Chapter NR 106

NR 106.52 History History: CR 07-111: cr. Register September 2010 No. 657, eff. 10-1-10.

NR 106.53 NR 106.53 Parameters used to establish water quality-based effluent limitations for temperature.

NR 106.53(1) (1) Receiving water flow rate (Qs). The value of receiving water flow rate (Qs) used to determine effluent limitations for discharges to flowing waters shall be as follows:

NR 106.53(1)(a) (a) Qs shall equal ¼ of the average minimum 7-day flow which occurs once in 10 years (¼ 7-day Q10) or, if sufficient information is available to calculate a biologically based receiving water design flow, ¼ of the flow which prevents an excursion from the applicable water quality criteria using a duration of 4 days and a frequency of less than once every 3 years (¼ 4-day, 3-year biological flow).

NR 106.53(1)(b) (b) Qs may be reduced from those values calculated in par. (a) wherever natural receiving water flow is significantly altered by flow regulation or other types of water diversion structures.

NR 106.53(1)(c) (c) The discharger shall be allowed to demonstrate, through appropriate and reasonable methods that an adequate passageway for movement of aquatic life 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 paragraph include water quality modeling or field dispersion studies.

NR 106.53(1)(d) (d) Based upon the results of a demonstration submitted under par. (c), Qs may be modified from that specified in par. (a) or (b). A modified Qs shall be determined on a case-by-case basis and shall be approved in writing by the department. Qs may not exceed the larger of the 7-day Q10 or the 4-day, 3-year biologically based design flow, except when a permit allows the use of real-time data for the determination of water quality based effluent limitations for temperature, as provided in s. NR 106.54 (4).

NR 106.53(1)(e) (e) The value of Qs may not exceed that of par. (a) if the department determines that the discharge has a potential to jeopardize the continued existence of any endangered or threatened species listed under ch. NR 27 or section 7 of the federal Endangered Species Act, 16 USC 1536.

NR 106.53(2) (2) Effluent flow rate (Qe). The value of effluent flow rate (Qe) used to determine effluent temperature limitations shall be as follows:

NR 106.53(2)(a) (a) Flow ratios. For purposes of determining a flow ratio pursuant to s. NR 106.55 (6) (a), Qe shall equal:

NR 106.53(2)(a)1. 1. For discharges subject to ch. NR 210 and which discharge for 24 hours per day on a year-round basis, Qe shall equal the maximum effluent flow, expressed as a daily average, that is anticipated to occur for 12 continuous months during the design life of the treatment facility unless it is demonstrated to the department that such a design flow rate is not representative of projected flows at the facility.

NR 106.53(2)(a)2. 2. For all other dischargers not subject to ch. NR 210, Qe shall equal the maximum effluent flow, expressed as a daily average, that has occurred for 12 continuous months and represents normal operations.

NR 106.53(2)(a)3. 3. For seasonal discharges, discharges proportional to stream flow, or other unusual discharge, Qe shall be determined on a case-by-case basis.

NR 106.53(2)(b) (b) Acute temperature limitation. For purposes of determining acute temperature limitations pursuant to s. NR 106.55 (6) (b), Qea shall be the highest daily maximum effluent flow rate, expressed as mgd, which has occurred for each calendar month of the year and represents normal operating conditions.

NR 106.53(2)(c) (c) Sub-lethal temperature limitation. For purposes of determining sub-lethal temperature limitations pursuant to s. NR 106.55 (6) (a), (Qesl) shall be the highest 7-day rolling average effluent flow rate within a calendar month, expressed as mgd, which has occurred for each calendar month of the year and represents normal operating conditions.

NR 106.53(2)(d) (d) Non-typical effluent flows. For purposes of determining effluent temperature limitations pursuant to s. NR 106.55 (6) (a) and (7), Qea and Qesl may be determined on a case-by-case basis for seasonal discharges, discharges proportional to stream flow, or other unusual discharge situations.

NR 106.53 History History: CR 07-111: cr. Register September 2010 No. 657, eff. 10-1-10.

NR 106.54 NR 106.54 Representative effluent temperature data.

NR 106.54(1) (1) The representative daily maximum effluent temperature is the highest effluent temperature known or expected to occur on any day under normal operating conditions at the time of permit issuance. Representative daily maximum effluent temperature shall be measured at a frequency of not less than once per week whenever a discharge occurs.

NR 106.54(2) (2) The representative weekly average effluent temperature is the highest weekly average effluent temperature known or expected to occur under normal operating conditions at the time of permit issuance.

NR 106.54(3) (3) The department may require a permittee to collect additional data if the department determines that the requirements of subs. (1) and (2) do not provide adequate data to document the operational variability of a discharge.

NR 106.54(4) (4) A permittee may request, at the time of application for a WPDES permit, calculation of effluent temperature limitations to be included in a permit based on real-time data. Any permittee that makes such a request shall provide effluent flow, effluent temperature, receiving water flow, and receiving water temperature at a frequency no less than one result per hour that is representative of normal operating conditions, including variability.

NR 106.54 History History: CR 07-111: cr. Register September 2010 No. 657, eff. 10-1-10.

NR 106.55 NR 106.55 Determination of water quality-based effluent limitations for temperature in WPDES permits.

NR 106.55(1) (1) General. The department shall determine water quality-based effluent limitations for temperature to attain and maintain water quality standards and criteria specified in or determined according to procedures in subch. II of ch. NR 102.

NR 106.55(2) (2) Limitations for waters designated as limited aquatic life. The daily maximum effluent temperature limitation shall be 86°F for discharges to surface waters classified as limited aquatic life according to s. NR 104.02 (3) (b) 1. and as defined in s. NR 104.02 (1), except for those classified as wastewater effluent channels and for wetlands regulated under ch. NR 103.

NR 106.55(3) (3) Limitations for waters designated as wastewater effluent channels. The daily maximum effluent temperature limitation shall be 120°F for discharges to surface waters classified as limited aquatic life wastewater effluent channels according to s. NR 104.02 (3) (b) 1. and as defined in s. NR 104.02 (1) (d).

NR 106.55(4) (4) Limitations for wetlands. Effluent temperature limitations shall be established for wetlands on a case-by-case basis to meet the water quality standards provided in ch. NR 103, but in no case shall the effluent temperature limitation be greater than 120°F.

NR 106.55(5) (5) Limitations for discharges to storm sewers.

NR 106.55(5)(a) (a) General. A permittee may request, at time of permit application, an effluent limitation greater than the effluent temperature limitations required under subs. (2) to (4), (6) or (7) if the discharge is to a storm sewer or other storm water conveyance channel. The permittee may request that the higher effluent limitation be greater than 120°F if the permittee is able to demonstrate to the satisfaction of the department that the heated effluent is not discharged in a manner that will cause a potential for scalding of humans. An effluent temperature limitation established under this subsection shall be determined according to the following equation:

Tss =   Tdir + (HLV x (L/100))

Where:

NR 106.55(5)(b) (b) Alternative heat loss value. An alternative heat loss value (HLV) may be used in the equation in par. (a). The alternative value shall be representative of seasonal influences on heat loss and be based on a comparison of effluent temperature at the location of discharge to the storm sewer or storm water conveyance channel and the point at which the storm sewer or storm water conveyance channel discharges to a surface water of the state.

NR 106.55(5)(c) (c) Site-specific information. The department may use available site-specific information to determine an alternative heat loss value or other data demonstrating the amount of heat loss in a storm sewer to establish an effluent temperature limitation for discharges to a storm sewer.

NR 106.55(6) (6) Limitations for receiving waters with unidirectional flow not designated as limited aquatic life. Except as provided in subs. (2) to (5), the department shall establish water quality-based effluent limitations to ensure that effluent is not discharged at elevated temperatures that may adversely affect humans or aquatic life at or near the point of discharge for discharges to surface waters with unidirectional flow.

NR 106.55(6)(a) (a) Flow ratio categories. Effluent temperature limitations shall be established based upon the designated use of the water and the ratio of streamflow to effluent flow as determined in Table 1. Effluent flow shall be equal to the value specified in s. NR 106.53 (2) (a).

Table 1 — Flow Ratio Categories

NR 106.55(6)(b) (b) Calculation of limitations. The methods described in this paragraph apply to the determination of both acute and sub-lethal effluent temperature limitations. Water quality-based effluent temperature limitations to meet the requirements of this subsection shall be determined using the following procedures:

WQBEL = [((WQC - Ta)(Qs + (1 - f)Qe)) / Qe] + Ta

Where:

NR 106.55(6)(c) (c) Limitations for mussel control. Short-term excursions from the effluent temperature limitation determined in this subsection may occur for the purposes of zebra or other mussel control if approved by the department and authorized in a permit on a case-by-case basis.

NR 106.55(6)(d) (d) More stringent limitations. The department shall establish more stringent effluent temperature limitations than those determined under the provisions of this subsection whenever it is demonstrated that the temperature of the discharge may cause or contribute to nonattainment of aquatic life uses and that more stringent limitations are necessary to assure the protection and propagation of a balanced indigenous population of shellfish, fish and wildlife in or on the body of water into which the discharge is made. Effluent temperature limitations under this paragraph shall be established whenever one or more of the mixing zone requirements in s. NR 102.05 (3), as they apply to temperature, are not maintained.

NR 106.55(7) (7) Limitations for inland lakes, impoundments and great lakes waters. The department shall establish water quality-based effluent limitations to ensure that the effluent is not discharged at elevated temperatures that may adversely affect humans or aquatic life at or near the point of discharge for discharges to surface waters that are inland lakes, impoundments, or Great Lakes waters that do not exhibit unidirectional flow.

NR 106.55(7)(a) (a) Limitations for mussel control. Short-term excursions from the effluent temperature limitation determined in this subsection may occur for the purposes of zebra or other mussel control if approved by the department and authorized in a permit on a case-by-case basis.

NR 106.55(7)(b) (b) Calculation of limitations. The methods described in this paragraph apply to the determination of both acute and sub-lethal effluent temperature limitations. Water quality-based effluent temperature limitations to meet the requirements of this subsection shall be determined using the following procedures:

WQBEL = [(WQC- Ta)/(e-a)] + Ta

Where:

a = [(A)(54.7 + B(150))] / [(8,345,000)(Qe)]

Where:

A =   Area of mixing zone in square feet, as follows:

B = A coefficient which is a function of Ta as follows:

Qe =   Effluent flow rate in mgd as specified in s. NR
  106.53 (2)

NR 106.55(8) (8) Limitations for discharges with fluctuating or variable effluent flow rates. A permittee may request flow-related effluent temperature limitations for discharge flows that fluctuate or vary on a frequent basis. Flow-related effluent temperature limitations shall be determined as follows:

NR 106.55(8)(a) (a) At the time of permit application, the permittee shall submit representative minimum and maximum effluent flow data for the interval of variability for which effluent flow-related limitations are requested.

NR 106.55 Note Note: For example, if the interval of variability is for a particular season or time of the year, then maximum and minimum effluent flow data submitted should be for that season.

NR 106.55(8)(b) (b) Effluent temperature limitations shall be determined following the procedures of subs. (6) or (7), as appropriate, using both the minimum and maximum effluent flow rates submitted in par. (a).

NR 106.55(8)(c) (c) Effluent temperature limitations determined in accordance with par. (b) shall be expressed in a permit as a function of effluent flow.

NR 106.55(8)(d) (d) Permits that contain flow-related effluent temperature limitations shall require daily monitoring of effluent temperature during times of discharge.

NR 106.55(9) (9) Limitations to protect downstream waters. The department may calculate more stringent effluent temperature limitations than those determined under this section whenever more stringent limitations are necessary to attain or maintain water quality standards in downstream or other nearby waters that may be affected by the heated discharge.

NR 106.55(10) (10) Limitations based on site-specific mixing zone analysis. The department may calculate effluent temperature limitations that differ from those determined under this section. A request by the permittee for a site specific mixing zone shall include all of the following:

NR 106.55(10)(a) (a) A mixing zone analysis that details the full extent and condition of the mixing zone.

NR 106.55(10)(b) (b) A demonstration that such effluent temperature limitations meet all mixing zone provisions of s. NR 102.05 (3).

NR 106.55(10)(c) (c) A demonstration that such effluent temperature limitations shall attain all aquatic life uses in the body of water into which the discharge is made.

NR 106.55(10)(d) (d) A demonstration that such effluent temperature limitations shall provide a level of protection equivalent to or better than that provided by the temperature water quality criteria in ch. NR 102.

NR 106.55(11) (11) Limitations based on installation of diffusers and other mechanical devices. The department may calculate effluent temperature limitations that differ from those determined under this section whenever the permittee installs diffusers or other mechanical devices used to ensure rapid mixing of effluent and significantly reduces or eliminates the size of the mixing zone. It shall be demonstrated that the resulting mixing zone meets all mixing zone provisions of s. NR 102.05 (3), and that the resulting mixing zone will attain all aquatic life uses in the body of water into which the discharge is made and provide a level of protection equivalent to or better than that provided by the temperature water quality criteria in ch. NR 102.

NR 106.55(12) (12) More stringent limitations. The department shall establish more stringent effluent temperature limitations than those determined under s. NR 106.55 (2) to (11) whenever the department determines that the discharge may cause or contribute to non-attainment of s. NR 102.04 (4) (e).

NR 106.55(13) (13) Limitations based on water quality models. The department may calculate water quality-based effluent limitations that differ from those specified in this section using water quality modeling submitted pursuant to s. NR 106.58.

NR 106.55 History History: CR 07-111: cr. Register September 2010 No. 657, eff. 10-1-10; CR 15-085: am. Table 1 (title) Register August 2016 No. 728, eff. 9-1-16.

NR 106.56 NR 106.56 Establishment of water quality-based effluent limitations for temperature in WPDES permits.

NR 106.56(1) (1) General. The department shall use the methods in this section to determine the need to establish water quality-based effluent temperature limitations in a permit.

NR 106.56(2) (2) Reasonable potential to exceed an acute effluent limitation. An acute water quality-based effluent limitation for temperature shall be established in a WPDES permit for each month in which the representative daily maximum effluent temperature for that month exceeds the acute water quality-based effluent limitation determined in s. NR 106.55. The representative daily maximum effluent temperature used in this subsection shall be the greater of the following:

NR 106.56(2)(a) (a) The highest recorded representative daily maximum effluent temperature as measured or determined according to s. NR 106.54 (1).

NR 106.56(2)(b) (b) The projected 99th percentile of all representative daily maximum effluent temperatures as measured or determined according to s. NR 106.54 (1).

NR 106.56(3) (3) Reasonable potential to exceed a sub-lethal effluent limitation. A sub-lethal water quality-based effluent limitation for temperature shall be established in a WPDES permit for each month in which the representative weekly average effluent temperature for that month exceeds the sub-lethal water quality-based effluent limitation calculated in s. NR 106.55. The representative weekly average effluent temperature used in this subsection shall be the greater of the following:

NR 106.56(3)(a) (a) The highest weekly average effluent temperature for the month as measured or determined according to s. NR 106.54 (2).

NR 106.56(3)(b) (b) The projected 99th percentile of all representative weekly average effluent temperatures for the month as measured or determined according to s. NR 106.54 (2).

NR 106.56(4) (4) Reasonable potential to exceed a limited aquatic life effluent limitation. A daily maximum effluent temperature limitation of 86°F shall be established in a WPDES permit for each month in which the representative daily maximum effluent temperature exceeds 86°F for discharges to limited aquatic life waters not classified as a wastewater effluent channel according to s. NR 104.02 (1), storm sewers or as a wetland regulated under ch. NR 103.

NR 106.56(5) (5) Reasonable potential to exceed a wastewater effluent channel effluent limitation. A daily maximum effluent temperature limitation of 120°F shall be established in a WPDES permit for each month in which the representative daily maximum effluent temperature exceeds 120°F for discharges to a wastewater effluent channel, as classified in s. NR 104.02 (1).

NR 106.56(6) (6) Reasonable potential to exceed a storm sewer effluent limitation. A daily maximum effluent temperature limitation greater than 120°F shall be established in a WPDES permit for a discharge to a storm sewer for each month in which the representative daily maximum effluent temperature exceeds the limitation determined according to the procedure in s. NR 106.55 (5).

NR 106.56(7) (7) Reasonable potential to exceed a wetland effluent limitation. A daily maximum or weekly average effluent temperature limitation shall be established in a WPDES permit for each month in which the representative daily maximum or weekly average effluent temperature, respectively, exceeds the limits for a discharge to a wetland determined according to the provisions in s. NR 106.55 (4).

NR 106.56(8) (8) Reasonable potential to exceed limitations for the protection of public health and welfare. A daily maximum effluent temperature limitation of 120°F shall be established in a WPDES permit for each month in which the representative daily maximum effluent temperature exceeds 120°F, unless the permittee demonstrates to the satisfaction of the department that the heated effluent is not discharged in a manner that will cause a potential for scalding of humans.

NR 106.56(9) (9) Limitations to protect downstream waters. Whenever the department determines that more stringent effluent temperature limitations than those established according to subs. (1) through (6) are necessary to attain or maintain water quality standards in downstream or other adjacent waters and the representative daily maximum or weekly average effluent temperatures exceed the limitations, then more stringent effluent temperature limitations shall be established in a WPDES permit.

NR 106.56(10) (10) Limitations to protect for cold shock. The department shall determine on a case-by-case basis if any additional conditions are necessary in a WPDES permit to protect against cold shock and in accordance with the standard specified in s. NR 102.28. Provisions under this subsection shall be in addition to the water quality-based effluent temperature limitations determined under this section.

NR 106.56(11) (11) Limitations to protect for rate of temperature change. The department shall determine on a case-by-case basis if any conditions are necessary in a WPDES permit to protect against detrimental health or reproductive effects to fish and aquatic life caused by excessive rates of temperature change.

NR 106.56(12) (12) Representative data unavailable. Whenever after October 1, 2010, the department issues or reissues a permit to a discharger for which representative effluent temperature data as described in s. NR 106.54 is not available, the following requirements shall be included in the issued or reissued permit:

NR 106.56(12)(a) (a) Monitoring to obtain representative effluent temperature as described in s. NR 106.54. Monitoring shall be required for a period of not less than one year. When effluent temperatures in any month are highly variable, monitoring for 2 years may be required. If the facility only operates during certain portions of the year, representative effluent temperature shall be measured during the period of operation.

NR 106.56(12)(b) (b) Water quality-based effluent temperature limitations determined under applicable methods described in s. NR 106.55 and as determined necessary under any applicable provision of this section. Compliance with the limitations shall be attained as soon as reasonably possible, but no later than the expiration date of the permit. The department may modify the permit at any time during the permit term and establish a compliance date to attain effluent temperature limitations sooner than the expiration date of the permit.

NR 106.56(12)(c) (c) If, after the data collection required under par. (a), it is determined that an effluent temperature limitation is not necessary under any applicable provision of this section, the water quality-based effluent temperature limitations in the permit may not be effective. A condition shall be included in the permit that invalidates any effluent temperature limitations and the compliance schedule in the permit. Continued monitoring of effluent temperature may be required.

NR 106.56(13) (13) Monitoring. The department shall establish on a case-by-case basis the monitoring and reporting frequency for temperature in a WPDES permit.