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.