NR 105.06(5)(e)(e) For a given substance, if the SMACR appears to increase or decrease as the species or genus mean acute values (SMAVs or GMAVs) calculated for that substance using the procedure described in s. NR 105.05 increase, the final acute-chronic ratio (FACR) shall be equal to the geometric mean of the SMACRs for species with SMAVs closest to the final acute value.

NR 105.06(5)(f)(f) For a given substance, if no trend is apparent regarding changes in SMACRs and GMAVs, the FACR shall be equal to the geometric mean of all SMACRs available for that substance.

NR 105.06(5)(g)(g) For a given substance, the final chronic value (FCV) shall be equal to the final acute value (FAV) divided by the final acute-chronic ratio (FACR). The chronic toxicity criterion shall be equal to the lower of the FCV and the final plant value as calculated using the procedure in s. NR 105.11, if available.

NR 105.06(5)(h)(h) Chronic toxicity criteria for the fish and aquatic life subcategories listed in s. NR 102.04 (3) that are calculated using acute-chronic ratios are listed in Table 5 for substances with acute toxicity unrelated to water quality parameters and in Table 6 for substances with acute toxicity related to water quality parameters. Equations listed in Table 6 are applicable over the range of water quality parameters as contained in Table 4A. Table 2A should be used where no range is listed in Table 4A.

NR 105.06(6)(6) Secondary chronic values. If all 8 minimum data requirements for calculating FCVs in sub. (1) (a) are not met for a substance, secondary chronic values (SCVs) shall be calculated for that substance using the procedure in this subsection.

NR 105.06(6)(a)(a) If any one of the combinations of information in subds. 1. to 3. is available, a SCV may be calculated. To calculate a SCV for a substance, the acute value from subds. 1. to 3. is divided by the applicable acute-chronic ratio in the same subdivision.

NR 105.06(6)(a)1.1. Calculate a FAV using the procedure in s. NR 105.05 (2) and divide it by a secondary acute-chronic ratio (SACR) using the procedure in sub. (7).

NR 105.06(6)(a)2.2. Calculate a SAV using the procedure in s. NR 105.05 (4) and divide it by a final acute-chronic ratio (FACR) using the procedure in sub. (5).

NR 105.06(6)(a)3.3. Calculate a SAV using the procedure in s. NR 105.05 (4) and divide it by a SACR using the procedure in sub. (7).

NR 105.06(6)(b)(b) If appropriate, the SCV shall be made a function of a water quality characteristic in a manner similar to that described in sub. (4) (a).

NR 105.06(6)(c)(c) If, for a commercially, recreationally or ecologically important species, the SMCV is lower than the calculated SCV, that SMCV shall be used as the SCV instead of the calculated SCV.

NR 105.06(6)(d)(d) If there is an FPV available using the procedure in s. NR 105.11 which is lower than the calculated SCV, that FPV shall be used as the SCV instead of the calculated SCV.

NR 105.06(7)(7) Secondary acute-chronic ratios.

NR 105.06(7)(a)(a) If a FACR cannot be calculated using the procedure in sub. (5) because SMACRs are not available for a fish, an invertebrate or an acutely sensitive freshwater species, a secondary acute-chronic ratio (SACR) may be calculated using the procedure in this subsection.

NR 105.06(7)(b)(b) The SACR shall be equal to the geometric mean of 3 acute-chronic ratios. Those ratios consist of the SMACRs available for the species in sub. (5) (c). When SMACRs are not available for the species in par. (a), the default acute-chronic ratio to be used is 18. Use of a SACR will result in the calculation of a secondary chronic value.

NR 105.06(8)(8) Chronic toxicity criteria expressed in the dissolved form. Chronic water quality criteria may be expressed as a dissolved concentration. The conversion of a chronic water quality criterion expressed as a total recoverable concentration to a chronic water quality criterion expressed as a dissolved concentration, the portion of the substance which will pass through a 0.45 um filter, shall be done using the equations in pars. (a) and (b). Substances which may have criteria expressed as a dissolved concentration are listed in par. (a) with corresponding conversion factors.

NR 105.06(8)(a)(a) The conversion of the water quality criterion expressed as total recoverable (WQCTotal R.) to the water quality criterion expressed as dissolved (WQCD) shall be performed as follows: