Chapter NR 106

NR 106.32(3)(c) (c) Receiving water design flow (Qs). Subject to the application of the zone of passage factors in subd. 3. or 4., the value of Qs to be used in calculating the effluent limitation for discharges to flowing waters shall be determined using one of the approaches in subd. 1. or 2.

NR 106.32(3)(c)1. 1. To calculate limits based on 4-day chronic ammonia criteria, Qs shall equal the average minimum 7-day flow which occurs once in 10 years (7-day Q10) or, if sufficient information is available to calculate a biologically based receiving water design flow, the flow which prevents an excursion from the criterion using a duration of 4 days and a frequency of less than once every 3 years (4-day, 3-year biological flow). To calculate limits based on 30-day chronic ammonia criteria, Qs shall equal the average minimum 30-day flow which occurs once in 5 years (30-day Q5) or 85% of the average minimum 7-day flow which occurs once in 2 years (7-day Q2).

NR 106.32(3)(c)2. 2. If approved by the department, the value of Qs of the receiving water for calculating effluent limitations based upon the chronic toxicity criteria specified in s. NR 105.06 may be determined on a case-by-case basis, using historical flow data or real time data. Qs may be based on real-time streamflow data if the permittee demonstrates that modifications to effluent quality or quantity can be achieved in response to changing stream conditions. Appropriate modifications to effluent quality or quantity may include, but are not limited to, land application, storage, shutdown or reduction in ammonia feed rates.

NR 106.32(3)(c)3. 3. To provide for an adequate zone of passage, the value of Qs to be used in the equation in par. (b) 1. shall be determined by multiplying the applicable value from subd. 1. or 2. by the following zone of passage factors:

NR 106.32(3)(c)3.a. a. 0.25 when the receiving water temperature is less than 11 degrees Celsius.

NR 106.32(3)(c)3.b. b. 0.50 when the receiving water temperature is equal to or greater than 11 degrees Celsius and equal to or less than 16 degrees Celsius.

NR 106.32(3)(c)3.c. c. 1.00 when the receiving water temperature is greater than 16 degrees Celsius.

NR 106.32(3)(c)4. 4. Based on the zone of passage or rapid dilution demonstration in this subdivision, the department may determine that alternative zone of passage factors to those provided in subd. 3. apply. The permittee may demonstrate, through appropriate and reasonable methods approved by the department, and by using information on the mixing and dilution characteristics of the discharge, that an adequate zone of free passage exists in the cross-section of the receiving water or that dilution is accomplished rapidly such that the extent of the mixing zone is minimized. In complex situations, the department may require that the demonstration under this subdivision include water quality modeling or field dispersion studies.

NR 106.32(3)(c)5. 5. The department may adjust Qs from the values in subd. 1. where natural receiving water flow is significantly altered by flow regulation.

NR 106.32(3)(d) (d) Effluent flows (Qe). Effluent flows used in the calculation of ammonia limits shall be determined using the procedures in s. NR 106.06 (4) (d).

NR 106.32(3)(e) (e) Background concentrations of ammonia (Cs). Background ammonia concentrations used in the calculation of ammonia limits shall be determined using the procedures in s. NR 106.06 (4) (e).

NR 106.32(4) (4) Values for parameters which affect the limit. Effluent limitations for ammonia shall be based upon the effects of pH and temperature on the toxicity of ammonia. The department shall determine the value of the pH and temperature on a case-by-case basis as follows:

NR 106.32(4)(a) (a) Receiving water.

NR 106.32(4)(a)1. 1. The geometric mean of temperature and the arithmetic mean for pH in the receiving water shall be used to establish the chronic toxicity criteria for purposes of determining the effluent limitation for ammonia. Representative seasonal values of pH and temperature may be used. The pH and temperature determined under this subdivision may be modified to account for the mixture of the receiving and effluent flows when either of the following conditions occur:

NR 106.32(4)(a)1.a. a. Whenever the value of the pH and temperature of the effluent as determined in par. (b) is significantly greater than or less than the value in the receiving water.

NR 106.32(4)(a)1.b. b. Whenever, as a result of demonstrated or measured physical, chemical or biological reactions, the value of the pH and temperature, after mixing of the receiving water and the effluent, is significantly different than the respective background value of the pH and temperature in the receiving water.

NR 106.32(4)(a)2. 2. If information on the pH and temperature of the receiving water is not available, information on the quality of similar water bodies in the area and best professional judgment of the department may be used.

NR 106.32(4)(b) (b) Effluent.

NR 106.32(4)(b)1. 1. The daily maximum effluent pH shall be used to calculate the daily maximum ammonia limit based on acute toxicity criteria and in any calculations under par. (a).

NR 106.32(4)(b)2. 2. If information on the effluent pH is not available, then values representative of similar effluents may be used.

NR 106.32(4)(c) (c) A permittee may conduct an investigation to demonstrate that alternate values for the pH and temperature determined under pars. (a) and (b) should be used. The investigation shall be based on site-specific conditions and shall address all of the following: critical loading conditions; buffering capacity of the stream; whether pH changes persist long enough to allow decay of ammonia to non-toxic levels; the effect of seasonal variations; maintaining the pH at the edge of the chronic mixing zone within the range of 6.0 to 9.0; and separate analyses for chronic mixing zone and an acute zone of initial dilution.

NR 106.32 Note Note: It is suggested that the permittee submit a plan of study to the department prior to undertaking a demonstration under this paragraph.

NR 106.32(4)(d) (d) Real-time data. Effluent limitations may be established based on real-time effluent and stream data provided the permittee demonstrates that the real-time data can be collected, and the discharge can be controlled to attain the effluent limitations. Adjustment of effluent pH may be an appropriate modification for compliance with real-time daily maximum limits. Real-time stream data may not be used to calculate ammonia limits if the department determines that the discharge may affect the existence of any endangered or threatened species listed under ch. NR 27.

NR 106.32(5) (5) Application of water quality based ammonia limitations in permits and monitoring.

NR 106.32(5)(a) (a) Limitations based on acute toxicity criteria. Effluent limitations for ammonia that are established in permits based on the acute toxicity criteria in ch. NR 105 shall be expressed only as concentrations.

NR 106.32(5)(b) (b) Limitations based on chronic toxicity criteria. Effluent limitations for ammonia that are established in permits based on the chronic toxicity criteria in ch. NR 105 shall be expressed as concentrations, except mass limits may also be included in a permit if there is more than one discharger of ammonia at a location or where the discharge is to an exceptional resource water designated under s. NR 102.11 or outstanding resource water designated under s. NR 102.10. If mass limits are determined to be necessary by the department, they shall be calculated using the procedure in s. NR 106.07 (2).

NR 106.32(5)(c) (c) Maximum and average ammonia limitations. Effluent limitations based on acute toxicity criteria shall be expressed in permits as daily maximum limitations. Effluent limitations based on 4-day chronic toxicity criteria shall be expressed in permits as weekly average limitations. Effluent limitations based on 30-day chronic toxicity criteria shall be expressed in permits as monthly average limitations.

NR 106.32(5)(d) (d) Monitoring frequency. The department shall determine on a case-by-case basis the monitoring frequency for ammonia to be required in a permit.

NR 106.32 History History: CR 03-050: cr. Register February 2004 No. 578, eff. 3-1-04; CR 15-085: am. (2) (b) (intro.), 2., cr. (2) (e), am. (3) (a) 4. a. Register August 2016 No. 728, eff. 9-1-16.

NR 106.33 NR 106.33 Determination of the necessity for water quality-based effluent limits for ammonia.

NR 106.33(1) (1) Reasonable potential.

NR 106.33(1)(a) (a) For a permitted discharge that is not already subject to an ammonia water quality-based effluent limitation, the procedures specified in s. NR 106.05 shall be used to determine if water quality-based effluent limitations for ammonia are necessary in a reissued permit. When application of the procedures in s. NR 106.05 results in a determination that ammonia effluent limits are not necessary in a permit, the permit holder shall continue to be operated in a manner that optimizes the removal of ammonia within the design capabilities of the wastewater treatment plant. The department may require that the permittee monitor ammonia at a frequency established on a case-by-case basis in its permit for the purpose of determining representative discharge levels.

NR 106.33(1)(b) (b) If a permittee is subject to an ammonia limitation in an existing permit, the limitation shall be included in any reissued permit. Ammonia limitations shall be included in the permit if the permitted facility will be providing treatment for ammonia discharges.

NR 106.33(2) (2) Permit limitations for continuous POTWs. The procedures for expressing limitations in permits in this subsection apply to continuous discharges subject to ch. NR 210 when there is reasonable potential under s. NR 106.05 to exceed an ammonia limitation. Both a weekly average and monthly average permit limitations shall be included in a permit for ammonia whenever any water quality-based effluent limitation for ammonia is determined necessary under sub. (1). A daily maximum limitation shall be included in permits in addition to weekly average and monthly average limitations if necessary under sub. (1). The department shall use all of the following procedures to include weekly average and monthly average limitations in permits:

NR 106.33(2)(a) (a) If a daily maximum limitation is the only ammonia limitation determined necessary under sub. (1), a weekly average limitation shall be set equal to the WQBEL based on the 4-day chronic toxicity criteria calculated under s. NR 106.32 (3) or the daily maximum limitation, whichever is more restrictive.

NR 106.33(2)(b) (b) If a weekly average ammonia limitation is determined necessary under sub. (1), and a monthly average limitation is not already determined necessary, a monthly average limitation shall be set equal to the WQBEL based on the 30-day chronic toxicity criteria calculated under s. NR 106.32 (3) or the weekly average limitation, whichever is more restrictive, except as provided under par. (c).

NR 106.33(2)(c) (c) The department may on a case-by-case basis use an alternative methodology for calculating monthly average limitations whenever historical flow data or real time data are used to calculate weekly average limitations under s. NR 106.32 (3) (c) 2. and these limitations are determined to be necessary under sub. (1).

NR 106.33(2)(d) (d) If a monthly average limitation is the only ammonia limitation determined to be necessary under sub. (1), weekly average limitations shall be set equal to the WQBEL based on the 4-day chronic toxicity criteria calculated under s. NR 106.32 (3) or a weekly average limitation calculated using the following procedure, whichever is more restrictive:

Weekly Average Limitation = (Monthly Average Limitation x MF)

NR 106.33(3) (3) Permit limitations for other continuous discharges. The procedures for expressing limitations in this subsection apply to continuous discharges that are not subject to ch. NR 210 and when there is reasonable potential under s. NR 106.05 to exceed an ammonia limitation. Both a daily maximum and monthly average permit limitation shall be included in a permit for ammonia whenever any water quality-based effluent limitation for ammonia is determined necessary under s. NR 106.05. A weekly average limitation shall be included in permits in addition to a daily maximum and monthly average limitation if necessary under sub. (1). The department shall use all of the following procedures to include daily maximum and monthly average limitations in permits:

NR 106.33(3)(a) (a) If a weekly average limitation is the only ammonia limitation determined necessary under sub. (1), a monthly average limitation shall be set equal to the WQBEL based on the 30-day chronic toxicity criteria or the weekly average limitation, whichever is more restrictive except as provided in par. (c). A daily maximum limitation shall also be included in the permit and set equal to the daily maximum ammonia WQBEL under s. NR 106.32 (2) or a daily maximum limitation calculated using the following procedure, whichever is more restrictive:

Daily Maximum Limitation= Weekly Average Limitation x DMF

NR 106.33(3)(b) (b) If a daily maximum ammonia limitation is determined necessary under sub. (1), and a monthly average limitation is not already determined necessary, a monthly average limitation shall be set equal to the WQBEL based on the 30-day chronic toxicity criteria calculated according to s. NR 106.32 (3) or the daily maximum limitation, whichever is more restrictive, except as provided in par. (c).

NR 106.33(3)(c) (c) The department may on a case-by-case basis use an alternative methodology for calculating daily maximum or monthly average limitations whenever historical flow data or real time data are used to calculate weekly average limitations under s. NR 106.32 (3) (c) 2. and these limitations are determined to be necessary under sub. (1).

NR 106.33(3)(d) (d) If a monthly average limitation is determined necessary and a daily maximum limitation is not already determined necessary under sub. (1), a daily maximum limitation shall be set equal to the daily maximum ammonia WQBEL under s. NR 106.32 (2) or a daily maximum limitation calculated using the following procedure, whichever is more restrictive:

Daily Maximum Limitation = (Monthly Average Limitation x MF)

NR 106.33(4) (4) Permit limitations for noncontinuous discharges. The department shall include ammonia water quality-based effluent permit limitations in permits for seasonal discharges, discharges proportional to stream flow, or other unusual discharge situations that do not meet the definition of a continuous discharge whenever ammonia water quality-based effluent limitations are determined necessary under sub. (1). Ammonia limitations shall be expressed in accordance with s. NR 106.32 (5) unless the department determines on a case-by-case basis that an alternative averaging period is appropriate. The department shall consider all of the following when making a case-by-case determination:

NR 106.33(4)(a) (a) Frequency and duration of discharge.

NR 106.33(4)(b) (b) Total mass of discharge.

NR 106.33(4)(c) (c) Maximum flow rate of discharge.

NR 106.33(4)(d) (d) Whether ammonia is subject to a technology-based limitation or other limitation expressed by mass, concentration, or other appropriate measure in the permit.

NR 106.33 History History: CR 03-050: cr. Register February 2004 No. 578, eff. 3-1-04; CR 15-085: r. and recr. Register August 2016 No. 728, eff. 9-1-16; correction in (3) (a), (b), (d) made under s. 35.17, Stats., Register August 2016 No. 728.

NR 106.36 NR 106.36 Alternative whole effluent toxicity monitoring for certain discharges of ammonia.

NR 106.36(1) (1) In addition to water quality based effluent limitations for ammonia, the department may establish whole effluent toxicity testing requirements and limitations pursuant to ss. NR 106.08 and 106.09.

NR 106.36(2) (2) Chronic fathead minnow whole effluent toxicity test samples may be modified to remove ammonia prior to testing when all of the following conditions are met:

NR 106.36(2)(a) (a) The whole effluent toxicity test is being conducted during a period when ammonia effluent limitations based on early life stage absent criteria are in effect.

NR 106.36(2)(b) (b) The permittee has demonstrated compliance with applicable acute and chronic water quality based effluent limitations for ammonia during the testing period.

NR 106.36(2)(c) (c) Total ammonia measured in whole effluent toxicity test effluent samples is less than the applicable chronic water quality based effluent limitation contained in the WPDES permit, but greater than the “ammonia threshold number”, determined as follows:

NR 106.36(2)(c)1. 1. Measure the pH of the whole effluent toxicity test effluent sample after the sample has been warmed to the test temperature.

NR 106.36 Note Note: Effluent samples should not be aerated to remove supersaturation of dissolved oxygen prior to use in the whole effluent toxicity test. The measured pH value shall be rounded to the nearest one-tenth of a unit.

NR 106.36(2)(c)2. 2. Using the pH value of the sample as determined in subd. 1., determine the value of the ammonia multiplier in Table 1 for the pH range corresponding to the effluent pH.

NR 106.36(2)(c)3. 3. Divide 100 by the appropriate in-stream waste concentration, as a percentage, contained in the WPDES permit; then multiply the resulting value by the ammonia multiplier determined in subd. 2. to obtain the ammonia threshold number.

NR 106.36(3) (3) If all of the criteria in sub. (2) have been met, ammonia may be removed from the test sample.

NR 106.36 History History: CR 03-050: cr. Register February 2004 No. 578, eff. 3-1-04; CR 15-085: am. Table 1 (title), r. (4) Register August 2016 No. 728, eff. 9-1-16.

NR 106.37 NR 106.37 Schedules of compliance.

NR 106.37(1) (1) The department shall determine and specify a reasonable compliance schedule in the permit if the permittee is unable to meet the ammonia effluent limits determined according to this subchapter at the time of permit reissuance. The department shall establish the term of the compliance schedule on a case-by-case basis consistent with the requirements in s. NR 106.117. When establishing a compliance schedule, the department shall consider factors such as necessary planning, complexity of wastewater treatment issues, scope of construction, equipment delivery time, and construction seasons in establishing a schedule. In no circumstance may the date of compliance with the limits extend more than 5 years after the date of permit reissuance.

NR 106.37(2) (2) If the department modifies or reissues the permit to adjust ammonia limitations based on an approval of demonstrations made under either s. NR 106.32 (2) (b) 2. or (3) (a) 4. the department may adjust the compliance schedule if necessary and appropriate.

NR 106.37(4) (4) Any point source discharge which was not authorized by a WPDES permit prior to March 1, 2004 may not be provided with a schedule of compliance for achieving ammonia limits, but rather shall meet the limits upon initiation of discharge. A point source discharge previously authorized by a WPDES permit but relocated in the same receiving water body may be allowed a schedule of compliance.

NR 106.37 History History: CR 03-050: cr. Register February 2004 No. 578, eff. 3-1-04; CR 15-085: am. (1), r. and recr. (2), r. (3) Register August 2016 No. 728, eff. 9-1-16.

subch. V of ch. NR 106 Subchapter V — Effluent Limitations for Temperature

NR 106.50 NR 106.50 Purpose. The purpose of this subchapter is to specify how the department will calculate water quality-based effluent limitations for temperature under s. 283.13 (5), Stats., and to specify how the department will determine when the limitations will be included in Wisconsin pollution discharge elimination system (WPDES) permits. Water quality-based effluent limitations for temperature are necessary to assure attainment and maintenance of surface water quality standards for temperature established in accordance with s. 281.15 (1), Stats., and set forth in subch. II of ch. NR 102.

NR 106.50 History History: CR 07-111: cr. Register September 2010 No. 657, eff. 10-1-10.

NR 106.51 NR 106.51 Applicability. This subchapter applies to point sources that discharge cooling water, non-contact cooling water, or other wastewater to surface waters of the state if the discharge contains an associated heat load or is elevated in temperature relative to the ambient temperature of the receiving water. The procedures for calculation of effluent limitations identified in this subchapter do not apply to storm water discharges. Effluent limitations determined under this subchapter supersede any temperature limitations listed in s. NR 104.06 (2) (b).

NR 106.51 Note Note: Section 283.11 (2) (b), Stats., states that rules concerning storm water discharges may be no more stringent than the requirements under the federal water pollution control act and regulations adopted under that act. Storm water pollution prevention plans may address thermal issues on a case-by-case basis.

NR 106.51 Note Note: The department will use enforcement discretion whenever there are exceedances of effluent temperature limitations in a WPDES permit for an electric generating facility during an energy emergency warning or when an energy emergency event has been declared under a Federal Energy Regulatory Commission order (Standard EOP-002, North American Electric Reliability Corporation).

NR 106.51 History History: CR 07-111: cr. Register September 2010 No. 657, eff. 10-1-10.

NR 106.52 NR 106.52 Definitions. In this subchapter, the following definitions are applicable to terms used:

NR 106.52(1) (1) “Ambient temperature” means the typical existing temperature of a surface water outside the direct influence of any point source discharge, which may include daily and seasonal changes.

NR 106.52(2) (2) “cfs” means cubic feet per second, usually pertaining to stream or effluent flow.

NR 106.52(3) (3) “Cold shock” means exposure of aquatic organisms to a rapid decrease in temperature and a sustained exposure to low temperature that induces abnormal behavioral or physiological performance and may lead to death.

NR 106.52(4) (4) “Daily maximum effluent temperature” means the highest temperature measured in a calendar day.

NR 106.52(5) (5) “Daily maximum effluent temperature limitation” means the daily maximum effluent temperature limitation established in a permit.

NR 106.52(6) (6) “mgd” means million gallons per day, usually pertaining to stream or effluent flow.

NR 106.52(7) (7) “New facility” means any new point source facility or new point source discharge that commences operation after October 1, 2010.

NR 106.52(8) (8) “Seven-day rolling average effluent flow” means the arithmetic average of the effluent flow measured on a particular day and the 6 preceding days within that calendar month.

NR 106.52(9) (9) “Water quality standards” means applicable water quality standards set forth in chs. NR 102 to 104, or any federally promulgated water quality standards applicable to surface waters of the state.

NR 106.52(10) (10) “Weekly average effluent temperature” means the arithmetic mean of all daily maximum effluent temperature values recorded in a calendar week, Sunday through Saturday.

NR 106.52(11) (11) “Weekly average effluent temperature limitation” means the maximum allowable weekly average temperature determined as the arithmetic mean of all daily maximum effluent temperature values recorded in a calendar week, Sunday through Saturday.

NR 106.52(12) (12) “WPDES” or “WPDES permit” means Wisconsin pollutant discharge elimination system permit issued under ch. 283, Stats., but does not include storm water permits issued under s. 283.35, Stats.