Approval and Promulgation of Air Quality Implementation Plans; State of Wyoming; Sheridan PM10

The Environmental Protection Agency (EPA) is approving the Limited Maintenance Plan (LMP), submitted by the State of Wyoming to the EPA on June 2, 2017, for the Sheridan moderate PM10 nonattainment area (Sheridan NAA) and concurrently redesignating the Sheridan NAA to attainment of the National Ambient Air Quality Standard (NAAQS) for particulate matter with an aerodynamic diameter less than or equal to a nominal 10 micrometers (PM10). In order to approve the LMP and redesignation, the EPA is determining that the Sheridan NAA has attained the 1987 24-hour PM10 NAAQS of 150 [micro]g/m3. This determination is based upon monitored air quality data for the PM10 NAAQS during the years 2014-2016. Additionally, the EPA is approving the Sheridan LMP as meeting the appropriate transportation conformity requirements found in 40 CFR 93, subpart A.