{"data":{"id":"us/40-cfr-81.51","jurisdiction":"us","citation":"40 CFR 81.51","heading":"Portland Interstate Air Quality Control Region.","body":"The Portland Interstate Air Quality Control Region (Oregon-Washington) has been revised to consist of the territorial area encompassed by the boundaries of the following jurisdictions or described area (including the territorial area of all municipalities (as defined in section 302(f) of the Clean Air Act, 42 U.S.C. 1857h(f)) geographically located within the outermost boundaries of the area so delimited):\nIn the State of Oregon: Benton County, Clackamas County, Columbia County, Lane County, Linn County, Marion County, Multnomah County, Polk County, Washington County, Yamhill County.\nIn the State of Washington: Clark County, Cowlitz County, Lewis County, Skamania County, Wahkiakum County.\nNote:\nFor purposes of identification, the Portland Interstate Air Quality Control Region (Oregon-Washington) will be referred to by Washington authorities as the Portland (Oregon)-Southwest Washington Interstate Air Quality Control Region.","path":["Title 40—Protection of Environment","CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY","SUBCHAPTER C—AIR PROGRAMS","PART 81—DESIGNATION OF AREAS FOR AIR QUALITY PLANNING PURPOSES","Subpart B—Designation of Air Quality Control Regions"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-40.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:04Z","sha256":"adc294dd1015ba01bbb445a18b98275fe65817a91a5951bf729b0a35ab2f6744","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-81.50","next":"us/40-cfr-81.52"},"notice":"GroundRules: Original legal text. Not legal advice."}