The Environmental Protection Agency (EPA) is approving a state implementation plan (SIP) revision submitted by the State of Utah. The revision fulfills the base year inventory requirement for the 2015 8- hour ozone national ambient air quality standard (NAAQS) for the Uinta Basin, Northern Wasatch Front, and Southern Wasatch Front nonattainment areas (NAAs). Utah submitted the base year emissions inventories to meet, in part, the nonattainment requirements for Marginal ozone NAAs under the 2015 8-hour ozone NAAQS.