Chapter NR 217

NR 217.13(2)(c)2.a. a. The maximum effluent flow, expressed as a 365 day rolling average of daily discharges that has occurred for 12 continuous months and represents normal operations.

NR 217.13(2)(c)2.b. b. The maximum effluent flow, expressed as a 30 day rolling average, which has occurred for 30 continuous days and represents normal operations.

NR 217.13(2)(c)3. 3. For seasonal discharges, discharges proportional to stream flow, or other non-continuous discharge situations, Qe shall be determined on a case by case basis.

NR 217.13(2)(d) (d) Upstream concentrations (Cs). The representative upstream concentration of phosphorus shall be used in specific water quality based effluent limit calculations. The representative upstream concentration shall be a concentration derived by the department based on data from the specific stream or from a similar location. Where data are collected on the upstream location, the site’s upstream concentration shall be calculated as a median using the procedures specified in s. NR 102.07 (1) (b) to (c). Neither the two-sided 80 percent confidence interval around the median specified in s. NR 102.07 (2) nor the combined assessment procedures specified in s. NR 102.60 are applicable for purposes in this paragraph. Upstream concentrations may not be measured at a location within the direct influence of a point source discharge. The determination of upstream concentrations shall be evaluated at each permit reissuance.

NR 217.13 Note Note: The department has guidance on collection methods for ambient water sampling and may develop guidance for the evaluation of representative data. The guidance may be obtained from the offices of the department of natural resources, bureau of water quality at 101 South Webster Street, P.O. Box 7921, Madison, Wisconsin 53707.

NR 217.13(3) (3) Discharges to inland lakes and reservoirs. For discharges of phosphorus directly to inland lakes, reservoirs, and other receiving waters which do not exhibit a unidirectional flow at the point of discharge, the department shall set the effluent limit equal to the criterion for the receiving water or the downstream water.

NR 217.13 Note Note: As described in s. NR 217.16, effluent limitations for discharges to lakes may also be based on the wasteload allocation of a total maximum daily load, where the total maximum daily load has been approved by US EPA.

NR 217.13(4) (4) Discharges directly to Great Lakes. For discharges directly to the Great Lakes, the department shall set effluent limits consistent with nearshore or whole lake model results approved by the department. The department may set an interim effluent limit based on the best readily available phosphorus removal technology commonly used in Wisconsin.

NR 217.13 Note Note: At the time this rule was promulgated, December 1, 2010, the best readily available phosphorus removal technology indicates a limit of 0.6 mg/L.

NR 217.13(5) (5) Other methods of limit calculation. The department may use other models and equations for calculating a water quality based effluent limitation if, in the best professional judgment of the department, the model provides a more accurate representation of the conditions.

NR 217.13(6) (6) Multiple discharges.

NR 217.13(6)(a) (a) Except as provided in par. (b), whenever the department determines that more than one discharge may be affecting the water quality of the same receiving water, 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 subsection, 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 subsection. Permittees shall be given the opportunity to comment to the department on any determination made under this subsection.

NR 217.13(6)(b) (b) This subsection does not apply if there is a US EPA approved TMDL for phosphorus for the receiving water. If there is a US EPA approved TMDL, the combined allowable load shall be divided in accordance with the approved TMDL.

NR 217.13(7) (7) Minimum effluent limitations. If the water quality based effluent limitation calculated pursuant to the procedures in this section is less than the phosphorus criterion specified in s. NR 102.06 for the water body, the effluent limit shall be set to be equal to the criterion.

NR 217.13(8) (8) New dischargers. If a new discharger is proposing a discharge of phosphorus to a receiving or downstream water that is a phosphorus impaired water, the new discharger may not discharge phosphorus except as follows:

NR 217.13(8)(a) (a) The new discharge of phosphorus is allocated part of the reserve capacity or part of the wasteload allocation in a US EPA approved TMDL;

NR 217.13(8)(b) (b) The new discharger can demonstrate the new discharge of phosphorus will improve water quality in the phosphorus impaired segment; or

NR 217.13(8)(c) (c) The new discharger can demonstrate that the new phosphorus load will be offset through a phosphorus trade or other means with another discharge of phosphorus to the 303 (d) listed water. The offset must be approved by the department and must be implemented prior to discharge.

NR 217.13 Note Note: Section 283.84, Stats., establishes requirements for pollutant trades.

NR 217.13 History History: CR 10-035: cr. Register November 2010 No. 659, eff. 12-1-10; CR 19-094: am. (2) (d) Register September 2022 No. 801, eff. 10-1-22; correction in (2) (d) made under s. 35.17, Stats., Register September 2022 No. 801.

NR 217.14 NR 217.14 Expression of limitations.

NR 217.14(1) (1) General.

NR 217.14(1)(a) (a) Water quality based effluent limitations, when required pursuant to s. NR 217.15, shall be expressed in a discharge permit as a concentration. A mass limit shall also be included in a permit for discharges of phosphorus to any of the following receiving or downstream waters:

NR 217.14(1)(a)1. 1. A lake or reservoir;

NR 217.14(1)(a)2. 2. An outstanding or exceptional resource water, as designated in ss. NR 102.10 and 102.11;

NR 217.14(1)(a)3. 3. A phosphorus impaired water; or

NR 217.14(1)(a)4. 4. A surface water that has an approved TMDL for phosphorus.

NR 217.14(1)(b) (b) The department may establish mass limitations in permits for any other discharges of phosphorus if a concentration limit for phosphorus is included in the permit, and where an increase in phosphorus load is likely to result in adverse effects on water quality in the receiving water or downstream water.

NR 217.14(1)(c) (c) For discharges to lakes, the department shall also include an annual mass limit for phosphorus in the permit.

NR 217.14(1)(d) (d) If there is a US EPA approved TMDL for the receiving water, the department shall include a mass limit expressed in the manner consistent with the requirements of the TMDL. As provided in s. NR 217.16, this TMDL based mass limit may be included in the permit in addition to, or in lieu of the mass limit established pursuant to this section.

NR 217.14 Note Note: In accordance with s. 283.84, Stats., the department may approve the use of phosphorus trading as a means for a point source to achieve compliance with the water quality based effluent limitation, including a TMDL based limitation. The trade shall be incorporated into the terms of the WPDES permit for the point source and must be approved by the department prior to implementation.

NR 217.14(2) (2) Concentration based limitations. Concentration effluent limitations calculated under s. NR 217.13 shall be expressed as a monthly average in permits, except for concentrations of less than or equal to 0.3 mg/L for which limitations may be expressed as six-month averages. If a concentration limitation expressed as a six-month average is included in a permit, a monthly average concentration limitation equal to three times the water based effluent limitation calculated under s. NR 217.13 shall also be included in the permit.

NR 217.14(3) (3) Mass based limitations. Concentration effluent limitations calculated under s. NR 217.13 shall be converted into mass effluent limitations using the effluent flow identified in s. NR 217.13 and an appropriate conversion factor, and expressed as a monthly average in the permit, except for concentration based limitations of less than or equal to 0.3 mg/L for which mass limitations may be expressed as six-month averages.

NR 217.14 History History: CR 10-035: cr. Register November 2010 No. 659, eff. 12-1-10; CR 15-085: am. (2), (3) Register August 2016 No. 728, eff. 9-1-16.

NR 217.15 NR 217.15 Determination of necessity for water quality based effluent limitations for phosphorus.

NR 217.15(1) (1) 

NR 217.15(1)(a) (a) General. The department shall include a water quality based effluent limitation for phosphorus in a permit whenever the discharge or discharges from a point source or point sources contain phosphorus at concentrations or loadings which will cause, has the reasonable potential to cause or contribute to, an exceedance of the water quality standards in s. NR 102.06 in either the receiving water or downstream waters. The department shall use the procedures in this section to make this determination.

NR 217.15(1)(b) (b) Permittees with existing phosphorus limitations. If a permittee has a technology based phosphorus limitation in a permit that is less restrictive than a water quality based effluent limitation for phosphorus calculated pursuant to s. NR 217.13, then the department shall include the water quality based effluent limitation in the permit.

NR 217.15(1)(c) (c) Permittees without existing phosphorus limitations. If a permittee discharges phosphorus, but does not have a technology based limitation for phosphorus in its permit, the department shall use the procedures in this paragraph to determine whether a discharge will cause, has the reasonable potential to cause or contribute to an exceedance of the phosphorus water quality criterion in s. NR 102.06 in the receiving or downstream waters, and whether to include a water quality based effluent limit for phosphorus in the WPDES permit.

NR 217.15(1)(c)1. 1. Using at least 11 daily discharge concentrations of phosphorus, if the upper 99th percentile of the 30 day average discharge concentration of phosphorus exceeds the potential phosphorus limitation calculated under s. NR 217.13, then the water quality based effluent limitation for phosphorus shall be included in the WPDES permit. If the upper 99th percentile of the 30 day average discharge concentration of phosphorus is less than the potential phosphorus limitation calculated under s. NR 217.13, then a water quality based effluent limitation for phosphorus is not required in the WPDES permit. The upper 99th percentile of available discharge concentrations shall be calculated pursuant to s. NR 106.05 (5).

NR 217.15(1)(c)2. 2. If 11 daily discharge concentrations of phosphorus are not available for a permittee, then a water quality based effluent limitation for phosphorus shall be included in the permit when the mean of available effluent concentrations is greater than one-fifth of the limit.

NR 217.15(1)(c)3. 3. If no phosphorus effluent data is available for an existing permittee, the department may require phosphorus sampling as part of a permit application for reissuance to determine whether a water quality based effluent limit is necessary in the WPDES permit under par. (a), or the department may use effluent data information from similar point sources to make the determination under par. (a).

NR 217.15 Note Note: The department will develop guidance regarding the administration of this section to ensure that permitted discharges with a reasonable potential to cause or contribute to exceedances of the applicable phosphorus water quality criterion in s. NR 102.06 are identified.

NR 217.15(1)(d) (d) Sampling. Prior to permit reissuance, a permittee discharging any phosphorus shall collect effluent samples of phosphorus at a frequency specified by the department in the permit application for reissuance.

NR 217.15(1)(e) (e) New dischargers. The department shall include a water quality based phosphorus limitation in a permit for a new discharger if the department determines the new discharger will discharge phosphorus at concentrations or loadings which may cause or contribute to exceedances of the water quality criteria in s. NR 102.06 in either the receiving water or downstream waters. To estimate the amount of phosphorus discharged by a new discharger, the department may consider projected discharge information from the permit applicant and phosphorus discharge information from similar sources.

NR 217.15(2) (2) If the department determines a water quality based effluent limitation is not necessary in a permit based on the procedures in this section, the department may still require monitoring for phosphorus discharges.

NR 217.15 History History: CR 10-035: cr. Register November 2010 No. 659, eff. 12-1-10; correction in (1) (c) 1. made under s. 13.92 (4) (b) 7., Stats., Register November 2010 No. 659.

NR 217.16 NR 217.16 Relationship of WQBELs and TMDL based limitations.

NR 217.16(1) (1) In addition to a water quality based effluent limitation calculated pursuant to s. NR 217.13, the department may derive a water quality based effluent limitation for phosphorus consistent with the wasteload allocation and assumptions of a US EPA approved TMDL that is designed to achieve water quality standards in ch. NR 102. This TMDL based limitation may be included in a permit in addition to, or in lieu of, the water quality based limitation calculated under s. NR 217.13. When deciding whether to use a TMDL based limit as a substitute for the limitation calculated under s. NR 217.13, the department shall consider the following factors:

NR 217.16(1)(a) (a) The degree to which nonpoint sources contribute phosphorus to the impaired water;

NR 217.16(1)(b) (b) Whether waters upstream of the impaired waters are meeting the phosphorus criteria; and

NR 217.16(1)(c) (c) Whether waters downstream of the impaired water are meeting the phosphorus criteria.

NR 217.16(2) (2) If the phosphorus limitation based on an approved TMDL is less stringent than the water quality based effluent limitation calculated in s. NR 217.13, the department may include the TMDL based limit in lieu of the limit calculated in s. NR 217.13 if the limit calculated under s. NR 217.13 has not yet taken effect. If the department includes the TMDL based limitation for phosphorus in the WPDES permit in lieu of the limit calculated in s. NR 217.13, the TMDL based limit may remain in the permit for up to two permit terms to allow time for implementation of the TMDL, or the implementation period specified in the TMDL, whichever is less. The department may include a schedule of compliance to achieve a TMDL based limit if the department determines a schedule of compliance is necessary. If after two permit terms, the department determines the nonpoint source load allocation has not been substantially reduced, the department may impose the more stringent water quality based effluent limitation calculated under s. NR 217.13, or may include the TMDL based limitation for an additional permit term if the department determines there will be significant nonpoint source load reductions within the upcoming permit term. If the department decides to remove a TMDL based phosphorus limit from a permit and instead include a more stringent water quality based phosphorus limit in the permit calculated under s. NR 217.13, the department may provide a schedule of compliance for the more stringent limit if the department determines additional time is needed for the permittee to comply with the revised limit. Such schedules shall require compliance as soon as possible, but in no case no more than five years from the date that the permit is reissued or modified to include the revised effluent limitations.

NR 217.16(3) (3) If a phosphorus water quality based limit calculated under s. NR 217.13 has already taken effect in a permit, the department may replace the limit with a less stringent TMDL based limit, if allowed pursuant to antidegradation procedures in ch. NR 207.

NR 217.16 Note Note: The TMDL based limitation may be less stringent than the water quality based effluent limitation calculated under s. NR 217.13 in cases where nonpoint sources are the significant phosphorus sources responsible for the impairment.

NR 217.16(4) (4) If the phosphorus limitation based on an approved TMDL is more stringent than the water quality based effluent limitation calculated under s. NR 217.13, the department shall include the more stringent TMDL based limitation in the WPDES permit.

NR 217.16 History History: CR 10-035: cr. Register November 2010 No. 659, eff. 12-1-10.

NR 217.17 NR 217.17 Schedules of compliance.

NR 217.17(1) (1) General.

NR 217.17(1)(a) (a) Except as provided in sub. (4), the department may provide a schedule of compliance for a water quality based phosphorus limitation in a WPDES permit, where based on available information the department finds that:

NR 217.17(1)(a)1. 1. The schedule of compliance will lead to compliance with the water quality based effluent limitation as soon as possible; and

NR 217.17(1)(a)2. 2. The schedule of compliance is appropriate and necessary because the permittee cannot immediately achieve compliance with the water quality based effluent limitation based on existing operation of its treatment system.

NR 217.17 Note Note: Before any compliance schedule is established in a permit pursuant to this subchapter, the department must make the finding in par. (a).

NR 217.17(1)(b) (b) In determining whether a compliance schedule is appropriate and determining the length of the compliance schedule, the department shall consider all of the following factors:

NR 217.17(1)(b)1. 1. Whether there is any need for modifications to the treatment facilities, operations or measures to meet the water quality based effluent limitation, and if so, how long it will take to implement the modifications. If the department determines that a permittee only needs to make operational changes to achieve compliance with a limitation, the compliance schedule shall be as brief as possible and only allow time for operational start-up adjustments.

NR 217.17(1)(b)2. 2. The amount of time the discharger has already had to meet the water quality based effluent limitation under prior permits.

NR 217.17(1)(b)3. 3. The extent to which the discharger has made good faith efforts to comply with the water quality based effluent limitation and other requirements in prior permits, if applicable.

NR 217.17(1)(b)4. 4. The extent to which the phosphorus removal process technologies have been developed and proven to be effective.

NR 217.17(1)(c) (c) In determining whether a compliance schedule is appropriate and determining the length of the compliance schedule, the department may also consider any of the following factors:

NR 217.17(1)(c)1. 1. Whether there is a need to acquire a substantial amount of property to accommodate the needed modifications; and

NR 217.17(1)(c)2. 2. Whether there is a need to develop an extensive financing plan and obtain financing for the proposed treatment plant upgrade.

NR 217.17 Note Note: A compliance schedule may be provided for a water quality based effluent limit for phosphorus calculated under s. NR 217.13 and a TMDL based limit for phosphorus.

NR 217.17(2) (2) Maximum compliance schedule period. Except for situations where filtration or a similar phosphorus removal process is required, any compliance schedule established by the department under sub. (1) may not exceed seven years from the date a permit was first modified or reissued to include a water quality based phosphorus limit calculated under s. NR 217.13. Where compliance with the water quality based phosphorus limit requires the construction of filtration or a similar phosphorus removal process, the department may grant a schedule of compliance not to exceed nine years from the date that the permit is first reissued or modified to include effluent limitations developed under provisions of this subchapter. In cases where a compliance schedule extends beyond five years, the department may revise the schedule at reissuance or pursuant to a permit modification.

NR 217.17(3) (3) requirements, limitations, dates, and reporting. When granting a schedule of compliance, the department shall include, as conditions of the permit, the following:

NR 217.17(3)(a) (a) Dates for achievement of interim requirements. The time between interim dates may not exceed one year.

NR 217.17(3)(b) (b) A sequence of actions or operations that may include, as appropriate, but are not limited to:

NR 217.17(3)(b)1. 1. Development and implementation of a phosphorus discharge optimization plan for the current operation.

NR 217.17(3)(b)2. 2. Preparation of preliminary and final designs for new or modified treatment technology.

NR 217.17(3)(b)3. 3. Initiation and completion of construction.

NR 217.17(3)(c) (c) Interim effluent limitations representing good management and operation for similar treatment processes based on performance of other wastewater treatment facilities that will lead to compliance with the final water quality based effluent limitation.

NR 217.17(3)(d) (d) A requirement that no later than 30 days following each interim date and the final date of compliance, the permittee shall notify the department in writing of its compliance or non-compliance with the interim or final requirements, including submittal of progress reports. If any interim requirement will take more than one year to complete, the permit shall also include a projected completion date for the interim requirement.

NR 217.17(3)(e) (e) The final water quality based effluent limit for phosphorus calculated pursuant to s. NR 217.13 shall be included in the permit even if the limit is not effective during the permit term. The department may revise the final limit at permit reissuance or pursuant to a permit modification.

NR 217.17(3)(f) (f) If the permittee chooses to engage in pollutant trading as a means to achieve compliance with interim limitation or final water quality based effluent limitations, then the terms and conditions related to the trade shall be incorporated into the permit.

NR 217.17(4) (4) New dischargers. Any new discharger may not receive a compliance schedule to achieve compliance with a phosphorus water quality based effluent limitation.

NR 217.17 History History: CR 10-035: cr. Register November 2010 No. 659, eff. 12-1-10.

NR 217.18 NR 217.18 Watershed adaptive management option.

NR 217.18(1) (1) General. The adaptive management option is a strategy to achieve the phosphorus water quality criteria in s. NR 102.06 in the most economically efficient manner, and as soon as possible, taking into consideration the contributions of phosphorus from point and nonpoint sources in a watershed.

NR 217.18(2) (2) Application. If requested by the permittee in the permit application for reissuance and if approved by the department, the permittee may implement a watershed adaptive management approach under this section as a means to achieve compliance with the phosphorus water quality standards in s. NR 102.06. The department may approve and authorize the adaptive management option in this section only if the permittee demonstrates and the department concurs that all of the following conditions are met:

NR 217.18(2)(a) (a) The exceedance of the applicable phosphorus criterion in s. NR 102.06 is caused by phosphorus contributions from both point sources and nonpoint sources.