NR 105.06(1)(a)(a) To derive a chronic toxicity criterion for aquatic life, the minimum information required shall be results of acceptable chronic toxicity tests with one or more species of freshwater animal in at least 8 different families provided that of the 8 species:

NR 105.06(1)(a)1.1. At least one is a salmonid fish, in the family Salmonidae in the class Osteichthyes,

NR 105.06(1)(a)2.2. At least one is a non-salmonid fish, from another family in the class Osteichthyes, preferably a commercially or recreationally important warmwater species,

NR 105.06(1)(a)3.3. At least one is a planktonic crustacean (e.g., cladoceran, copepod),

NR 105.06(1)(a)4.4. At least one is a benthic crustacean (e.g., ostracod, isopod, amphipod, crayfish),

NR 105.06(1)(a)5.5. At least one is an insect (e.g., mayfly, dragonfly, damselfly, stonefly, caddisfly, mosquito, midge),

NR 105.06(1)(a)6.6. At least one is a fish or amphibian from a family in the phylum Chordata not already represented in one of the other subdivisions,

NR 105.06(1)(a)7.7. At least one is an organism from a family in a phylum other than Arthropoda or Chordata (e.g., Rotifera, Annelida, Mollusca), and

NR 105.06(1)(a)8.8. At least one is an organism from a family in any order of insect or any other phylum not already represented in subds. 1. to 7.

NR 105.06(1)(a)9.9. If all 8 of the families in subds. 1. to 8. are represented, a chronic toxicity criterion may be developed for surface waters classified as cold water using information on all of those families. If a chronic toxicity criterion is developed for surface waters classified as cold water, chronic toxicity criteria may also be developed for any of the surface water classifications in s. NR 102.04 (3) (b) to (e) using the procedure in sub. (2) or (3) and data on families in subds. 1. to 8. which are representative of the aquatic life communities associated with those classifications. For each substance, in no case may the criterion for a lower quality fish and aquatic life subcategory as defined in s. NR 102.04 be less than the criterion for a higher quality fish and aquatic life subcategory.

NR 105.06(1)(a)10.10. For a substance, if all the families in subds. 1. to 8. are not represented, acute-chronic ratios as calculated in sub. (5) may be used to generate the chronic toxicity values necessary to calculate a chronic toxicity criterion.

NR 105.06(1)(a)11.11. For a substance, if all of the families in subds. 1. to 8. are not represented, a chronic toxicity criterion may not be developed for that substance except as provided in subd. 10. Instead, any available data may be used to develop a secondary acute value (SAV) for that substance according to sub. (4).

NR 105.06(1)(b)(b) The acceptability of chronic toxicity test results shall be judged according to the guidelines in section VI of the United States environmental protection agency’s 1985 “Guidelines for Deriving National Numerical Water Quality Criteria for the Protection of Aquatic Organisms and Their Uses” or 40 CFR Part 132 Appendix A, sections VI and VII as stated on September 1, 1997, is incorporated by reference.

NR 105.06 NoteNote: Copies of 40 CFR Part 132, Appendix A, Sections VI and VII are available for inspection in the offices of the department of natural resources, secretary of state and the legislative reference bureau, Madison, WI or may be purchased from the superintendent of documents, US government printing office, Washington, D.C. 20402.

NR 105.06(2)(2) Calculation of a chronic concentration. A chronic concentration is obtained by calculating the geometric mean of the chronic lowest observable adverse effect level and the chronic no observable adverse effect level.

NR 105.06(3)(3) Chronic toxicity criteria for substances with toxicity unrelated to water quality parameters. If the chronic toxicity of a substance has not been adequately shown to be related to a water quality parameter, i.e., hardness, pH, temperature, etc., the chronic toxicity criterion (CTC) is calculated using the procedures specified in this subsection.

NR 105.06(3)(a)1.1. For each species for which at least one chronic value is available, the species mean chronic value (SMCV) is calculated as the geometric mean of all acceptable chronic toxicity tests using the guidelines in sub. (1) (b).

NR 105.06(3)(a)2.2. For each genus for which one or more SMCVs are available, the genus mean chronic value (GMCV) is calculated as the geometric mean of the SMCVs available for the genus.

NR 105.06(3)(c)(c) Ranks (R) are assigned to the GMCVs from 1 for the lowest to N for the highest. If 2 or more GMCVs are identical, successive ranks are arbitrarily assigned.

NR 105.06(3)(f)1.1. Let EV = sum of the 4 ln GMCVs,
EW = sum of the 4 squares of the ln GMCVs,
EP = sum of the 4 P values,
EPR = sum of the 4 square roots of P, and
JR = square root of 0.05.