Section NR 106.08 - Determination of the necessity for whole effluent toxicity testing requirements and limitations(1) GENERAL. The department shall establish whole effluent toxicity testing requirements and limitations whenever necessary to meet applicable water quality standards as specified in chs. NR 102 to 105 as measured by exposure of aquatic organisms to an effluent and specified effluent dilutions. When considering the necessity for whole effluent toxicity testing requirements and limitations, the department shall consider in-stream biosurvey data and data from ambient toxicity analyses, whenever such data are available.(2) DETERMINATION OF NECESSITY. If representative discharge data are available for an effluent being discharged from a point source, whole effluent toxicity testing requirements are necessary when any of the following apply: (a) Existing aquatic life toxicity test data generated according to standard test protocols indicate a potential for an effluent from a point source discharge to adversely impact the receiving water aquatic life community.(b) A water quality-based effluent limitation for a toxic substance is determined necessary in s. NR 106.05.(3) REPRESENTATIVE DATA. Toxicity test data available to the department shall be considered representative when all of those data meet the following conditions: (a) Data are representative of normal discharge conditions and current effluent quality.(b) Data were produced by a lab certified or registered under ch. NR 149.(c) Data were produced from toxicity test procedures specified in the permit.(d) Data were produced from toxicity tests that met all applicable quality assurance or quality control requirements specified in the permit.(4) NO REPRESENTATIVE DATA. If no representative discharge data are available for an effluent being discharged from a point source, whole effluent toxicity testing requirements are necessary if, in the judgment of the department, water quality standards may be exceeded. In such cases, all of the following factors shall be considered: (a) Any relevant information that is available that indicates a potential for an effluent to impact the receiving water aquatic life community.(b) Available dilution in the receiving water.(c) Discharge category and predicted effluent quality.(d) Proximity to other point source dischargers.(5) OTHER CONSIDERATIONS. Regardless of the results of the analysis conducted under this section, the department may, whenever determined necessary, require whole effluent toxicity testing for a point source discharge. The department may use information submitted under s. 323.60(5) (c) and (d), Stats., together with other information, in determining when whole effluent toxicity testing is necessary.(6) REASONABLE POTENTIAL TO RECEIVE AN ACUTE OR CHRONIC WHOLE EFFLUENT TOXICITY LIMIT. (a)General. Whole effluent toxicity limits are established in a permit according to s. NR 106.09 whenever representative, facility-specific whole effluent toxicity data demonstrate that the effluent is or may be discharged at a level that will cause, have the potential to cause, or contribute to an excursion of a water quality standard. Whole effluent toxicity limits may also be imposed in the absence of facility-specific whole effluent toxicity test data, on a case-by-case basis, whenever facility-specific or site-specific data or conditions indicate toxicity to aquatic life that is attributable to the discharger.(b)Reasonable potential.1. If a zone of initial dilution has not been approved by the department, the potential to exceed an acute criterion shall be calculated using the following equation: (TUa effluent) (B) > 1.0
Where:
TUa ef fluent = Maximum calculated TUa from the most sensitive species in the data set
B = Reasonable potential multiplication factor determined under par . (c)
1.0 = Numeric acute WET limitation in acute toxic units (TUa) derived from narrative criterion in s. NR 102.04(1) (d)
2. If a zone of initial dilution has been approved by the department, the potential to exceed an acute criterion shall be calculated using the following equation: [(TUa effluent) (B) (AMZ)] > 1.0
Where:
TUa effluent = Maximum calculated TUa from the most sensitive species in the data set
B = Reasonable potential multiplication factor determined under par . (c)
AMZ = Acute mixing zone concentration based on presence of a zone of initial dilution as defined in s. NR 106.03(1) expressed as a decimal
1.0 = Numeric acute WET limitation in acute toxic units (TUa) derived from narrative criterion in s. NR 102.04(1) (d)
3. The potential to exceed a chronic criterion shall be calculated using the following equation: [(TUc effluent) (B) (IWC)]> 1.0
Where:
TUc ef fluent = Maximum calculated TUc from the most sensitive species in the data set
B = Reasonable potential multiplication factor determined under par . (c)
IWC = Instream waste concentration as defined in s. NR 106.03(6) expressed as a decimal
1.0 = Numeric chronic WET limitation in chronic toxic units (TUc) derived from narrative criterion in s. NR 102.04(4) (d)
(c)Reasonable potential multiplication factor. The department shall use the reasonable potential multiplication factor in par. (b) to convert the calculated effluent toxicity value to the estimated 95th percentile toxicity value. The department shall use all of the following methods to select a reasonable potential multiplication factor: 1. When there are less than 10 individual toxicity detects, the multiplication factor shall be taken from Table 4 and based on a coefficient of variation of 0.6.2. When there are 10 or more individual toxicity detects, the multiplication factor shall be taken from Table 4 and based on coefficient of variation calculated as the standard deviation of the WET test endpoints, IC25, IC50, or LC50, divided by the arithmetic mean of the WET tests. Table 4 Reasonable Potential Multiplication Factor
Coefficient of variation (CV) |
Number of samples (n) | 0.1 | 0.2 | 0.3 | 0.4 | 0.5 | 0.6 | 0.7 | 0.8 | 0.9 | 1.0 | 1.1 | 1.2 | 1.3 | 1.4 | 1.5 | 1.6 | 1.7 | 1.8 | 1.9 | 2.0 |
1 | - | - | - | - | - | 6.2 | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
2 | - | - | - | - | - | 3.8 | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
3 | - | - | - | - | - | 3.0 | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
4 | - | - | - | - | - | 2.6 | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
5 | - | - | - | - | - | 2.3 | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
6 | - | - | - | - | - | 2.1 | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
7 | - | - | - | - | - | 2.0 | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
8 | - | - | - | - | - | 1.9 | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
9 | - | - | - | - | - | 1.8 | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
10 | 1.1 | 1.2 | 1.3 | 1.5 | 1.6 | 1.7 | 1.9 | 2.0 | 2.2 | 2.3 | 2.4 | 2.6 | 2.7 | 2.8 | 3.0 | 3.1 | 3.2 | 3.3 | 3.4 | 3.6 |
11 | 1.1 | 1.2 | 1.3 | 1.4 | 1.6 | 1.7 | 1.8 | 1.9 | 2.1 | 2.2 | 2.3 | 2.4 | 2.5 | 2.7 | 2.8 | 2.9 | 3.0 | 3.1 | 3.2 | 3.3 |
12 | 1.1 | 1.2 | 1.3 | 1.4 | 1.5 | 1.6 | 1.7 | 1.9 | 2.0 | 2.1 | 2.2 | 2.3 | 2.4 | 2.5 | 2.6 | 2.7 | 2.8 | 2.9 | 3.0 | 3.0 |
13 | 1.1 | 1.2 | 1.3 | 1.4 | 1.5 | 1.6 | 1.7 | 1.8 | 1.9 | 2.0 | 2.1 | 2.2 | 2.3 | 2.4 | 2.5 | 2.5 | 2.6 | 2.7 | 2.8 | 2.9 |
14 | 1.1 | 1.2 | 1.3 | 1.4 | 1.4 | 1.5 | 1.6 | 1.7 | 1.8 | 1.9 | 2.0 | 2.1 | 2.2 | 2.3 | 2.3 | 2.4 | 2.5 | 2.6 | 2.6 | 2.7 |
15 | 1.1 | 1.2 | 1.2 | 1.3 | 1.4 | 1.5 | 1.6 | 1.7 | 1.8 | 1.8 | 1.9 | 2.0 | 2.1 | 2.2 | 2.2 | 2.3 | 2.4 | 2.4 | 2.5 | 2.5 |
16 | 1.1 | 1.1 | 1.2 | 1.3 | 1.4 | 1.5 | 1.6 | 1.6 | 1.7 | 1.8 | 1.9 | 1.9 | 2.0 | 2.1 | 2.1 | 2.2 | 2.3 | 2.3 | 2.4 | 2.4 |
17 | 1.1 | 1.1 | 1.2 | 1.3 | 1.4 | 1.4 | 1.5 | 1.6 | 1.7 | 1.7 | 1.8 | 1.9 | 1.9 | 2.0 | 2.0 | 2.1 | 2.2 | 2.2 | 2.3 | 2.3 |
18 | 1.1 | 1.1 | 1.2 | 1.3 | 1.3 | 1.4 | 1.5 | 1.6 | 1.6 | 1.7 | 1.7 | 1.8 | 1.9 | 1.9 | 2.0 | 2.0 | 2.1 | 2.1 | 2.2 | 2.2 |
19 | 1.1 | 1.1 | 1.2 | 1.3 | 1.3 | 1.4 | 1.5 | 1.5 | 1.6 | 1.6 | 1.7 | 1.8 | 1.8 | 1.9 | 1.9 | 2.0 | 2.0 | 2.0 | 2.1 | 2.1 |
20 | 1.1 | 1.1 | 1.2 | 1.2 | 1.3 | 1.4 | 1.4 | 1.5 | 1.5 | 1.6 | 1.6 | 1.7 | 1.7 | 1.8 | 1.8 | 1.9 | 1.9 | 2.0 | 2.0 | 2.0 |
30 | 1.0 | 1.1 | 1.1 | 1.1 | 1.2 | 1.2 | 1.2 | 1.3 | 1.3 | 1.3 | 1.3 | 1.4 | 1.4 | 1.4 | 1.4 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 |
40 | 1.0 | 1.0 | 1.1 | 1.1 | 1.1 | 1.1 | 1.1 | 1.1 | 1.2 | 1.2 | 1.2 | 1.2 | 1.2 | 1.2 | 1.2 | 1.2 | 1.2 | 1.2 | 1.3 | 1.3 |
50 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.1 | 1.1 | 1.1 | 1.1 | 1.1 | 1.1 | 1.1 | 1.1 | 1.1 | 1.1 | 1.1 | 1.1 | 1.1 |
60 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 |
70 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 |
80 | 1.0 | 1.0 | 1.0 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 |
90 | 1.0 | 1.0 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 |
100 | 1.0 | 1.0 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.7 | 0.7 | 0.7 |
(d)Maximum toxicity values. The department shall set the TUc effluent and TUa effluent values in par. (b) equal to zero whenever toxicity is not detected or the LC50, IC25, or IC50 equals or exceeds 100% effluent.(e)Exception. WET limits are not necessary under this subsection when the department determines chemical-specific limits for the effluent are sufficient to attain and maintain applicable numeric and narrative water quality standards, taking into consideration all of the following: 1. Existing controls on the discharge.2. Controls on the pollutant discharged by nonpoint source pollution in the watershed.3. The variability of the pollutant or parameter in the effluent discharged.4. Sensitivity of species to toxicity testing when evaluating whole effluent toxicity as defined in s. NR 106.03.5. Dilution of the effluent in the receiving water.(f)Fact sheet. If the department determines WET limitations are not necessary under par. (e), all of the factors that are required for the determination must be specifically discussed in the fact sheet for the permit.(7) DATA EXCLUSIONS. The department may exclude data from a WET reasonable potential determination when those data meet any of the following conditions: (a) Data are not representative under sub. (3).(b) Positive WET results are caused by deficiency toxicity only.(c) Positive WET results are caused by groundwater or surface water remediation needed to correct or prevent an existing surface or groundwater contamination situation or a public health problem.Wis. Admin. Code Department of Natural Resources § NR 106.08
Cr. Register, February, 1989, No. 398, eff. 3-1-89; am. (1), r. and recr. (5), Register, August, 1997, No. 500, eff. 9-1-97; CR 09-123: am. (5) (a) Register July 2010 No. 655, eff. 8-1-10; correction in (4) made under s. 13.92(4) (b) 7, Stats., Register July 2010 No. 655.Amended by, CR 15-085: r. and recr. Register August 2016 No. 728, eff. 9/1/2016Amended by, CR 17-002: cr. (6) (e), (f) Register April 2018 No. 748, eff.5/1/2018