NR 106.07(4)(e)(e) Additional permit limitations. Both a daily maximum and monthly average permit limitation shall be included in a permit for a pollutant whenever any water quality-based effluent limitation for that pollutant is determined necessary under pars. (b) to (d). A weekly average limitation shall be included in a permit in addition to daily maximum and monthly average limitation if the weekly average limit is determined necessary under par. (c). The department shall use all of the following procedures to include daily maximum and monthly average limitations in permits: NR 106.07(4)(e)1.1. If a daily maximum limitation is the only limitation determined necessary for a pollutant under s. NR 106.05, a monthly average limitation shall still be included in the permit and set equal to the daily maximum limitation or the monthly average water quality-based effluent limitation calculated under s. NR 106.06, whichever is more restrictive. NR 106.07(4)(e)2.2. If a weekly average limitation is the only limitation determined necessary for a pollutant under s. NR 106.05 a monthly average limitation shall still be included in the permit and shall be set equal to the weekly average limitation or the monthly average water quality-based effluent limitation calculated under s. NR 106.06, whichever is more restrictive. A daily maximum limitation shall also be included in the permit and set equal to the daily maximum water quality-based effluent limitation calculated under s. NR 106.06 or a daily maximum limitation calculated using the following procedure, whichever is more restrictive: Daily Maximum Limitation= WQBELc x DMF
Table 2 — Daily Multiplication Factor
NR 106.07(4)(e)3.3. If a monthly average limitation is determined necessary, but a daily maximum limitation is not determined necessary for that pollutant under s. NR 106.05, a daily maximum limitation shall still be included in the permit and shall be set equal to the daily maximum water quality-based effluent limitation calculated under s. NR 106.06 or a daily maximum limitation calculated using the following procedure, whichever is more restrictive: Daily Maximum Limitation = (Monthly Average Limitation x MF)
NR 106.07(4)(e)4.4. Limitations calculated under subds. 1. to 3. shall be expressed in terms of concentration unless the department determines that a mass limitation is also necessary to protect fish and aquatic life, human health, or wildlife due to the variability of effluent flow or stream flow or other site-specific factors. NR 106.07 NoteNote: This methodology is based on the Technical Support Document for Water Quality-based Toxics Control (March 1991). PB91-127415.
NR 106.07(5)(5) Expression of concentration limitations in permits for noncontinuous discharges. NR 106.07(5)(a)(a) Applicability. The procedures for expressing limitations in this subsection apply to seasonal discharges, discharges proportional to stream flow, or other unusual discharge situations that do not meet the definition of a continuous discharge under s. NR 205.03 (9g) when there is reasonable potential under s. NR 106.05 to exceed a water quality-based effluent limitation based on fish and aquatic life protection, human health, or wildlife protection. Water quality-based effluent limitations shall be calculated under s. NR 106.06. NR 106.07(5)(b)(b) Acute reasonable potential. Pursuant to s. NR 106.05, if there is reasonable potential to exceed a water quality-based effluent limitation for a pollutant that is based on an acute criterion or secondary value then the acute concentration limitation calculated under s. NR 106.06 shall be expressed as a daily maximum and included in the permit. NR 106.07(5)(c)(c) Chronic and human health or wildlife reasonable potential. Pursuant to s. NR 106.05, if there is reasonable potential to exceed a water quality-based effluent limitation for a pollutant based on a chronic, a human health, or a wildlife criterion or secondary value, limitations shall be included in the permit and expressed on a case-by-case basis. The department shall consider all of the following factors: NR 106.07(5)(c)4.4. Whether the pollutant is subject to a technology-based limitation or other limitation expressed by mass, concentration, or other appropriate measure in the permit. NR 106.07(5m)(a)(a) The coefficient of variation (CV) shall be calculated as the ratio of the standard deviation of the representative effluent data divided by the arithmetic average of the representative effluent data, except as provided in par. (b). NR 106.07(5m)(b)(b) If there are fewer than 10 representative data points the CV shall be set equal to 0.6. NR 106.07(5m)(c)(c) When calculating the CV in par. (a) a monitoring result less than the limit of detection may be assigned a value of zero. If the effluent limitation is less than the limit of detection, the department may substitute a value other than zero for results less than the limit of detection, after considering the number of monitoring results that are greater than the limit of detection and if warranted when applying appropriate statistical techniques. NR 106.07(6)(6) limitations below the level of detection or quantification. When the water quality based effluent limitation for any substance in a permit is less than the limit of detection or the limit of quantitation, the following conditions shall apply: NR 106.07(6)(a)(a) The permittee shall perform monitoring required in the permit using an acceptable analytical methodology for that substance in the effluent which produces the lowest limit of detection and limit of quantitation. NR 106.07(6)(b)(b) The permittee shall determine the limit of detection and limit of quantitation using a method specified by the department. NR 106.07(6)(c)(c) Compliance with concentration and mass limitations shall be determined as follows: NR 106.07(6)(c)1.1. When the water quality based effluent limitation is less than the limit of detection, effluent levels less than the limit of detection are in compliance with the effluent limitation. NR 106.07(6)(c)2.2. When the water quality based effluent limitation is less than the limit of detection, effluent levels greater than the limit of detection, but less than the limit of quantitation are in compliance with the effluent limitation except when analytically confirmed and statistically confirmed by a sufficient number of analyses of multiple samples and use of appropriate statistical techniques. The department may require in a permit additional monitoring when effluent levels are between the limit of detection and the limit of quantitation. NR 106.07(6)(c)3.3. When the water quality based effluent limitation is greater than the limit of detection, but less than the limit of quantitation effluent levels less than the limit of detection or less than the limit of quantitation are in compliance with the effluent limitation. NR 106.07(6)(d)(d) When the water quality based effluent limitation is expressed in the permit as a daily maximum or average mass limitation, compliance is determined according to par. (c) after converting the limit of detection and limit of quantitation to mass values using appropriate conversion factors and the actual daily effluent flow, or actual average effluent flow for the averaging period. NR 106.07(6)(e)(e) Except as provided in this paragraph, when calculating an average or mass discharge level for determining compliance with an effluent limitation according to the provisions of par. (c), a monitoring result less than the limit of detection may be assigned a value of zero. If the effluent limitation is less than the limit of detection, the department may substitute a value other than zero for results less than the limit of detection, after considering the number of monitoring results that are greater than the limit of detection and if warranted when applying appropriate statistical techniques. NR 106.07(6)(f)(f) Unless the permittee can demonstrate continuous compliance with the limit, the department shall include a condition in the permit requiring the permittee to develop and implement or update and implement a cost-effective pollutant minimization program as specified in s. NR 106.04 (5). NR 106.07(7)(7) Whole effluent toxicity as alternative limit. The department may establish a whole effluent toxicity limitation according to s. NR 106.09 as an alternative to a chemical specific water quality-based effluent limitation based on a fish and aquatic life secondary acute or secondary chronic value determined according to ss. NR 105.05 (4) and 105.06 (6). The alternative whole effluent toxicity limitation shall meet all the following conditions: NR 106.07(7)(a)(a) The fathead minnow (Pimephales promelas) or the cladoceran Ceridaphnia dubia were represented in the toxicological database used to generate the secondary value: NR 106.07(7)(b)(b) The permittee has requested the alternative whole effluent toxicity limitation; and NR 106.07(7)(c)(c) Whole effluent toxicity testing required in the permit shall be conducted at a frequency to be determined by the department, but at least once every 3 months during the entire term of the permit. NR 106.07(8)(8) Secondary values and studies within the Great Lakes basin. If the effluent limitation based on a secondary value is established in a permit, a permittee discharging to the Great Lakes as defined in s. NR 102.22 (5) may request that additional time be added to the compliance schedule, according to s. NR 106.117 (2), for the permittee to conduct studies, other than studies for site-specific criteria under s. NR 105.02 (1), that are needed to propose a revision to the secondary value upon which the effluent limitation is based. During this time, the permittee may provide additional data necessary to either refine the secondary value or calculate a water quality criterion. NR 106.07(9)(9) Wet weather mass limitations. In addition to the mass limitation calculated under sub. (2) (c), for a discharger subject to ch. NR 210 and which discharges on a year-around basis, the department shall include in the permit an alternative wet weather mass limitation. For purposes of compliance, this alternative wet weather mass limitation shall apply when the mass discharge level exceeds the mass limitation calculated under sub. (2) (c) and when the permittee demonstrates to the satisfaction of the department that the discharge exceedance is caused by and occurs during a wet weather event. For purposes of this subsection, a wet weather event occurs during and immediately following periods of precipitation or snowmelt, including but not limited to rain, sleet, snow, hail or melting snow, during which water from the precipitation, snowmelt or elevated groundwater enters the sewerage system through infiltration or inflow, or both. In calculating this alternative wet weather mass limitation, the department shall use the concentration limit determined by the procedures in s. NR 106.06, the appropriate conversion factor and the appropriate effluent flow given in either par. (a) or (b). NR 106.07(9)(a)(a) For effluent limitations based on aquatic life chronic toxicity criteria or secondary chronic values, the maximum effluent flow, expressed as a daily average, that is anticipated to occur for 7 continuous days during the design life of the treatment facility. NR 106.07(9)(b)(b) For effluent limitations based on wildlife, human threshold or human cancer criteria or secondary values, or taste and odor criteria, the maximum effluent flow, expressed as a daily average, that is anticipated to occur for 30 continuous days during the design life of the treatment facility. NR 106.07(10)(10) Alternative methods for limit expression. The department may use an alternative method from the methodology specified in subs. (3) to (5) to express water quality-based effluent limitations in permits if the department determines that the methods in subs. (3) to (5) are impracticable and an alternative methodology is necessary and appropriate and adequately protective of the designated uses of the receiving and downstream waters as specified in ch. NR 102. NR 106.07 HistoryHistory: Cr. Register, February, 1989, No. 398, eff. 3-1-89; renum. (2) to (5) to be (3) to (6) and am., cr. (2), (6) (d) to (f) and (7) to (9), Register, August, 1997, No. 500, eff. 9-1-97; correction in (7) made under s. 13.93 (2m) (b) 1., Stats., Register, October, 1999, No. 526; correction in (8) made under s. 13.93 (2m) (b) 7., Stats., Register February 2004 No. 578; CR 09-123: am. (2) (intro.), (a) and (b) Register July 2010 No. 655, eff. 8-1-10; CR 15-085: cr. (1) (title), r. and recr. (2) to (5), cr. (5m), (6) (title), (7) (title), (8) (title), am. (8), cr. (9) (title), (10) Register August 2016 No. 728, eff. 9-1-16. NR 106.08NR 106.08 Determination of the necessity for whole effluent toxicity testing requirements and limitations. NR 106.08(1)(1) General. The department shall establish whole effluent toxicity testing requirements and limitations whenever necessary to meet applicable water quality standards as specified in chs. NR 102 to 105 as measured by exposure of aquatic organisms to an effluent and specified effluent dilutions. When considering the necessity for whole effluent toxicity testing requirements and limitations, the department shall consider in-stream biosurvey data and data from ambient toxicity analyses, whenever such data are available. NR 106.08(2)(2) Determination of necessity. If representative discharge data are available for an effluent being discharged from a point source, whole effluent toxicity testing requirements are necessary when any of the following apply: NR 106.08(2)(a)(a) Existing aquatic life toxicity test data generated according to standard test protocols indicate a potential for an effluent from a point source discharge to adversely impact the receiving water aquatic life community. NR 106.08(2)(b)(b) A water quality-based effluent limitation for a toxic substance is determined necessary in s. NR 106.05. NR 106.08(3)(3) Representative data. Toxicity test data available to the department shall be considered representative when all of those data meet the following conditions: NR 106.08(3)(a)(a) Data are representative of normal discharge conditions and current effluent quality. NR 106.08(3)(c)(c) Data were produced from toxicity test procedures specified in the permit. NR 106.08(3)(d)(d) Data were produced from toxicity tests that met all applicable quality assurance or quality control requirements specified in the permit. NR 106.08(4)(4) No representative data. If no representative discharge data are available for an effluent being discharged from a point source, whole effluent toxicity testing requirements are necessary if, in the judgment of the department, water quality standards may be exceeded. In such cases, all of the following factors shall be considered: NR 106.08(4)(a)(a) Any relevant information that is available that indicates a potential for an effluent to impact the receiving water aquatic life community. NR 106.08(5)(5) Other considerations. Regardless of the results of the analysis conducted under this section, the department may, whenever determined necessary, require whole effluent toxicity testing for a point source discharge. The department may use information submitted under s. 323.60 (5) (c) and (d), Stats., together with other information, in determining when whole effluent toxicity testing is necessary. NR 106.08(6)(6) Reasonable potential to receive an acute or chronic whole effluent toxicity limit. NR 106.08(6)(a)(a) General. Whole effluent toxicity limits are established in a permit according to s. NR 106.09 whenever representative, facility-specific whole effluent toxicity data demonstrate that the effluent is or may be discharged at a level that will cause, have the potential to cause, or contribute to an excursion of a water quality standard. Whole effluent toxicity limits may also be imposed in the absence of facility-specific whole effluent toxicity test data, on a case-by-case basis, whenever facility-specific or site-specific data or conditions indicate toxicity to aquatic life that is attributable to the discharger. NR 106.08(6)(b)1.1. If a zone of initial dilution has not been approved by the department, the potential to exceed an acute criterion shall be calculated using the following equation: (TUa effluent) (B) > 1.0
NR 106.08(6)(b)2.2. If a zone of initial dilution has been approved by the department, the potential to exceed an acute criterion shall be calculated using the following equation: [(TUa effluent) (B) (AMZ)] > 1.0
NR 106.08(6)(b)3.3. The potential to exceed a chronic criterion shall be calculated using the following equation: [(TUc effluent) (B) (IWC)]> 1.0
NR 106.08(6)(c)(c) Reasonable potential multiplication factor. The department shall use the reasonable potential multiplication factor in par. (b) to convert the calculated effluent toxicity value to the estimated 95th percentile toxicity value. The department shall use all of the following methods to select a reasonable potential multiplication factor: NR 106.08(6)(c)1.1. When there are less than 10 individual toxicity detects, the multiplication factor shall be taken from Table 4 and based on a coefficient of variation of 0.6. NR 106.08(6)(c)2.2. When there are 10 or more individual toxicity detects, the multiplication factor shall be taken from Table 4 and based on coefficient of variation calculated as the standard deviation of the WET test endpoints, IC25, IC50, or LC50, divided by the arithmetic mean of the WET tests. Table 4 — Reasonable Potential Multiplication Factor
NR 106.08(6)(d)(d) Maximum toxicity values. The department shall set the TUc effluent and TUa effluent values in par. (b) equal to zero whenever toxicity is not detected or the LC50, IC25, or IC50 equals or exceeds 100% effluent. NR 106.08(6)(e)(e) Exception. WET limits are not necessary under this subsection when the department determines chemical-specific limits for the effluent are sufficient to attain and maintain applicable numeric and narrative water quality standards, taking into consideration all of the following: NR 106.08(6)(e)2.2. Controls on the pollutant discharged by nonpoint source pollution in the watershed. NR 106.08(6)(e)3.3. The variability of the pollutant or parameter in the effluent discharged. NR 106.08(6)(e)4.4. Sensitivity of species to toxicity testing when evaluating whole effluent toxicity as defined in s. NR 106.03. NR 106.08(6)(f)(f) Fact sheet. If the department determines WET limitations are not necessary under par. (e), all of the factors that are required for the determination must be specifically discussed in the fact sheet for the permit. NR 106.08(7)(7) Data Exclusions. The department may exclude data from a WET reasonable potential determination when those data meet any of the following conditions: NR 106.08(7)(b)(b) Positive WET results are caused by deficiency toxicity only. NR 106.08(7)(c)(c) Positive WET results are caused by groundwater or surface water remediation needed to correct or prevent an existing surface or groundwater contamination situation or a public health problem. NR 106.08 HistoryHistory: Cr. Register, February, 1989, No. 398, eff. 3-1-89; am. (1), r. and recr. (5), Register, August, 1997, No. 500, eff. 9-1-97; CR 09-123: am. (5) (a) Register July 2010 No. 655, eff. 8-1-10; correction in (4) made under s. 13.92 (4) (b) 7., Stats., Register July 2010 No. 655; CR 15-085: r. and recr. Register August 2016 No. 728, eff. 9-1-16; CR 17-002: cr. (6) (e), (f) Register April 2018 No. 748, eff. 5-1-18. NR 106.09NR 106.09 Whole effluent toxicity data evaluation and limitations. NR 106.09(1)(1) Data evaluation. Data evaluation procedures are specified in the whole effluent toxicity test methods specified in s. NR 219.04, Table A. In the event of a WET test failure, facility specific requirements shall be established in the WPDES permit which specify required follow-up actions. NR 106.09(2)(a)(a) Except as provided in par. (c), the department shall establish acute whole effluent toxicity limitations to ensure that substances shall not be present in amounts which are acutely harmful to aquatic life in all surface waters including the mixing zone and effluent channel as required by s. NR 102.04 (1). NR 106.09(2)(b)(b) To assure compliance with par. (a), a whole effluent toxicity test may not result in a statistically valid LC50 less than 100% with the following taxa-specific exposure periods: NR 106.09(2)(b)1.1. 48 hours for aquatic invertebrate organisms (including Ceriodaphnia dubia);
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