Chapter NR 106

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 History History: 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 106.08 NR 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)(b) (b) Data were produced by a lab certified or registered under ch. NR 149.

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(4)(b) (b) Available dilution in the receiving water.

NR 106.08(4)(c) (c) Discharge category and predicted effluent quality.

NR 106.08(4)(d) (d) Proximity to other point source dischargers.

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) (b) Reasonable potential.

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)1. 1. Existing controls on the discharge.

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)(e)5. 5. Dilution of the effluent in the receiving water.

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)(a) (a) Data are not representative under sub. (3).

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 History History: 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 106.09 NR 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) (2) Acute whole effluent toxicity.

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);

NR 106.09(2)(b)2. 2. 96 hours for aquatic vertebrate organisms (including fathead minnows (Pimephales promelas));

NR 106.09(2)(b)3. 3. Any other exposure period deemed appropriate by the department for a specific test organism.

NR 106.09(2)(c) (c) If a zone of initial dilution is determined appropriate in accordance with the provisions of s. NR 106.06 (3) (c), whole effluent acute toxicity limitations determined by this subsection shall be adjusted such that the effluent meets the following condition. The adjustment shall insure that after dilution of the effluent with the receiving water at a concentration equal to 3.3 times the percent dilution value calculated through application of the zone of initial dilution, the test solution of effluent and receiving water shall not produce a statistically valid LC50 less than 3.3 times the percent dilution value determined through application of the zone of initial dilution with the exposure periods as provided in par. (b).

NR 106.09(2)(d) (d) If, in the judgment of the department, the statistical interpretation methods used to test for LC50 are not appropriate for a specific data set, empirical interpretation methods may be used to determine the significance of an effect.

NR 106.09(2)(e) (e) Acute whole effluent toxicity limits shall be expressed as 1.0 TUa unless an AMZ is approved in which case these limits shall be expressed as a value that is 100 divided by the AMZ. Compliance with an acute whole effluent toxicity water quality-based limitation shall be determined by comparing the TUa endpoint from each toxicity test to the limitation. Pursuant to s. NR 106.08 (6) (d) a calculated LC50 that exceeds 100% is set equal to zero.

NR 106.09 Note Note: A toxicity reduction evaluation study is not always required in the event an acute WET limit is imposed in a permit.

NR 106.09(2)(f) (f) Whole effluent acute toxicity limitations shall be expressed in permits as daily maximum limitations.

NR 106.09(3) (3) Chronic whole effluent toxicity.

NR 106.09(3)(a) (a) The department shall establish chronic whole effluent toxicity limitations to ensure that concentrations of substances are not discharged from a point source that alone or in combination with other materials present are toxic to fish or other aquatic life as required by s. NR 102.04 (4) (d).

NR 106.09(3)(b) (b) To assure compliance with par. (a), an effluent, after dilution with an appropriate allowable quantity of receiving water flow equivalent to that provided by receiving water flows specified in s. NR 106.06 (3) (c) or implied in s. NR 106.06 (3) (b) 2., may not cause a significant adverse effect to a test organism population when compared to an appropriate control, as determined by applying all of the following:

NR 106.09(3)(b)1. 1. Using statistical interpretation methods appropriate to the toxicity test protocol, an adverse effect will be determined to be significant if the statistically derived IC25 or IC50, as specified for each species in the whole effluent toxicity test methods required in s. NR 219.04, Table A, from the whole effluent toxicity test, is less than the calculated IWC.

NR 106.09(3)(b)2. 2. If, in the judgment of the department, the statistical interpretation methods used to test for significance are not appropriate for a specific data set, empirical interpretation methods may be used to determine the significance of an effect.

NR 106.09(3)(c) (c) Chronic whole effluent toxicity limits shall be expressed as a value that is 100 divided by the IWC. Compliance with a chronic whole effluent toxicity water quality-based limitation shall be determined by comparing the monthly average calculated TUc from all toxicity tests conducted during that month to the limitation. Pursuant to s. NR 106.08 (6) (d), a calculated IC25 or IC50 that exceeds 100% is set equal to zero.

NR 106.09 Note Note: A toxicity reduction evaluation study is not always required in the event a chronic WET limit is imposed in a permit.

NR 106.09(3)(d) (d) Whole effluent chronic toxicity limitations shall be expressed in permits as monthly average limitations.

NR 106.09 History History: Cr. Register, February, 1989, No. 398, eff. 3-1-89; renum. (1) (a), (b), (c) (intro.) and 2. and (2) to be (2) (a) to (c) and (3) and am. (2) (b), (c), (3) (a), (b) (intro.) and 1., r. (1) (c) 1., cr. (1), Register, August, 1997, No. 500, eff. 9-1-96; CR 03-050: am. (2) (b) (intro.) Register February 2004 No. 578, eff. 3-1-04; CR 04-101: am. (1) Register May 2005 No. 593, eff. 6-1-05; CR 15-085: r. and recr. (2) (e), cr. (2) (f), am. (3) (b) (intro.), 1., r. and recr. (3) (c), cr. (3) (d) Register August 2016 No. 728, eff. 9-1-16.

NR 106.10 NR 106.10 Noncontact cooling water additives. The department shall establish water quality based effluent limitations for toxic and organoleptic substances in noncontact cooling water discharges as follows:

NR 106.10(1) (1) For toxic and organoleptic substances commonly added by suppliers of drinking water systems and present in the noncontact cooling water, a water quality based effluent limitation calculated under s. NR 106.06 that is based on the applicable water quality criterion or secondary value shall be included in the permit unless the permittee demonstrates at least one of the following:

NR 106.10(1)(a) (a) The concentration of the substance in the intake water is dissipated within the system that supplies the intake water to the permittee and is consistently less than the water quality based effluent limitation.

NR 106.10(1)(b) (b) An effluent limitation is not necessary as determined using the reasonable potential procedures in s. NR 106.05.

NR 106.10(1)(c) (c) Prior to reaching the receiving water, the substance dissipates or is removed to a level that is below the water quality based effluent limitation.

NR 106.10(2) (2) For other toxic and organoleptic substances intentionally added to noncontact cooling water by the permittee, the department shall follow the procedures specified in ss. NR 106.05 and 106.06 to calculate a water quality based effluent limitation and determine whether the limitation is necessary in the permit. If there is no water quality criterion for an additive and there are potential water quality impacts from the additive, the department shall establish a secondary value for the additive in accordance with ch. NR 105 and calculate a limitation based on that value. All of the following requirements apply to the use and discharge of additives:

NR 106.10(2)(a) (a) A permittee shall obtain written approval from the department prior to use of the additive.

NR 106.10(2)(b) (b) A permittee shall provide the department with dosage information and safety data sheets and toxicological data, as requested by the department to meet minimum data requirements specified in ss. NR 105.05 (4) and 105.06 (6) for each additive for which approval is sought.

NR 106.10(2)(c) (c) Prior to increasing the usage of an additive in amounts greater than authorized by the department, a permittee shall get written approval from the department for the increased usage.

NR 106.10(2)(d) (d) After reissuance, if a permittee wants to use a new additive not previously approved by the department, the permittee shall get written approval from the department prior to use of the additive.

NR 106.10(2)(e) (e) A permittee may only use additives in accordance with the conditions of the department approval and any applicable permit terms. If the department does not approve use of the additive, the additive may not be discharged.

NR 106.10 History History: Cr. Register, February, 1989, No. 398, eff. 3-1-89; am. (1) (a), (b) and (2), cr. (1) (d), August, 1997, No. 500, eff. 9-1-97; CR 03-050: am. (1) (intro.) Register February 2004 No. 578, eff. 3-1-04; CR 15-084: r. and recr. Register August 2016 No. 728, eff. 9-1-16; correction in (2) (intro.) made under s. 35.17, Stats., Register August 2016 No. 728.

NR 106.11 NR 106.11 Multiple discharges. Whenever the department determines that more than one discharge may be affecting the water quality of the same receiving water for one or more substances, the provisions of this chapter shall be used to calculate the combined allowable load from the discharges necessary to meet the water quality criteria for the substances. The resultant combined allowable load shall be divided among the various discharges using an allocation method based on site-specific considerations. Whenever the department makes a determination under this section, the department shall notify all permittees who may be affecting the water quality of the same receiving water of the determination and any limitations developed under this section. Permittees shall be given the opportunity to comment to the department on any determination made under this section.

NR 106.11 Note Note: The method of allocating the combined allowable load in s. NR 106.11 is not required to be based on the effluent flow rates specified in s. NR 106.06 (4) (d).