b. If at any time during a lake’s summer stratification the applicable criterion in subd. 1. is not met, that year is an exceedance year. At least 2 years of data are needed to make an attainment determination. If any 2 or more years within the most recent 5-year period are exceedance years, the lake is not attaining the water quality criterion. If insufficient data are available from the most recent 5-year period, data from up to 10 years may be used if representative of current conditions.
Section 5 NR 102.04 (4) (b) is repealed.
Section 6 NR 102.04 (4) (d) is amended to read:
NR 102.04 (4) (d) OtherToxic substances. Unauthorized concentrations of substances are not permitted that alone or in combination with other materials present are toxic to fish or other aquatic life. Surface waters shall meet the acute and chronic criteria as set forth in or developed pursuant to ss. NR 105.05 and 105.06. Surface waters shall meet the criteria which correspond to the appropriate fish and aquatic life subcategory for the surface water, except as provided in s. NR 104.02 (3). Section 7 NR 102.04 (4) (f) is created to read:
NR 102.04 (4) (f) Other criteria. Surface waters shall meet all other criteria that correspond to the appropriate aquatic life subcategory for the surface water, including narrative criteria specified in sub. (1).
Section 8 NR 102.04 (5) (b) is amended to read:
NR 102.04 (5) (b) Exceptions. Whenever the department determines, in accordance with the procedures specified in s. NR 210.06 (3), that wastewater disinfection is not required to protect recreational uses, the criteria specified in par. (a)sub. (6) (a) and in chs. NR 103 and 104 do not apply. Section 9. NR 102.06 (1) and (2) (intro.) are amended to read:
NR 102.06 (1) General. This section identifies the water quality criteria for total phosphorus that shall be met in surface waters. Assessment procedures for waterbodies are specified in ss. NR 102.07 and 102.60. (2) Definitions. In this section, the following definitions apply:
Section 10. NR 102.06 (2) (a), (f), (fm), and (j) are renumbered 102.03 (1o), (4s), as affected by CR 21-083, (6e), and (7m). [Note to LRB: A separate rule package, CR 21-083, creates a definition for s. NR 102.03 (4e) and (4m), which affects the numbering of definition (4s) renumbered under this Section.] Section 11. NR 102.06 (2) (g) and (2) (i) are renumbered 102.03 (6m) and (6s) and amended to read:
NR 102.03 (6m) “Stratified lake or reservoir” means a lake or reservoir where either of sufficient field data demonstrate that the lake is dimictic or, in absence of sufficient field data, the following equationsequation results in a value of greater than 3.8:
Maximum Depth (meters) — 0.1
Log10Lake Area (hectares)
Maximum Depth (feet)* 0.305 — 0.1
Log10Lake Area (acres) * 0.405
(6s) “Stratified two-story fishery lake” means a stratified lake which has supported a cold water fishery in its lower depths within the last 50 yearsor “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.
Section 12. NR 102.03 (6s) (Note) is created to read:
NR 102.03 (6s) 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. Section 13. NR 102.06 (3) (title) is repealed and recreated to read:
NR 102.06 (3) (title) Rivers, streams, and impounded flowing waters.
Section 14. NR 102.06 (4) (c) is renumbered 102.06 (3) (c) and amended to read:
NR 102.06 (3) (c) Waters impounded on rivers or streams that don’t meet the definition of reservoir in this sectionAn impounded flowing water shall meet the river andor stream criterion in sub. (3)par. (a) or (b) that applies to the primary stream or river entering the impounded water.
Section 15. NR 102.06 (7) (Note 2) is repealed.
Section 16. NR 102.07 is created to read:
NR 102.07 Assessing phosphorus concentration. (1) Data requirements. (a) Lakes and reservoirs. The total phosphorus criteria specified in s. NR 102.06 (4) apply to samples taken near a lake or reservoir’s deepest point, within 2 meters of the surface. For assessment purposes samples shall, whenever possible, be taken at least once per month for 3 months during the sampling period of June 1 to September 15. The department shall calculate a lake or reservoir’s arithmetic mean total phosphorus concentration using at least 2 years of data from the sampling period. Note: Reservoirs, multi-lobed lakes, or very large lakes may need more than one sampling station to assess the lake.
(b) Flowing waters. The total phosphorus criteria specified in s. NR 102.06 (3) apply to samples taken from the main channel near the area with greatest flow. For assessment purposes samples shall, whenever possible, be taken at least once per month for 6 months during the sampling period of May 1 to October 31. The department shall calculate the median total phosphorus concentration for a stream, river, or impounded flowing water using at least one year of data from the sampling period. (c) Assessment timeframe for lakes, reservoirs and flowing waters. 1. In this paragraph, “weather-controlled total phosphorus concentration” means a waterbody’s mean or median total phosphorus concentration during the applicable assessment period, estimated from measured data while controlling for weather variability using a method such as the department’s Phosphorus Mixed Effects Regression calculation method.
2. All representative data from the most recent 5 years shall be used for assessments, but data from the most recent 10 years may be used if representative of current conditions. If fewer than the recommended number of samples in par. (a) or (b) are available, the department may be able to make an assessment determination on a case-by-case basis. The department may calculate a site’s weather-controlled total phosphorus concentration to correct for weather variability and use this value to make an assessment determination in place of the mean or median calculated under par. (a) or (b).
Note: A mean total phosphorus concentration is used for lakes or reservoirs; a median concentration is used for streams, rivers, or impounded flowing waters. Total phosphorus data may be submitted and weather-controlled concentrations can be obtained by contacting the department at DNRSWIMS@wisconsin.gov for access to the department’s SWIMS database. The statistical computer programming script to run the Phosphorus Mixed Effects Regression calculation can be obtained through the department’s Water Evaluation Section by contacting the department’s call center at 1-888-WDNRINFo (1-888-936-7463) or using options provided on its website at https://dnr.wi.gov/contact/. Note: The procedures in pars. (b) to (c) are also used for determining upstream concentrations of phosphorus under s. NR 217.13 (2) (d) for purposes of calculating a water-quality based effluent limit for a Wisconsin pollutant discharge elimination system (WPDES) permit. (2) Exceedance determination. The department shall compare the mean or median calculated under sub. (1) to the waterbody’s applicable total phosphorus criterion specified in s. NR 102.06 to determine whether the waterbody is exceeding the criterion. To determine whether additional data are needed to make an attainment decision for section 303 (d) listing purposes, the department shall apply the confidence interval approach in s. NR 102.52 (2) (b) to (c). If application of those methods indicates that the waterbody is exceeding the phosphorus criterion, the department shall propose to include the waterbody on the section 303 (d) list as impaired for total phosphorus unless the department determines the waterbody is not exhibiting a biological response to phosphorus as specified in s. NR 102.60. Section 17. NR 102 Subchapter III is created to read:
Subchapter III – Waterbody Assessments and Reporting
NR 102.50 Waterbody assessments and reporting. As required under sections 303 (d) and 305 (b) of the Clean Water Act, 33 USC 1313 (d) and 1315 (b), the department shall report to U.S. EPA on the status of the state’s waterbodies and attainment of water quality standards every two years. Waterbody assessments are used to determine the condition of the state’s surface waters or segments thereof and whether waterbodies are attaining state and federal surface water quality standards. NR 102.51 Assessment types. The department may conduct different types of assessments to determine the status of waterbody health and attainment of water quality standards, depending on availability of data or methods used to collect the data. The department shall, at a minimum, conduct all of the following:
(1) Statewide condition assessments. As part of the biennial assessment report required under section 305 (b) of the Clean Water Act, 33 USC 1315 (b), and 40 CFR 130.8 and 130.10 (a) (1), the department shall report on water quality status and trends at the state, regional, or watershed levels. The department shall assess the extent to which surface waters of the state provide for the protection and propagation of a balanced population of shellfish, fish, and wildlife, and allow recreational activities in and on the water. Broad-scale approaches may be used to conduct these assessments, including randomized monitoring designs or other appropriate statistical methods. (2) Individual waterbody assessments and section 303 (d) list. (a) The department shall identify and report on waters not meeting any applicable water quality standard prescribed under statute or a promulgated rule, pursuant to section 303 (d) of the Clean Water Act, 33 USC 1313 (d), and 40 CFR 130.7 (b) and 130.10 (b) (2). The department shall assess individual waterbodies that have sufficient and readily available datasets, as specified in the department’s water quality standards and assessment protocols, to determine whether a waterbody is attaining water quality standards. The department determines whether a waterbody’s designated uses are supported by evaluating attainment of its water quality criteria and biological assessment thresholds. The department shall assess data collected from a waterbody against each applicable water quality standard or assessment threshold independently, unless a combined assessment procedure is specified in rule. The department shall report any waters not attaining applicable water quality standards to the U.S. EPA. Only water quality standards that have been promulgated via statute or rule may be considered for the purposes of listing a waterbody on the section 303 (d) list. (b) When the department submits the section 305 (b) biennial assessment report and section 303 (d) list, it shall provide all of the following information if an assessment indicates that one or more of a waterbody’s water quality standards are not attained:
1. A waterbody is listed on the section 303 (d) list for a pollutant if a pollutant’s water quality criterion is not attained and it may require a total maximum daily load analysis.
2. A waterbody is reported as having an observed effect of degradation if the waterbody does not attain one or more biological assessment thresholds or water quality criteria for parameters that are not pollutants, such as dissolved oxygen. In listing observed effects, the department may not formally attribute these effects to a specific pollutant until the department conducts an evaluation of potential causes, including nonchemical stressors such as habitat degradation or hydrological modification, and identifies one or more specific pollutants as causing or contributing to biological degradation. Listing of observed effects would not require development of a total daily maximum load for a waterbody unless a specific pollutant exceeding its promulgated water quality standard is identified by the department as a cause of the observed effect.
Note: If a waterbody is not attaining water quality criteria for a pollutant, it will be listed on the section 303 (d) list regardless of attainment of biological assessment thresholds unless otherwise specified in the pollutant’s criteria or procedures specified in those chapters (for instance, the combined assessment approach for phosphorus under s. NR 102.60), or if site-specific criteria are developed and attained. Note: This subsection does not preclude other types of assessments that may be needed or required for other purposes. The department has authority to research and assess the quality and condition of the state’s waters under s. 281.13, Stats. Note: As required under 40 CFR 130.7 (b) (4), waters on the section 303 (d) list may require a total maximum daily loadanalysis. The department prioritizes and develops total maximum daily load analyses as discussed in subch. III of ch. NR 212. In addition, if a specific pollutant is identified as contributing to biological degradation, a site-specific criterion for the pollutant may be developed through rulemaking if appropriate. NR 102.52 Assessment protocols. (1) General. The department’s protocols for assessing waterbodies shall be consistent with the state’s water quality standards and federal regulations and be based on relevant scientific information. The department’s protocols may include components such as minimum data requirements, sampling methods, quality control, statistical analysis of data, allowable frequency of exceedance of criteria or thresholds, and use of professional judgment.
Note: When assessing waterbodies, the department uses its guidance for waterbody assessments titled “Wisconsin Consolidated Assessment and Listing Methodology,” or WisCALM. Although a description of the state’s assessment methodology is required to be submitted to U.S. EPA, U.S. EPA does not approve or disapprove the state’s assessment methodology under section 303 (d) of the Clean Water Act.
(2) Sample variability and confidence intervals. (a) For assessment determinations, the department may determine that multiple samples are necessary to account for variability inherent in the waterbody, sampling results, or other conditions. The department may evaluate attainment of criteria or thresholds, using assessment methodology that accounts for both the central tendency of the data, such as the mean or median, and the variability of the samples.
(b) The department may apply a confidence interval approach to determine the number of samples needed and to increase certainty in the attainment decision. For metrics expressed as a mean or percentile of a group of samples, the department may use the two-sided 80 percent confidence interval of the mean or percentile for assessment. Other methods of calculating a confidence interval may be applied as appropriate for a specific metric, data type, or statistical goal. Once the confidence interval is determined under this paragraph, it is then compared to the criterion or threshold as specified in par. (c).
(c) When applying an approach under par. (b), the department shall compare the confidence interval to the applicable criterion or threshold using one of the following evaluation criteria:
1. If the entire confidence interval is attaining the criterion or threshold, no further samples are needed to make the attainment determination.
2. If the entire confidence interval is not attaining the criterion or threshold, no further samples are needed to make the non-attainment determination.
3. If the criterion or threshold is within the confidence interval, the assessment will be deferred until more data can be collected with the goal of narrowing the interval to determine whether subd. 1. or 2. applies. After further data collection, if the criterion or threshold continues to be within the confidence interval, the attainment determination shall be made by directly comparing the sample mean or percentile to the criterion or threshold.
Note: With confidence intervals calculated under par. (b), there is 90 percent confidence that the attainment decision is correct because there is 80 percent confidence that the waterbody’s true value is within the interval, 10 percent confidence that it is greater than the interval, and 10 percent confidence that it is less than the interval.
NR 102.53 Reporting, public participation, and approvals. (1) Report development. For development of the biennial assessment report and section 303 (d) list, the department shall assemble, evaluate, and submit water quality-related data, information, and assessment protocols to U.S. EPA.
(2) Public participation. (a) The department shall solicit assessment data from citizens and partner groups prior to the waterbody assessment process. Readily available data sets that meet minimum data requirements and are submitted in the department’s specified format during the biennial data solicitation period shall be considered by the department when conducting assessments.
(b) The department shall hold a public informational hearing and a public comment period of at least 30 days on the draft list of assessments and any proposed changes to the section 303 (d) list. The department shall provide notice of the public informational hearing and information regarding where written comments may be submitted on its website and through an electronic notification system.
Note: Prior to the data solicitation period under par. (a), the department provides an opportunity for the public to comment on the assessment guidance. The department generally responds to comments received during the comment periods for the assessment guidance and the draft section 303 (d) list. The department will provide a template for data submittal on the department’s waterbody assessment website. The public can subscribe to the electronic notification system for the water quality standards program on the department’s home page at http://dnr.wi.gov/. (3) Submittal of results to U.S. EPA. After the public participation process is completed, the department shall submit waterbody assessment results to U.S. EPA Region 5 by April 1 of every even numbered year for approval. Assessment results shall be submitted in a report that integrates both statewide condition and individual waterbody assessment results to satisfy the requirements of sections 305 (b) and 303 (d) of the Clean Water Act, respectively.
Note: U.S. EPA has authority to approve or disapprove the section 303 (d) list.
(4) Publication of the final section 303 (d) list. The U.S. EPA-approved section 303 (d) list shall be made public and available on the department’s website.
NR 102.54 Biological assessment of designated uses. Biological assessments conducted under this subchapter are used to determine attainment of designated uses by documenting the health of aquatic biological communities and any observed effects of degradation as described under s. NR 102.51 (2) (b) 2. If a biological assessment threshold under this subchapter is not attained, the waterbody may be considered as not attaining the applicable designated use. NR 102.55 Narrative biological assessment thresholds for aquatic life uses. (1) General. This section establishes narrative biological assessment thresholds that characterize the biological community condition and that are used to measure attainment of aquatic life designated uses specified in s. NR 102.04 (3) for surface waters. This section also establishes methods for evaluating attainment of narrative assessment thresholds. (2) Narrative biological assessment thresholds. (a) The aquatic life uses under s. NR 102.04 (3), except for those specified in s. NR 102.04 (3) (d) to (e), shall be considered suitable for the protection and propagation of a balanced aquatic life community. Those uses are intended to support the growth, development, reproduction, and life cycle of the aquatic life communities for their designated aquatic life use categories, although such waters may exhibit moderate changes in aquatic life community structure due to loss of some rare native taxa or shifts in relative abundance. In determining attainment of a waterbody’s designated uses, the department may compare its biological quality to the range of quality found in similar waterbodies under natural conditions. A waterbody with distinct natural characteristics that result in an aquatic life community different from or less diverse than other waters in the same use category may be considered attaining its aquatic life use if those differences are clearly related to natural characteristics. (b) A surface water that does not support a balanced aquatic life community as designated under s. NR 102.04 (3) (d) to (e) shall support its highest attainable use given its habitat and potential. (c) A surface water shall maintain at least the highest biological condition it has achieved since 1975.
Note: Paragraphs (b) and (c) reflect federal requirements under 40 CFR s. 131.10 (g), pertaining to highest attainable uses, and 40 CFR s. 131.3 (e), specifying November 28, 1975 as the benchmark date from which to determine “existing uses” for aquatic life. Note: Examples of waterbodies with distinct natural characteristics are wetland-dominated streams, naturally acidic bog lakes, and ephemeral streams with only small areas of short-term refugia. Biological condition assessments should not be conducted during periods when there is insufficient water due to natural conditions to support aquatic life.
(3) Assessment methods for narrative biological thresholds. Biological assessments for determining attainment of designated uses may be conducted in accordance with the assessment protocols specified in s. NR 102.52 and may include any of the following: (a) Biological community assessments. To conduct biological community assessments, the department shall use documented methods that have undergone technical review and produce consistent, objective, and repeatable results that account for methodological uncertainty and natural environmental variability. Such methods include indices of biological integrity or similar tools calculated from measured attributes of resident fish, aquatic invertebrates, aquatic plants, or other aquatic communities. Such indices or tools may include measures of species composition, diversity, and abundance; feeding and reproduction characteristics; condition of individual organisms; or other scientifically objective, credible, and supportable factors. Historic records of native species may also be used to assess whether a waterbody exhibits loss of native species.
(b) Biological integrity trends. All surface waters shall maintain existing biological integrity, such that no waterbody or portion thereof shall experience a significant declining trend since 1975 using indicators under par. (a) or other indicators of biological condition, as demonstrated through scientifically-based documentation.
Note: An example of methods the department uses for assessing biological health of surface waters are those found in the department’s guidance for waterbody assessments, “Wisconsin Consolidated Assessment and Listing Methodology,” or WisCALM. Protocols for assessing attainment of biological assessment thresholds using metrics such as fish or macroinvertebrate indices of biotic integrity or the macrophyte assessment of condition are contained in, or referenced in, WisCALM. WisCALM is available on the department’s surface water assessment website at https://dnr.wi.gov/topic/SurfaceWater/assessments.html and is updated every 2 years with public input. NR 102.56 Numeric biological assessment thresholds for lakes, reservoirs and impounded flowing waters. This section contains numeric biological assessment thresholds for evaluating the biological condition of lakes, reservoirs, and impounded flowing waters and determining whether applicable designated uses are being attained. Numeric biological assessment thresholds used to assess attainment of designated uses include all of the following:
(1) Aquatic life use thresholds. (a) Chlorophyll a. 1. ‘Assessment thresholds.’ a. A lake or reservoir other than a stratified two-story fishery lake is not attaining its aquatic life use if its arithmetic mean suspended chlorophyll a concentration exceeds 27 ug/L.
b. A two-story fishery lake is not attaining its aquatic life use if its arithmetic mean suspended chlorophyll a concentration exceeds 8 ug/L.
2. ‘Assessment methods.’ Data requirements for chlorophyll a are the same as those specified for phosphorus in s. NR 102.07 (1) (a), except that the sampling period for chlorophyll a is July 15 to September 15. To determine attainment of the chlorophyll a threshold under subd. 1., the department shall compare the waterbody’s mean suspended chlorophyll a concentration during the sampling period to the threshold, using the confidence interval approach described under s. NR 102.52 (2) (b) to (c) to determine if additional samples are needed. Note: The aquatic life chlorophyll a thresholds do not apply to streams, rivers, or impounded flowing waters, as they were established based on lake trophic status levels.
(b) Aquatic plants. 1. ‘Assessment thresholds.’ Thresholds for evaluating the general health of an aquatic plant community in a lake or reservoir to determine whether its aquatic life use is attained are shown in Table 8. Thresholds used in the macrophyte assessment of condition indicate the acceptable percentage of a lake or reservoir’s vegetated area supporting species that are in each of three tolerance categories. The tolerance categories specify whether a plant species is sensitive to, moderately tolerant of, or tolerant of disturbance.
Table 8
Aquatic plant community thresholds for lakes and reservoirs
Lake Subcategory1 | Macrophyte Assessment of Condition Is Attained If: |
Northern Seepage | Moderately tolerant ≤ 64% |
Northern Drainage | Tolerant ≤ 73% |
Southern Seepage | Sensitive > 15% |
Southern Drainage | Tolerant ≤ 50% |
1 In Table 8, northern lakes are those north of 44.84707°N latitude, and southern lakes are those south of that latitude. These thresholds do not apply to the Great Lakes or lakes less than 5 acres in surface area.
2. ‘Assessment methods.’ The percentage of a lake or reservoir’s vegetated area supporting each tolerance category shall be determined using department-approved protocols for assessing macrophyte condition. The sampling period for southern lakes is June 15 to September 15, and for northern lakes is July 1 to August 31 unless the department determines that an extension from June 15 to September 15 is appropriate during warmer than average years. The department shall consider the threshold attained if the most recent plant survey conducted within the past 10 years, or other more representative survey, attains the applicable threshold in Table 8.
