EPA approves two revisions to the Wyoming State Implementation Plan (SIP) regarding particulate matter. The SIP revisions include clarification and revisions to the particulate matter control requirements in section 25 of the Wyoming Air Quality Standards and Regulations (WAQSR) for the FMC Corporation Trona plant in the Trona Industrial Area of Wyoming, and the addition of guidelines for best available control technology (BACT) in the minor source construction permitting requirements of section 21 of the WAQSR for large mining operations. The State submitted these SIP revisions to EPA for approval on September 15, 1982 and on May 16, 1985, respectively. We approve these SIP revisions because they are consistent with Federal requirements. We also revise 40 CFR 52.2620 to list subsections 21(a)(iv), 24(a)(xix), 24(b)(iv), and 24(b)(xii)(H) of the WAQSR in the ``Incorporation by reference'' section. We approved these subsections in previous SIP approvals (on November 29, 1994 and on November 3, 1995, respectively) but we inadvertently neglected to identify those subsections as incorporated into the SIP in the CFR.