The EPA is finalizing revisions to the standards of performance for new stationary compression ignition internal combustion engines under section 111(b) of the Clean Air Act. The final rule requires more stringent standards for stationary compression ignition engines with displacement greater than or equal to 10 liters per cylinder and less than 30 liters per cylinder, consistent with recent revisions to standards for similar mobile source marine engines. In addition, the action revises the requirements for engines with displacement at or above 30 liters per cylinder to align more closely with recent standards for similar mobile source marine engines, and for engines in remote portions of Alaska that are not accessible by the Federal Aid Highway System. The action also provides additional flexibility to owners and operators of affected engines, and corrects minor mistakes in the original standards of performance. Finally, the action makes minor revisions to the standards of performance for new stationary spark ignition internal combustion engines to correct minor errors and to mirror certain revisions finalized for compression ignition engines, which provides consistency where appropriate for the regulation of stationary internal combustion engines. The final standards will reduce nitrogen oxides by an estimated 1,100 tons per year, particulate matter by an estimated 38 tons per year, and hydrocarbons by an estimated 18 tons per year in the year 2030.