"Federally enforceable" means all limitations and conditions that are enforceable by USEPA, including those requirements developed under 40 CFR 60, 61, 62 and 63 (incorporated by reference in Section 204.100), requirements within the SIP, any permit requirements established under 40 CFR 52.21 (incorporated by reference in Section 204.100) or this Part or under regulations approved under 40 CFR 51, subpart I (incorporated by reference in Section 204.100), including operating permits issued under a USEPA-approved program that is incorporated into the SIP and expressly requires adherence to any permit issued under such program.
Ill. Admin. Code tit. 35, § 204.400