{"data":{"id":"us/40-cfr-81.327","jurisdiction":"us","citation":"40 CFR 81.327","heading":"Montana.","body":"Montana—1971 Sulfur Dioxide NAAQS\n[Primary and Secondary]\nDesignated area Does not meet primary standards Does not meet secondary standards Cannot be classified Better than national standards\nLaurel Area X\nEast Helena Area X\nAnaconda Area X\nRest of State X\nMontana—2010 Sulfur Dioxide NAAQS\n[Primary]\nDesignated area 1 Designation\nDate 2 Type\nYellowstone County (part) 5/10/2016 Attainment.\nThe area originates at the point defined as the southwest corner of Section 11, Township 1S, Range 26E. From that point the boundary proceeds north along the western section line of Section 11 to the point of intersection with the midline of Interstate Highway 90. From that point the boundary follows the midline of Interstate Highway 90, across the Yellowstone River, to the point where the highway midline intersects the northern boundary of Section 35, Township 1N, Range 26E. From that point the boundary proceeds east along the northern section line of Sections 35 and 36 to the point where Old US 87/Hardin Road leaves the section line and turns southeast. The boundary follows the midline of Old US 87/Hardin Road southeast to the point where the road intersects the western boundary of the SE 1⁄4 of the SE 1⁄4 of Section 31, Township 1N, Range 27E. From that point the boundary proceeds south along the 1⁄4 section line to the southern boundary of Township 1N, then east to the northeast corner of Section 5, Township 1S, Range 27E. The boundary then proceeds south along the eastern section line of sections 5 and 8 to the southeast corner of Section 8, Township 1S, Range 27E, where it turns west and follows the south section line of Sections 8 and 7, Township 1S, Range 27E; and Sections 12 and 11, Township 1S, Range 26E, back to the point of origin\nBeaverhead County Attainment/Unclassifiable.\nBig Horn County Attainment/Unclassifiable.\nBlaine County Attainment/Unclassifiable.\nBroadwater County Attainment/Unclassifiable.\nCarbon County Attainment/Unclassifiable.\nCarter County Attainment/Unclassifiable.\nCascade County Attainment/Unclassifiable.\nChouteau County Attainment/Unclassifiable.\nCuster County Attainment/Unclassifiable.\nDaniels County Attainment/Unclassifiable.\nDawson County Attainment/Unclassifiable.\nDeer Lodge County Attainment/Unclassifiable.\nFallon County Attainment/Unclassifiable.\nFergus County Attainment/Unclassifiable.\nFlathead County Attainment/Unclassifiable.\nGallatin County Attainment/Unclassifiable.\nGarfield County Attainment/Unclassifiable.\nGlacier County Attainment/Unclassifiable.\nGolden Valley County Attainment/Unclassifiable.\nGranite County Attainment/Unclassifiable.\nHill County Attainment/Unclassifiable.\nJefferson County Attainment/Unclassifiable.\nJudith Basin County Attainment/Unclassifiable.\nLake County Attainment/Unclassifiable.\nLewis and Clark County Attainment/Unclassifiable.\nLiberty County Attainment/Unclassifiable.\nLincoln County Attainment/Unclassifiable.\nMcCone County Attainment/Unclassifiable.\nMadison County Attainment/Unclassifiable.\nMeagher County Attainment/Unclassifiable.\nMineral County Attainment/Unclassifiable.\nMissoula County Attainment/Unclassifiable.\nMusselshell County Attainment/Unclassifiable.\nPark County Attainment/Unclassifiable.\nPetroleum County Attainment/Unclassifiable.\nPhillips County Attainment/Unclassifiable.\nPondera County Attainment/Unclassifiable.\nPowder River County Attainment/Unclassifiable.\nPowell County Attainment/Unclassifiable.\nPrairie County Attainment/Unclassifiable.\nRavalli County Attainment/Unclassifiable.\nRichland County Attainment/Unclassifiable.\nRoosevelt County Attainment/Unclassifiable.\nRosebud County Attainment/Unclassifiable.\nSanders County Attainment/Unclassifiable.\nSheridan County Attainment/Unclassifiable.\nSilver Bow County Attainment/Unclassifiable.\nStillwater County Attainment/Unclassifiable.\nSweet Grass County Attainment/Unclassifiable.\nTeton County Attainment/Unclassifiable.\nToole County Attainment/Unclassifiable.\nTreasure County Attainment/Unclassifiable.\nValley County Attainment/Unclassifiable.\nWheatland County Attainment/Unclassifiable.\nWibaux County Attainment/Unclassifiable.\nYellowstone County (part) (remainder) Attainment/Unclassifiable.\n1 Includes any Indian country in each county or area, unless otherwise specified. EPA is not determining the boundaries of any area of Indian country in this table, including any area of Indian country located in the larger designation area. The inclusion of any Indian country in the designation area is not a determination that the state has regulatory authority under the Clean Air Act for such Indian country.\n2 This date is April 9, 2018, unless otherwise noted.\nMontana—Carbon Monoxide\nDesignated Area Designation Classification\nDate 1 Type Date 1 Type\nBillings Area\nYellowstone County (part):\nThe following areas of Yellowstone Co. (Range and Township) sections: R25E T1N—Sections 24 through 27 and 34 through 36; R25E T1S—Sections 1, 2, and 12; R26E T1N Sections 19 through 22 and 27 through 34; R26E T1S Sections 2 through 11 and 15 through 18. April 22, 2002. Attainment\nGreat Falls Area July 8, 2002 Attainment\nCascade County (part)\nGreat Falls designated area: North boundary—9th Avenue South or its straight line extension; East boundary—54th Street South or its straight line extension; South boundary—11th Avenue South or its straight line extension; West boundary—2nd Street South or its straight line extension\nMissoula Area:\nMissoula County (part) September 17, 2007 Attainment\nMissoula and vicinity including the following (Range and Township) sections: R19W T14N—sections: 29 and 32; R19W T13N—sections 2, 5, 7, 8, 11, 14 through 24, and 26 through 34; R19W T12N—sections: 4 through 7; R20W T13N—sections: 23 through 26, 35 and 36\nBeaverhead County Unclassifiable/Attainment\nBig Horn County (part) excluding Crow, Northern Cheyenne Indian Reservations Unclassifiable/Attainment\nBlaine County (part) excluding Fort Belknap Indian Reservation Unclassifiable/Attainment\nBroadwater County Unclassifiable/Attainment\nCarbon County Unclassifiable/Attainment\nCarter County Unclassifiable/Attainment\nCascade County (part)\nRemainder of Cascade County Unclassifiable/Attainment\nChouteau County (part) excluding Rocky Boy Indian Reservation Unclassifiable/Attainment\nCuster County Unclassifiable/Attainment\nDaniels County (part) excluding Fort Peck Indian Reservation Unclassifiable/Attainment\nDawson County Unclassifiable/Attainment\nDeer Lodge County Unclassifiable/Attainment\nFallon County Unclassifiable/Attainment\nFergus County Unclassifiable/Attainment\nFlathead County (part) excluding Flathead Indian Resevation Unclassifiable/Attainment\nGallatin County Unclassifiable/Attainment\nGarfield County Unclassifiable/Attainment\nGlacier County (part) excluding Blackfeet Indian Reservation Unclassifiable/Attainment\nGolden Valley County Unclassifiable/Attainment\nGranite County Unclassifiable/Attainment\nHill County (part) excluding Rocky Boy Indian Reservation Unclassifiable/Attainment\nJefferson County Unclassifiable/Attainment\nJudith Basin County Unclassifiable/Attainment\nLake County (part) excluding Flathead Indian Reservation Unclassifiable/Attainment\nLewis and Clark County Unclassifiable/Attainment\nLiberty County Unclassifiable/Attainment\nLincoln County Unclassifiable/Attainment\nMadison County Unclassifiable/Attainment\nMcCone County Unclassifiable/Attainment\nMeagher County Unclassifiable/Attainment\nMineral County Unclassifiable/Attainment\nMissoula County (part)\nRemainder of Missoula County Unclassifiable/Attainment\nMusselshell County Unclassifiable/Attainment\nPark County Unclassifiable/Attainment\nPetroleum County Unclassifiable/Attainment\nPhillips County (part) excluding Fort Belknap Indian Reservation Unclassifiable/Attainment\nPondera County (part) excluding Blackfeet Indian Reservation Unclassifiable/Attainment\nPowder River County Unclassifiable/Attainment\nPowell County Unclassifiable/Attainment\nPrairie County Unclassifiable/Attainment\nRavalli County Unclassifiable/Attainment\nRichland County Unclassifiable/Attainment\nRoosevelt County (part) excluding Fort Peck Indian Reservation Unclassifiable/Attainment\nRosebud County (part) excluding Northern Cheyenne Indian Reservation Unclassifiable/Attainment\nSanders County (part) excluding Flathead Indian Reservation Unclassifiable/Attainment\nSheridan County (part) excluding Fort Peck Indian Reservation Unclassifiable/Attainment\nSilver Bow County Unclassifiable/Attainment\nStillwater County Unclassifiable/Attainment\nSweet Grass County Unclassifiable/Attainment\nTeton County Unclassifiable/Attainment\nToole County Unclassifiable/Attainment\nTreasure County Unclassifiable/Attainment\nValley County (part) excluding Fort Peck Indian Reservation Unclassifiable/Attainment\nWheatland County Unclassifiable/Attainment\nWibaux County Unclassifiable/Attainment\nYellowstone County (part)\nRemainder of Yellowstone County Unclassifiable/Attainment\nYellowstone National Park Unclassifiable/Attainment\nBlackfeet Indian Reservation Unclassifiable/Attainment\nGlacier County (part)\narea inside Blackfeet Reservation\nPondera County (part)\narea inside Blackfeet Reservation\nCrow Indian Reservation Unclassifiable/Attainment\nBighorn County (part)\narea inside Crow Reservation\nYellowstone (part)\narea inside Crow Reservation\nFlathead Indian Reservation Unclassifiable/Attainment\nFlathead County (part)\narea inside Flathead Reservation\nLake County (part)\narea inside Flathead Reservation\nMissoula County (part)\narea inside Flathead Reservation\nSanders County (part)\narea inside Flathead Reservation\nFort Belknap Indian Reservation Unclassifiable/Attainment\nBlaine County (part)\narea inside Fort Belknap Reservation\nPhillips County (part)\narea inside Fort Belknap Reservation\nFort Peck Indian Reservation Unclassifiable/Attainment\nDaniels County (part)\narea inside Fort Peck Reservation\nRoosevelt County (part)\narea inside Fort Peck Reservation\nSheridan County (part)\narea inside Fort Peck Reservation\nValley County (part)\narea inside Fort Peck Reservation\nNorthern Cheyenne Indian Reservation Unclassifiable/Attainment\nBighorn County (part)\narea inside Northern Cheyenne Reservation\nRosebud County (part)\narea inside Northern Cheyenne Reservation\nRocky Boy Indian Reservation Unclassifiable/Attainment\nChouteau County (part)\narea inside Rocky Boy Reservation\nHill County (part)\narea inside Rocky Boy Reservation\n1 This date is November 15, 1990, unless otherwise noted.\nMontana—1978 Lead NAAQS\nDesignated Area Designation Classification\nDate Type Date Type\nLewis \u0026 Clark County (part)\nCity of East Helena and vicinity October 11, 2019 Attainment.\nNorthern boundary - horizontal universal transverse mercatur(UTM) 5,162,000 mN; eastern boundary - vertical UTM 432,500 mE; southern boundary - horizontal UTM 5,158,000 mN; western boundary - vertical UTM 427,000 mE\nRest of State Not Designated\nMontana—Ozone (1-Hour Standard)2\nDesignated area Designation Classification\nDate 1 Type Date 1 Type\nBeaverhead County Unclassifiable/Attainment\nBig Horn County (part) excluding Crow, Northern Cheyenne Indian Reservations Unclassifiable/Attainment\nBlaine County (part) excluding Fort Belknap Indian Reservation\nBroadwater County Unclassifiable/Attainment\nCarbon County Unclassifiable/Attainment\nCarter County Unclassifiable/Attainment\nCascade County Unclassifiable/Attainment\nChouteau County (part) excluding Rocky Boy Indian Reservation Unclassifiable/Attainment\nCuster County Unclassifiable/Attainment\nDaniels County (part) excluding Fort Peck Indian Reservation Unclassifiable/Attainment\nDawson County Unclassifiable/Attainment\nDeer Lodge County Unclassifiable/Attainment\nFallon County Unclassifiable/Attainment\nFergus County Unclassifiable/Attainment\nFlathead County (part) excluding Flathead Indian Reservation Unclassifiable/Attainment\nGallatin County Unclassifiable/Attainment\nGarfield County Unclassifiable/Attainment\nGlacier County (part) excluding Blackfeet Indian Reservation Unclassifiable/Attainment\nGolden Valley County Unclassifiable/Attainment\nGranite County Unclassifiable/Attainment\nHill County (part) excluding Rocky Boy Indian Reservation Unclassifiable/Attainment\nJefferson County Unclassifiable/Attainment\nJudith Basin County Unclassifiable/Attainment\nLake County (part) excluding Flathead Indian Reservation Unclassifiable/Attainment\nLewis and Clark County Unclassifiable/Attainment\nLiberty County Unclassifiable/Attainment\nLincoln County Unclassifiable/Attainment\nMadison County Unclassifiable/Attainment\nMcCone County Unclassifiable/Attainment\nMeagher County Unclassifiable/Attainment\nMineral County Unclassifiable/Attainment\nMissoula County (part) excluding Flathead Indian Reservation Unclassifiable/Attainment\nMusselshell County Unclassifiable/Attainment\nPark County Unclassifiable/Attainment\nPetroleum County Unclassifiable/Attainment\nPhillips County (part) excluding Fort Belknap Indian Reservation Unclassifiable/Attainment\nPondera County (part) excluding Blackfeet Indian Reservation Unclassifiable/Attainment\nPowder River County Unclassifiable/Attainment\nPowell County Unclassifiable/Attainment\nPrairie County Unclassifiable/Attainment\nRavalli County Unclassifiable/Attainment\nRichland County Unclassifiable/Attainment\nRoosevelt County (part) excluding Fort Peck Indian Reservation Unclassifiable/Attainment\nRosebud County (part) excluding Northern Cheyenne Indian Reservation Unclassifiable/Attainment\nSanders County (part) excluding Flathead Indian Reservation Unclassifiable/Attainment\nSheridan County (part) excluding Fort Peck Indian Reservation Unclassifiable/Attainment\nSilver Bow County Unclassifiable/Attainment\nStillwater County Unclassifiable/Attainment\nSweet Grass County Unclassifiable/Attainment\nTeton County Unclassifiable/Attainment\nToole County Unclassifiable/Attainment\nTreasure County Unclassifiable/Attainment\nValley County (part) excluding Fort Peck Indian Reservation Unclassifiable/Attainment\nWheatland County Unclassifiable/Attainment\nWibaux County Unclassifiable/Attainment\nYellowstone County (part) excluding Crow Indian Reservation Unclassifiable/Attainment\nYellowstone Natl Park Unclassifiable/Attainment\nBlackfeet Indian Reservation Unclassifiable/Attainment\nGlacier County (part) area inside Blackfeet Reservation\nPondera County (part) area inside Blackfeet Reservation\nCrow Indian Reservation Unclassifiable/Attainment\nBighorn County (part) area inside Crow Reservation\nYellowstone (part) area inside Crow Reservation\nFlathead Indian Reservation Unclassifiable/Attainment\nFlathead County (part) area inside Flathead Reservation\nLake County (part) area inside Flathead Reservation\nMissoula County (part) area inside Flathead Reservation\nSanders County (part) area inside Flathead Reservation\nFort Belknap Indian Reservation Unclassifiable/Attainment\nBlaine County (part) area inside Fort Belknap Reservation\nPhillips County (part) area inside Fort Belknap Reservation\nFort Peck Indian Reservation Unclassifiable/Attainment\nDaniels County (part) area inside Fort Peck Reservation\nRoosevelt County (part) area inside Fort Peck Reservation\nSheridan County (part) area inside Fort Peck Reservation\nValley County (part) area inside Fort Peck Reservation\nNorthern Cheyenne Indian Reservation Unclassifiable/Attainment\nBighorn County (part) area inside Northern Cheyenne Reservation\nRosebud County (part) area inside Northern Cheyenne Reservation\nRocky Boy Indian Reservation Unclassifiable/Attainment\nChouteau County (part) area inside Rocky Boy Reservation\nHill County (part) area inside Rocky Boy Reservation\n1 This date is October 18, 2000, unless otherwise noted.\n2 The 1-hour ozone standard is revoked effective June 15, 2005 for all areas in Montana.\nMontana—PM-10\nDesignated Area Designation Classification\nDate Type Date Type\nCascade County, Great Falls area 11/15/1990 Unclassifiable\nFlathead County:\nThe area bounded by lines from Universal Transmercator (UTM) coordinate 700000mE, 5347000mN, east to 704000mE, 5347000mN, south to 704000mE, 5341000mN, west to 703000mE, 5341000mN, south to 703000mE, 5340000mN, west to 702000mE, 5340000mN, south to 702000mE, 5339000mN, east to 703000mE, 5339000mN, south to 703000mE, 5338000mN, east to 704000mE, 5338000mN, south to 704000mE, 5336000mN, west to 702000mE, 5336000mN, south to 702000mE, 5335000mN, west to 700000mE, 5335000mN, north to 700000mE, 5340000mN, west to 695000mE, 5340000mN, north to 695000mE, 5345000mN, east to 700000mE, 5345000mN, north to 700000mE, 5347000mN 7/27/2020 Attainment\nColumbia Falls and vicinity 11/15/1990 Nonattainment 11/15/1990 Moderate.\nTownship T30N, R20W—Sections 7, 8, 9, 16, 17, and 18\nThe City of Whitefish and surrounding vicinity bounded by lines from Universal Transmercator (UTM) coordinates 695000 mE, 5370000 mN, east to 699000 mE, 5370000 mN, south to 699000 mE, 5361000 mN, west to 695000 mN, 5361000 mN, and north to 695000 mE, 5370000 mN 7/8/2022 Attainment\nLake County, Ronan, Polson 11/15/1990 Nonattainment 11/15/1990 Moderate.\nLincoln County, Libby and vicinity 11/15/1990 Nonattainment 11/15/1990 Moderate.\nT30N, R31W—Sections 2, 3, 4, 5, 9, 10, 11, 14, 15, 23, 26, 35, and west 1⁄2 of Section 24, west 1⁄2 of Section 25, and west 1⁄2 of Section 36; plus T31N, R31W—Sections 26, 27, 29, 32, 33, 34, 35 and the east 1⁄2 of Section 30.\nLewis and Clark County, East Helena area 11/15/1990 Unclassifiable\nMissoula County, Missoula and vicinity including the following sections: 6/24/2019 Attainment\nT13N, R19W—2, 8, 11, 14, 15, 16, 17, 19, 20, 21, 22, 23, 24, 27, 28, 29, 30, 31, 32, 33, and 34; T12N, R19W—Sections 4, 5, 6, 7; T13N, R20W—Sections 23, 24, 25, 26, 35, and 36.\nRosebud County:\nLame Deer 11/15/1990 Nonattainment 11/15/1990 Moderate.\nColstrip area 11/15/1990 Unclassifiable\nSanders County (part) 7/8/2022 Attainment\nThompson Falls and vicinity: Including the following Sections: R29W, T21N—Sections 5, 6, 7, 8, 9, 10, 15, and 16\nSilver Bow County, Butte 7/26/2021 Attainment.\nThe following area of Butte-Silver Bow excluding the territorial limits of the City of Walkerville: Beginning at the Northwest corner of Section 2, T.3N., R.8W., thence Easterly to Northeast corner Section 5, T.3N., R.7W.; then Southerly to Northwest corner Section 9, T.3N., R.7W.; thence Easterly to Northeast corner Section 10, T.3N., R.7W.; thence Southerly to Southeast corner Section 22, T.2N., R.7W.; thence Westerly to Southwest corner Section 19, T.2N., R.7W.; thence Northerly to Northwest corner Section 19, T.2N., R.7W.; thence Westerly to Southwest corner Section 14, T.2N., R.8W.; thence Northerly to Southwest corner Section 35, T.3N., R.8W.; thence Westerly to Southwest corner Section 34, T.3N., R.8W.; thence Northerly to Northwest corner Section 27, T.3N., R.8W.; thence Westerly to Southwest corner Section 20, T.3N., R.8W.; thence Northerly to Northwest corner Section 17, T.3N., R.8W.; thence Easterly to Northwest corner Section 14, T.3N., R.8W.; thence Northerly to the point of beginning.\nYellowstone County, Billings area 11/15/1990 Unclassifiable\nRest of State1 11/15/1990 Unclassifiable\n1 Denotes a single area designation for PSD baseline area purposes.\nMontana—1997 Annual PM2.5 NAAQS\n[Primary and Secondary]\nDesignated area Designation a Classification\nDate 1 Type Date 2 Type\nLibby, MT:\nLincoln County (part) 8/23/2023 Attainment\nThe area bounded by lines from Universal Transverse Mercador Zone 11 (North American Datum 1983) coordinates beginning at 600,000mE, 5,370,000mN east to 620,000mE, 5370,000mN south to 620,000mE, 5340,000mN west to 600,000mE, 5,340,000mN north to 600,000mE, 5,370,000mN\nRest of State:\nBeaverhead County Unclassifiable/Attainment.\nBig Horn County Unclassifiable/Attainment.\nBlaine County Unclassifiable/Attainment.\nBroadwater County Unclassifiable/Attainment.\nCarbon County Unclassifiable/Attainment.\nCarter County Unclassifiable/Attainment.\nCascade County Unclassifiable/Attainment.\nChouteau County Unclassifiable/Attainment.\nCuster County Unclassifiable/Attainment.\nDaniels County Unclassifiable/Attainment.\nDawson County Unclassifiable/Attainment.\nDeer Lodge County Unclassifiable/Attainment.\nFallon County Unclassifiable/Attainment.\nFergus County Unclassifiable/Attainment.\nFlathead County Unclassifiable/Attainment.\nGallatin County Unclassifiable/Attainment.\nGarfield County Unclassifiable/Attainment.\nGlacier County Unclassifiable/Attainment.\nGolden Valley County Unclassifiable/Attainment.\nGranite County Unclassifiable/Attainment.\nHill County Unclassifiable/Attainment.\nJefferson County Unclassifiable/Attainment.\nJudith Basin County Unclassifiable/Attainment.\nLake County Unclassifiable/Attainment.\nLewis and Clark County Unclassifiable/Attainment.\nLiberty County Unclassifiable/Attainment.\nLincoln County (remainder) Unclassifiable/Attainment.\nMcCone County Unclassifiable/Attainment.\nMadison County Unclassifiable/Attainment.\nMeagher County Unclassifiable/Attainment.\nMineral County Unclassifiable/Attainment.\nMissoula County Unclassifiable/Attainment.\nMusselshell County Unclassifiable/Attainment.\nPark County Unclassifiable/Attainment.\nPetroleum County Unclassifiable/Attainment.\nPhillips County Unclassifiable/Attainment.\nPondera County Unclassifiable/Attainment.\nPowder River County Unclassifiable/Attainment.\nPowell County Unclassifiable/Attainment.\nPrairie County Unclassifiable/Attainment.\nRavalli County Unclassifiable/Attainment.\nRichland County Unclassifiable/Attainment.\nRoosevelt County Unclassifiable/Attainment.\nRosebud County Unclassifiable/Attainment.\nSanders County Unclassifiable/Attainment.\nSheridan County Unclassifiable/Attainment.\nSilver Bow County Unclassifiable/Attainment.\nStillwater County Unclassifiable/Attainment.\nSweet Grass County Unclassifiable/Attainment.\nTeton County Unclassifiable/Attainment.\nToole County Unclassifiable/Attainment.\nTreasure County Unclassifiable/Attainment.\nValley County Unclassifiable/Attainment.\nWheatland County Unclassifiable/Attainment.\nWibaux County Unclassifiable/Attainment.\nYellowstone County Unclassifiable/Attainment.\na Includes Indian Country located in each county or area, except as otherwise specified.\n1 This date is 90 days after January 5, 2005, unless otherwise noted.\n2 This date is July 2, 2014, unless otherwise noted.\nMontana—2012 Annual PM2.5 NAAQS\n[Primary]\nDesignated area 1 Designation Classification\nDate 2 Type Date 2 Type\nStatewide:\nBeaverhead County Unclassifiable/Attainment\nBig Horn County Unclassifiable/Attainment\nBlaine County Unclassifiable/Attainment\nBroadwater County Unclassifiable/Attainment\nCarbon County Unclassifiable/Attainment\nCarter County Unclassifiable/Attainment\nCascade County Unclassifiable/Attainment\nChouteau County Unclassifiable/Attainment\nCuster County Unclassifiable/Attainment\nDaniels County Unclassifiable/Attainment\nDawson County Unclassifiable/Attainment\nDeer Lodge County Unclassifiable/Attainment\nFallon County Unclassifiable/Attainment\nFergus County Unclassifiable/Attainment\nFlathead County Unclassifiable/Attainment\nGallatin County Unclassifiable/Attainment\nGarfield County Unclassifiable/Attainment\nGlacier County Unclassifiable/Attainment\nGolden Valley County Unclassifiable/Attainment\nGranite County Unclassifiable/Attainment\nHill County Unclassifiable/Attainment\nJefferson County Unclassifiable/Attainment\nJudith Basin County Unclassifiable/Attainment\nLake County Unclassifiable/Attainment\nLewis and Clark County Unclassifiable/Attainment\nLiberty County Unclassifiable/Attainment\nLincoln County Unclassifiable/Attainment\nMcCone County Unclassifiable/Attainment\nMadison County Unclassifiable/Attainment\nMeagher County Unclassifiable/Attainment\nMineral County Unclassifiable/Attainment\nMissoula County Unclassifiable/Attainment\nMusselshell County Unclassifiable/Attainment\nPark County Unclassifiable/Attainment\nPetroleum County Unclassifiable/Attainment\nPhillips County Unclassifiable/Attainment\nPondera County Unclassifiable/Attainment\nPowder River County Unclassifiable/Attainment\nPowell County Unclassifiable/Attainment\nPrairie County Unclassifiable/Attainment\nRavalli County Unclassifiable/Attainment\nRichland County Unclassifiable/Attainment\nRoosevelt County Unclassifiable/Attainment\nRosebud County Unclassifiable/Attainment\nSanders County Unclassifiable/Attainment\nSheridan County Unclassifiable/Attainment\nSilver Bow County Unclassifiable/Attainment\nStillwater County Unclassifiable/Attainment\nSweet Grass County Unclassifiable/Attainment\nTeton County Unclassifiable/Attainment\nToole County Unclassifiable/Attainment\nTreasure County Unclassifiable/Attainment\nValley County Unclassifiable/Attainment\nWheatland County Unclassifiable/Attainment\nWibaux County Unclassifiable/Attainment\nYellowstone County Unclassifiable/Attainment\n1 Includes areas of Indian country located in each county or area, except as otherwise specified.\n2 This date is April 15, 2015, unless otherwise noted.\nMontana—1997 24-Hour PM2.5 NAAQS\n[Primary and Secondary]\nDesignated area Designation a Classification\nDate 1 Type Date Type\nStatewide:\nBeaverhead County Unclassifiable/Attainment.\nBig Horn County Unclassifiable/Attainment.\nBlaine County Unclassifiable/Attainment.\nBroadwater County Unclassifiable/Attainment.\nCarbon County Unclassifiable/Attainment.\nCarter County Unclassifiable/Attainment.\nCascade County Unclassifiable/Attainment.\nChouteau County Unclassifiable/Attainment.\nCuster County Unclassifiable/Attainment.\nDaniels County Unclassifiable/Attainment.\nDawson County Unclassifiable/Attainment.\nDeer Lodge County Unclassifiable/Attainment.\nFallon County Unclassifiable/Attainment.\nFergus County Unclassifiable/Attainment.\nFlathead County Unclassifiable/Attainment.\nGallatin County Unclassifiable/Attainment.\nGarfield County Unclassifiable/Attainment.\nGlacier County Unclassifiable/Attainment.\nGolden Valley County Unclassifiable/Attainment.\nGranite County Unclassifiable/Attainment.\nHill County Unclassifiable/Attainment.\nJefferson County Unclassifiable/Attainment.\nJudith Basin County Unclassifiable/Attainment.\nLake County Unclassifiable/Attainment.\nLewis and Clark County Unclassifiable/Attainment.\nLiberty County Unclassifiable/Attainment.\nLincoln County Unclassifiable/Attainment.\nMcCone County Unclassifiable/Attainment.\nMadison County Unclassifiable/Attainment.\nMeagher County Unclassifiable/Attainment.\nMineral County Unclassifiable/Attainment.\nMissoula County Unclassifiable/Attainment.\nMusselshell County Unclassifiable/Attainment.\nPark County Unclassifiable/Attainment.\nPetroleum County Unclassifiable/Attainment.\nPhillips County Unclassifiable/Attainment.\nPondera County Unclassifiable/Attainment.\nPowder River County Unclassifiable/Attainment.\nPowell County Unclassifiable/Attainment.\nPrairie County Unclassifiable/Attainment.\nRavalli County Unclassifiable/Attainment.\nRichland County Unclassifiable/Attainment.\nRoosevelt County Unclassifiable/Attainment.\nRosebud County Unclassifiable/Attainment.\nSanders County Unclassifiable/Attainment.\nSheridan County Unclassifiable/Attainment.\nSilver Bow County Unclassifiable/Attainment.\nStillwater County Unclassifiable/Attainment.\nSweet Grass County Unclassifiable/Attainment.\nTeton County Unclassifiable/Attainment.\nToole County Unclassifiable/Attainment.\nTreasure County Unclassifiable/Attainment.\nValley County Unclassifiable/Attainment.\nWheatland County Unclassifiable/Attainment.\nWibaux County Unclassifiable/Attainment.\nYellowstone County Unclassifiable/Attainment.\na Includes Indian Country located in each county or area, except as otherwise specified.\n1 This date is 90 days after January 5, 2005, unless otherwise noted.\nMontana—2006 24-Hour PM2.5 NAAQS\n[Primary and Secondary]\nDesignated area Designation a Classification\nDate 1 Type Date Type\nStatewide:\nBeaverhead County Unclassifiable/Attainment.\nBig Horn County Unclassifiable/Attainment.\nBlaine County Unclassifiable/Attainment.\nBroadwater County Unclassifiable/Attainment.\nCarbon County Unclassifiable/Attainment.\nCarter County Unclassifiable/Attainment.\nCascade County Unclassifiable/Attainment.\nChouteau County Unclassifiable/Attainment.\nCuster County Unclassifiable/Attainment.\nDaniels County Unclassifiable/Attainment.\nDawson County Unclassifiable/Attainment.\nDeer Lodge County Unclassifiable/Attainment.\nFallon County Unclassifiable/Attainment.\nFergus County Unclassifiable/Attainment.\nFlathead County Unclassifiable/Attainment.\nGallatin County Unclassifiable/Attainment.\nGarfield County Unclassifiable/Attainment.\nGlacier County Unclassifiable/Attainment.\nGolden Valley County Unclassifiable/Attainment.\nGranite County Unclassifiable/Attainment.\nHill County Unclassifiable/Attainment.\nJefferson County Unclassifiable/Attainment.\nJudith Basin County Unclassifiable/Attainment.\nLake County Unclassifiable/Attainment.\nLewis and Clark County Unclassifiable/Attainment.\nLiberty County Unclassifiable/Attainment.\nLincoln County Unclassifiable/Attainment.\nMcCone County Unclassifiable/Attainment.\nMadison County Unclassifiable/Attainment.\nMeagher County Unclassifiable/Attainment.\nMineral County Unclassifiable/Attainment.\nMissoula County Unclassifiable/Attainment.\nMusselshell County Unclassifiable/Attainment.\nPark County Unclassifiable/Attainment.\nPetroleum County Unclassifiable/Attainment.\nPhillips County Unclassifiable/Attainment.\nPondera County Unclassifiable/Attainment.\nPowder River County Unclassifiable/Attainment.\nPowell County Unclassifiable/Attainment.\nPrairie County Unclassifiable/Attainment.\nRavalli County Unclassifiable/Attainment.\nRichland County Unclassifiable/Attainment.\nRoosevelt County Unclassifiable/Attainment.\nRosebud County Unclassifiable/Attainment.\nSanders County Unclassifiable/Attainment.\nSheridan County Unclassifiable/Attainment.\nSilver Bow County Unclassifiable/Attainment.\nStillwater County Unclassifiable/Attainment.\nSweet Grass County Unclassifiable/Attainment.\nTeton County Unclassifiable/Attainment.\nToole County Unclassifiable/Attainment.\nTreasure County Unclassifiable/Attainment.\nValley County Unclassifiable/Attainment.\nWheatland County Unclassifiable/Attainment.\nWibaux County Unclassifiable/Attainment.\nYellowstone County Unclassifiable/Attainment.\na Includes Indian Country located in each county or area, except as otherwise specified.\n1 This date is 30 days after November 13, 2009, unless otherwise noted.\nMontana—NO2 (1971 Annual Standard)\nDesignated area Does not meet primary standards Cannot be classified or better than national standards\nEntire State X\nMontana—NO2 (2010 1-Hour Standard)\nDesignated area Designation a\nDate 1 Type\nBeaverhead County Unclassifiable/Attainment.\nBig Horn County Unclassifiable/Attainment.\nBlaine County Unclassifiable/Attainment.\nBroadwater County Unclassifiable/Attainment.\nCarbon County Unclassifiable/Attainment.\nCarter County Unclassifiable/Attainment.\nCascade County Unclassifiable/Attainment.\nChouteau County Unclassifiable/Attainment.\nCuster County Unclassifiable/Attainment.\nDaniels County Unclassifiable/Attainment.\nDawson County Unclassifiable/Attainment.\nDeer Lodge County Unclassifiable/Attainment.\nFallon County Unclassifiable/Attainment.\nFergus County Unclassifiable/Attainment.\nFlathead County Unclassifiable/Attainment.\nGallatin County Unclassifiable/Attainment.\nGarfield County Unclassifiable/Attainment.\nGlacier County Unclassifiable/Attainment.\nGolden Valley County Unclassifiable/Attainment.\nGranite County Unclassifiable/Attainment.\nHill County Unclassifiable/Attainment.\nJefferson County Unclassifiable/Attainment.\nJudith Basin County Unclassifiable/Attainment.\nLake County Unclassifiable/Attainment.\nLewis and Clark County Unclassifiable/Attainment.\nLiberty County Unclassifiable/Attainment.\nLincoln County Unclassifiable/Attainment.\nMcCone County Unclassifiable/Attainment.\nMadison County Unclassifiable/Attainment.\nMeagher County Unclassifiable/Attainment.\nMineral County Unclassifiable/Attainment.\nMissoula County Unclassifiable/Attainment.\nMusselshell County Unclassifiable/Attainment.\nPark County Unclassifiable/Attainment.\nPetroleum County Unclassifiable/Attainment.\nPhillips County Unclassifiable/Attainment.\nPondera County Unclassifiable/Attainment.\nPowder River County Unclassifiable/Attainment.\nPowell County Unclassifiable/Attainment.\nPrairie County Unclassifiable/Attainment.\nRavalli County Unclassifiable/Attainment.\nRichland County Unclassifiable/Attainment.\nRoosevelt County Unclassifiable/Attainment.\nRosebud County Unclassifiable/Attainment.\nSanders County Unclassifiable/Attainment.\nSheridan County Unclassifiable/Attainment.\nSilver Bow County Unclassifiable/Attainment.\nStillwater County Unclassifiable/Attainment.\nSweet Grass County Unclassifiable/Attainment.\nTeton County Unclassifiable/Attainment.\nToole County Unclassifiable/Attainment.\nTreasure County Unclassifiable/Attainment.\nValley County Unclassifiable/Attainment.\nWheatland County Unclassifiable/Attainment.\nWibaux County Unclassifiable/Attainment.\nYellowstone County Unclassifiable/Attainment.\na Includes Indian Country located in each county or area, except as otherwise specified.\n1 This date is 90 days after October 31, 2011, unless otherwise noted.\nMontana—1997 8-Hour Ozone NAAQS\n[Primary and Secondary]\nDesignated area Designation a Category/classification\nDate 1 Type Date 1 Type\nStatewide:\nBeaverhead County Unclassifiable/Attainment\nBig Horn County Unclassifiable/Attainment\nBlaine County Unclassifiable/Attainment\nBroadwater County Unclassifiable/Attainment\nCarbon County Unclassifiable/Attainment\nCarter County Unclassifiable/Attainment\nCascade County Unclassifiable/Attainment\nChouteau County Unclassifiable/Attainment\nCuster County Unclassifiable/Attainment\nDaniels County Unclassifiable/Attainment\nDawson County Unclassifiable/Attainment\nDeer Lodge County Unclassifiable/Attainment\nFallon County Unclassifiable/Attainment\nFergus County Unclassifiable/Attainment\nFlathead County Unclassifiable/Attainment\nGallatin County Unclassifiable/Attainment\nGarfield County Unclassifiable/Attainment\nGlacier County Unclassifiable/Attainment\nGolden Valley County Unclassifiable/Attainment\nGranite County. Unclassifiable/Attainment\nHill County Unclassifiable/Attainment\nJefferson County Unclassifiable/Attainment\nJudith Basin County Unclassifiable/Attainment\nLake County Unclassifiable/Attainment\nLewis and Clark County Unclassifiable/Attainment\nLiberty County Unclassifiable/Attainment\nLincoln County Unclassifiable/Attainment\nMadison County Unclassifiable/Attainment\nMcCone County Unclassifiable/Attainment\nMeagher County Unclassifiable/Attainment\nMineral County Unclassifiable/Attainment\nMissoula County Unclassifiable/Attainment\nMusselshell County Unclassifiable/Attainment\nPark County Unclassifiable/Attainment\nPetroleum County Unclassifiable/Attainment\nPhillips County Unclassifiable/Attainment\nPondera County Unclassifiable/Attainment\nPowder River County Unclassifiable/Attainment\nPowell County Unclassifiable/Attainment\nPrairie County Unclassifiable/Attainment\nRavalli County Unclassifiable/Attainment\nRichland County Unclassifiable/Attainment\nRoosevelt County Unclassifiable/Attainment\nRosebud County Unclassifiable/Attainment\nSanders County Unclassifiable/Attainment\nSheridan County Unclassifiable/Attainment\nSilver Bow County Unclassifiable/Attainment\nStillwater County Unclassifiable/Attainment\nSweet Grass County Unclassifiable/Attainment\nTeton County Unclassifiable/Attainment\nToole County Unclassifiable/Attainment\nTreasure County Unclassifiable/Attainment\nValley County Unclassifiable/Attainment\nWheatland County Unclassifiable/Attainment\nWibaux County Unclassifiable/Attainment\nYellowstone County Unclassifiable/Attainment\nYellowstone Natl Park Unclassifiable/Attainment\na Includes Indian Country located in each county or area, except as otherwise specified.\n1 This date is June 15, 2004, unless otherwise noted.\nMontana—2008 8-Hour Ozone NAAQS\n[Primary and Secondary]\nDesignated area Designation Classification\nDate 1 Type Date 1 Type\nStatewide and Any Areas of Indian Country Unclassifiable/Attainment\n1 This date is July 20, 2012, unless otherwise noted.\nMontana—2015 8-Hour Ozone NAAQS\n[Primary and Secondary]\nDesignated area 1 Designation Classification\nDate 2 Type Date Type\nBeaverhead County Attainment/Unclassifiable.\nBig Horn County Attainment/Unclassifiable.\nBlaine County Attainment/Unclassifiable.\nBroadwater County Attainment/Unclassifiable.\nCarbon County Attainment/Unclassifiable.\nCarter County Attainment/Unclassifiable.\nCascade County Attainment/Unclassifiable.\nChouteau County Attainment/Unclassifiable.\nCuster County Attainment/Unclassifiable.\nDaniels County Attainment/Unclassifiable.\nDawson County Attainment/Unclassifiable.\nDeer Lodge County Attainment/Unclassifiable.\nFallon County Attainment/Unclassifiable.\nFergus County Attainment/Unclassifiable.\nFlathead County Attainment/Unclassifiable.\nGallatin County Attainment/Unclassifiable.\nGarfield County Attainment/Unclassifiable.\nGlacier County Attainment/Unclassifiable.\nGolden Valley County Attainment/Unclassifiable.\nGranite County Attainment/Unclassifiable.\nHill County Attainment/Unclassifiable.\nJefferson County Attainment/Unclassifiable.\nJudith Basin County Attainment/Unclassifiable.\nLake County Attainment/Unclassifiable.\nLewis and Clark County Attainment/Unclassifiable.\nLiberty County Attainment/Unclassifiable.\nLincoln County Attainment/Unclassifiable.\nMcCone County Attainment/Unclassifiable.\nMadison County Attainment/Unclassifiable.\nMeagher County Attainment/Unclassifiable.\nMineral County Attainment/Unclassifiable.\nMissoula County Attainment/Unclassifiable.\nMusselshell County Attainment/Unclassifiable.\nPark County Attainment/Unclassifiable.\nPetroleum County Attainment/Unclassifiable.\nPhillips County Attainment/Unclassifiable.\nPondera County Attainment/Unclassifiable.\nPowder River County Attainment/Unclassifiable.\nPowell County Attainment/Unclassifiable.\nPrairie County Attainment/Unclassifiable.\nRavalli County Attainment/Unclassifiable.\nRichland County Attainment/Unclassifiable.\nRoosevelt County Attainment/Unclassifiable.\nRosebud County Attainment/Unclassifiable.\nSanders County Attainment/Unclassifiable.\nSheridan County Attainment/Unclassifiable.\nSilver Bow County Attainment/Unclassifiable.\nStillwater County Attainment/Unclassifiable.\nSweet Grass County Attainment/Unclassifiable.\nTeton County Attainment/Unclassifiable.\nToole County Attainment/Unclassifiable.\nTreasure County Attainment/Unclassifiable.\nValley County Attainment/Unclassifiable.\nWheatland County Attainment/Unclassifiable.\nWibaux County Attainment/Unclassifiable.\nYellowstone County Attainment/Unclassifiable.\n1 Includes any Indian country in each county or area, unless otherwise specified. EPA is not determining the boundaries of any area of Indian country in this table, including any area of Indian country located in the larger designation area. The inclusion of any Indian country in the designation area is not a determination that the state has regulatory authority under the Clean Air Act for such Indian country.\n2 This date is January 16, 2018, unless otherwise noted.\nMontana—2008 Lead NAAQS\nDesignated area Designation for the 2008 NAAQS a\nDate 1 Type\nWhole State Unclassifiable/Attainment.\na Includes Indian Country located in each county or area, except as otherwise specified.\n1 December 31, 2011 unless otherwise noted.","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 C—Section 107 Attainment Status Designations"],"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":"87d57fd4f80f5a23455522cf56443696925d2665ce3fc549c6c703f4940b0dd1","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-81.326","next":"us/40-cfr-81.328"},"notice":"GroundRules: Original legal text. Not legal advice."}