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).