Section NR 106.32 - Calculation of water quality-based effluent limitations for ammonia(1) BASIS FOR LIMITATIONS.(a) The department shall establish water quality based effluent limitations for point source dischargers of ammonia whenever the limitations are necessary, as determined by any method in this section, to meet the applicable water quality standards and criteria in chs. NR 102 to 105.(b) Water quality based effluent limitations for ammonia shall be determined to attain and maintain water quality standards and criteria specified in or determined according to procedures in ch. NR 105, at the point of discharge. Effluent limitations shall be established to protect downstream waters whenever the department has information to make the determinations.(2) LIMITATIONS BASED ON ACUTE TOXICITY. (a) The department shall establish daily maximum water quality based effluent limitations to ensure that ammonia is not present in amounts that are acutely harmful to aquatic life in all surface waters, including those portions of the mixing zone normally habitable by aquatic life as required by s. NR 102.04(1).(b) To assure compliance with par. (a) and except as provided in pars. (c) and (e), water quality-based effluent limitations for ammonia shall equal the final acute value as determined in s. NR 105.05 for the respective fish and aquatic life subcategory for which the receiving water is classified. The water quality-based limitations based on acute toxicity shall be established using all of the following methods: 1. Effluent limitations for ammonia for discharges to water bodies classified as cold water communities shall be established using the ammonia criteria for the CW Category 1, shown in ch. NR 105, Table 2C, except as provided in subd. 2.2. If the permittee can demonstrate to the department through site specific information that the fish present in the receiving water are limited to those included in CW Category 2, CW Category 3, or CW Category 5, as described in ch. NR 105, Table 2C, then effluent limitations shall be established based on the criteria shown in ch. NR 105 Table 2C for the respective CW Category. If the department grants approval for an alternative limitation based on CW Category 2, 3, or 5, the department shall include the alternative limit in a modified or reissued permit provided antidegradation requirements in ch. NR 207 have been satisfied.3. In all cases, effluent limitations for ammonia for discharges directly to Lake Superior, Lake Michigan and Green Bay north of 44° 32' 30" north latitude shall be established using the ammonia criteria for the CW Category 1 shown in ch. NR 105, Table 2C.(c) Water quality based effluent limitations for ammonia may exceed the final acute value within a zone of initial dilution that meets all of the conditions in s. NR 106.06(3) (c).(d) Effluent limitations for ammonia shall be calculated using the pH value of the effluent as determined in sub. (4) (b) and this paragraph. The department may also establish effluent limitations or other requirements for pH according to the following procedure: 1. Whenever the department establishes an effluent limitation based on the acute ammonia criteria in ch. NR 105, the department may also establish a maximum effluent limitation for pH equal to the pH value that was used to calculate the ammonia effluent limitation.2. The department may allow a permittee to chemically adjust effluent pH to a lower value for the purpose of obtaining a higher ammonia effluent limitation. The adjusted pH shall be used to calculate the ammonia effluent limitation. The pH value of an effluent may not be adjusted to less than 6.0. Whenever the effluent pH is adjusted, the department may require continuous monitoring of the pH of the effluent.3. The department may establish an alternative pH for calculating the limitation under this section to protect downstream uses whenever the receiving water pH is significantly different from the effluent, or if a zone of initial dilution is applicable based on par. (c).(e) To assure compliance with par. (a), the department may calculate acute water quality-based effluent limitations using the following procedure if the department concludes that limitations calculated in par. (b) or (c) are not sufficiently protective of fish and aquatic life. The department may include the calculated WQBEL in a permit if this limitation is more stringent than the limitation calculated in par. (b) or (c): Limitation = (WQC) (Qs+(1-f)Qe) - (Qs- fQ e) (Cs) Qe
Where:
WQC = The acute ammonia toxicity criterion appropriate for the receiving water as specified in ch. NR 105 and par . (d).
Qs = Receiving water design flow (in units of volume per unit time) as defined in s. NR 106.06(3) (bm)
Qe = Effluent flow (in units of volume per unit time) as specified in s. NR 106.06(4) (d)
f = Fraction of the effluent flow that is with - drawn from the receiving water, and
Cs = Background concentration of the sub - stance (in units of mass per unit volume) as specified in s. NR 106.06(4) (e).
(3) LIMITATIONS BASED ON CHRONIC TOXICITY OR LONG-TERM IMPACTS.(a)Water quality criteria. The department shall calculate water quality based effluent limitations for ammonia to ensure that the chronic toxicity criteria applicable to the receiving water as specified in chs. NR 102 to 105 will be met after taking into account dilution with an appropriate quantity of receiving water flow allowed in this subsection. The available dilution shall be determined according to par. (c) unless the conditions specified in s. NR 102.05(3) require less dilution or no dilution be allowed. The chronic toxicity criteria to be used in the calculation of ammonia effluent limitations shall apply as follows: 1. The applicable early life stages present ammonia criteria in s. NR 105.05 Table 4B shall be used to calculate effluent limitations for all times of the year for all discharges to Class I and Class II trout waters, as identified by the department's Wisconsin Trout Streams publication referenced in s. NR 102.04(3) (a), and any additional Class I and Class II trout waters identified in ss. NR 102.10(1) (d) and (e), and 102.11(1) (b) and (c).2. The applicable early life stages present ammonia criteria in s. NR 105.05 Table 4B shall be used to calculate effluent limitations for all discharges to all waters supporting warm water sport fish and warm water forage fish during the month of April or whenever the receiving water temperature, as determined in s. NR 106.32(4), is greater than or equal to 14.6 degrees Celsius. Note: Effluent limitations are determined based on monthly average water temperatures determined from historical records. For many waters supporting warmwater fish species, the monthly average water temperature is 14.6 degrees Celsius or greater during the months of May through September.
3. Except as provided in subd. 4., the applicable early life stage absent ammonia criteria in s. NR 105.05 Table 4B shall be used to calculate effluent limitations for all discharges to all waters supporting warm water sport fish and warm water forage fish whenever the receiving water temperature, as determined in s. NR 106.32(4), is less than 14.6 degrees Celsius, but not including the month of April.4. The applicable early life stages present ammonia criteria in s. NR 105.05 Table 4B shall be used to calculate effluent limitations applicable for the months of January, February, and March for all discharges to waters where the department determines that early life stages of burbot are present. Note: Burbot are not present in limited aquatic life streams, limited forage fish streams and small or shallow headwater streams and rivers.
a. Whenever the department determines that early life stage present ammonia criteria are applicable under this subdivision, the permittee may make a demonstration that the early life stages of burbot are not present at the discharge location and will not be affected by the discharge during the months of January and February. If the department grants approval for an alternative limitation based on results of this study, the department shall include the alternative limitation in a permit modification or reissuance provided antidegradation requirements in ch. NR 207 have been satisfied.b. If the permittee can demonstrate to the satisfaction of the department that the early life stages of burbot are not present at the discharge location and will not be affected by the discharge, the early life stage absent ammonia criteria in s. NR 105.05 Table 4B shall be used to calculate effluent limitations that apply to the permittee and the department shall propose a permit modification to incorporate the limitations. If the permittee does not make a sufficient demonstration, the early life present ammonia criteria in s. NR 105 Table 4B shall apply.5. The applicable early life stages present ammonia criteria in s. NR 105.05 Table 4B shall be used to calculate effluent limitations for the months of May through September for all discharges to waters designated in ch. NR 104 as limited forage fish waters. The early life stages absent ammonia criteria in s. NR 105.05 Table 4B shall be used to calculate effluent limitations for the months of October through April for all discharges to waters designated in ch. NR 104 as limited forage fish waters.6. The applicable ammonia criteria in s. NR 105.05 Table 4B shall be used to calculate effluent limitations for all discharges to waters designated in ch. NR 104 as limited aquatic life waters.(b)Calculation of limits. Water quality based effluent limitations to meet the requirements of this subsection shall be calculated using the procedure specified in subd. 1. or 2., except as provided in s. NR 106.06(6). 1. For discharges of ammonia to flowing receiving waters, the water quality based effluent limitation shall be calculated using the following conservation of mass equation whenever the background concentration is less than the water quality criterion: Limitation = (CTC) (Qs + (1-f)Qe) - (Qs - fQe) (Cs)/Qe
Where:
Limitation = Water quality based effluent limitation (in units of mass per unit of volume)
CTC = The chronic toxicity criterion (concentration in units of mass per unit volume) as referenced in par. (a)
Qs = Receiving water design flow (in units of volume per unit time) as specified in par. (c)
Qe = Effluent flow (in units of volume per unit time) as specified in par. (d)
f = Fraction of the effluent flow that is withdrawn from the receiving water
Cs = Background concentration of ammonia (in units of mass per unit volume) as specified in par.(e)
Note: In applying this equation, all units for the flow and concentration parameters respectively shall be consistent.
2. For discharges of ammonia to receiving waters which do not exhibit a unidirectional flow at the point of discharge, such as lakes or impoundments, the department may calculate, in the absence of specific data, water quality based effluent limitations using the following equation whenever the background concentration is less than the water quality criterion: Limitation = 11 (CTC) - 10Cs
Where:
Limitation = Water quality based effluent limitation (in units of mass per unit of volume)
CTC = The chronic toxicity criterion (concentration in units of mass per unit volume) as referenced in par. (a)
Cs = Background concentration of ammonia (in units of mass per unit volume) as specified in par. (e)
3. On a case-by-case basis other dilutional factors may be used, but in no case may the dilution allowed exceed an area greater than the area where discharge induced mixing occurs. The discharge is also subject to the conditions specified in s. NR 102.05(3). The permittee may be required to determine the size of the mixing zone using models or dye studies that are determined to be acceptable by the department.(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. 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 Q 10) 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 Q 5) or 85% of the average minimum 7-day flow which occurs once in 2 years (7-day Q 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.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: a. 0.25 when the receiving water temperature is less than 11 degrees Celsius.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.c. 1.00 when the receiving water temperature is greater than 16 degrees Celsius.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.5. The department may adjust Qs from the values in subd. 1. where natural receiving water flow is significantly altered by flow regulation. (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).(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).(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: (a)Receiving water.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: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.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.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.(b)Effluent.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). 2. If information on the effluent pH is not available, then values representative of similar effluents may be used.(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. Note: It is suggested that the permittee submit a plan of study to the department prior to undertaking a demonstration under this paragraph.
(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.(5) APPLICATION OF WATER QUALITY BASED AMMONIA LIMITATIONS IN PERMITS AND MONITORING. (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.(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).(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.(d)Monitoring frequency. The department shall determine on a case-by-case basis the monitoring frequency for ammonia to be required in a permit.Wis. Admin. Code Department of Natural Resources NR 106.32
CR 03-050: cr. Register February 2004 No. 578, eff. 3-1-04.Amended by, CR 15-085: am. (2) (b) (intro.), 2., cr. (2) (e), am. (3) (a) 4. a. Register August 2016 No. 728, eff. 9/1/2016