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 Code of Federal Regulations (Last Updated: November 8, 2024)
 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

  § 81.327 - Montana.  

Latest version.

  • § 81.327 Montana.

    Montana—1971 Sulfur Dioxide NAAQS

    [Primary and Secondary]
    Designated areaDoes not meet primary standardsDoes not meet secondary standardsCannot be classifiedBetter than national standards
    Laurel AreaX
    East Helena AreaX
    Anaconda AreaX
    Rest of StateX

    Montana—2010 Sulfur Dioxide NAAQS

    [Primary]
    Designated area1 Designation
    Date2 Type
    Yellowstone County (part)5/10/16Attainment.
    The 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
    Beaverhead CountyAttainment/Unclassifiable.
    Big Horn CountyAttainment/Unclassifiable.
    Blaine CountyAttainment/Unclassifiable.
    Broadwater CountyAttainment/Unclassifiable.
    Carbon CountyAttainment/Unclassifiable.
    Carter CountyAttainment/Unclassifiable.
    Cascade CountyAttainment/Unclassifiable.
    Chouteau CountyAttainment/Unclassifiable.
    Custer CountyAttainment/Unclassifiable.
    Daniels CountyAttainment/Unclassifiable.
    Dawson CountyAttainment/Unclassifiable.
    Deer Lodge CountyAttainment/Unclassifiable.
    Fallon CountyAttainment/Unclassifiable.
    Fergus CountyAttainment/Unclassifiable.
    Flathead CountyAttainment/Unclassifiable.
    Gallatin CountyAttainment/Unclassifiable.
    Garfield CountyAttainment/Unclassifiable.
    Glacier CountyAttainment/Unclassifiable.
    Golden Valley CountyAttainment/Unclassifiable.
    Granite CountyAttainment/Unclassifiable.
    Hill CountyAttainment/Unclassifiable.
    Jefferson CountyAttainment/Unclassifiable.
    Judith Basin CountyAttainment/Unclassifiable.
    Lake CountyAttainment/Unclassifiable.
    Lewis and Clark CountyAttainment/Unclassifiable.
    Liberty CountyAttainment/Unclassifiable.
    Lincoln CountyAttainment/Unclassifiable.
    McCone CountyAttainment/Unclassifiable.
    Madison CountyAttainment/Unclassifiable.
    Meagher CountyAttainment/Unclassifiable.
    Mineral CountyAttainment/Unclassifiable.
    Missoula CountyAttainment/Unclassifiable.
    Musselshell CountyAttainment/Unclassifiable.
    Park CountyAttainment/Unclassifiable.
    Petroleum CountyAttainment/Unclassifiable.
    Phillips CountyAttainment/Unclassifiable.
    Pondera CountyAttainment/Unclassifiable.
    Powder River CountyAttainment/Unclassifiable.
    Powell CountyAttainment/Unclassifiable.
    Prairie CountyAttainment/Unclassifiable.
    Ravalli CountyAttainment/Unclassifiable.
    Richland CountyAttainment/Unclassifiable.
    Roosevelt CountyAttainment/Unclassifiable.
    Rosebud CountyAttainment/Unclassifiable.
    Sanders CountyAttainment/Unclassifiable.
    Sheridan CountyAttainment/Unclassifiable.
    Silver Bow CountyAttainment/Unclassifiable.
    Stillwater CountyAttainment/Unclassifiable.
    Sweet Grass CountyAttainment/Unclassifiable.
    Teton CountyAttainment/Unclassifiable.
    Toole CountyAttainment/Unclassifiable.
    Treasure CountyAttainment/Unclassifiable.
    Valley CountyAttainment/Unclassifiable.
    Wheatland CountyAttainment/Unclassifiable.
    Wibaux CountyAttainment/Unclassifiable.
    Yellowstone County (part) (remainder)Attainment/Unclassifiable.
    1 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.
    2 This date is April 9, 2018, unless otherwise noted.

    Montana—Carbon Monoxide
    Designated AreaDesignationClassification
    Date1 TypeDate1 Type
    Billings Area
    Yellowstone County (part):
    The 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
    Great Falls AreaJuly 8, 2002Attainment
    Cascade County (part)
    Great 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
    Missoula Area:
    Missoula County (part)September 17, 2007Attainment
    Missoula 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
    Beaverhead CountyUnclassifiable/Attainment
    Big Horn County (part)
    excluding Crow, Northern Cheyenne Indian Reservations    		Unclassifiable/Attainment
    Blaine County (part)
    excluding Fort Belknap Indian Reservation    		Unclassifiable/Attainment
    Broadwater CountyUnclassifiable/Attainment
    Carbon CountyUnclassifiable/Attainment
    Carter CountyUnclassifiable/Attainment
    Cascade County (part)
    Remainder of Cascade CountyUnclassifiable/Attainment
    Chouteau County (part)
    excluding Rocky Boy Indian Reservation    		Unclassifiable/Attainment
    Custer CountyUnclassifiable/Attainment
    Daniels County (part)
    excluding Fort Peck Indian Reservation    		Unclassifiable/Attainment
    Dawson CountyUnclassifiable/Attainment
    Deer Lodge CountyUnclassifiable/Attainment
    Fallon CountyUnclassifiable/Attainment
    Fergus CountyUnclassifiable/Attainment
    Flathead County (part)
    excluding Flathead Indian Resevation    		Unclassifiable/Attainment
    Gallatin CountyUnclassifiable/Attainment
    Garfield CountyUnclassifiable/Attainment
    Glacier County (part)
    excluding Blackfeet Indian Reservation    		Unclassifiable/Attainment
    Golden Valley CountyUnclassifiable/Attainment
    Granite CountyUnclassifiable/Attainment
    Hill County (part)
    excluding Rocky Boy Indian Reservation    		Unclassifiable/Attainment
    Jefferson CountyUnclassifiable/Attainment
    Judith Basin CountyUnclassifiable/Attainment
    Lake County (part)
    excluding Flathead Indian Reservation    		Unclassifiable/Attainment
    Lewis and Clark CountyUnclassifiable/Attainment
    Liberty CountyUnclassifiable/Attainment
    Lincoln CountyUnclassifiable/Attainment
    Madison CountyUnclassifiable/Attainment
    McCone CountyUnclassifiable/Attainment
    Meagher CountyUnclassifiable/Attainment
    Mineral CountyUnclassifiable/Attainment
    Missoula County (part)
    Remainder of Missoula CountyUnclassifiable/Attainment
    Musselshell CountyUnclassifiable/Attainment
    Park CountyUnclassifiable/Attainment
    Petroleum CountyUnclassifiable/Attainment
    Phillips County (part)
    excluding Fort Belknap Indian Reservation    		Unclassifiable/Attainment
    Pondera County (part)
    excluding Blackfeet Indian Reservation    		Unclassifiable/Attainment
    Powder River CountyUnclassifiable/Attainment
    Powell CountyUnclassifiable/Attainment
    Prairie CountyUnclassifiable/Attainment
    Ravalli CountyUnclassifiable/Attainment
    Richland CountyUnclassifiable/Attainment
    Roosevelt County (part)
    excluding Fort Peck Indian Reservation    		Unclassifiable/Attainment
    Rosebud County (part)
    excluding Northern Cheyenne Indian Reservation    		Unclassifiable/Attainment
    Sanders County (part)
    excluding Flathead Indian Reservation    		Unclassifiable/Attainment
    Sheridan County (part)
    excluding Fort Peck Indian Reservation    		Unclassifiable/Attainment
    Silver Bow CountyUnclassifiable/Attainment
    Stillwater CountyUnclassifiable/Attainment
    Sweet Grass CountyUnclassifiable/Attainment
    Teton CountyUnclassifiable/Attainment
    Toole CountyUnclassifiable/Attainment
    Treasure CountyUnclassifiable/Attainment
    Valley County (part)
    excluding Fort Peck Indian Reservation    		Unclassifiable/Attainment
    Wheatland CountyUnclassifiable/Attainment
    Wibaux CountyUnclassifiable/Attainment
    Yellowstone County (part)
    Remainder of Yellowstone CountyUnclassifiable/Attainment
    Yellowstone National ParkUnclassifiable/Attainment
    Blackfeet Indian ReservationUnclassifiable/Attainment
    Glacier County (part)
    area inside Blackfeet Reservation
    Pondera County (part)
    area inside Blackfeet Reservation
    Crow Indian ReservationUnclassifiable/Attainment
    Bighorn County (part)
    area inside Crow Reservation
    Yellowstone (part)
    area inside Crow Reservation
    Flathead Indian ReservationUnclassifiable/Attainment
    Flathead County (part)
    area inside Flathead Reservation
    Lake County (part)
    area inside Flathead Reservation
    Missoula County (part)
    area inside Flathead Reservation
    Sanders County (part)
    area inside Flathead Reservation
    Fort Belknap Indian ReservationUnclassifiable/Attainment
    Blaine County (part)
    area inside Fort Belknap Reservation
    Phillips County (part)
    area inside Fort Belknap Reservation
    Fort Peck Indian ReservationUnclassifiable/Attainment
    Daniels County (part)
    area inside Fort Peck Reservation
    Roosevelt County (part)
    area inside Fort Peck Reservation
    Sheridan County (part)
    area inside Fort Peck Reservation
    Valley County (part)
    area inside Fort Peck Reservation
    Northern Cheyenne Indian ReservationUnclassifiable/Attainment
    Bighorn County (part)
    area inside Northern Cheyenne Reservation
    Rosebud County (part)
    area inside Northern Cheyenne Reservation
    Rocky Boy Indian ReservationUnclassifiable/Attainment
    Chouteau County (part)
    area inside Rocky Boy Reservation
    Hill County (part)
    area inside Rocky Boy Reservation
    1 This date is November 15, 1990, unless otherwise noted.

    Montana—1978 Lead NAAQS
    Designated AreaDesignationClassification
    DateTypeDateType
    Lewis & Clark County (part)
    City of East Helena and vicinityOctober 11, 2019Attainment.
    Northern 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
    Rest of State Not Designated

    Montana—Ozone (1-Hour Standard)2
    Designated areaDesignationClassification
    Date1 TypeDate1 Type
    Beaverhead CountyUnclassifiable/Attainment
    Big Horn County (part) excluding Crow, Northern Cheyenne Indian ReservationsUnclassifiable/Attainment
    Blaine County (part) excluding Fort Belknap Indian Reservation
    Broadwater CountyUnclassifiable/Attainment
    Carbon CountyUnclassifiable/Attainment
    Carter CountyUnclassifiable/Attainment
    Cascade CountyUnclassifiable/Attainment
    Chouteau County (part) excluding Rocky Boy Indian ReservationUnclassifiable/Attainment
    Custer CountyUnclassifiable/Attainment
    Daniels County (part) excluding Fort Peck Indian ReservationUnclassifiable/Attainment
    Dawson CountyUnclassifiable/Attainment
    Deer Lodge CountyUnclassifiable/Attainment
    Fallon CountyUnclassifiable/Attainment
    Fergus CountyUnclassifiable/Attainment
    Flathead County (part) excluding Flathead Indian ReservationUnclassifiable/Attainment
    Gallatin CountyUnclassifiable/Attainment
    Garfield CountyUnclassifiable/Attainment
    Glacier County (part) excluding Blackfeet Indian ReservationUnclassifiable/Attainment
    Golden Valley CountyUnclassifiable/Attainment
    Granite CountyUnclassifiable/Attainment
    Hill County (part) excluding Rocky Boy Indian ReservationUnclassifiable/Attainment
    Jefferson CountyUnclassifiable/Attainment
    Judith Basin CountyUnclassifiable/Attainment
    Lake County (part) excluding Flathead Indian ReservationUnclassifiable/Attainment
    Lewis and Clark CountyUnclassifiable/Attainment
    Liberty CountyUnclassifiable/Attainment
    Lincoln CountyUnclassifiable/Attainment
    Madison CountyUnclassifiable/Attainment
    McCone CountyUnclassifiable/Attainment
    Meagher CountyUnclassifiable/Attainment
    Mineral CountyUnclassifiable/Attainment
    Missoula County (part) excluding Flathead Indian ReservationUnclassifiable/Attainment
    Musselshell CountyUnclassifiable/Attainment
    Park CountyUnclassifiable/Attainment
    Petroleum CountyUnclassifiable/Attainment
    Phillips County (part) excluding Fort Belknap Indian ReservationUnclassifiable/Attainment
    Pondera County (part) excluding Blackfeet Indian ReservationUnclassifiable/Attainment
    Powder River CountyUnclassifiable/Attainment
    Powell CountyUnclassifiable/Attainment
    Prairie CountyUnclassifiable/Attainment
    Ravalli CountyUnclassifiable/Attainment
    Richland CountyUnclassifiable/Attainment
    Roosevelt County (part) excluding Fort Peck Indian ReservationUnclassifiable/Attainment
    Rosebud County (part) excluding Northern Cheyenne Indian ReservationUnclassifiable/Attainment
    Sanders County (part) excluding Flathead Indian ReservationUnclassifiable/Attainment
    Sheridan County (part) excluding Fort Peck Indian ReservationUnclassifiable/Attainment
    Silver Bow CountyUnclassifiable/Attainment
    Stillwater CountyUnclassifiable/Attainment
    Sweet Grass CountyUnclassifiable/Attainment
    Teton CountyUnclassifiable/Attainment
    Toole CountyUnclassifiable/Attainment
    Treasure CountyUnclassifiable/Attainment
    Valley County (part) excluding Fort Peck Indian ReservationUnclassifiable/Attainment
    Wheatland CountyUnclassifiable/Attainment
    Wibaux CountyUnclassifiable/Attainment
    Yellowstone County (part) excluding Crow Indian ReservationUnclassifiable/Attainment
    Yellowstone Natl ParkUnclassifiable/Attainment
    Blackfeet Indian ReservationUnclassifiable/Attainment
    Glacier County (part) area inside Blackfeet Reservation
    Pondera County (part) area inside Blackfeet Reservation
    Crow Indian ReservationUnclassifiable/Attainment
    Bighorn County (part) area inside Crow Reservation
    Yellowstone (part) area inside Crow Reservation
    Flathead Indian ReservationUnclassifiable/Attainment
    Flathead County (part) area inside Flathead Reservation
    Lake County (part) area inside Flathead Reservation
    Missoula County (part) area inside Flathead Reservation
    Sanders County (part) area inside Flathead Reservation
    Fort Belknap Indian ReservationUnclassifiable/Attainment
    Blaine County (part) area inside Fort Belknap Reservation
    Phillips County (part) area inside Fort Belknap Reservation
    Fort Peck Indian ReservationUnclassifiable/Attainment
    Daniels County (part) area inside Fort Peck Reservation
    Roosevelt County (part) area inside Fort Peck Reservation
    Sheridan County (part) area inside Fort Peck Reservation
    Valley County (part) area inside Fort Peck Reservation
    Northern Cheyenne Indian ReservationUnclassifiable/Attainment
    Bighorn County (part) area inside Northern Cheyenne Reservation
    Rosebud County (part) area inside Northern Cheyenne Reservation
    Rocky Boy Indian ReservationUnclassifiable/Attainment
    Chouteau County (part) area inside Rocky Boy Reservation
    Hill County (part) area inside Rocky Boy Reservation
    1 This date is October 18, 2000, unless otherwise noted.
    2 The 1-hour ozone standard is revoked effective June 15, 2005 for all areas in Montana.

    Montana—PM-10
    Designated AreaDesignationClassification
    DateTypeDateType
    Cascade County, Great Falls area11/15/90Unclassifiable
    Flathead County:
    The 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, 5347000mN7/27/2020Attainment.
    Columbia Falls and vicinity11/15/90Nonattainment11/15/90Moderate.
    Township T30N, R20W—Sections 7, 8, 9, 16, 17, and 18
    The 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 mN7/8/2022Attainment
    Lake County, Ronan, Polson11/15/90Nonattainment11/15/90Moderate.
    Lincoln County, Libby and vicinity11/15/90Nonattainment11/15/90Moderate.
    T30N, 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.
    Lewis and Clark County, East Helena area11/15/90Unclassifiable
    Missoula County, Missoula and vicinity including the following sections:6/24/2019Attainment
    T13N, 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.
    Rosebud County:
    Lame Deer11/15/90Nonattainment11/15/90Moderate.
    Colstrip area11/15/90Unclassifiable
    Sanders County (part)7/8/2022Attainment
    Thompson Falls and vicinity: Including the following Sections: R29W, T21N—Sections 5, 6, 7, 8, 9, 10, 15, and 16
    Silver Bow County, Butte7/26/2021Attainment.
    The 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.
    Yellowstone County, Billings area11/15/90Unclassifiable
    Rest of State1 11/15/90Unclassifiable
    1 Denotes a single area designation for PSD baseline area purposes.

    Montana—1997 Annual PM2.5 NAAQS

    [Primary and Secondary]
    Designated areaDesignationa Classification
    Date1 TypeDate2 Type
    Libby, MT:
    Lincoln County (part)8/23/23Attainment
    The 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
    Rest of State:
    Beaverhead CountyUnclassifiable/Attainment.
    Big Horn CountyUnclassifiable/Attainment.
    Blaine CountyUnclassifiable/Attainment.
    Broadwater CountyUnclassifiable/Attainment.
    Carbon CountyUnclassifiable/Attainment.
    Carter CountyUnclassifiable/Attainment.
    Cascade CountyUnclassifiable/Attainment.
    Chouteau CountyUnclassifiable/Attainment.
    Custer CountyUnclassifiable/Attainment.
    Daniels CountyUnclassifiable/Attainment.
    Dawson CountyUnclassifiable/Attainment.
    Deer Lodge CountyUnclassifiable/Attainment.
    Fallon CountyUnclassifiable/Attainment.
    Fergus CountyUnclassifiable/Attainment.
    Flathead CountyUnclassifiable/Attainment.
    Gallatin CountyUnclassifiable/Attainment.
    Garfield CountyUnclassifiable/Attainment.
    Glacier CountyUnclassifiable/Attainment.
    Golden Valley CountyUnclassifiable/Attainment.
    Granite CountyUnclassifiable/Attainment.
    Hill CountyUnclassifiable/Attainment.
    Jefferson CountyUnclassifiable/Attainment.
    Judith Basin CountyUnclassifiable/Attainment.
    Lake CountyUnclassifiable/Attainment.
    Lewis and Clark CountyUnclassifiable/Attainment.
    Liberty CountyUnclassifiable/Attainment.
    Lincoln County (remainder)Unclassifiable/Attainment.
    McCone CountyUnclassifiable/Attainment.
    Madison CountyUnclassifiable/Attainment.
    Meagher CountyUnclassifiable/Attainment.
    Mineral CountyUnclassifiable/Attainment.
    Missoula CountyUnclassifiable/Attainment.
    Musselshell CountyUnclassifiable/Attainment.
    Park CountyUnclassifiable/Attainment.
    Petroleum CountyUnclassifiable/Attainment.
    Phillips CountyUnclassifiable/Attainment.
    Pondera CountyUnclassifiable/Attainment.
    Powder River CountyUnclassifiable/Attainment.
    Powell CountyUnclassifiable/Attainment.
    Prairie CountyUnclassifiable/Attainment.
    Ravalli CountyUnclassifiable/Attainment.
    Richland CountyUnclassifiable/Attainment.
    Roosevelt CountyUnclassifiable/Attainment.
    Rosebud CountyUnclassifiable/Attainment.
    Sanders CountyUnclassifiable/Attainment.
    Sheridan CountyUnclassifiable/Attainment.
    Silver Bow CountyUnclassifiable/Attainment.
    Stillwater CountyUnclassifiable/Attainment.
    Sweet Grass CountyUnclassifiable/Attainment.
    Teton CountyUnclassifiable/Attainment.
    Toole CountyUnclassifiable/Attainment.
    Treasure CountyUnclassifiable/Attainment.
    Valley CountyUnclassifiable/Attainment.
    Wheatland CountyUnclassifiable/Attainment.
    Wibaux CountyUnclassifiable/Attainment.
    Yellowstone CountyUnclassifiable/Attainment.
    a Includes Indian Country located in each county or area, except as otherwise specified.
    1 This date is 90 days after January 5, 2005, unless otherwise noted.
    2 This date is July 2, 2014, unless otherwise noted.

    Montana—2012 Annual PM2.5 NAAQS

    [Primary]
    Designated area1 DesignationClassification
    Date2 TypeDate2 Type
    Statewide:
    Beaverhead CountyUnclassifiable/Attainment
    Big Horn CountyUnclassifiable/Attainment
    Blaine CountyUnclassifiable/Attainment
    Broadwater CountyUnclassifiable/Attainment
    Carbon CountyUnclassifiable/Attainment
    Carter CountyUnclassifiable/Attainment
    Cascade CountyUnclassifiable/Attainment
    Chouteau CountyUnclassifiable/Attainment
    Custer CountyUnclassifiable/Attainment
    Daniels CountyUnclassifiable/Attainment
    Dawson CountyUnclassifiable/Attainment
    Deer Lodge CountyUnclassifiable/Attainment
    Fallon CountyUnclassifiable/Attainment
    Fergus CountyUnclassifiable/Attainment
    Flathead CountyUnclassifiable/Attainment
    Gallatin CountyUnclassifiable/Attainment
    Garfield CountyUnclassifiable/Attainment
    Glacier CountyUnclassifiable/Attainment
    Golden Valley CountyUnclassifiable/Attainment
    Granite CountyUnclassifiable/Attainment
    Hill CountyUnclassifiable/Attainment
    Jefferson CountyUnclassifiable/Attainment
    Judith Basin CountyUnclassifiable/Attainment
    Lake CountyUnclassifiable/Attainment
    Lewis and Clark CountyUnclassifiable/Attainment
    Liberty CountyUnclassifiable/Attainment
    Lincoln CountyUnclassifiable/Attainment
    McCone CountyUnclassifiable/Attainment
    Madison CountyUnclassifiable/Attainment
    Meagher CountyUnclassifiable/Attainment
    Mineral CountyUnclassifiable/Attainment
    Missoula CountyUnclassifiable/Attainment
    Musselshell CountyUnclassifiable/Attainment
    Park CountyUnclassifiable/Attainment
    Petroleum CountyUnclassifiable/Attainment
    Phillips CountyUnclassifiable/Attainment
    Pondera CountyUnclassifiable/Attainment
    Powder River CountyUnclassifiable/Attainment
    Powell CountyUnclassifiable/Attainment
    Prairie CountyUnclassifiable/Attainment
    Ravalli CountyUnclassifiable/Attainment
    Richland CountyUnclassifiable/Attainment
    Roosevelt CountyUnclassifiable/Attainment
    Rosebud CountyUnclassifiable/Attainment
    Sanders CountyUnclassifiable/Attainment
    Sheridan CountyUnclassifiable/Attainment
    Silver Bow CountyUnclassifiable/Attainment
    Stillwater CountyUnclassifiable/Attainment
    Sweet Grass CountyUnclassifiable/Attainment
    Teton CountyUnclassifiable/Attainment
    Toole CountyUnclassifiable/Attainment
    Treasure CountyUnclassifiable/Attainment
    Valley CountyUnclassifiable/Attainment
    Wheatland CountyUnclassifiable/Attainment
    Wibaux CountyUnclassifiable/Attainment
    Yellowstone CountyUnclassifiable/Attainment
    1 Includes areas of Indian country located in each county or area, except as otherwise specified.
    2 This date is April 15, 2015, unless otherwise noted.

    Montana—1997 24-Hour PM2.5 NAAQS

    [Primary and Secondary]
    Designated areaDesignationa Classification
    Date1 TypeDateType
    Statewide:
    Beaverhead CountyUnclassifiable/Attainment.
    Big Horn CountyUnclassifiable/Attainment.
    Blaine CountyUnclassifiable/Attainment.
    Broadwater CountyUnclassifiable/Attainment.
    Carbon CountyUnclassifiable/Attainment.
    Carter CountyUnclassifiable/Attainment.
    Cascade CountyUnclassifiable/Attainment.
    Chouteau CountyUnclassifiable/Attainment.
    Custer CountyUnclassifiable/Attainment.
    Daniels CountyUnclassifiable/Attainment.
    Dawson CountyUnclassifiable/Attainment.
    Deer Lodge CountyUnclassifiable/Attainment.
    Fallon CountyUnclassifiable/Attainment.
    Fergus CountyUnclassifiable/Attainment.
    Flathead CountyUnclassifiable/Attainment.
    Gallatin CountyUnclassifiable/Attainment.
    Garfield CountyUnclassifiable/Attainment.
    Glacier CountyUnclassifiable/Attainment.
    Golden Valley CountyUnclassifiable/Attainment.
    Granite CountyUnclassifiable/Attainment.
    Hill CountyUnclassifiable/Attainment.
    Jefferson CountyUnclassifiable/Attainment.
    Judith Basin CountyUnclassifiable/Attainment.
    Lake CountyUnclassifiable/Attainment.
    Lewis and Clark CountyUnclassifiable/Attainment.
    Liberty CountyUnclassifiable/Attainment.
    Lincoln CountyUnclassifiable/Attainment.
    McCone CountyUnclassifiable/Attainment.
    Madison CountyUnclassifiable/Attainment.
    Meagher CountyUnclassifiable/Attainment.
    Mineral CountyUnclassifiable/Attainment.
    Missoula CountyUnclassifiable/Attainment.
    Musselshell CountyUnclassifiable/Attainment.
    Park CountyUnclassifiable/Attainment.
    Petroleum CountyUnclassifiable/Attainment.
    Phillips CountyUnclassifiable/Attainment.
    Pondera CountyUnclassifiable/Attainment.
    Powder River CountyUnclassifiable/Attainment.
    Powell CountyUnclassifiable/Attainment.
    Prairie CountyUnclassifiable/Attainment.
    Ravalli CountyUnclassifiable/Attainment.
    Richland CountyUnclassifiable/Attainment.
    Roosevelt CountyUnclassifiable/Attainment.
    Rosebud CountyUnclassifiable/Attainment.
    Sanders CountyUnclassifiable/Attainment.
    Sheridan CountyUnclassifiable/Attainment.
    Silver Bow CountyUnclassifiable/Attainment.
    Stillwater CountyUnclassifiable/Attainment.
    Sweet Grass CountyUnclassifiable/Attainment.
    Teton CountyUnclassifiable/Attainment.
    Toole CountyUnclassifiable/Attainment.
    Treasure CountyUnclassifiable/Attainment.
    Valley CountyUnclassifiable/Attainment.
    Wheatland CountyUnclassifiable/Attainment.
    Wibaux CountyUnclassifiable/Attainment.
    Yellowstone CountyUnclassifiable/Attainment.
    a Includes Indian Country located in each county or area, except as otherwise specified.
    1 This date is 90 days after January 5, 2005, unless otherwise noted.

    Montana—2006 24-Hour PM2.5 NAAQS

    [Primary and Secondary]
    Designated areaDesignationa Classification
    Date1 TypeDateType
    Statewide:
    Beaverhead CountyUnclassifiable/Attainment.
    Big Horn CountyUnclassifiable/Attainment.
    Blaine CountyUnclassifiable/Attainment.
    Broadwater CountyUnclassifiable/Attainment.
    Carbon CountyUnclassifiable/Attainment.
    Carter CountyUnclassifiable/Attainment.
    Cascade CountyUnclassifiable/Attainment.
    Chouteau CountyUnclassifiable/Attainment.
    Custer CountyUnclassifiable/Attainment.
    Daniels CountyUnclassifiable/Attainment.
    Dawson CountyUnclassifiable/Attainment.
    Deer Lodge CountyUnclassifiable/Attainment.
    Fallon CountyUnclassifiable/Attainment.
    Fergus CountyUnclassifiable/Attainment.
    Flathead CountyUnclassifiable/Attainment.
    Gallatin CountyUnclassifiable/Attainment.
    Garfield CountyUnclassifiable/Attainment.
    Glacier CountyUnclassifiable/Attainment.
    Golden Valley CountyUnclassifiable/Attainment.
    Granite CountyUnclassifiable/Attainment.
    Hill CountyUnclassifiable/Attainment.
    Jefferson CountyUnclassifiable/Attainment.
    Judith Basin CountyUnclassifiable/Attainment.
    Lake CountyUnclassifiable/Attainment.
    Lewis and Clark CountyUnclassifiable/Attainment.
    Liberty CountyUnclassifiable/Attainment.
    Lincoln CountyUnclassifiable/Attainment.
    McCone CountyUnclassifiable/Attainment.
    Madison CountyUnclassifiable/Attainment.
    Meagher CountyUnclassifiable/Attainment.
    Mineral CountyUnclassifiable/Attainment.
    Missoula CountyUnclassifiable/Attainment.
    Musselshell CountyUnclassifiable/Attainment.
    Park CountyUnclassifiable/Attainment.
    Petroleum CountyUnclassifiable/Attainment.
    Phillips CountyUnclassifiable/Attainment.
    Pondera CountyUnclassifiable/Attainment.
    Powder River CountyUnclassifiable/Attainment.
    Powell CountyUnclassifiable/Attainment.
    Prairie CountyUnclassifiable/Attainment.
    Ravalli CountyUnclassifiable/Attainment.
    Richland CountyUnclassifiable/Attainment.
    Roosevelt CountyUnclassifiable/Attainment.
    Rosebud CountyUnclassifiable/Attainment.
    Sanders CountyUnclassifiable/Attainment.
    Sheridan CountyUnclassifiable/Attainment.
    Silver Bow CountyUnclassifiable/Attainment.
    Stillwater CountyUnclassifiable/Attainment.
    Sweet Grass CountyUnclassifiable/Attainment.
    Teton CountyUnclassifiable/Attainment.
    Toole CountyUnclassifiable/Attainment.
    Treasure CountyUnclassifiable/Attainment.
    Valley CountyUnclassifiable/Attainment.
    Wheatland CountyUnclassifiable/Attainment.
    Wibaux CountyUnclassifiable/Attainment.
    Yellowstone CountyUnclassifiable/Attainment.
    a Includes Indian Country located in each county or area, except as otherwise specified.
    1 This date is 30 days after November 13, 2009, unless otherwise noted.

    Montana—NO2 (1971 Annual Standard)
    Designated areaDoes not meet primary standardsCannot be classified or better than national standards
    Entire StateX

    Montana—NO2 (2010 1-Hour Standard)
    Designated areaDesignationa
    Date1 Type
    Beaverhead CountyUnclassifiable/Attainment.
    Big Horn CountyUnclassifiable/Attainment.
    Blaine CountyUnclassifiable/Attainment.
    Broadwater CountyUnclassifiable/Attainment.
    Carbon CountyUnclassifiable/Attainment.
    Carter CountyUnclassifiable/Attainment.
    Cascade CountyUnclassifiable/Attainment.
    Chouteau CountyUnclassifiable/Attainment.
    Custer CountyUnclassifiable/Attainment.
    Daniels CountyUnclassifiable/Attainment.
    Dawson CountyUnclassifiable/Attainment.
    Deer Lodge CountyUnclassifiable/Attainment.
    Fallon CountyUnclassifiable/Attainment.
    Fergus CountyUnclassifiable/Attainment.
    Flathead CountyUnclassifiable/Attainment.
    Gallatin CountyUnclassifiable/Attainment.
    Garfield CountyUnclassifiable/Attainment.
    Glacier CountyUnclassifiable/Attainment.
    Golden Valley CountyUnclassifiable/Attainment.
    Granite CountyUnclassifiable/Attainment.
    Hill CountyUnclassifiable/Attainment.
    Jefferson CountyUnclassifiable/Attainment.
    Judith Basin CountyUnclassifiable/Attainment.
    Lake CountyUnclassifiable/Attainment.
    Lewis and Clark CountyUnclassifiable/Attainment.
    Liberty CountyUnclassifiable/Attainment.
    Lincoln CountyUnclassifiable/Attainment.
    McCone CountyUnclassifiable/Attainment.
    Madison CountyUnclassifiable/Attainment.
    Meagher CountyUnclassifiable/Attainment.
    Mineral CountyUnclassifiable/Attainment.
    Missoula CountyUnclassifiable/Attainment.
    Musselshell CountyUnclassifiable/Attainment.
    Park CountyUnclassifiable/Attainment.
    Petroleum CountyUnclassifiable/Attainment.
    Phillips CountyUnclassifiable/Attainment.
    Pondera CountyUnclassifiable/Attainment.
    Powder River CountyUnclassifiable/Attainment.
    Powell CountyUnclassifiable/Attainment.
    Prairie CountyUnclassifiable/Attainment.
    Ravalli CountyUnclassifiable/Attainment.
    Richland CountyUnclassifiable/Attainment.
    Roosevelt CountyUnclassifiable/Attainment.
    Rosebud CountyUnclassifiable/Attainment.
    Sanders CountyUnclassifiable/Attainment.
    Sheridan CountyUnclassifiable/Attainment.
    Silver Bow CountyUnclassifiable/Attainment.
    Stillwater CountyUnclassifiable/Attainment.
    Sweet Grass CountyUnclassifiable/Attainment.
    Teton CountyUnclassifiable/Attainment.
    Toole CountyUnclassifiable/Attainment.
    Treasure CountyUnclassifiable/Attainment.
    Valley CountyUnclassifiable/Attainment.
    Wheatland CountyUnclassifiable/Attainment.
    Wibaux CountyUnclassifiable/Attainment.
    Yellowstone CountyUnclassifiable/Attainment.
    a Includes Indian Country located in each county or area, except as otherwise specified.
    1 This date is 90 days after October 31, 2011, unless otherwise noted.

    Montana—1997 8-Hour Ozone NAAQS

    [Primary and Secondary]
    Designated areaDesignationa Category/classification
    Date1 TypeDate1 Type
    Statewide:
    Beaverhead CountyUnclassifiable/Attainment
    Big Horn CountyUnclassifiable/Attainment
    Blaine CountyUnclassifiable/Attainment
    Broadwater CountyUnclassifiable/Attainment
    Carbon CountyUnclassifiable/Attainment
    Carter CountyUnclassifiable/Attainment
    Cascade CountyUnclassifiable/Attainment
    Chouteau CountyUnclassifiable/Attainment
    Custer CountyUnclassifiable/Attainment
    Daniels CountyUnclassifiable/Attainment
    Dawson CountyUnclassifiable/Attainment
    Deer Lodge CountyUnclassifiable/Attainment
    Fallon CountyUnclassifiable/Attainment
    Fergus CountyUnclassifiable/Attainment
    Flathead CountyUnclassifiable/Attainment
    Gallatin CountyUnclassifiable/Attainment
    Garfield CountyUnclassifiable/Attainment
    Glacier CountyUnclassifiable/Attainment
    Golden Valley CountyUnclassifiable/Attainment
    Granite County.Unclassifiable/Attainment
    Hill CountyUnclassifiable/Attainment
    Jefferson CountyUnclassifiable/Attainment
    Judith Basin CountyUnclassifiable/Attainment
    Lake CountyUnclassifiable/Attainment
    Lewis and Clark CountyUnclassifiable/Attainment
    Liberty CountyUnclassifiable/Attainment
    Lincoln CountyUnclassifiable/Attainment
    Madison CountyUnclassifiable/Attainment
    McCone CountyUnclassifiable/Attainment
    Meagher CountyUnclassifiable/Attainment
    Mineral CountyUnclassifiable/Attainment
    Missoula CountyUnclassifiable/Attainment
    Musselshell CountyUnclassifiable/Attainment
    Park CountyUnclassifiable/Attainment
    Petroleum CountyUnclassifiable/Attainment
    Phillips CountyUnclassifiable/Attainment
    Pondera CountyUnclassifiable/Attainment
    Powder River CountyUnclassifiable/Attainment
    Powell CountyUnclassifiable/Attainment
    Prairie CountyUnclassifiable/Attainment
    Ravalli CountyUnclassifiable/Attainment
    Richland CountyUnclassifiable/Attainment
    Roosevelt CountyUnclassifiable/Attainment
    Rosebud CountyUnclassifiable/Attainment
    Sanders CountyUnclassifiable/Attainment
    Sheridan CountyUnclassifiable/Attainment
    Silver Bow CountyUnclassifiable/Attainment
    Stillwater CountyUnclassifiable/Attainment
    Sweet Grass CountyUnclassifiable/Attainment
    Teton CountyUnclassifiable/Attainment
    Toole CountyUnclassifiable/Attainment
    Treasure CountyUnclassifiable/Attainment
    Valley CountyUnclassifiable/Attainment
    Wheatland CountyUnclassifiable/Attainment
    Wibaux CountyUnclassifiable/Attainment
    Yellowstone CountyUnclassifiable/Attainment
    Yellowstone Natl ParkUnclassifiable/Attainment
    a Includes Indian Country located in each county or area, except as otherwise specified.
    1 This date is June 15, 2004, unless otherwise noted.

    Montana—2008 8-Hour Ozone NAAQS

    [Primary and Secondary]
    Designated areaDesignationClassification
    Date1 TypeDate1 Type
    Statewide and Any Areas of Indian CountryUnclassifiable/Attainment
    1 This date is July 20, 2012, unless otherwise noted.

    Montana—2015 8-Hour Ozone NAAQS

    [Primary and Secondary]
    Designated area1 DesignationClassification
    Date2 TypeDateType
    Beaverhead CountyAttainment/Unclassifiable.
    Big Horn CountyAttainment/Unclassifiable.
    Blaine CountyAttainment/Unclassifiable.
    Broadwater CountyAttainment/Unclassifiable.
    Carbon CountyAttainment/Unclassifiable.
    Carter CountyAttainment/Unclassifiable.
    Cascade CountyAttainment/Unclassifiable.
    Chouteau CountyAttainment/Unclassifiable.
    Custer CountyAttainment/Unclassifiable.
    Daniels CountyAttainment/Unclassifiable.
    Dawson CountyAttainment/Unclassifiable.
    Deer Lodge CountyAttainment/Unclassifiable.
    Fallon CountyAttainment/Unclassifiable.
    Fergus CountyAttainment/Unclassifiable.
    Flathead CountyAttainment/Unclassifiable.
    Gallatin CountyAttainment/Unclassifiable.
    Garfield CountyAttainment/Unclassifiable.
    Glacier CountyAttainment/Unclassifiable.
    Golden Valley CountyAttainment/Unclassifiable.
    Granite CountyAttainment/Unclassifiable.
    Hill CountyAttainment/Unclassifiable.
    Jefferson CountyAttainment/Unclassifiable.
    Judith Basin CountyAttainment/Unclassifiable.
    Lake CountyAttainment/Unclassifiable.
    Lewis and Clark CountyAttainment/Unclassifiable.
    Liberty CountyAttainment/Unclassifiable.
    Lincoln CountyAttainment/Unclassifiable.
    McCone CountyAttainment/Unclassifiable.
    Madison CountyAttainment/Unclassifiable.
    Meagher CountyAttainment/Unclassifiable.
    Mineral CountyAttainment/Unclassifiable.
    Missoula CountyAttainment/Unclassifiable.
    Musselshell CountyAttainment/Unclassifiable.
    Park CountyAttainment/Unclassifiable.
    Petroleum CountyAttainment/Unclassifiable.
    Phillips CountyAttainment/Unclassifiable.
    Pondera CountyAttainment/Unclassifiable.
    Powder River CountyAttainment/Unclassifiable.
    Powell CountyAttainment/Unclassifiable.
    Prairie CountyAttainment/Unclassifiable.
    Ravalli CountyAttainment/Unclassifiable.
    Richland CountyAttainment/Unclassifiable.
    Roosevelt CountyAttainment/Unclassifiable.
    Rosebud CountyAttainment/Unclassifiable.
    Sanders CountyAttainment/Unclassifiable.
    Sheridan CountyAttainment/Unclassifiable.
    Silver Bow CountyAttainment/Unclassifiable.
    Stillwater CountyAttainment/Unclassifiable.
    Sweet Grass CountyAttainment/Unclassifiable.
    Teton CountyAttainment/Unclassifiable.
    Toole CountyAttainment/Unclassifiable.
    Treasure CountyAttainment/Unclassifiable.
    Valley CountyAttainment/Unclassifiable.
    Wheatland CountyAttainment/Unclassifiable.
    Wibaux CountyAttainment/Unclassifiable.
    Yellowstone CountyAttainment/Unclassifiable.
    1 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.
    2 This date is January 16, 2018, unless otherwise noted.

    Montana—2008 Lead NAAQS
    Designated areaDesignation for the 2008 NAAQSa
    Date1 Type
    Whole StateUnclassifiable/Attainment.
    a Includes Indian Country located in each county or area, except as otherwise specified.
    1 December 31, 2011 unless otherwise noted.

    [43 FR 8964, Mar. 3, 1978]

    Editorial Note

    Editorial Note:

    For Federal Register citations affecting § 81.327, see the List of CFR Sections Affected, which appears in the Finding Aids section of the printed volume and at www.govinfo.gov.