- a) A combination of substances must not exceed concentrations greater than a NOAEL as determined for the most sensitive of the species tested.
- b) Three resident or indigenous species of ecologically diverse taxa must be tested initially. If resident or indigenous species are not available for testing, non-resident species may be used if the non-resident species is of the same family or genus and has a similar habitat and environmental tolerance.
A CATC for any combination of substances (including effluent mixtures) may be determined by toxicity testing procedures pursuant to the following:
(Source: Amended at 47 Ill. Reg. 4437, effective March 23, 2023)