1. Regulations
  2. title 40
  3. chapter I-i19
  4. part 81
  5. subpart C
  6. § 81.327

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 1Designation Date 2Type 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 Area Designation Classification Date 1Type Date 1Type 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 1Type Date 1Type 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 area11/15/90Unclassifiable 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 State 111/15/90Unclassifiable

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

Montana—1997 Annual PM2.5 NAAQS

[Primary and Secondary]

Designated area Designation aClassification Date 1Type Date 2Type 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 area 1Designation Classification Date 2Type Date 2Type 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 aClassification Date 1Type 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 aClassification Date 1Type 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 aDate 1Type 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 aCategory/classification Date 1Type Date 1Type 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 1Type Date 1Type 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 1Designation Classification Date 2Type 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 aDate 1Type 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