NR 102.56(1)(b)2.2. ‘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.

NR 102.56 NoteNote: Examples of department-approved sampling protocols include the “Recommended Baseline Monitoring of Aquatic Plants in Wisconsin,” available on the department’s website in the Electronic Guidance and Documents (EGAD) system at https://dnr.wi.gov/water/egadsearch.aspx. Examples of department-approved analysis protocols include the “Macrophyte Assessment of Condition – General” (MAC-Gen) for general condition assessments applicable to this section, and the “Macrophyte Assessment of Condition – Phosphorus” (MAC-P) for phosphorus-specific assessments under s. NR 102.60 (2) (c). Each MAC protocol contains the tolerance groups assigned to each species. MAC-Gen and MAC-P scores can be obtained by contacting the department at DNRSWIMS@wisconsin.gov and submitting aquatic plant data collected and formatted according to department specifications. Computer programming script written in the R language to compute the MAC calculations 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/.

NR 102.56 NoteNote: Lakes and reservoirs are subcategorized based on both their stratification status (stratified vs. unstratified) and whether or not they have an outlet stream or river (drainage vs. seepage). To find a lake or reservoir’s subcategory, also known as its natural community, go to the department’s Surface Water Data Viewer online map at https://dnr.wi.gov/topic/surfacewater/swdv/ and turn on the layer for Surface Water: Lake Natural Communities. On the natural communities layer, unstratified is referred to as “shallow,” and stratified is referred to as “deep.” Headwater and lowland lakes are types of drainage lakes.

NR 102.56 NoteNote: The U.S. EPA has set human health swimming advisory levels for microcystin and cylindrospermopsin that accurately reflect the latest scientific information on the potential human health effects from recreational exposure to these two cyanotoxins. The department recommends that local and tribal public health agencies use these swimming advisory levels for notification purposes in recreational waters to protect the public. More information can be found at
https://dnr.wisconsin.gov/topic/lakes/bluegreenalgae.

NR 102.56(2)(c)(c) 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 in all waterbody types is July 15 to September 15. To determine attainment of the threshold, the department shall determine a waterbody’s frequency of moderate algae levels during the chlorophyll a summer sampling period using the confidence interval for a percentile of a normal distribution, and use the approach described under s. NR 102.52 (2) (b) and (c) to compare that frequency to the applicable threshold in Table 9.

NR 102.56 NoteNote: The statistical calculation for determining the frequency of moderate algae levels is contained in Wisconsin’s Consolidated Assessment and Listing Methodology (WisCALM) guidance document.

NR 102.60(1)(a)(a) This section establishes a combined assessment approach for making total phosphorus attainment determinations for surface waters in cases specified in par. (b). This approach is designed to account for variability in how waterbodies respond to phosphorus. The combined approach evaluates a waterbody’s quality by considering the total phosphorus concentration in the surface water in conjunction with an evaluation of the phosphorus response indicators specified in subs. (2) to (4). The phosphorus response indicators characterize the condition or abundance of aquatic organisms that are responsive to total phosphorus to determine whether aquatic life and recreation uses are being met. Together, the total phosphorus criteria and response indicators may be used to determine whether the phosphorus water quality standards are attained or whether the waterbody should be listed as impaired for total phosphorus on the section 303 (d) list.

NR 102.60(1)(b)1.1. If a waterbody’s calculated total phosphorus concentration exceeds its total phosphorus criterion using the assessment procedure under s. NR 102.07 and the waterbody’s calculated phosphorus concentration is within the combined assessment range shown in Table 10, the department may make the total phosphorus attainment or impairment determination using phosphorus response indicators specified in subs. (2) to (4) if sufficient biological data are available to conduct these assessments. In that case, the following decision protocols apply:

NR 102.60 NoteNote: If a waterbody is not considered impaired using the combined approach, it may be a candidate for a less stringent phosphorus site-specific criterion under ch. NR 119. If a waterbody attains its phosphorus criterion but one or more phosphorus response indicators are not attained, it may be a candidate for a more stringent site-specific phosphorus criterion under ch. NR 119.

NR 102.60(1)(b)1.b.b. If a waterbody does not attain one or more of the applicable phosphorus response indicators in subs. (2) to (4) or if the department does not have sufficient data to evaluate all of the applicable response indicators, then the waterbody shall be considered impaired for total phosphorus and the department shall propose inclusion of the waterbody on the section 303 (d) list as not attaining its phosphorus criterion. As part of the public comment period for the section 303 (d) list, the department shall provide a list of waterbodies needing additional data to determine whether phosphorus response indicators are met. If sufficient phosphorus response indicator data becomes available in the future, the waterbody may be reassessed.

NR 102.60(1)(b)2.2. If a waterbody’s calculated phosphorus concentration exceeds its total phosphorus criterion using the assessment procedure under s. NR 102.07 and the waterbody’s calculated phosphorus concentration also exceeds the upper limit of the combined assessment range shown in Table 10, then the waterbody shall be considered impaired for total phosphorus regardless of attainment of phosphorus response indicators, and the department shall propose to include the waterbody on the section 303 (d) list.