EPA is taking direct final action approving a State Implementation Plan (SIP) revisions submitted by the State of South Dakota on January 14, 2005. The January 14, 2005 submittal revises the Administrative Rules of South Dakota, Air Pollution Control Program, by modifying the chapters pertaining to definitions, ambient air quality, air quality episodes, operating permits for minor sources, regulated air pollutant emissions, new source review, performance testing, control of visible emissions, and continuous emission monitoring systems. In addition, the State made revisions to the Prevention of Significant Deterioration program, which has been delegated to the State. The intended effect of this action is to make these revisions federally enforceable. We are also announcing that on March 23, 2005, we updated the delegation of authority for the implementation and enforcement of the New Source Performance Standards to the State of South Dakota. These actions are being taken under sections 110 and 111 of the Clean Air Act.