Chapter NR 102

NR 102.25   Ambient temperatures and water quality criteria for the protection of fish and other aquatic life.

NR 102.26   Site-specific ambient temperatures.

NR 102.27   Site-specific water quality criteria.

NR 102.28   Cold shock standard.

NR 102.29   Rate of temperature change standard.

NR 102.30   Variances to water quality standards for temperature.

Subchapter III — Waterbody Assessments and Reporting

NR 102.50   Waterbody assessments and reporting.

NR 102.51   Assessment types.

NR 102.52   Assessment protocols.

NR 102.53   Reporting, public participation, and approvals.

NR 102.54   Biological assessment of designated uses.

NR 102.55   Narrative biological assessment thresholds for aquatic life uses.

NR 102.56   Numeric biological assessment thresholds for lakes, reservoirs and impounded flowing waters.

NR 102.60   Combined assessment procedure for phosphorus.

Ch. NR 102 Note Note: Chapter NR 102 as it existed on September 30, 1973 was repealed and a new chapter NR 102 was created, effective October 1, 1973. Corrections made under s. 13.93 (2m) (b) 7., Stats., Register, August, 1997, No. 500.

subch. I of ch. NR 102 Subchapter I — General

NR 102.01 NR 102.01 Purpose.

NR 102.01(1) (1) The purpose of this chapter is to establish, in conjunction with chs. NR 103 to 105, water quality standards for surface waters of the state pursuant to s. 281.15, Stats. This chapter describes the designated use categories for such waters and the water quality criteria necessary to support these uses. This chapter, chs. NR 103 to 105, and ch. NR 119 constitute the water quality standards for the surface waters of Wisconsin.

NR 102.01(2) (2) The long-range goal of Wisconsin water quality standards is to protect the use of water resources for all lawful purposes. Water quality standards shall protect the public interest, which includes the protection of public health and welfare and the present and prospective uses of all waters of the state for public and private water supplies, propagation of fish and other aquatic life and wild and domestic animals, domestic and recreational purposes, and agricultural, commercial, industrial, and other legitimate uses. In all cases where the potential uses are in conflict, water quality standards shall protect the general public interest.

NR 102.01(3) (3) Water quality standards serve as a basis for developing and implementing control strategies to achieve legislative policies and goals. Water quality standards are the basis for deriving water quality based effluent limitations and the limitations shall be determined to attain and maintain uses and criteria, unless more stringent effluent limitations are established to protect downstream waters. Water quality standards also serve as a basis for decisions in other regulatory, permitting or funding activities that impact water quality.

NR 102.01 History History: Cr. Register, February, 1989, No. 398, eff. 3-1-89; CR 07-111: am. (1), (2) and (3) Register September 2010 No. 657, eff. 10-1-10; CR 19-093: am. (1) Register September 2022 No. 801, eff. 10-1-22.

NR 102.02 NR 102.02 Applicability. The provisions of this chapter are applicable to surface waters of Wisconsin.

NR 102.02 History History: Cr. Register, February, 1989, No. 398, eff. 3-1-89.

NR 102.03 NR 102.03 Definitions. In this chapter, the following definitions apply:

NR 102.03(1) (1) “Ambient temperature” means the typical existing temperature of a surface water outside the direct influence of any point source discharge, which may include daily and seasonal changes.

NR 102.03(1c) (1c) “Benthic” means relating to the ecological zone at the bottom of a body of water, including the sediment surface and subsurface layers.

NR 102.03(1e) (1e) “Biological assessment threshold” means a numeric value or condition description used to measure the quality of a waterbody’s biological community and to determine attainment of its designated uses.

NR 102.03(1g) (1g) “Chlorophyll a” means a green pigment present in all green plants and in cyanobacteria, responsible for the absorption of light to provide energy for photosynthesis.

NR 102.03(1i) (1i) “Clean Water Act” means the federal Clean Water Act of 1972 and amendments.

NR 102.03(1k) (1k) “Confidence interval” means a range within which the true value of a parameter is likely to occur, with a specified level of confidence.

NR 102.03(1m) (1m) “Diatom” means a common and diverse group of unicellular algae of the phylum Chrysophyta, having cell walls containing silica.

NR 102.03(1o) (1o) “Drainage lake” means a lake with an outlet stream that continually flows under average summer conditions based on the past 30 years.

NR 102.03(1q) (1q) “Impounded flowing water” means a waterbody impounded by a constructed outlet structure on a river or stream that is not a reservoir as defined in sub. (4s).

NR 102.03(1v) (1v) “Macrophyte” means an aquatic plant large enough to be seen without the use of a microscope.

NR 102.03(2) (2) “Mixing zone” means a region in which a discharge of different characteristics than the receiving water is in transit and progressively diluted from the source to the receiving system.

NR 102.03(3) (3) “Natural conditions” means the normal daily and seasonal variations in climatic and atmospheric conditions, and the existing physical and chemical characteristics of a water or the course in which it flows.

NR 102.03(4) (4) “Natural temperature” means the normal existing temperature of a surface water including daily and seasonal changes outside the zone of influence of any artificial inputs.

NR 102.03(4e) (4e) “PFOA” means perfluorooctanoic acid in its anionic, cationic, and acidic forms as well as any salts of perfluorooctanoic acid.

NR 102.03(4m) (4m) “PFOS” means perfluorooctane sulfonate, including its anionic, cationic, and acidic forms as well as any salts of perfluorooctane sulfonate.

NR 102.03(4s) (4s) “Reservoir” means a waterbody with a constructed outlet structure intended to impound water and raise the depth of the water by more than two times relative to the conditions prior to construction of the dam, and that has a mean water residence time of 14 days or more under summer mean flow conditions using information collected over or derived for a 30 year period.

NR 102.03(5) (5) “Resource management” means the application of control techniques to enhance or preserve a surface water in accordance with statutory provisions and in the general public interest.

NR 102.03(6) (6) “Section 303 (d) list” means a list of waters that do not attain water quality standards and require a total maximum daily load analysis, as specified under section 303 (d) of the Clean Water Act, 33 USC 1313 (d).

NR 102.03(6e) (6e) “Seepage lake” means a lake that does not have an outlet stream that continually flows under average summer conditions based on the past 30 years.

NR 102.03(6m) (6m) “Stratified lake or reservoir” means a lake or reservoir where sufficient field data demonstrate that the lake is dimictic or, in absence of sufficient field data, the following equation results in a value of greater than 3.8:

Maximum Depth (meters) - 0.1

Log10Lake Area (hectares)

NR 102.03(6s) (6s) “Stratified two-story fishery lake” or “two-story fishery lake” means a lake greater than 5 acres in size that is typically stratified in the summer, with the potential for an oxygenated hypolimnion, that has documentation at any time since 1975 of a population of cold water fish species such as cisco, whitefish, or trout that is sustained through natural reproduction or long-term active stocking with year-to-year survival.

NR 102.03 Note Note: A list of two-story fishery lakes that contain naturally reproducing lake trout, whitefish, or cisco, or are stocked and managed by the department for brook, brown, rainbow, or lake trout, is available on the department’s designated uses website at https://dnr.wi.gov/topic/SurfaceWater/usedesignations.html.

NR 102.03(7) (7) “Surface waters” means all natural and artificial named and unnamed lakes and all naturally flowing streams within the boundaries of the state, but not including cooling lakes, farm ponds and facilities constructed for the treatment of wastewaters (the term waters as used in this chapter means surface waters).

NR 102.03(7m) (7m) “Total phosphorus” means all of the phosphorus in a water sample analyzed using the methods identified under the provisions of s. NR 219.04 (1).

NR 102.03(8) (8) “Unauthorized concentrations of substances” means pollutants or other chemicals introduced into surface waters without prior permit or knowledge of the department, but not including accidental or unintentional spills.

NR 102.03(9) (9) “U.S. EPA” means the United States environmental protection agency.

NR 102.03 History History: Cr. Register, September, 1973, No. 213, eff. 10-1-73; r. (1), renum. from NR 102.01, Register, February, 1989, No. 398, eff. 3-1-89; cr. (10), Register, May, 1993, No. 449, eff. 6-1-93; CR 07-111: cr. (intro.) and (1), r. (8) to (10), renum. (1) to (7) to be (2) to (8) Register September 2010 No. 657, eff. 10-1-10; CR 19-014: renum. (6) to NR 210.03 (10m), cr. (9) Register April 2020 No. 772, eff. 5-1-20; CR 21-083: cr. (4e), (4m) Register July 2022 No. 799, eff. 8-1-22; CR 19-094: am. (intro), cr. (1c) to (1m), renum. (1o) from NR 102.06 (2) (a), cr. (1q), (1v), renum. (4s) from NR 102.06 (2) (f), cr. (6), renum. (6e), (6m), (6s), (7m) from NR 102.06 (2) (fm), (g), (i), (j) and am. (6m), (6s) Register September 2022 No. 801, eff. 10-1-22; correction in (1q) made under s. 13.92 (4) (b) 7., Stats., Register September 2022 No. 801.

NR 102.04 NR 102.04 Categories of surface water uses and criteria.

NR 102.04(1) (1) General. To preserve and enhance the quality of waters, surface water uses and criteria are established to govern water management decisions. Practices attributable to municipal, industrial, commercial, domestic, agricultural, land development or other activities shall be controlled so that all surface waters including the mixing zone meet the following conditions at all times and under all flow and water level conditions:

NR 102.04(1)(a) (a) Substances that will cause objectionable deposits on the shore or in the bed of a body of water, shall not be present in such amounts as to interfere with public rights in waters of the state.

NR 102.04(1)(b) (b) Floating or submerged debris, oil, scum or other material shall not be present in such amounts as to interfere with public rights in waters of the state.

NR 102.04(1)(c) (c) Materials producing color, odor, taste or unsightliness shall not be present in such amounts as to interfere with public rights in waters of the state.

NR 102.04(1)(d) (d) Substances in concentrations or combinations which are toxic or harmful to humans shall not be present in amounts found to be of public health significance, nor shall substances be present in amounts which are acutely harmful to animal, plant or aquatic life.

NR 102.04 Note Note: For levels of public health significance for PFOA and PFOS, see s. NR 102.04 (8) (d) 1.

NR 102.04(2) (2) Revised uses and criteria. The following uses and criteria may be revised as new information or advancing technology indicate that revisions are in the public interest. Water used for hydropower and commercial shipping depends mainly on quantity, depth and elevation; consequently, no specific quality criteria for these uses have been prepared.

NR 102.04(3) (3) Fish and other aquatic life uses. All surface waters shall belong in one of the fish and other aquatic life subcategories described in this subsection. Only those use subcategories identified in pars. (a) to (c) shall be considered suitable for the protection and propagation of a balanced fish and other aquatic life community as provided in the federal water pollution control act amendments of 1972, P.L. 92-500; 33 USC 1251 et seq.

NR 102.04(3)(a) (a) Cold water communities. This subcategory includes surface waters capable of supporting a community of cold water fish and other aquatic life, or serving as a spawning area for cold water fish species. This subcategory includes, but is not restricted to, surface waters identified as trout water by the department of natural resources (Wisconsin Trout Streams, publication 6-3600 (80)).

NR 102.04(3)(b) (b) Warm water sport fish communities. This subcategory includes surface waters capable of supporting a community of warm water sport fish or serving as a spawning area for warm water sport fish.

NR 102.04(3)(c) (c) Warm water forage fish communities. This subcategory includes surface waters capable of supporting an abundant diverse community of forage fish and other aquatic life.

NR 102.04(3)(d) (d) Limited forage fish communities. (Intermediate surface waters). This subcategory includes surface waters of limited capacity and naturally poor water quality or habitat. These surface waters are capable of supporting only a limited community of forage fish and other aquatic life.

NR 102.04(3)(e) (e) Limited aquatic life. (Marginal surface waters). This subcategory includes surface waters of severely limited capacity and naturally poor water quality or habitat. These surface waters are capable of supporting only a limited community of aquatic life.

NR 102.04(4) (4) Criteria for fish and aquatic life. Except for natural conditions, all waters classified for fish and aquatic life shall meet the following criteria:

NR 102.04(4)(a) (a) Dissolved oxygen.

NR 102.04(4)(a)1. 1. For streams, rivers, and impounded flowing waters, dissolved oxygen criteria apply to samples taken from the main channel near the area with greatest flow. For lakes or reservoirs, the dissolved oxygen criteria in this paragraph apply to the epilimnion of stratified lakes and to all but the deepest one meter of the water column of unstratified lakes.

NR 102.04(4)(a)2. 2. Except as provided in subds. 3. to 7. and par. (am), surface waters shall attain a minimum dissolved oxygen concentration of 5 mg/L at all times.

NR 102.04(4)(a)3. 3. A waterbody classified by the department as a trout class I or II water under s. NR 1.02 (7), a cold water community that is not a two-story fishery lake covered under par. (am), or a great lakes tributary used by salmonids for spawning during the period of habitation, shall attain all of the following:

NR 102.04(4)(a)3.a. a. A minimum dissolved oxygen concentration of 6.0 mg/L at all times.

NR 102.04(4)(a)3.b. b. A minimum dissolved oxygen concentration of 7.0 mg/L when cold water fish are spawning through fry emergence from their redds, or gravel nests.

NR 102.04 Note Note: The period from spawning through fry emergence from their gravel nests is approximately mid-October through April, but varies depending on water temperature and location in the state.

NR 102.04(4)(a)3.c. c. Dissolved oxygen concentrations and diurnal patterns may not be altered from natural background levels to such an extent that cold water populations are adversely affected.

NR 102.04(4)(a)4. 4. A waterbody classified by the department as trout class III under s. NR 1.02 (7) shall attain a minimum dissolved oxygen concentration of 6.0 mg/L at all times.

NR 102.04(4)(a)5. 5. A waterbody for which a use attainability analysis under 40 CFR 131.10 (g) (1) to (6) demonstrates that its otherwise applicable designated use category is unattainable shall attain the following:

NR 102.04(4)(a)5.a. a. For a coldwater community with an approved use attainability analysis that redesignates it as warmwater, a minimum dissolved oxygen concentration of 5 mg/L at all times.

NR 102.04(4)(a)5.b. b. For any other community except those under subd. 7., a minimum dissolved oxygen concentration of 3 mg/L at all times to protect aquatic life.

NR 102.04 Note Note: Waterbodies described in subd. 5. are also known as altered waters.

NR 102.04(4)(a)6. 6. A waterbody designated by the department as limited forage fish shall attain a minimum dissolved oxygen concentration of 3 mg/L at all times.

NR 102.04(4)(a)7. 7. A waterbody designated by the department as limited aquatic life or wetlands, or classified as diffuse surface waters or wastewater effluent channels shall attain a minimum dissolved oxygen concentration of 1 mg/L at all times when water is present.

NR 102.04(4)(am) (am) Oxythermal layer thickness for two-story fishery lakes.

NR 102.04(4)(am)1. 1. ‘Criteria.’ A two-story fishery lake shall maintain, during its period of summer stratification, an oxythermal layer of at least 1 meter in thickness that maintains both a dissolved oxygen concentration of at least 6 mg/L and a maximum temperature of the following:

NR 102.04(4)(am)1.a. a. For a two-story fishery lake with lake trout, 57°F or less.

NR 102.04(4)(am)1.b. b. For a two-story fishery lake with whitefish but not lake trout, 66°F or less.