Regulations last checked for updates: Feb 09, 2026

Title 40 - Protection of Environment last revised: Dec 22, 2026
All TitlesTitle 40Chapter IPart 81Subpart C - Subpart C—Section 107 Attainment Status Designations
View all text of Subpart C [§ 81.300 - § 81.356]
§ 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 AreaX
East Helena AreaX
Anaconda AreaX
Rest of StateX

Montana—2010 Sulfur Dioxide NAAQS

[Primary]

Designated area 1 Designation
Date 2 Type
Yellowstone County (part)5/10/2016Attainment.
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 Area Designation Classification
Date 1 Type Date 1 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 Area Designation Classification
Date Type Date Type
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 area Designation Classification
Date 1 Type Date 1 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 Area Designation Classification
Date Type Date Type
Cascade County, Great Falls area11/15/1990Unclassifiable
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 vicinity11/15/1990Nonattainment11/15/1990Moderate.
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, Polson11/15/1990Nonattainment11/15/1990Moderate.
Lincoln County, Libby and vicinity11/15/1990Nonattainment11/15/1990Moderate.
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 area11/15/1990Unclassifiable
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 Deer11/15/1990Nonattainment11/15/1990Moderate.
Colstrip area11/15/1990Unclassifiable
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 area11/15/1990Unclassifiable
Rest of State 1 11/15/1990Unclassifiable

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

Montana—1997 Annual PM2.5 NAAQS

[Primary and Secondary]

Designated area Designation a Classification
Date 1 Type Date 2 Type
Libby, MT:
Lincoln County (part)8/23/2023Attainment
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 area 1 Designation Classification
Date 2 Type Date 2 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 area Designation a Classification
Date 1 Type Date 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.

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 Designation a Classification
Date 1 Type Date 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.

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 StateX

Montana—NO2 (2010 1-Hour Standard)

Designated area Designation a
Date 1 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 area Designation a Category/classification
Date 1 Type Date 1 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 area Designation Classification
Date 1 Type Date 1 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 area 1 Designation Classification
Date 2 Type Date Type
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 area Designation for the 2008 NAAQS a
Date 1 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: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.
authority: 42 U.S.C. 7401,
source: 36 FR 22421, Nov. 25, 1971, unless otherwise noted.
cite as: 40 CFR 81.327
© 2014 CustomsMobile | Disclaimer | Privacy | About