Class I Designation Criteria

Mandatory Federal

  • Designated by Congress in the 1977 amendments to the Clean Air Act (CAA § 162(a))
  • Areas in existence prior to August 1977, including:
    • International Parks
    • national memorial parks and national wilderness areas exceeding 5,000 acres
    • national parks exceeding 6,000 acres
  • May not be redesignated


  • Federal lands within a state or tribal lands, designated by EPA at the request of the state or tribe (Indian lands held in trust not considered federal lands under the PSD program), including:
    • national monuments, national primitive areas and national preserves, national recreation areas, national wild and scenic rivers, national wildlife refuges, national lakeshores or national seashores exceeding 10,000 acres. CCA 164(a)
    • national park or national wilderness area established after August 7, 1977, exceeding 10,000 acres
  • No Federal Class I areas requested presently
  • Can be redesignated to Class I or Class II only


  • Lands under the jurisdiction of a state or a tribe may be redesignated to Class I at the request of that state or that tribe
  • No size/acreage restrictions
  • No state Class I redesignations requested presently
  • Five Tribal Reservations have been redesignated as of 2014