Section 302.563  Determining the Tier II Lake Michigan Basin Acute Aquatic Life Toxicity Value (LMAATV)

If all eight minimum data requirements for calculating a FAV using Tier I procedures are not met, a Tier II LMAATV must be calculated for a substance as follows:

a)         The lowest GMAV in the database is divided by the Secondary Acute Factor (SAF) corresponding to the number of satisfied minimum data requirements listed in the Tier I methodology (Section 302.553).  To calculate a Tier II LMAATV, the database must contain, at a minimum, a GMAV for one of the following three genera in the family Daphnidae – Ceriodaphnia sp., Daphnia sp., or Simocephalus sp.  The Secondary Acute Factors are:

b)         If dependent on a water quality characteristic, the Tier II LMAATV must be calculated according to Section 302.560.

(Source:  Amended at 47 Ill. Reg. 4437, effective March 23, 2023)