Section NR 119.06 - Minimum requirements for an SSC submittal Any person may submit a request to the department to review a proposed SSC for a waterbody or waterbody segment. The department may also develop an SSC through rulemaking absent any request. A person submitting the request is responsible for developing the proposed SSC, including conducting monitoring and modeling if needed. An SSC request submittal shall contain all of the following:
(1) SSC STUDY AREA. The submittal shall contain identification of all waterbodies and segments within the SSC study area. The SSC study area includes all waterbodies and segments for which monitoring data are needed to determine whether a proposed SSC would be protective of designated uses. The study area is determined as follows: (a) For any SSC on an isolated waterbody such as a seepage lake, the isolated waterbody may comprise the entire SSC study area. At least one monitoring site within the waterbody is required.(b) For a more stringent SSC on a flowing water system, a single waterbody or segment may comprise the SSC study area. In this case, at least one monitoring site within the waterbody is required. A larger study area may also be established.(c) For a less stringent SSC on a flowing water system, the study area shall include monitoring sites on all of the following upstream and downstream waters:1. A site upstream from the segment under consideration for an SSC.2. At least one site within the segment under consideration for an SSC. This site shall be located downstream from any WPDES permitted dischargers present on the segment.3. Downstream of the SSC segment, one site per Strahler stream order until the terminal waterbody defined in subd. 4. is reached.4. At least one site within the study area's terminal waterbody, which is the nearest downstream waterbody that has a statewide phosphorus criterion different from the statewide phosphorus criterion applicable to the proposed SSC segment. If no terminal waterbody is reached before the Mississippi River, the Mississippi River is the terminal waterbody. Note: Sampling beyond state lines is not usually necessary unless the department determines it is needed for protection of a downstream water with a more stringent phosphorus criterion in an adjacent state.
Note: The combined sites listed in par. (c) should typically result in 6 or fewer sites. If more than one discharger is present, additional sampling sites may be needed. The delineation of the study area is consistent with the approach used by the department when developing an SSC.
(2) APPLICABLE WATER QUALITY STANDARDS, PHOSPHORUS RESPONSE INDICATORS, AND BIOLOGICAL ASSESSMENT THRESHOLDS. For each waterbody or segment identified in sub. (1), the submittal shall contain identification of all applicable designated uses under s. NR 102.04, phosphorus criteria under s. NR 102.06, phosphorus response indicators under s. NR 102.60 (2) to (4), and biological assessment thresholds under subch. III of ch. NR 102. (3) MONITORING. The submittal shall contain sampling data for each of the study area monitoring sites specified in sub. (1) . Data shall be collected following the department's monitoring and quality assurance protocols for each metric. If additional relevant data are available beyond the minimum requirements specified in this section, such as more frequent data or a longer-term data record, they shall also be submitted and analyzed under sub. (4). Monitoring data requirements include all of the following:(a) At least 2 years of total phosphorus data. Sampling frequency at each site shall comply with one of the following:1. For lakes and reservoirs, a minimum of 12 phosphorus samples are required over a 2-year period. Collection of 12 samples requires 6 samples from June 1 to September 15 each year.2. For flowing waters, a minimum of 12 phosphorus samples are required over a 2-year period. Collection of 12 samples requires monthly sampling from May to October each year.3. For sites with total phosphorus concentrations that are more variable than typical or where the phosphorus concentration is close to the statewide criterion, more frequent sampling than the minimum specified in subds. 1. to 2. may be necessary to demonstrate the need for an SSC and the appropriate SSC value. A requestor may consult with the department to determine if a higher sampling frequency is necessary. Note: For example, if the two-sided 80% confidence interval around the proposed SSC phosphorus concentration contains the statewide criterion, then more frequent samples may be necessary to demonstrate the need for an SSC. A power analysis can be used to statistically estimate the amount of additional data needed.
(b) At least 2 years of data for each of the applicable phosphorus response indicators and biological assessment thresholds. For biological sampling, the department may approve sampling to be conducted by the requestor, conduct the sampling itself, or agree to a designee.(c) Documentation of the monitoring protocols and quality assurance methods followed.(d) Depending on site-specific circumstances, for the purposes of making an SSC determination, the department may require an additional number of samples, monitoring sites, or other chemical, biological, or physical metrics in addition to those specified in this section. Note: The department's monitoring protocols and standard operating procedures, including quality assurance protocols, and existing data housed by the department may be accessed through the department's SWIMS database. Contact the department at DNRSWIMS@wisconsin.gov for access to the database. More information is available by contacting the department's surface water monitoring section or on its surface water monitoring website at https://dnr.wi.gov/topic/SurfaceWater/monitoring.html.
(4) ANALYSIS. The submittal shall contain an analysis of the data, including all of the following: (a) An analysis of monitoring data following the department's assessment protocols to indicate current and historic attainment status of all water quality standards, phosphorus response indicators, and biological assessment thresholds identified in sub. (2). This shall include identifying whether any waters are or have been on the section 303(d) list, and any trends observable over time. If any relevant water quality standard is not attained, evaluate whether there is a relationship between phosphorus and the non-attainment, and any other potential factors that may be causing the non-attainment. Note: The department's surface water assessment protocols are found under specific metrics within chs. NR 102 and 105 and in guidance titled "Wisconsin Consolidated Assessment and Listing Methodology," or WisCALM, which is available on the department's surface water assessments website at https://dnr.wi.gov/topic/SurfaceWater/assessments.html.
(b) A statistical or modeling analysis if needed to determine the appropriate SSC, as specified in s. NR 119.05 (2), and documentation of methods and results. The analysis shall demonstrate a clear link between phosphorus and attainment of a designated use, including characterization of the relationship between phosphorus and the applicable phosphorus response indicators. The analysis shall be based on or calibrated to data from the waterbody that are representative of the range of environmental variability that may influence the applicable phosphorus response indicators. For rivers that contain a reservoir, impounded flowing water, or natural drainage lake, the model may be based on attainment of the applicable phosphorus response indicators for frequency of moderate algae levels and chlorophyll a specified in s. NR 102.60 (2) (a) to (b). In those cases, a model demonstrating attainment of the river phosphorus response indicator for chlorophyll a specified in s. NR 102.60 (3) is not required. For rivers without a reservoir, impounded flowing water, or natural drainage lake, modeling shall include a demonstration that the river phosphorus response indicator for chlorophyll a specified in s. NR 102.60 (3) is expected to be attained. Note: The option for rivers with impounded flowing waters, reservoirs, or natural drainage lakes is provided because modeling chlorophyll a - phosphorus correlations is more cost-effective for these waters than modeling such correlations in rivers, and attaining the chlorophyll a targets for lakes, reservoirs, and impounded flowing waters should ensure that chlorophyll a targets are also met within the river.
(5) PROPOSED SSC EXTENT. The submittal shall contain identification of the extent of the study area that may be eligible for the SSC. For a less stringent SSC, this may include any segments within the study area that do not attain their applicable phosphorus criteria but do attain all phosphorus response indicators and biological assessment thresholds. For a more stringent SSC, this may include any segments that are demonstrated to need a more stringent phosphorus criterion to protect designated uses. Note: Typically, monitoring and analysis under subs. (3) to (4) will need to be completed before the extent of the study area eligible for the SSC can be identified.
(6) DOWNSTREAM PROTECTION. For less stringent SSC, the submittal shall contain a demonstration that potentially affected downstream waters' uses are protected by the proposed SSC, using one of the following methods:(a) Waters in the study area under sub. (1) that are downstream of the extent of the study area that may be eligible for the SSC as determined under sub. (5) shall be assessed as follows: 1. If the downstream segment adjacent to the proposed SSC extent attains its applicable phosphorus criteria, phosphorus response indicators, and biological assessment thresholds, the SSC is protective of downstream waters.2. If the proposed SSC extent directly joins a river listed in s. NR 102.06 (3) that is not attaining one or more of its phosphorus response indicators or biological assessment thresholds, an SSC may be established but shall not be set higher than either the phosphorus criterion of the river or the ambient total phosphorus concentration of the SSC extent. Note: Under this paragraph, Strahler stream order should be used to determine the length of the adjacent downstream segment.
(b) If a demonstration for downstream protection under par. (a) is not appropriate or feasible, an alternative demonstration of downstream protection may be submitted by the requestor to the department.(7) PROPOSED SSC AND SUPPORTING MATERIALS. The submittal shall contain the proposed SSC and materials supporting the proposal, including all of the following:(a) Determination of the SSC that would be appropriately protective of designated uses in the waterbody and downstream, based on the analyses in this section.(b) Demonstration that there is a statistically significant difference between the proposed SSC and the statewide phosphorus criterion, based on estimation of the uncertainty in the relationships developed under sub. (4) (b). Note: For example, an SSC may be demonstrated to be significantly different from the statewide criterion if the statewide phosphorus criterion is outside the 2-sided 80% confidence interval around the proposed phosphorus SSC concentration.
(c) A draft technical support document that contains the information required in this chapter to support the SSC and meets the requirements specified in s. 281.15, Stats. All raw data and calculations shall also be submitted to the department. Note: Section 281.15(2) (b) to (e), Stats., requires information on socioeconomic costs and considerations, a demonstration that the criterion is no more stringent than reasonably necessary to assure attainment of a waterbody's designated uses, application of reasonable statistical techniques, and a technical support document detailing methods used to develop the criterion.
Wis. Admin. Code Department of Natural Resources NR 119.06
Adopted by, CR 19-093: cr. Register September 2022 No. 801, eff. 10/1/2022The department recommends that requestors meet with the department early in the process to determine additional data needs and protocols before developing a monitoring or modeling plan or submitting an SSC request. The department may provide technical assistance as resources allow. Any preliminary advice provided by the department is not binding, but is meant to inform the requestor's decision on whether to develop an SSC and the information needed to do so.