Regulatory Pathway for Section 111

Like many other requirements of the Clean Air Act (the Act), the standards of performance under section 111 are designed and implemented through a federal-state partnership. EPA lists the categories of sources and establishes performance standards for new and modified emitters within listed categories. EPA also establishes a mandatory “guideline” for states, creating a federal “floor” for regulation of existing sources that applies only if the states fail to set their own standards of performance that meet or exceed this floor. In promulgating these plans, the states will have considerable flexibility, since the standards of performance under section 111(d) may take the form of traditional emissions rate limitations or any number of other more flexible mechanisms.