EPA is promulgating corrections to the State Implementation Plan (SIP) for the State of Wyoming regarding the State's ambient standards for fluorides and hydrogen sulfide and the State's odor control regulation. EPA has determined that these rules were erroneously incorporated into the SIP. EPA is removing these rules from the approved Wyoming SIP because the rules do not have a reasonable connection to the national ambient air quality standards (NAAQS) and related air quality goals of the Clean Air Act. The intended effect of this correction to the SIP is to make the SIP consistent with the requirements of the Clean Air Act, as amended in 1990 (``the Act''), regarding EPA action on SIP submittals and SIPs for national primary and secondary ambient air quality standards. In addition, EPA is amending the boundary description for the ``Powder River Basin'' PM-10 unclassifiable area in 40 CFR 81.351. EPA promulgated revisions to 40 CFR 81.351 in a November 3, 1995 rulemaking, and EPA erroneously published an incorrect boundary description for the Powder River Basin area. This document corrects that error.