion value or formula, and then by the appropriate CF. A value of one (1) must be used for the WER unless an alternate value is established under section 8.9 of this rule. The dissolved AAC and CAC must be rounded to two (2) significant digits, except when the criteria are used as intermediate values in a calculation, such as in the calculation of water quality-based effluent limitations (WQBELs). [2]The hardness values used in the equations for these criteria must not be greater than 400 mg/l as calcium carbonate (CaCO), and 3 the criteria at a hardness of 400 mg/l as CaCO are used for a water hardness above 400 mg/l as CaCO. The term "lnH" is the natural 3 3 log of hardness. [3]Aquatic life criteria for this metal are expressed as a total recoverable concentration. [4]These substances are bioaccumulative chemicals of concern. [5]The AAC for these substances is one-half (½) of the Final Acute Value (FAV) as calculated by procedures developed by U.S. EPA in 1980. This value would correspond to acute aquatic values calculated using procedures of the department or U.S. EPA procedures developed in 1985 in which the calculated FAV is divided by two (2) to reduce acute toxicity. [6]To be considered an intermittent discharge, total residual chlorine must not be detected in the discharge for a period of more than forty (40) minutes in duration, and these time periods must be separated by at least five (5) hours. (4) Surface water quality criterion for selenium must meet the following: (A) The surface water quality criterion for selenium, except for waters where the department has made, and U.S. EPA has approved, a site-specific determination that the criterion in Table 6-1b are applicable, is as follows: Table 6-1a Surface Water Quality Aquatic Life Criterion for Selenium (CAS # 7782492) Chronic Aquatic Criterion (CAC) Media Type Fish Tissue[1] Water Column[5][7] Criterion Egg/Ovary[2] Fish Whole-Body or Monthly Average Element Muscle[3] Exposure Intermittent Exposure[6] Magnitude 15.1 mg/kg dw 8.5 mg/kg dw 1.5 µg/l in lentic aquatic whole-body or 11.3 systems mg/kg dw muscle (skinless, boneless 3.1 µg/l in lotic aquatic filet) systems Duration Instantaneous Instantaneous Thirty (30) days Number of days per month with measurement[4] measurement[4] an elevated concentration Frequency Not to be Not to be exceeded Not more than once in Not more than once in three (3) exceeded three (3) years on average years on average [1]Fish tissue elements are expressed as steady-state; the aquatic system should not be experiencing new or increasing inputs of selenium. [2]Egg or ovary supersedes any whole-body, muscle, or water column element when fish egg or ovary concentrations are measured. Any proposal to sample egg or ovary fish tissue must be submitted to the department for review and approval prior to initiation of sampling, and the department will evaluate all representative egg or ovary fish tissue data to determine compliance with this criterion Indiana Administrative Code Page 6 WATER QUALITY STANDARDS element. [3]Fish whole-body or muscle tissue supersedes the water column element when both fish tissue and water concentrations are measured. Any proposal to sample fish whole-body or muscle tissue must be submitted to the department for review and approval prior to initiation of sampling, and the department will evaluate all representative fish whole-body or muscle tissue data to determine compliance with this criterion element. [4]Fish tissue data provide instantaneous point measurements that reflect integrative accumulation of selenium over time and space in fish populations at a given site. [5]Water column values are the applicable criterion element in the absence of steady-state condition fish tissue data and for fishless waters. Water column values are based on dissolved total selenium in water and are derived from fish tissue values via bioaccumulation modeling. Instead of the requirements in 327 IAC 5-2-11.1(b)(2), the allowable mixing zone dilution will be determined by applying the guideline in 327 IAC 2-1-4 to the thirty (30) day, ten (10) year (Q )low flow of the receiving stream 30,10 for the chronic aquatic criterion (CAC) water column criterion element applicable to lotic aquatic systems, in the absence of site- specific mixing zone data. [6]Intermittent Exposure Equation variables mean the following: WQC is the water column intermittent element. int WQC is the water column monthly element for either lentic or lotic waters. 30-day C is the average background selenium concentration. bkgrnd f is the fraction of any 30-day period during which elevated selenium concentrations occur, with f assigned a value (cid:36)0.033 int int (corresponding to one (1) day). [7]The water column criterion element may be modified on a site-specific basis in accordance with clause (C). (B) The surface water quality criterion for selenium, where the department has made, and U.S. EPA has approved, a site- specific determination that fishes in the Order Acipenseriformes (Order includes sturgeon and paddlefish) do not occur at the site, is as follows: Table 6-1b Site-specific Surface Water Quality Aquatic Life Criterion for Selenium (CAS # 7782492) in Non-Acipenseriformes (No Sturgeon or Paddlefish) Waters[1] Chronic Aquatic Criterion (CAC) Media Type Fish Tissue[2] Water Column[6][8] Criterion Egg/Ovary[3] Fish Whole-Body Monthly Average Intermittent Exposure[7] Element or Muscle[4] Exposure Magnitude 19.0 mg/kg dw 9.5 mg/kg dw 2.7 µg/l in lentic aquatic whole-body or 13.1 systems mg/kg dw muscle (skinless, boneless 5.5 µg/l in lotic aquatic filet) systems Duration Instantaneous Instantaneous Thirty (30) days Number of days per month with an measurement[5] measurement[5] elevated concentration Frequency Not to be exceeded Not to be exceeded Not more than once in Not more than once in three (3) three (3) years on years on average average [1]This criterion is applicable to surface waters for which the department has made, and U.S. EPA has approved, a site-specific determination that fishes in the Order Acipenseriformes do not occur at the site. In making this determination, the department must comply with the procedures in clause (D). [2]Fish tissue elements are expressed as steady-state; the aquatic system should not be experiencing new or increasing inputs of selenium. [3]Egg or ovary supersedes any whole-body, muscle, or water column element when fish egg or ovary concentrations are measured. Any proposal to sample egg or ovary fish tissue must be submitted to the department for review and approval prior to initiation of sampling, and the department will evaluate all representative egg or ovary fish tissue data to determine compliance with this criterion Indiana Administrative Code Page 7 WATER QUALITY STANDARDS element. [4]Fish whole-body or muscle tissue supersedes the water column element when both fish tissue and water concentrations are measured. Any proposal to sample fish whole-body or muscle tissue must be submitted to the department for review and approval prior to initiation of sampling, and the department will evaluate all representative fish whole-body or muscle tissue data to determine compliance with this criterion element. [5]Fish tissue data provide instantaneous point measurements that reflect integrative accumulation of selenium over time and space in fish populations at a given site. [6]Water column values are the applicable criterion element in the absence of steady-state condition fish tissue data and for fishless waters. Water column values are based on dissolved total selenium in water and are derived from fish tissue values via bioaccumulation modeling. Instead of the requirements in 327 IAC 5-2-11.1(b)(2), the allowable mixing zone dilution will be determined by applying the guideline in 327 IAC 2-1-4 to the thirty (30) day, ten (10) year (Q ) low flow of the receiving stream 30,10 for the chronic aquatic criterion (CAC) water column criterion element applicable to lotic aquatic systems, in the absence of site- specific mixing zone data. [7]Intermittent Exposure Equation variables mean the following: WQC is the water column intermittent element. int WQC is the water column monthly element for either lentic or lotic waters. 30-day C is the average background selenium concentration. bkgrnd f is the fraction of any 30-day period during which elevated selenium concentrations occur, with f assigned a value (cid:36)0.033 int int (corresponding to one (1) day). [8]The water column criterion element may be modified on a site-specific basis in accordance with clause (C). (C) Modification of the selenium water column criterion element must be achieved according to the following: (i) Site-specific water column criterion elements must be derived using either the empirical bioaccumulation factor (BAF) or mechanistic modeling method provided in Aquatic Life Ambient Water Quality Criterion for Selenium – Freshwater, EPA-822-R-16-006, Appendix K: Translation of a Selenium Fish Tissue Criterion Element to a Site-Specific Water Column Value (June 2016)*. (ii) Any proposal to derive a site-specific water column criterion element must be submitted to the department for review and approval of the methodology and sampling plan prior to initiation of sampling. The department shall evaluate and approve the applicability of and use of all representative data used to derive a site-specific water column criterion element. (iii) Any proposal to derive a site-specific water column criterion element must be protective of downstream designated uses for aquatic life and human health. (iv) Upon receipt of an application for a site-specific water column criterion element, the department shall do the following: (AA) Publish on the department's website all pertinent information about the proposed site-specific modification. (BB) Provide notice and request comment on the application. (v) Upon approval of a site-specific water column criterion element, the department shall do the following: (AA) Publish a notice in the Indiana Register. (BB) Place on the department's website all pertinent information about the approved site-specific modification. (CC) Submit the site-specific modification to U.S. EPA for approval. (DD) If approved by U.S. EPA, incorporate the site-specific modification into the water quality standards during the next revision of the water quality standards. (vi) Site-specific modifications of this criterion must not be incorporated into a final NPDES permit or used for other Clean Water Act purposes until approved by U.S. EPA. (D) Upon receipt of an application for a site-specific determination that fishes in the Order Acipenseriformes (Order includes sturgeon and paddlefish) do not occur at the site, the department shall do the following: (i) Review available species occurrence and distribution information and do one (1) of the following: (AA) Make a tentative determination that fishes in the Order Acipenseriformes do not occur at the site. (BB) Make a determination that fishes in the Order Acipenseriformes occur at the site and deny the Indiana Administrative Code Page 8