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 Code of Federal Regulations (Last Updated: July 5, 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 area Does not meet primary standards Does not meet secondary standards Cannot be classified Better than national standards
    Laurel Area X
    East Helena Area X
    Anaconda Area X
    Rest of State X

    Montana—2010 Sulfur Dioxide NAAQS

    [Primary]

    Designated area1 Designation
    Date2 Type
    Yellowstone County (part) 5/10/16 Attainment.
    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 County Attainment/Unclassifiable.
    Big Horn County Attainment/Unclassifiable.
    Blaine County Attainment/Unclassifiable.
    Broadwater County Attainment/Unclassifiable.
    Carbon County Attainment/Unclassifiable.
    Carter County Attainment/Unclassifiable.
    Cascade County Attainment/Unclassifiable.
    Chouteau County Attainment/Unclassifiable.
    Custer County Attainment/Unclassifiable.
    Daniels County Attainment/Unclassifiable.
    Dawson County Attainment/Unclassifiable.
    Deer Lodge County Attainment/Unclassifiable.
    Fallon County Attainment/Unclassifiable.
    Fergus County Attainment/Unclassifiable.
    Flathead County Attainment/Unclassifiable.
    Gallatin County Attainment/Unclassifiable.
    Garfield County Attainment/Unclassifiable.
    Glacier County Attainment/Unclassifiable.
    Golden Valley County Attainment/Unclassifiable.
    Granite County Attainment/Unclassifiable.
    Hill County Attainment/Unclassifiable.
    Jefferson County Attainment/Unclassifiable.
    Judith Basin County Attainment/Unclassifiable.
    Lake County Attainment/Unclassifiable.
    Lewis and Clark County Attainment/Unclassifiable.
    Liberty County Attainment/Unclassifiable.
    Lincoln County Attainment/Unclassifiable.
    McCone County Attainment/Unclassifiable.
    Madison County Attainment/Unclassifiable.
    Meagher County Attainment/Unclassifiable.
    Mineral County Attainment/Unclassifiable.
    Missoula County Attainment/Unclassifiable.
    Musselshell County Attainment/Unclassifiable.
    Park County Attainment/Unclassifiable.
    Petroleum County Attainment/Unclassifiable.
    Phillips County Attainment/Unclassifiable.
    Pondera County Attainment/Unclassifiable.
    Powder River County Attainment/Unclassifiable.
    Powell County Attainment/Unclassifiable.
    Prairie County Attainment/Unclassifiable.
    Ravalli County Attainment/Unclassifiable.
    Richland County Attainment/Unclassifiable.
    Roosevelt County Attainment/Unclassifiable.
    Rosebud County Attainment/Unclassifiable.
    Sanders County Attainment/Unclassifiable.
    Sheridan County Attainment/Unclassifiable.
    Silver Bow County Attainment/Unclassifiable.
    Stillwater County Attainment/Unclassifiable.
    Sweet Grass County Attainment/Unclassifiable.
    Teton County Attainment/Unclassifiable.
    Toole County Attainment/Unclassifiable.
    Treasure County Attainment/Unclassifiable.
    Valley County Attainment/Unclassifiable.
    Wheatland County Attainment/Unclassifiable.
    Wibaux County Attainment/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 Area Designation Classification
    Date1 Type Date1 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 Area July 8, 2002 Attainment
    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, 2007 Attainment
    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 County Unclassifiable/Attainment
    Big Horn County (part)
    excluding Crow, Northern Cheyenne Indian Reservations    		 Unclassifiable/Attainment
    Blaine County (part)
    excluding Fort Belknap Indian Reservation    		 Unclassifiable/Attainment
    Broadwater County Unclassifiable/Attainment
    Carbon County Unclassifiable/Attainment
    Carter County Unclassifiable/Attainment
    Cascade County (part)
    Remainder of Cascade County Unclassifiable/Attainment
    Chouteau County (part)
    excluding Rocky Boy Indian Reservation    		 Unclassifiable/Attainment
    Custer County Unclassifiable/Attainment
    Daniels County (part)
    excluding Fort Peck Indian Reservation    		 Unclassifiable/Attainment
    Dawson County Unclassifiable/Attainment
    Deer Lodge County Unclassifiable/Attainment
    Fallon County Unclassifiable/Attainment
    Fergus County Unclassifiable/Attainment
    Flathead County (part)
    excluding Flathead Indian Resevation    		 Unclassifiable/Attainment
    Gallatin County Unclassifiable/Attainment
    Garfield County Unclassifiable/Attainment
    Glacier County (part)
    excluding Blackfeet Indian Reservation    		 Unclassifiable/Attainment
    Golden Valley County Unclassifiable/Attainment
    Granite County Unclassifiable/Attainment
    Hill County (part)
    excluding Rocky Boy Indian Reservation    		 Unclassifiable/Attainment
    Jefferson County Unclassifiable/Attainment
    Judith Basin County Unclassifiable/Attainment
    Lake County (part)
    excluding Flathead Indian Reservation    		 Unclassifiable/Attainment
    Lewis and Clark County Unclassifiable/Attainment
    Liberty County Unclassifiable/Attainment
    Lincoln County Unclassifiable/Attainment
    Madison County Unclassifiable/Attainment
    McCone County Unclassifiable/Attainment
    Meagher County Unclassifiable/Attainment
    Mineral County Unclassifiable/Attainment
    Missoula County (part)
    Remainder of Missoula County Unclassifiable/Attainment
    Musselshell County Unclassifiable/Attainment
    Park County Unclassifiable/Attainment
    Petroleum County Unclassifiable/Attainment
    Phillips County (part)
    excluding Fort Belknap Indian Reservation    		 Unclassifiable/Attainment
    Pondera County (part)
    excluding Blackfeet Indian Reservation    		 Unclassifiable/Attainment
    Powder River County Unclassifiable/Attainment
    Powell County Unclassifiable/Attainment
    Prairie County Unclassifiable/Attainment
    Ravalli County Unclassifiable/Attainment
    Richland County Unclassifiable/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 County Unclassifiable/Attainment
    Stillwater County Unclassifiable/Attainment
    Sweet Grass County Unclassifiable/Attainment
    Teton County Unclassifiable/Attainment
    Toole County Unclassifiable/Attainment
    Treasure County Unclassifiable/Attainment
    Valley County (part)
    excluding Fort Peck Indian Reservation    		 Unclassifiable/Attainment
    Wheatland County Unclassifiable/Attainment
    Wibaux County Unclassifiable/Attainment
    Yellowstone County (part)
    Remainder of Yellowstone County Unclassifiable/Attainment
    Yellowstone National Park Unclassifiable/Attainment
    Blackfeet Indian Reservation Unclassifiable/Attainment
    Glacier County (part)
    area inside Blackfeet Reservation
    Pondera County (part)
    area inside Blackfeet Reservation
    Crow Indian Reservation Unclassifiable/Attainment
    Bighorn County (part)
    area inside Crow Reservation
    Yellowstone (part)
    area inside Crow Reservation
    Flathead Indian Reservation Unclassifiable/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 Reservation Unclassifiable/Attainment
    Blaine County (part)
    area inside Fort Belknap Reservation
    Phillips County (part)
    area inside Fort Belknap Reservation
    Fort Peck Indian Reservation Unclassifiable/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 Reservation Unclassifiable/Attainment
    Bighorn County (part)
    area inside Northern Cheyenne Reservation
    Rosebud County (part)
    area inside Northern Cheyenne Reservation
    Rocky Boy Indian Reservation Unclassifiable/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 Area Designation Classification
    Date Type Date Type
    Lewis & Clark County (part)
    City of East Helena and vicinity October 11, 2019 Attainment.
    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 area Designation Classification
    Date1 Type Date1 Type
    Beaverhead County Unclassifiable/Attainment
    Big Horn County (part) excluding Crow, Northern Cheyenne Indian Reservations Unclassifiable/Attainment
    Blaine County (part) excluding Fort Belknap Indian Reservation
    Broadwater County Unclassifiable/Attainment
    Carbon County Unclassifiable/Attainment
    Carter County Unclassifiable/Attainment
    Cascade County Unclassifiable/Attainment
    Chouteau County (part) excluding Rocky Boy Indian Reservation Unclassifiable/Attainment
    Custer County Unclassifiable/Attainment
    Daniels County (part) excluding Fort Peck Indian Reservation Unclassifiable/Attainment
    Dawson County Unclassifiable/Attainment
    Deer Lodge County Unclassifiable/Attainment
    Fallon County Unclassifiable/Attainment
    Fergus County Unclassifiable/Attainment
    Flathead County (part) excluding Flathead Indian Reservation Unclassifiable/Attainment
    Gallatin County Unclassifiable/Attainment
    Garfield County Unclassifiable/Attainment
    Glacier County (part) excluding Blackfeet Indian Reservation Unclassifiable/Attainment
    Golden Valley County Unclassifiable/Attainment
    Granite County Unclassifiable/Attainment
    Hill County (part) excluding Rocky Boy Indian Reservation Unclassifiable/Attainment
    Jefferson County Unclassifiable/Attainment
    Judith Basin County Unclassifiable/Attainment
    Lake County (part) excluding Flathead Indian Reservation Unclassifiable/Attainment
    Lewis and Clark County Unclassifiable/Attainment
    Liberty County Unclassifiable/Attainment
    Lincoln County Unclassifiable/Attainment
    Madison County Unclassifiable/Attainment
    McCone County Unclassifiable/Attainment
    Meagher County Unclassifiable/Attainment
    Mineral County Unclassifiable/Attainment
    Missoula County (part) excluding Flathead Indian Reservation Unclassifiable/Attainment
    Musselshell County Unclassifiable/Attainment
    Park County Unclassifiable/Attainment
    Petroleum County Unclassifiable/Attainment
    Phillips County (part) excluding Fort Belknap Indian Reservation Unclassifiable/Attainment
    Pondera County (part) excluding Blackfeet Indian Reservation Unclassifiable/Attainment
    Powder River County Unclassifiable/Attainment
    Powell County Unclassifiable/Attainment
    Prairie County Unclassifiable/Attainment
    Ravalli County Unclassifiable/Attainment
    Richland County Unclassifiable/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 County Unclassifiable/Attainment
    Stillwater County Unclassifiable/Attainment
    Sweet Grass County Unclassifiable/Attainment
    Teton County Unclassifiable/Attainment
    Toole County Unclassifiable/Attainment
    Treasure County Unclassifiable/Attainment
    Valley County (part) excluding Fort Peck Indian Reservation Unclassifiable/Attainment
    Wheatland County Unclassifiable/Attainment
    Wibaux County Unclassifiable/Attainment
    Yellowstone County (part) excluding Crow Indian Reservation Unclassifiable/Attainment
    Yellowstone Natl Park Unclassifiable/Attainment
    Blackfeet Indian Reservation Unclassifiable/Attainment
    Glacier County (part) area inside Blackfeet Reservation
    Pondera County (part) area inside Blackfeet Reservation
    Crow Indian Reservation Unclassifiable/Attainment
    Bighorn County (part) area inside Crow Reservation
    Yellowstone (part) area inside Crow Reservation
    Flathead Indian Reservation Unclassifiable/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 Reservation Unclassifiable/Attainment
    Blaine County (part) area inside Fort Belknap Reservation
    Phillips County (part) area inside Fort Belknap Reservation
    Fort Peck Indian Reservation Unclassifiable/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 Reservation Unclassifiable/Attainment
    Bighorn County (part) area inside Northern Cheyenne Reservation
    Rosebud County (part) area inside Northern Cheyenne Reservation
    Rocky Boy Indian Reservation Unclassifiable/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 Area Designation Classification
    Date Type Date Type
    Cascade County, Great Falls area 11/15/90 Unclassifiable
    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, 5347000mN 7/27/2020 Attainment.
    Columbia Falls and vicinity 11/15/90 Nonattainment 11/15/90 Moderate.
    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 mN 7/8/2022 Attainment
    Lake County, Ronan, Polson 11/15/90 Nonattainment 11/15/90 Moderate.
    Lincoln County, Libby and vicinity 11/15/90 Nonattainment 11/15/90 Moderate.
    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 area 11/15/90 Unclassifiable
    Missoula County, Missoula and vicinity including the following sections: 6/24/2019 Attainment
    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 Deer 11/15/90 Nonattainment 11/15/90 Moderate.
    Colstrip area 11/15/90 Unclassifiable
    Sanders County (part) 7/8/2022 Attainment
    Thompson Falls and vicinity: Including the following Sections: R29W, T21N—Sections 5, 6, 7, 8, 9, 10, 15, and 16
    Silver Bow County, Butte 7/26/2021 Attainment.
    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 area 11/15/90 Unclassifiable
    Rest of State1 11/15/90 Unclassifiable

    1 Denotes a single area designation for PSD baseline area purposes.

    Montana—1997 Annual PM2.5 NAAQS

    [Primary and Secondary]

    Designated area Designationa Classification
    Date1 Type Date2 Type
    Libby, MT:
    Lincoln County (part) 8/23/23 Attainment
    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 County Unclassifiable/Attainment.
    Big Horn County Unclassifiable/Attainment.
    Blaine County Unclassifiable/Attainment.
    Broadwater County Unclassifiable/Attainment.
    Carbon County Unclassifiable/Attainment.
    Carter County Unclassifiable/Attainment.
    Cascade County Unclassifiable/Attainment.
    Chouteau County Unclassifiable/Attainment.
    Custer County Unclassifiable/Attainment.
    Daniels County Unclassifiable/Attainment.
    Dawson County Unclassifiable/Attainment.
    Deer Lodge County Unclassifiable/Attainment.
    Fallon County Unclassifiable/Attainment.
    Fergus County Unclassifiable/Attainment.
    Flathead County Unclassifiable/Attainment.
    Gallatin County Unclassifiable/Attainment.
    Garfield County Unclassifiable/Attainment.
    Glacier County Unclassifiable/Attainment.
    Golden Valley County Unclassifiable/Attainment.
    Granite County Unclassifiable/Attainment.
    Hill County Unclassifiable/Attainment.
    Jefferson County Unclassifiable/Attainment.
    Judith Basin County Unclassifiable/Attainment.
    Lake County Unclassifiable/Attainment.
    Lewis and Clark County Unclassifiable/Attainment.
    Liberty County Unclassifiable/Attainment.
    Lincoln County (remainder) Unclassifiable/Attainment.
    McCone County Unclassifiable/Attainment.
    Madison County Unclassifiable/Attainment.
    Meagher County Unclassifiable/Attainment.
    Mineral County Unclassifiable/Attainment.
    Missoula County Unclassifiable/Attainment.
    Musselshell County Unclassifiable/Attainment.
    Park County Unclassifiable/Attainment.
    Petroleum County Unclassifiable/Attainment.
    Phillips County Unclassifiable/Attainment.
    Pondera County Unclassifiable/Attainment.
    Powder River County Unclassifiable/Attainment.
    Powell County Unclassifiable/Attainment.
    Prairie County Unclassifiable/Attainment.
    Ravalli County Unclassifiable/Attainment.
    Richland County Unclassifiable/Attainment.
    Roosevelt County Unclassifiable/Attainment.
    Rosebud County Unclassifiable/Attainment.
    Sanders County Unclassifiable/Attainment.
    Sheridan County Unclassifiable/Attainment.
    Silver Bow County Unclassifiable/Attainment.
    Stillwater County Unclassifiable/Attainment.
    Sweet Grass County Unclassifiable/Attainment.
    Teton County Unclassifiable/Attainment.
    Toole County Unclassifiable/Attainment.
    Treasure County Unclassifiable/Attainment.
    Valley County Unclassifiable/Attainment.
    Wheatland County Unclassifiable/Attainment.
    Wibaux County Unclassifiable/Attainment.
    Yellowstone County Unclassifiable/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 Designation Classification
    Date2 Type Date2 Type
    Statewide:
    Beaverhead County Unclassifiable/Attainment
    Big Horn County Unclassifiable/Attainment
    Blaine County Unclassifiable/Attainment
    Broadwater County Unclassifiable/Attainment
    Carbon County Unclassifiable/Attainment
    Carter County Unclassifiable/Attainment
    Cascade County Unclassifiable/Attainment
    Chouteau County Unclassifiable/Attainment
    Custer County Unclassifiable/Attainment
    Daniels County Unclassifiable/Attainment
    Dawson County Unclassifiable/Attainment
    Deer Lodge County Unclassifiable/Attainment
    Fallon County Unclassifiable/Attainment
    Fergus County Unclassifiable/Attainment
    Flathead County Unclassifiable/Attainment
    Gallatin County Unclassifiable/Attainment
    Garfield County Unclassifiable/Attainment
    Glacier County Unclassifiable/Attainment
    Golden Valley County Unclassifiable/Attainment
    Granite County Unclassifiable/Attainment
    Hill County Unclassifiable/Attainment
    Jefferson County Unclassifiable/Attainment
    Judith Basin County Unclassifiable/Attainment
    Lake County Unclassifiable/Attainment
    Lewis and Clark County Unclassifiable/Attainment
    Liberty County Unclassifiable/Attainment
    Lincoln County Unclassifiable/Attainment
    McCone County Unclassifiable/Attainment
    Madison County Unclassifiable/Attainment
    Meagher County Unclassifiable/Attainment
    Mineral County Unclassifiable/Attainment
    Missoula County Unclassifiable/Attainment
    Musselshell County Unclassifiable/Attainment
    Park County Unclassifiable/Attainment
    Petroleum County Unclassifiable/Attainment
    Phillips County Unclassifiable/Attainment
    Pondera County Unclassifiable/Attainment
    Powder River County Unclassifiable/Attainment
    Powell County Unclassifiable/Attainment
    Prairie County Unclassifiable/Attainment
    Ravalli County Unclassifiable/Attainment
    Richland County Unclassifiable/Attainment
    Roosevelt County Unclassifiable/Attainment
    Rosebud County Unclassifiable/Attainment
    Sanders County Unclassifiable/Attainment
    Sheridan County Unclassifiable/Attainment
    Silver Bow County Unclassifiable/Attainment
    Stillwater County Unclassifiable/Attainment
    Sweet Grass County Unclassifiable/Attainment
    Teton County Unclassifiable/Attainment
    Toole County Unclassifiable/Attainment
    Treasure County Unclassifiable/Attainment
    Valley County Unclassifiable/Attainment
    Wheatland County Unclassifiable/Attainment
    Wibaux County Unclassifiable/Attainment
    Yellowstone County Unclassifiable/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 area Designationa Classification
    Date1 Type Date Type
    Statewide:
    Beaverhead County Unclassifiable/Attainment.
    Big Horn County Unclassifiable/Attainment.
    Blaine County Unclassifiable/Attainment.
    Broadwater County Unclassifiable/Attainment.
    Carbon County Unclassifiable/Attainment.
    Carter County Unclassifiable/Attainment.
    Cascade County Unclassifiable/Attainment.
    Chouteau County Unclassifiable/Attainment.
    Custer County Unclassifiable/Attainment.
    Daniels County Unclassifiable/Attainment.
    Dawson County Unclassifiable/Attainment.
    Deer Lodge County Unclassifiable/Attainment.
    Fallon County Unclassifiable/Attainment.
    Fergus County Unclassifiable/Attainment.
    Flathead County Unclassifiable/Attainment.
    Gallatin County Unclassifiable/Attainment.
    Garfield County Unclassifiable/Attainment.
    Glacier County Unclassifiable/Attainment.
    Golden Valley County Unclassifiable/Attainment.
    Granite County Unclassifiable/Attainment.
    Hill County Unclassifiable/Attainment.
    Jefferson County Unclassifiable/Attainment.
    Judith Basin County Unclassifiable/Attainment.
    Lake County Unclassifiable/Attainment.
    Lewis and Clark County Unclassifiable/Attainment.
    Liberty County Unclassifiable/Attainment.
    Lincoln County Unclassifiable/Attainment.
    McCone County Unclassifiable/Attainment.
    Madison County Unclassifiable/Attainment.
    Meagher County Unclassifiable/Attainment.
    Mineral County Unclassifiable/Attainment.
    Missoula County Unclassifiable/Attainment.
    Musselshell County Unclassifiable/Attainment.
    Park County Unclassifiable/Attainment.
    Petroleum County Unclassifiable/Attainment.
    Phillips County Unclassifiable/Attainment.
    Pondera County Unclassifiable/Attainment.
    Powder River County Unclassifiable/Attainment.
    Powell County Unclassifiable/Attainment.
    Prairie County Unclassifiable/Attainment.
    Ravalli County Unclassifiable/Attainment.
    Richland County Unclassifiable/Attainment.
    Roosevelt County Unclassifiable/Attainment.
    Rosebud County Unclassifiable/Attainment.
    Sanders County Unclassifiable/Attainment.
    Sheridan County Unclassifiable/Attainment.
    Silver Bow County Unclassifiable/Attainment.
    Stillwater County Unclassifiable/Attainment.
    Sweet Grass County Unclassifiable/Attainment.
    Teton County Unclassifiable/Attainment.
    Toole County Unclassifiable/Attainment.
    Treasure County Unclassifiable/Attainment.
    Valley County Unclassifiable/Attainment.
    Wheatland County Unclassifiable/Attainment.
    Wibaux County Unclassifiable/Attainment.
    Yellowstone County Unclassifiable/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 area Designationa Classification
    Date1 Type Date Type
    Statewide:
    Beaverhead County Unclassifiable/Attainment.
    Big Horn County Unclassifiable/Attainment.
    Blaine County Unclassifiable/Attainment.
    Broadwater County Unclassifiable/Attainment.
    Carbon County Unclassifiable/Attainment.
    Carter County Unclassifiable/Attainment.
    Cascade County Unclassifiable/Attainment.
    Chouteau County Unclassifiable/Attainment.
    Custer County Unclassifiable/Attainment.
    Daniels County Unclassifiable/Attainment.
    Dawson County Unclassifiable/Attainment.
    Deer Lodge County Unclassifiable/Attainment.
    Fallon County Unclassifiable/Attainment.
    Fergus County Unclassifiable/Attainment.
    Flathead County Unclassifiable/Attainment.
    Gallatin County Unclassifiable/Attainment.
    Garfield County Unclassifiable/Attainment.
    Glacier County Unclassifiable/Attainment.
    Golden Valley County Unclassifiable/Attainment.
    Granite County Unclassifiable/Attainment.
    Hill County Unclassifiable/Attainment.
    Jefferson County Unclassifiable/Attainment.
    Judith Basin County Unclassifiable/Attainment.
    Lake County Unclassifiable/Attainment.
    Lewis and Clark County Unclassifiable/Attainment.
    Liberty County Unclassifiable/Attainment.
    Lincoln County Unclassifiable/Attainment.
    McCone County Unclassifiable/Attainment.
    Madison County Unclassifiable/Attainment.
    Meagher County Unclassifiable/Attainment.
    Mineral County Unclassifiable/Attainment.
    Missoula County Unclassifiable/Attainment.
    Musselshell County Unclassifiable/Attainment.
    Park County Unclassifiable/Attainment.
    Petroleum County Unclassifiable/Attainment.
    Phillips County Unclassifiable/Attainment.
    Pondera County Unclassifiable/Attainment.
    Powder River County Unclassifiable/Attainment.
    Powell County Unclassifiable/Attainment.
    Prairie County Unclassifiable/Attainment.
    Ravalli County Unclassifiable/Attainment.
    Richland County Unclassifiable/Attainment.
    Roosevelt County Unclassifiable/Attainment.
    Rosebud County Unclassifiable/Attainment.
    Sanders County Unclassifiable/Attainment.
    Sheridan County Unclassifiable/Attainment.
    Silver Bow County Unclassifiable/Attainment.
    Stillwater County Unclassifiable/Attainment.
    Sweet Grass County Unclassifiable/Attainment.
    Teton County Unclassifiable/Attainment.
    Toole County Unclassifiable/Attainment.
    Treasure County Unclassifiable/Attainment.
    Valley County Unclassifiable/Attainment.
    Wheatland County Unclassifiable/Attainment.
    Wibaux County Unclassifiable/Attainment.
    Yellowstone County Unclassifiable/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 area Does not meet primary standards Cannot be classified or better than national standards
    Entire State X

    Montana—NO2 (2010 1-Hour Standard)

    Designated area Designationa
    Date1 Type
    Beaverhead County Unclassifiable/Attainment.
    Big Horn County Unclassifiable/Attainment.
    Blaine County Unclassifiable/Attainment.
    Broadwater County Unclassifiable/Attainment.
    Carbon County Unclassifiable/Attainment.
    Carter County Unclassifiable/Attainment.
    Cascade County Unclassifiable/Attainment.
    Chouteau County Unclassifiable/Attainment.
    Custer County Unclassifiable/Attainment.
    Daniels County Unclassifiable/Attainment.
    Dawson County Unclassifiable/Attainment.
    Deer Lodge County Unclassifiable/Attainment.
    Fallon County Unclassifiable/Attainment.
    Fergus County Unclassifiable/Attainment.
    Flathead County Unclassifiable/Attainment.
    Gallatin County Unclassifiable/Attainment.
    Garfield County Unclassifiable/Attainment.
    Glacier County Unclassifiable/Attainment.
    Golden Valley County Unclassifiable/Attainment.
    Granite County Unclassifiable/Attainment.
    Hill County Unclassifiable/Attainment.
    Jefferson County Unclassifiable/Attainment.
    Judith Basin County Unclassifiable/Attainment.
    Lake County Unclassifiable/Attainment.
    Lewis and Clark County Unclassifiable/Attainment.
    Liberty County Unclassifiable/Attainment.
    Lincoln County Unclassifiable/Attainment.
    McCone County Unclassifiable/Attainment.
    Madison County Unclassifiable/Attainment.
    Meagher County Unclassifiable/Attainment.
    Mineral County Unclassifiable/Attainment.
    Missoula County Unclassifiable/Attainment.
    Musselshell County Unclassifiable/Attainment.
    Park County Unclassifiable/Attainment.
    Petroleum County Unclassifiable/Attainment.
    Phillips County Unclassifiable/Attainment.
    Pondera County Unclassifiable/Attainment.
    Powder River County Unclassifiable/Attainment.
    Powell County Unclassifiable/Attainment.
    Prairie County Unclassifiable/Attainment.
    Ravalli County Unclassifiable/Attainment.
    Richland County Unclassifiable/Attainment.
    Roosevelt County Unclassifiable/Attainment.
    Rosebud County Unclassifiable/Attainment.
    Sanders County Unclassifiable/Attainment.
    Sheridan County Unclassifiable/Attainment.
    Silver Bow County Unclassifiable/Attainment.
    Stillwater County Unclassifiable/Attainment.
    Sweet Grass County Unclassifiable/Attainment.
    Teton County Unclassifiable/Attainment.
    Toole County Unclassifiable/Attainment.
    Treasure County Unclassifiable/Attainment.
    Valley County Unclassifiable/Attainment.
    Wheatland County Unclassifiable/Attainment.
    Wibaux County Unclassifiable/Attainment.
    Yellowstone County Unclassifiable/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 area Designationa Category/classification
    Date1 Type Date1 Type
    Statewide:
    Beaverhead County Unclassifiable/Attainment
    Big Horn County Unclassifiable/Attainment
    Blaine County Unclassifiable/Attainment
    Broadwater County Unclassifiable/Attainment
    Carbon County Unclassifiable/Attainment
    Carter County Unclassifiable/Attainment
    Cascade County Unclassifiable/Attainment
    Chouteau County Unclassifiable/Attainment
    Custer County Unclassifiable/Attainment
    Daniels County Unclassifiable/Attainment
    Dawson County Unclassifiable/Attainment
    Deer Lodge County Unclassifiable/Attainment
    Fallon County Unclassifiable/Attainment
    Fergus County Unclassifiable/Attainment
    Flathead County Unclassifiable/Attainment
    Gallatin County Unclassifiable/Attainment
    Garfield County Unclassifiable/Attainment
    Glacier County Unclassifiable/Attainment
    Golden Valley County Unclassifiable/Attainment
    Granite County. Unclassifiable/Attainment
    Hill County Unclassifiable/Attainment
    Jefferson County Unclassifiable/Attainment
    Judith Basin County Unclassifiable/Attainment
    Lake County Unclassifiable/Attainment
    Lewis and Clark County Unclassifiable/Attainment
    Liberty County Unclassifiable/Attainment
    Lincoln County Unclassifiable/Attainment
    Madison County Unclassifiable/Attainment
    McCone County Unclassifiable/Attainment
    Meagher County Unclassifiable/Attainment
    Mineral County Unclassifiable/Attainment
    Missoula County Unclassifiable/Attainment
    Musselshell County Unclassifiable/Attainment
    Park County Unclassifiable/Attainment
    Petroleum County Unclassifiable/Attainment
    Phillips County Unclassifiable/Attainment
    Pondera County Unclassifiable/Attainment
    Powder River County Unclassifiable/Attainment
    Powell County Unclassifiable/Attainment
    Prairie County Unclassifiable/Attainment
    Ravalli County Unclassifiable/Attainment
    Richland County Unclassifiable/Attainment
    Roosevelt County Unclassifiable/Attainment
    Rosebud County Unclassifiable/Attainment
    Sanders County Unclassifiable/Attainment
    Sheridan County Unclassifiable/Attainment
    Silver Bow County Unclassifiable/Attainment
    Stillwater County Unclassifiable/Attainment
    Sweet Grass County Unclassifiable/Attainment
    Teton County Unclassifiable/Attainment
    Toole County Unclassifiable/Attainment
    Treasure County Unclassifiable/Attainment
    Valley County Unclassifiable/Attainment
    Wheatland County Unclassifiable/Attainment
    Wibaux County Unclassifiable/Attainment
    Yellowstone County Unclassifiable/Attainment
    Yellowstone Natl Park Unclassifiable/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 area Designation Classification
    Date1 Type Date1 Type
    Statewide and Any Areas of Indian Country Unclassifiable/Attainment

    1 This date is July 20, 2012, unless otherwise noted.

    Montana—2015 8-Hour Ozone NAAQS

    [Primary and Secondary]

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

    Montana—2008 Lead NAAQS

    Designated area Designation for the 2008 NAAQSa
    Date1 Type
    Whole State Unclassifiable/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.