Chapter NR 207
ANTIDEGRADATION AND ANTIBACKSLIDING
Subchapter I — Antidegradation
NR 207.011 Purpose and applicability. NR 207.031 Antidegradation procedures for individual WPDES permits. NR 207.041 General permit antidegradation review. Subchapter II — Antibacksliding
NR 207.10 Purpose and applicability. NR 207.12 Antibacksliding.
NR 207.001NR 207.001 Definitions. In this chapter: NR 207.001(2)(2) “Loading" means the concentration or amount of a parameter within a discharge multiplied by the flow of that discharge. NR 207.001 NoteNote: Under implementation procedures under s. NR 106.06 (4) (b) 3., a conversion factor is also applied to a loading calculation to align the units in the equation. Example: Loading (lbs/day) = parameter concentration (mg/L) x flow of discharge (million gallons/day) x an appropriate conversion factor (8.34 lbs of water per gallon). NR 207.001(3)(3) “Parameter” means a chemical, physical, or biological property that can be tested or monitored as a measure of water quality. NR 207.001 NoteNote: Water quality parameters that are frequently sampled or monitored include pollutants, temperature, dissolved oxygen, biochemical oxygen demand (BOD) and pH. Parameters also include biological metrics such as chlorophyll a (an algal indicator) or plant, fish or insect communities; however, these are typically not applied for purposes of antidegradation review.
NR 207.001(4)(4) “Receiving water" means the portion of a surface water affected by a proposed new or increased discharge. NR 207.001 NoteNote: Waters not attaining water quality standards are also referred to as “impaired waters” in subch. II of this chapter and elsewhere in natural resources administrative codes.
NR 207.001(8)(8) “U.S. EPA” means the United States environmental protection agency. NR 207.001(9)(9) “WPDES” or “WPDES permit” means Wisconsin pollutant discharge elimination system permit issued by the department under ch. 283, Stats. NR 207.001(10)(10) “WQBEL” or “water quality based effluent limitation” means an effluent limitation established by the department under s. 283.13 (5), Stats. NR 207.001 HistoryHistory: CR 23-010: cr. Register January 2026 No. 841, eff. 7-1-26; (8m) renumbered from (11) under s. 13.92 (4) (b) 1., Stats., Register January 2026 No. 841. NR 207.011(1)(1) Purpose. The purpose of this subchapter is to establish implementation procedures for the antidegradation policy under s. NR 102.045. This subchapter sets procedures applicable to proposed new or increased discharges to the surface waters of the state. NR 207.011(2)(a)(a) Except as provided in par. (b), this subchapter applies to any person proposing to increase an existing discharge or create a new discharge to the surface waters of the state at any of the following actions after July 1, 2026: NR 207.011(2)(a)1.1. Submittal of an application for individual WPDES permit issuance, reissuance, modification, or revocation and reissuance, if antidegradation review was not previously conducted under subds. 2. to 4. NR 207.011(2)(a)3.3. Submittal of new or amended municipal plans and specifications if antidegradation review was not previously conducted during the facility planning stage. NR 207.011(2)(b)(b) If the department has already reviewed and approved a new or increased discharge for any action under par. (a) within 5 years prior to July 1, 2026, additional antidegradation review is not required under this subchapter. NR 207.011(2)(c)(c) For a proposed increased discharge, an antidegradation review shall be conducted for the portion of the discharge that represents an increase from the existing, authorized discharge. NR 207.011(2)(d)(d) For general WPDES permits, the department shall apply antidegradation procedures under s. NR 207.041 when the department issues a notice of intent to issue, reissue, modify, or revoke and reissue the permit. NR 207.011(2)(f)(f) For all other new or increased discharges to high quality waters, including new concentrated animal feeding operations seeking an alternative discharge limitation under s. NR 243.13 (2) (b) or (3) (c), the procedures under ss. NR 207.031 to 207.041 shall be followed. NR 207.011(2)(g)(g) An antidegradation review under this subchapter is not required for temporary discharges or for water quality trades that result in an overall net reduction to the receiving water of the pollutant being traded. NR 207.011 NoteNote: A concentrated animal feeding operation (CAFO) permit containing production area discharge limitations under s. NR 243.13 (2) is only authorized to discharge from the production area on a temporary basis during very limited, precipitation-induced discharge events. Given that such discharges are temporary, sporadic, and rare, antidegradation procedures contained in this chapter cannot be implemented for these types of CAFO permits. Antidegradation does not apply to agricultural storm water discharges from a CAFO’s land spreading activities because those discharges are not point sources subject to the WPDES permit under s. 283.01 (12), Stats. NR 207.011 HistoryHistory: CR 23-010: cr. Register January 2026 No. 841, eff. 7-1-26. NR 207.021(3)(a)(a) “Increased discharge” means an actual or proposed change in concentration, level, or loading of a parameter that lowers water quality, is caused by or will be caused by a facility expansion, outfall relocation, process modification, connection of a pollutant source to an existing public or private wastewater treatment system, or other change, and which causes any of the following: NR 207.021(3)(a)1.1. Exceedance of an effluent limitation specified in a current WPDES permit. NR 207.021(3)(a)2.2. Exceedance of a mass limit or its equivalent mass load based on the concentration limit in the permit and the effluent flow rates as calculated under s. NR 106.06 (4) (d). For purposes of this subdivision, these flow calculations apply not only to toxics but to any parameter for which a mass calculation is appropriate. NR 207.021(3)(a)3.3. Initial imposition of an effluent limitation for a parameter that has not previously had a limit in an existing WPDES permit, except as specified under par. (b). NR 207.021(3)(b)(b) “Increased discharge” does not include any of the following instances if the applicant is not proposing to change the concentration, level, or loading of a parameter in the discharge such that it will lower water quality: NR 207.021(3)(b)1.1. The initial imposition of an effluent limitation for a parameter that is in an existing discharge but was not limited in a prior or the current permit if the initial imposition of the limitation is due only to one of the following:
/code/admin_code/nr/200/207
true
administrativecode
/code/admin_code/nr/200/207
Department of Natural Resources (NR)
Chs. NR 200-299; Environmental Protection – Wisconsin Pollutant Discharge Elimination System
administrativecode/ch. NR 207
administrativecode/ch. NR 207
section
true
