35 Ill. Adm. Code 309.152
Toxic Pollutants
Section 309
Section 309.152 Toxic
Pollutants
Any NPDES Permit issued must
include as a condition that if a toxic effluent standard or prohibition
(including any schedule of compliance specified in the effluent standard or
prohibition) is established under section 307(a) of the CWA for a toxic
pollutant present in the permittee's discharge and that standard or prohibition
is more stringent than any limitation upon the pollutant in the NPDES Permit,
the Agency must revise or modify the permit according to the more stringent
standard or prohibition and must notify the permittee.