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 Code of Federal Regulations (Last Updated: April 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

  § 81.306 - Colorado.  

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  • § 81.306 Colorado.

    Colorado—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
    Entire StateX

    Colorado—2010 Sulfur Dioxide NAAQS

    [Primary]

    Designated area1 Designation
    Date3 Type
    Colorado Springs, CO9/12/16Unclassifiable.
    El Paso County (part)
    Manitou Springs
    Colorado Springs (and certain unincorporated areas) as follows; Areas east of the western city limits of Colorado Springs, north of the southern city limits of Colorado Springs with the addition of the area termed “Stratmoor” bounded on the south by South Academy Boulevard, west of Powers Blvd, and south of East Woodman Blvd (east of Academy Blvd. N) and the northern city limits of Colorado Springs (west of Academy Blvd. N).
    Eastern Morgan County, CO9/12/16Unclassifiable.
    Morgan County (part)
    Circle with a 12-kilometer radius centered on the Pawnee Power Plant
    State AQCR 01 (remainder)Attainment/Unclassifiable.
    Logan County
    Morgan County (part) (remainder)
    Phillips County
    Sedgwick County
    Washington County
    Yuma County
    State AQCR 02Attainment/Unclassifiable.
    Larimer County
    Weld County
    State AQCR 03Attainment/Unclassifiable.
    Adams County
    Arapahoe County
    Boulder County
    Broomfield County
    Clear Creek County
    Denver County
    Douglas County
    Gilpin County
    Jefferson County
    State AQCR 04 (remainder)Attainment/Unclassifiable.
    El Paso County (part) (remainder)
    Park County
    Teller County
    State AQCR 05Attainment/Unclassifiable.
    Cheyenne County
    Elbert County
    Kit Carson County
    Lincoln County
    State AQCR 06Attainment/Unclassifiable.
    Baca County
    Bent County
    Crowley County
    Kiowa County
    Otero County
    Prowers County
    State AQCR 07Attainment/Unclassifiable.
    Huerfano
    Las Animas
    Pueblo
    State AQCR 08Attainment/Unclassifiable.
    Alamosa County
    Conejos County
    Costilla County
    Mineral County
    Rio Grande County
    Saguache County
    State AQCR 09Attainment/Unclassifiable.
    Archuleta County2
    Dolores
    La Plata2
    Montezuma2
    San Juan
    State AQCR 10Attainment/Unclassifiable.
    Delta County
    Gunnison County
    Hinsdale County
    Montrose County
    Ouray County
    San Miguel County
    State AQCR 11Attainment/Unclassifiable.
    Garfield County
    Mesa County
    Moffat County
    Rio Blanco County
    State AQCR 12Attainment/Unclassifiable.
    Eagle County
    Grand County
    Jackson County
    Pitkin County
    Routt County
    Summit County
    State AQCR 13Attainment/Unclassifiable.
    Chaffee County
    Custer County
    Fremont County
    Lake County
    Southern Ute Indian ReservationAttainment/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 Does not include the Southern Ute Indian Reservation, which is being designated separately.

    3 This date is April 9, 2018, unless otherwise noted.

    Colorado—Carbon Monoxide

    Designated Area Designation Classification
    Date1 Type Date1 Type
    Colorado Springs Area:October 25, 1999Attainment
    Urban Transportation Planing Study Area as defined in 1989.
    Beginning near the Town of Palmer Lake, at the Northwest corner of the Study Area at a point on the El Paso/Douglas County line, also on the Pike National Forest boundary, then:
    east along the County line to Elbert Road; south on Elbert Road to Judge Orr Road; east on Judge Orr Road to Ellicott Highway; south on Ellicott Highway to Squirrel Creek Road; west on Squirrel Creek Road to Williams Creek; south along Williams Creek to the confluence of Williams and Fountain Creeks; south along Fountain Creek to the El Paso/Douglas County line; west on the County line to I–25; north on I–25 to Exit 132; west on McGrath to 35th; south on 35th to Specker; northwest on Specker to Titus Blvd.; west on Titus Blvd. to SH–115;
    south on SH–115 to Rock Creek;
    northwest along Rock Creek to the Pike National Forest boundary; north along the Forest boundary to Old Stage Road; southwest on Old Stage Road to Gold Camp Road; north on Gold Camp Road to High Drive; north on High Drive to Lower Gold Camp Road; north on Lower Gold Camp Road to the Pike National Forest boundary; west along the Forest boundary, following the boundary north, then east to US–24; northwest on US–24 to the Pikes Peak Toll Road; west on the Toll Road to the El Paso/Teller County line;
    north along the County line to Crystola Creek; west on Crystola Creek to County Road 282, north on Road 282 to US–24; northeast on US–24 to Trout Creek Road; northwest on Trout Creek Road to Trout Creek; north along Trout Creek to the confluence of Trout and Mule Creeks; north along Mule Creek to Long Gulch; east along Long Gulch to White Gulch; east along White Gulch to Rampart Range Road; southeast on Rampart Range Road to the Pike National Forest Boundary; north along the Forest boundary to the El Paso/Douglas County line, to the point of origin.
    El Paso County (part)
    Teller County (part)
    Denver-Boulder Area:
    The boundaries for the Denver nonattainment area for carbon monixide (CO) are described as follows: Start at Colorado Highway 52 where it intersects the eastern boundary of Boulder County; Follow Highway 52 west until it intersects Colorado Highway 119; Follow northern boundary of Boulder city limits west to the 6,000-ft. elevation line; Follow the 6000-ft. elevation line south through Boulder and Jefferson Counties to US 6 in Jefferson County; Follow US 6 west to the Jefferson County-Clear Creek County line; Follow the Jefferson County western boundary south for approximately 16.25 miles; Follow a line east for approximately 3.75 mile to South Turkey Creek; Follow South Turkey Creek northeast for approximately 3.5 miles; Follow a line southeast for approximately 2.0 miles to the junction of South Deer Creek Road and South Deer Creek Canyon Road; Follow South Deer Creek Canyon Road northeast for approximately 3.75 miles; Follow a line southeast for approximately five miles to the northern-most boundary of Pike National Forest where it intersects the Jefferson County-Douglas County line; follow the Pike National forest boundary southeast through Douglas County to the Douglas County-El Paso County line; Follow the southern boundary on Douglas County east to the Elbert County line; Follow the eastern boundary of Douglas County north to the Arapahoe County line; Follow the southern boundary of Araphoe County east to Kiowa Creek; Follow Kiowa Creek northeast through Arapahoe and Adams Counties to the Adams-Weld County line; Follow the northern boundary of Adams County west to the Boulder County line; Follow the eastern boundary of Boulder County north to Highway 52January 14, 2002Attainment
    Adams County (part)
    Arapahoe County (part)
    Boulder County (part)
    Denver County
    Douglas County (part)
    Jefferson County (part)
    Fort Collins Area:
    Larimer County (part)Sept. 22, 2003Attainment
    Fort Collins Urban Growth Area Boundary as adopted by the City of Fort Collins and the Larimer County Commissioners and in effect as of July 30, 1991.
    Greeley Area:Attainment
    Weld County (part)May 10, 1999
    Urban boundaries as defined in the North Front Range Regional Transportation Plan, May, 1990.
    Longmont AreaNov. 23, 1999Attainment
    Hwy 52 west from the Boulder/Weld County line to 95th Street/Hoover Road, then north on 95th Street/Hoover Road to the intersection of Plateau Road and SH 119, then west on Plateau Road to the intersection of Hygiene Road, then due north to the Boulder/Larimer County line, then due east to the intersection of the Boulder/Larimer/Weld County lines, then south along the Boulder/Weld County line to Hwy 52, plus the portion of the City of Longmont east of the Boulder/Weld County line in Weld County.
    Boulder County (part):
    Weld County (part):
    State AQCR 1Unclassifiable/Attainment
    Logan County
    Morgan County
    Phillips County
    Sedgwick County
    Washington County
    Yuma County
    State AQCR 2 (Remainder of)
    Larimer County (part)Unclassifiable/Attainment
    Area outside Fort Collins Urban Growth Area Boundary
    Weld County (part)
    Remainder of countyUnclassifiable/Attainment
    State AQCR 3 (Remainder of)Unclassifiable/Attainment
    Adams County (part)
    Remainder of County
    Arapahoe County (part)
    Remainder of County
    Boulder County (part)
    Remainder of County
    Clear Creek County
    Douglas County (part)
    Remainder of County
    Gilpin County
    Jefferson County (part)
    Remainder of County
    State AQCR 4 (Remainder of)Unclassifiable/Attainment
    El Paso County (part)
    Area other than Urban Transportation Planning Study Area as defined in 1989
    Park County
    Teller County (part)
    Remainder of County
    State AQCR's 5-13Unclassifiable/Attainment
    Alamosa County
    Archuleta County
    Baca County
    Bent County
    Chaffee County
    Cheyenne County
    Conejos County
    Costilla County
    Crowley County
    Custer County
    Delta County
    Dolores County
    Eagle County
    Elbert County
    Fremont County
    Garfield County
    Grand County
    Gunnison County
    Hinsdale County
    Huerfano County
    Jackson County
    Kiowa County
    Kit Carson County
    La Plata County
    Lake County
    Las Animas County
    Lincoln County
    Mesa County
    Mineral County
    Moffat County
    Montezuma County
    Montrose County
    Otero County
    Ouray County
    Pitkin County
    Prowers County
    Pueblo County
    Rio Blanco County
    Rio Grande County
    Routt County
    Saguache County
    San Juan County
    San Miguel County
    Summit County

    1 This date is November 15, 1990, unless otherwise noted.

    Colorado—Ozone (1-Hour Standard)4

    Designated area Designation Classification
    Date1 Type Date1 Type
    Denver-Boulder Area:
    Adams County (part)
    West of Kiowa Creek10/11/01Attainment
    Arapahoe County (part)
    West of Kiowa CreekAttainment
    Boulder County (part) excluding Rocky Mountain National ParkAttainment
    Denver CountyAttainment
    Douglas CountyAttainment
    Jefferson CountyAttainment
    State AQCR 01Unclassifiable/Attainment
    Logan County
    Morgan County
    Phillips County
    Sedgwick County
    Washington County
    Yuma County
    State AQCR 02Unclassifiable/Attainment
    Larimer County
    Weld County
    State AQCR 03 (Remainder of)Unclassifiable/Attainment
    Adams County (part) East of Kiowa Creek
    Arapahoe County (part) East of Kiowa Creek
    Boulder County (part) Rocky Mtn. National Park Only
    Clear Creek County
    Gilpin County
    State AQCR 11Unclassifiable/Attainment
    Garfield County
    Mesa County
    Moffat County
    Rio Blanco County
    Rest of StateUnclassifiable/Attainment
    Alamosa County
    Archuleta County
    Baca County
    Bent County
    Chaffee County
    Cheyenne County
    Conejos County
    Costilla County
    Crowley County
    Custer County
    Delta County
    Dolores County
    Eagle County
    El Paso County
    Elbert County
    Fremont County
    Grand County
    Gunnison County
    Hinsdale County
    Huerfano County
    Jackson County
    Kiowa County
    Kit Carson County
    La Plata County
    Lake County
    Las Animas County
    Lincoln County
    Mineral County
    Montezuma County
    Montrose County
    Otero County
    Ouray County
    Park County
    Pitkin County
    Prowers County
    Pueblo County
    Rio Grande County
    Routt County
    Saguache County
    San Juan County
    San Miguel County
    Summit County
    Teller County

    1 This date is October 18, 2000, unless otherwise noted.

    2 An area designated as an ozone nonattainment area as of the date of enactment of the CAAA of the 1990 that did not violate the ozone NAAQS during the period of 1987–1989.

    3 This date is January 16, 2001.

    4 The 1-hour ozone standard is revoked effective June 15, 2005 for all areas in Colorado except the Denver (Denver-Boulder-Greeley-Ft. Collins-Love) area where it is revoked effective November 20, 2008.

    Colorado—PM–10

    Designated area Designation Classification
    Date Type Date Type
    Archuleta County
    Pagosa Springs Area8/14/01Attainment
    Township 35N–Range 2W: Sections 13, 14, 15; Section 23 NE, N 1⁄2 SE; Section 24 all except SWSW; Section 25 N 1⁄2NE, NENW.
    Township 35N–Range 1W: Section 18 W 1⁄2
    Adams, Denver, and Boulder Counties
    Denver Metropolitan area10/16/02Attainment
    All of Denver, Jefferson, and Douglas Counties, Boulder County (excluding the Rocky Mountain National Park) and the Colorado automobile inspection and readjustment program portions of Adams and Arapahoe Counties
    San Miguel County
    Telluride8/14/01Attainment
    The Telluride attainment/maintenance area begins at the intersection of Colorado State Highway 145 and the Telluride service area boundary, as it existed in 1991. The western edge of the nonattainment area until it meets Remine Creek is defined as follows: A tract of land located in a portion of the west one-half of Section 28 and the east one-half of Section 29, Township 43 North, Range 9 west, of New Mexico Principal Meridian, County of San Miguel, State of Colorado, described as follows: Beginning at the southwest corner of the said Section 28; Thence N 89 deg.36′00″ W. 292.70 Feet; Thence S 04 deg.05′12″ W. 538.63 Feet; Thence N 03 deg.29′42″ W. 780.19 Feet; Thence N 22 deg.15′00″ E. 3344.16 Feet; Thence S 51 deg.51′49″ E. 570.44 Feet; Thence S 03 deg.15′36″ E. 1106.22 Feet; Thence S 45 deg.24′42″ E. 546.96 Feet; Thence S 28 deg.41′12″ W. 549.62 Feet; Thence S 29 deg.40′09″ E. 169.68 Feet; Thence S 44 deg.30′03″ W. 649.51 Feet; Thence S 85 deg.54′00″ E. 660.00 Feet; Thence S 04 deg.06′00″ W. 660.00 Feet; Thence N 89 deg.56′00″ E. 1318.68 Feet; to the true point of beginning containing 11249 acres as described above. Then, at Remine Creek, the attainment/maintenance boundary follows the service area boundary for 9.65 miles to the 9,200 foot contour line. The boundary then intersects Bear Creek. Here the attainment/maintenance boundary diverges from the service area boundary (9,200 foot contour line). The attainment/maintenance boundary continues in a west, southwest direction for 0.92 miles from the intersection of the 9,200 foot contour line and Bear Creek to the top of ski lift number 9 in the Telluride Ski Area at an elevation of about 11,900 feet. The boundary then shifts and runs in a north-westerly direction for 0.83 miles from the top of lift 9 to the top of lift 7, which is located at an elevation of 10,490 feet. From the top of lift 7, the attainment/maintenance boundary continues in a north-westerly direction for 0.5 miles to the intersection of lift 3 with the 10,000 foot control line. The attainment/maintenance boundary follows the 10,000 foot contour line in a south, south-west direction for 3.2 miles, until it intersects Skunk Creek. Here the boundary diverges from the 10,000 foot contour line and follows Skunk Creek in a northerly direction for 2.25 miles. At the intersection of Skunk Creek and Colorado State Highway 145, the attainment/maintenance boundary leaves the creek and follows Highway 145 in a northerly direction until it meets the service area boundary as it existed prior to changes adopted in 1991.
    Prowers County
    Lamar12/27/05Attainment
    Pitkin County:
    Aspen/Pitkin County Area—The area encompassed by the following Parcel ID numbers, as defined by the Pitkin County Planning Department: 2337–29, 2737–28, 2737–21, 2737–20, 2737–19, 2737–18, 2737–17, 2737–08, 2737–07, 2737–06, 2735–22, 2735–15, 2735–14, 2735–13, 2735–12, 2735–11, 2735–10, 2735–03, 2735–02, 2735–01, 2641–31, 2643–36, 2643–35, 2643–34, 2643–27, 2643–267/14/03Attainment.
    Fremont County
    Canon City Area7/31/00Attainment
    Township 18S—Range 70W: All of sections 21, 22, 27, 28, 33, and 34; the E 1⁄2, NENW, NESW, SENW, SESW quarters of sections 20, 29, 32; and the W 1⁄2 of sections 23, 26, and 35; Township 19S—Range 70W: All of sections 3, 4, 9, 10; E 1⁄2, NENW, NESW, SENW, SESW quarters of sections 5 and 8; W 1⁄2 of sections 2 and 11.
    Routt County (part):
    Steamboat Springs11/24/04Attainment.
    On the East—The Routt National Forest.
    On the South—The southern border of sections 19, 10, 21, T4N, R84W of the 6th P.M. and the southern border of sections 23, 24, T4N, R85W of the 6th P.M.
    On the West—Beginning at the southwestern corner of section 23, T4N, R85W of the 6th P.M. North along the western border of sections 23, 14, 11, T4N, R85W. Thence, along the ridge which bisects sections 35, 36, 25, 24, 13, 14, 11, 12, 1, T5N, R85W, and sections 36, 25, 24, T6N, R85W. Thence heading northwest along the ridge which bisects sections 23, 15, 10, 9, 4, T6N, R85W of 6th P.M. Thence, heading northeast along the ridge which bisects sections 33, 34, 35, 36, 25, T7N, R85W and sections 30 and 10 of T7N, R84W. Thence, north along the N 1/2 of the western edge of section 19, to the NW corner of section 18, T7N, R84W.
    On the North—The northern boundary of sections 16, 17, 18, T7N, R84W of 6th P.M.
    AQCR 111/15/90Unclassifiable
    AQCR 211/15/90Unclassifiable
    AQCR 3 (excluding the Denver Metropolitan PM–10 nonattainment area)11/15/90Unclassifiable
    AQCR 411/15/90Unclassifiable
    AQCR 511/15/90Unclassifiable
    AQCR 6 (excluding the Lamar PM–10 nonattainment area)11/15/90Unclassifiable
    AQCR 711/15/90Unclassifiable
    AQCR 811/15/90Unclassifiable
    AQCR 9 (excluding the Pagosa Springs PM–10 nonattainment area)11/15/90Unclassifiable
    AQCR 10 (excluding the Telluride PM–10 nonattainment area)11/15/90Unclassifiable
    AQCR 1111/15/90Unclassifiable
    AQCR 12 (excluding the Aspen/Pitkin County and Steamboat Springs Area Airshed PM–10 nonattainment areas)11/15/90Unclassifiable
    AQCR 13 (excluding the Canon City PM–10 nonattainment area)1/15/90Unclassifiable

    Colorado—1997 Annual PM2.5 NAAQS

    [Primary and Secondary]

    Designated area Designationa Classification
    Date1 Type Date Type
    Denver-Boulder Area:
    Adams County (part) West of Kiowa CreekUnclassifiable/Attainment
    Arapahoe County (part) West of Kiowa CreekUnclassifiable/Attainment
    Boulder County (part) Excluding Rocky Mountain National ParkUnclassifiable/Attainment
    Broomfield CountyUnclassifiable/Attainment
    Denver CountyUnclassifiable/Attainment
    Douglas CountyUnclassifiable/Attainment
    Jefferson CountyUnclassifiable/Attainment
    State AQCR 01:
    Logan CountyUnclassifiable/Attainment
    Morgan CountyUnclassifiable/Attainment
    Phillips CountyUnclassifiable/Attainment
    Sedgwick CountyUnclassifiable/Attainment
    Washington CountyUnclassifiable/Attainment
    Yuma CountyUnclassifiable/Attainment
    State AQCR 02:
    Larimer CountyUnclassifiable/Attainment
    Weld CountyUnclassifiable/Attainment
    State AQCR 03 (remainder of):
    Adams County (remainder)Unclassifiable/Attainment
    Arapahoe County (remainder)Unclassifiable/Attainment
    Boulder County (remainder)Unclassifiable/Attainment
    Clear Creek CountyUnclassifiable/Attainment
    Gilpin CountyUnclassifiable/Attainment
    State AQCR 04:
    El Paso CountyUnclassifiable/Attainment
    Park CountyUnclassifiable/Attainment
    Teller CountyUnclassifiable/Attainment
    State AQCR 05:
    Cheyenne CountyUnclassifiable/Attainment
    Elbert CountyUnclassifiable/Attainment
    Kit Carson CountyUnclassifiable/Attainment
    Lincoln CountyUnclassifiable/Attainment
    State AQCR 06:
    Baca CountyUnclassifiable/Attainment
    Bent CountyUnclassifiable/Attainment
    Crowley CountyUnclassifiable/Attainment
    Kiowa CountyUnclassifiable/Attainment
    Otero CountyUnclassifiable/Attainment
    Prowers CountyUnclassifiable/Attainment
    State AQCR 07:
    Huerfano CountyUnclassifiable/Attainment
    Las Animas CountyUnclassifiable/Attainment
    Pueblo CountyUnclassifiable/Attainment
    State AQCR 08:
    Alamosa CountyUnclassifiable/Attainment
    Conejos CountyUnclassifiable/Attainment
    Costilla CountyUnclassifiable/Attainment
    Mineral CountyUnclassifiable/Attainment
    Rio Grande CountyUnclassifiable/Attainment
    Saguache CountyUnclassifiable/Attainment
    State AQCR 09:
    Archuleta CountyUnclassifiable/Attainment
    Dolores CountyUnclassifiable/Attainment
    La Plata CountyUnclassifiable/Attainment
    Montezuma CountyUnclassifiable/Attainment
    San Juan CountyUnclassifiable/Attainment
    State AQCR 10:
    Delta CountyUnclassifiable/Attainment
    Gunnison CountyUnclassifiable/Attainment
    Hinsdale CountyUnclassifiable/Attainment
    Montrose CountyUnclassifiable/Attainment
    Ouray CountyUnclassifiable/Attainment
    San Miguel CountyUnclassifiable/Attainment
    State AQCR 11:
    Garfield CountyUnclassifiable/Attainment
    Mesa CountyUnclassifiable/Attainment
    Moffat CountyUnclassifiable/Attainment
    Rio Blanco CountyUnclassifiable/Attainment
    State AQCR 12:
    Eagle CountyUnclassifiable/Attainment
    Grand CountyUnclassifiable/Attainment
    Jackson CountyUnclassifiable/Attainment
    Pitkin CountyUnclassifiable/Attainment
    Routt CountyUnclassifiable/Attainment
    Summit CountyUnclassifiable/Attainment
    State AQCR 13:
    Chaffee CountyUnclassifiable/Attainment
    Custer CountyUnclassifiable/Attainment
    Fremont CountyUnclassifiable/Attainment
    Lake CountyUnclassifiable/Attainment

    a Includes Indian Country located in each county or area, except as otherwise specified.

    1This date is 90 days after January 5, 2005, unless otherwise noted.

    Colorado—2012 Annual PM2.5 NAAQS

    [Primary]

    Designated area1 Designation Classification
    Date2 Type Date2 Type
    State AQCR 01:
    Logan CountyUnclassifiable/Attainment
    Morgan CountyUnclassifiable/Attainment
    Phillips CountyUnclassifiable/Attainment
    Sedgwick CountyUnclassifiable/Attainment
    Washington CountyUnclassifiable/Attainment
    Yuma CountyUnclassifiable/Attainment
    State AQCR 02:
    Larimer CountyUnclassifiable/Attainment
    Weld CountyUnclassifiable/Attainment
    State AQCR 03:
    Adams CountyUnclassifiable/Attainment
    Arapahoe CountyUnclassifiable/Attainment
    Boulder CountyUnclassifiable/Attainment
    Broomfield CountyUnclassifiable/Attainment
    Clear Creek CountyUnclassifiable/Attainment
    Denver CountyUnclassifiable/Attainment
    Douglas CountyUnclassifiable/Attainment
    Gilpin CountyUnclassifiable/Attainment
    Jefferson CountyUnclassifiable/Attainment
    State AQCR 04:
    El Paso CountyUnclassifiable/Attainment
    Park CountyUnclassifiable/Attainment
    Teller CountyUnclassifiable/Attainment
    State AQCR 05:
    Cheyenne CountyUnclassifiable/Attainment
    Elbert CountyUnclassifiable/Attainment
    Kit Carson CountyUnclassifiable/Attainment
    Lincoln CountyUnclassifiable/Attainment
    State AQCR 06:
    Baca CountyUnclassifiable/Attainment
    Bent CountyUnclassifiable/Attainment
    Crowley CountyUnclassifiable/Attainment
    Kiowa CountyUnclassifiable/Attainment
    Otero CountyUnclassifiable/Attainment
    Prowers CountyUnclassifiable/Attainment
    State AQCR 07:
    Huerfano CountyUnclassifiable/Attainment
    Las Animas CountyUnclassifiable/Attainment
    Pueblo CountyUnclassifiable/Attainment
    State AQCR 08:
    Alamosa CountyUnclassifiable/Attainment
    Conejos CountyUnclassifiable/Attainment
    Costilla CountyUnclassifiable/Attainment
    Mineral CountyUnclassifiable/Attainment
    Rio Grande CountyUnclassifiable/Attainment
    Saguache CountyUnclassifiable/Attainment
    State AQCR 09:
    Archuleta CountyUnclassifiable/Attainment
    Dolores CountyUnclassifiable/Attainment
    La Plata CountyUnclassifiable/Attainment
    Montezuma CountyUnclassifiable/Attainment
    San Juan CountyUnclassifiable/Attainment
    State AQCR 10:
    Delta CountyUnclassifiable/Attainment
    Gunnison CountyUnclassifiable/Attainment
    Hinsdale CountyUnclassifiable/Attainment
    Montrose CountyUnclassifiable/Attainment
    Ouray CountyUnclassifiable/Attainment
    San Miguel CountyUnclassifiable/Attainment
    State AQCR 11:
    Garfield CountyUnclassifiable/Attainment
    Mesa CountyUnclassifiable/Attainment
    Moffat CountyUnclassifiable/Attainment
    Rio Blanco CountyUnclassifiable/Attainment
    State AQCR 12:
    Eagle CountyUnclassifiable/Attainment
    Grand CountyUnclassifiable/Attainment
    Jackson CountyUnclassifiable/Attainment
    Pitkin CountyUnclassifiable/Attainment
    Routt CountyUnclassifiable/Attainment
    Summit CountyUnclassifiable/Attainment
    State AQCR 13:
    Chaffee CountyUnclassifiable/Attainment
    Custer CountyUnclassifiable/Attainment
    Fremont CountyUnclassifiable/Attainment
    Lake 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.

    Colorado—1997 24-Hour PM2.5 NAAQS

    [Primary and Secondary]

    Designated area Designationa Classification
    Date1 Type Date Type
    Denver-Boulder Area:
    Adams County (part) West of Kiowa CreekUnclassifiable/Attainment
    Arapahoe County (part) West of Kiowa CreekUnclassifiable/Attainment
    Boulder County (part) Excluding Rocky Mountain National ParkUnclassifiable/Attainment
    Broomfield CountyUnclassifiable/Attainment
    Denver CountyUnclassifiable/Attainment
    Douglas CountyUnclassifiable/Attainment
    Jefferson CountyUnclassifiable/Attainment
    State AQCR 01:
    Logan CountyUnclassifiable/Attainment
    Morgan CountyUnclassifiable/Attainment
    Phillips CountyUnclassifiable/Attainment
    Sedgwick CountyUnclassifiable/Attainment
    Washington CountyUnclassifiable/Attainment
    Yuma CountyUnclassifiable/Attainment
    State AQCR 02:
    Larimer CountyUnclassifiable/Attainment
    Weld CountyUnclassifiable/Attainment
    State AQCR 03 (remainder of):
    Adams County (remainder)Unclassifiable/Attainment
    Arapahoe County (remainder)Unclassifiable/Attainment
    Boulder County (remainder)Unclassifiable/Attainment
    Clear Creek CountyUnclassifiable/Attainment
    Gilpin CountyUnclassifiable/Attainment
    State AQCR 04:
    El Paso CountyUnclassifiable/Attainment
    Park CountyUnclassifiable/Attainment
    Teller CountyUnclassifiable/Attainment
    State AQCR 05:
    Cheyenne CountyUnclassifiable/Attainment
    Elbert CountyUnclassifiable/Attainment
    Kit Carson CountyUnclassifiable/Attainment
    Lincoln CountyUnclassifiable/Attainment
    State AQCR 06:
    Baca CountyUnclassifiable/Attainment
    Bent CountyUnclassifiable/Attainment
    Crowley CountyUnclassifiable/Attainment
    Kiowa CountyUnclassifiable/Attainment
    Otero CountyUnclassifiable/Attainment
    Prowers CountyUnclassifiable/Attainment
    State AQCR 07:
    Huerfano CountyUnclassifiable/Attainment
    Las Animas CountyUnclassifiable/Attainment
    Pueblo CountyUnclassifiable/Attainment
    State AQCR 08:
    Alamosa CountyUnclassifiable/Attainment
    Conejos CountyUnclassifiable/Attainment
    Costilla CountyUnclassifiable/Attainment
    Mineral CountyUnclassifiable/Attainment
    Rio Grande CountyUnclassifiable/Attainment
    Saguache CountyUnclassifiable/Attainment
    State AQCR 09:
    Archuleta CountyUnclassifiable/Attainment
    Dolores CountyUnclassifiable/Attainment
    La Plata CountyUnclassifiable/Attainment
    Montezuma CountyUnclassifiable/Attainment
    San Juan CountyUnclassifiable/Attainment
    State AQCR 10:
    Delta CountyUnclassifiable/Attainment
    Gunnison CountyUnclassifiable/Attainment
    Hinsdale CountyUnclassifiable/Attainment
    Montrose CountyUnclassifiable/Attainment
    Ouray CountyUnclassifiable/Attainment
    San Miguel CountyUnclassifiable/Attainment
    State AQCR 11:
    Garfield CountyUnclassifiable/Attainment
    Mesa CountyUnclassifiable/Attainment
    Moffat CountyUnclassifiable/Attainment
    Rio Blanco CountyUnclassifiable/Attainment
    State AQCR 12:
    Eagle CountyUnclassifiable/Attainment
    Grand CountyUnclassifiable/Attainment
    Jackson CountyUnclassifiable/Attainment
    Pitkin CountyUnclassifiable/Attainment
    Routt CountyUnclassifiable/Attainment
    Summit CountyUnclassifiable/Attainment
    State AQCR 13:
    Chaffee CountyUnclassifiable/Attainment
    Custer CountyUnclassifiable/Attainment
    Fremont CountyUnclassifiable/Attainment
    Lake CountyUnclassifiable/Attainment

    a Includes Indian Country located in each county or area, except as otherwise specified.

    1This date is 90 days after January 5, 2005, unless otherwise noted.

    Colorado—2006 24-Hour PM2.5 NAAQS

    [Primary and Secondary]

    Designated area Designationa Classification
    Date1 Type Date Type
    Denver-Boulder Area:
    Adams County (part) West of Kiowa CreekUnclassifiable/Attainment.
    Arapahoe County (part) West of Kiowa CreekUnclassifiable/Attainment.
    Boulder County (part) Excluding Rocky Mountain National ParkUnclassifiable/Attainment.
    Broomfield CountyUnclassifiable/Attainment.
    Denver CountyUnclassifiable/Attainment.
    Douglas CountyUnclassifiable/Attainment.
    Jefferson CountyUnclassifiable/Attainment.
    State AQCR 01:
    Logan CountyUnclassifiable/Attainment.
    Morgan CountyUnclassifiable/Attainment.
    Phillips CountyUnclassifiable/Attainment.
    Sedgwick CountyUnclassifiable/Attainment.
    Washington CountyUnclassifiable/Attainment.
    Yuma CountyUnclassifiable/Attainment.
    State AQCR 02:
    Larimer CountyUnclassifiable/Attainment.
    Weld CountyUnclassifiable/Attainment.
    State AQCR 03 (remainder of):
    Adams County (remainder)Unclassifiable/Attainment.
    Arapahoe County (remainder)Unclassifiable/Attainment.
    Boulder County (remainder)Unclassifiable/Attainment.
    Clear Creek CountyUnclassifiable/Attainment.
    Gilpin CountyUnclassifiable/Attainment.
    State AQCR 04:
    El Paso CountyUnclassifiable/Attainment.
    Park CountyUnclassifiable/Attainment.
    Teller CountyUnclassifiable/Attainment.
    State AQCR 05:
    Cheyenne CountyUnclassifiable/Attainment.
    Elbert CountyUnclassifiable/Attainment.
    Kit Carson CountyUnclassifiable/Attainment.
    Lincoln CountyUnclassifiable/Attainment.
    State AQCR 06:
    Baca CountyUnclassifiable/Attainment.
    Bent CountyUnclassifiable/Attainment.
    Crowley CountyUnclassifiable/Attainment.
    Kiowa CountyUnclassifiable/Attainment.
    Otero CountyUnclassifiable/Attainment.
    Prowers CountyUnclassifiable/Attainment.
    State AQCR 07:
    Huerfano CountyUnclassifiable/Attainment.
    Las Animas CountyUnclassifiable/Attainment.
    Pueblo CountyUnclassifiable/Attainment.
    State AQCR 08:
    Alamosa CountyUnclassifiable/Attainment.
    Conejos CountyUnclassifiable/Attainment.
    Costilla CountyUnclassifiable/Attainment.
    Mineral CountyUnclassifiable/Attainment.
    Rio Grande CountyUnclassifiable/Attainment.
    Saguache CountyUnclassifiable/Attainment.
    State AQCR 09:
    Archuleta CountyUnclassifiable/Attainment.
    Dolores CountyUnclassifiable/Attainment.
    La Plata CountyUnclassifiable/Attainment.
    Montezuma CountyUnclassifiable/Attainment.
    San Juan CountyUnclassifiable/Attainment.
    State AQCR 10:
    Delta CountyUnclassifiable/Attainment.
    Gunnison CountyUnclassifiable/Attainment.
    Hinsdale CountyUnclassifiable/Attainment.
    Montrose CountyUnclassifiable/Attainment.
    Ouray CountyUnclassifiable/Attainment.
    San Miguel CountyUnclassifiable/Attainment.
    State AQCR 11:
    Garfield CountyUnclassifiable/Attainment.
    Mesa CountyUnclassifiable/Attainment.
    Moffat CountyUnclassifiable/Attainment.
    Rio Blanco CountyUnclassifiable/Attainment.
    State AQCR 12:
    Eagle CountyUnclassifiable/Attainment.
    Grand CountyUnclassifiable/Attainment.
    Jackson CountyUnclassifiable/Attainment.
    Pitkin CountyUnclassifiable/Attainment.
    Routt CountyUnclassifiable/Attainment.
    Summit CountyUnclassifiable/Attainment.
    State AQCR 13:
    Chaffee CountyUnclassifiable/Attainment.
    Custer CountyUnclassifiable/Attainment.
    Fremont CountyUnclassifiable/Attainment.
    Lake 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.

    Colorado—NO2 (1971 Annual Standard)

    Designated area Better than national standards
    Entire StateX

    Colorado—NO2 (2010 1-Hour Standard)

    Designated area Designationa
    Date1 Type
    State AQCR 01:
    Logan CountyUnclassifiable/Attainment.
    Morgan CountyUnclassifiable/Attainment.
    Phillips CountyUnclassifiable/Attainment.
    Sedgwick CountyUnclassifiable/Attainment.
    Washington CountyUnclassifiable/Attainment.
    Yuma CountyUnclassifiable/Attainment.
    State AQCR 02:
    Larimer CountyUnclassifiable/Attainment.
    Weld CountyUnclassifiable/Attainment.
    State AQCR 03:
    Adams CountyUnclassifiable/Attainment.
    Arapahoe CountyUnclassifiable/Attainment.
    Boulder CountyUnclassifiable/Attainment.
    Broomfield CountyUnclassifiable/Attainment.
    Clear Creek CountyUnclassifiable/Attainment.
    Denver CountyUnclassifiable/Attainment.
    Douglas CountyUnclassifiable/Attainment.
    Jefferson CountyUnclassifiable/Attainment.
    Gilpin CountyUnclassifiable/Attainment.
    State AQCR 04:
    El Paso CountyUnclassifiable/Attainment.
    Park CountyUnclassifiable/Attainment.
    Teller CountyUnclassifiable/Attainment.
    State AQCR 05:
    Cheyenne CountyUnclassifiable/Attainment.
    Elbert CountyUnclassifiable/Attainment.
    Kit Carson CountyUnclassifiable/Attainment.
    Lincoln CountyUnclassifiable/Attainment.
    State AQCR 06:
    Baca CountyUnclassifiable/Attainment.
    Bent CountyUnclassifiable/Attainment.
    Crowley CountyUnclassifiable/Attainment.
    Kiowa CountyUnclassifiable/Attainment.
    Otero CountyUnclassifiable/Attainment.
    Prowers CountyUnclassifiable/Attainment.
    State AQCR 07:
    Huerfano CountyUnclassifiable/Attainment.
    Las Animas CountyUnclassifiable/Attainment.
    Pueblo CountyUnclassifiable/Attainment.
    State AQCR 08:
    Alamosa CountyUnclassifiable/Attainment.
    Conejos CountyUnclassifiable/Attainment.
    Costilla CountyUnclassifiable/Attainment.
    Mineral CountyUnclassifiable/Attainment.
    Rio Grande CountyUnclassifiable/Attainment.
    Saguache CountyUnclassifiable/Attainment.
    State AQCR 09:
    Archuleta CountyUnclassifiable/Attainment.
    Dolores CountyUnclassifiable/Attainment.
    La Plata CountyUnclassifiable/Attainment.
    Montezuma CountyUnclassifiable/Attainment.
    San Juan CountyUnclassifiable/Attainment.
    State AQCR 10:
    Delta CountyUnclassifiable/Attainment.
    Gunnison CountyUnclassifiable/Attainment.
    Hinsdale CountyUnclassifiable/Attainment.
    Montrose CountyUnclassifiable/Attainment.
    Ouray CountyUnclassifiable/Attainment.
    San Miguel CountyUnclassifiable/Attainment.
    State AQCR 11:
    Garfield CountyUnclassifiable/Attainment.
    Mesa CountyUnclassifiable/Attainment.
    Moffat CountyUnclassifiable/Attainment.
    Rio Blanco CountyUnclassifiable/Attainment.
    State AQCR 12:
    Eagle CountyUnclassifiable/Attainment.
    Grand CountyUnclassifiable/Attainment.
    Jackson CountyUnclassifiable/Attainment.
    Pitkin CountyUnclassifiable/Attainment.
    Routt CountyUnclassifiable/Attainment.
    Summit CountyUnclassifiable/Attainment.
    State AQCR 13:
    Chaffee CountyUnclassifiable/Attainment.
    Custer CountyUnclassifiable/Attainment.
    Fremont CountyUnclassifiable/Attainment.
    Lake 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.

    Colorado—1997 8-Hour Ozone NAAQS

    [Primary and Secondary]

    Designated area Designationa Category/classification
    Date1 Type Date1 Type
    Denver-Boulder-Greeley-Ft. Collins-Loveland, CO:
    Adams County2Nonattainment6/13/12Subpart 2/Marginal.
    Arapahoe County2Nonattainment6/13/12Subpart 2/Marginal.
    Boulder County (includes part of Rocky Mtn. Nat. Park)2Nonattainment6/13/12Subpart 2/Marginal.
    Broomfield County2Nonattainment6/13/12Subpart 2/Marginal.
    Denver County2Nonattainment6/13/12Subpart 2/Marginal.
    Douglas County2Nonattainment6/13/12Subpart 2/Marginal.
    Jefferson County2Nonattainment6/13/12Subpart 2/Marginal.
    Larimer County (part)2Nonattainment6/13/12Subpart 2/Marginal.
    (includes part of Rocky Mtn. Nat. Park). That portion of the county that lies south of a line described as follows: Beginning at a point on Larimer County's eastern boundary and Weld County's western boundary intersected by 40 degrees, 42 minutes, and 47.1 seconds north latitude, proceed west to a point defined by the intersection of 40 degrees, 42 minutes, 47.1 seconds north latitude and 105 degrees, 29 minutes, and 40.0 seconds west longitude, thence proceed south on 105 degrees, 29 minutes, 40.0 seconds west longitude to the intersection with 40 degrees, 33 minutes and 17.4 seconds north latitude, thence proceed west on 40 degrees, 33 minutes, 17.4 seconds north latitude until this line intersects Larimer County's western boundary and Grand County's eastern boundary.
    Weld County (part)2Nonattainment6/13/12Subpart 2/Marginal.
    That portion of the county that lies south of a line described as follows: Beginning at a point on Weld County's eastern boundary and Logan County's western boundary intersected by 40 degrees, 42 minutes, 47.1 seconds north latitude, proceed west on 40 degrees, 42 minutes, 47.1 seconds north latitude until this line intersects Weld County's western boundary and Larimer County's eastern boundary.
    State AQCR 01Unclassifiable/Attainment
    Logan County
    Phillips County
    Sedgwick County
    Washington County
    Yuma County
    State AQCR 03 (remainder of)Unclassifiable/Attainment
    Clear Creek County
    Gilpin County
    State AQCR 11Unclassifiable/Attainment
    Garfield County
    Mesa County
    Moffat County
    Rio Blanco County
    Rest of StateUnclassifiable/Attainment
    Alamosa County
    Archuleta County
    Baca County
    Bent County
    Chaffee County
    Cheyenne County
    Conejos County
    Costilla County
    Crowley County
    Custer County
    Delta County
    Dolores County
    Eagle County
    El Paso County
    Elbert County
    Fremont County
    Grand County (includes portion of W. Rocky Mtn. Nat. Park)
    Gunnison County
    Hinsdale County
    Huerfano County
    Jackson County
    Kiowa County
    Kit Carson County
    La Plata County
    Lake County
    Larimer County (part) remainder
    Las Animas County
    Lincoln County
    Mineral County
    Montezuma County
    Montrose County
    Morgan County
    Otero County
    Ouray County
    Park County
    Pitkin County
    Prowers County
    Pueblo County
    Rio Grande County
    Routt County
    Saguache County
    San Juan County
    San Miguel County
    Summit County
    Teller County
    Weld County (part) remainder

    a Includes Indian Country located in each county or area, except as otherwise specified.

    1 This date is June 15, 2004, unless otherwise noted.

    2 Effective November 20, 2007.

    Colorado—2008 8-Hour Ozone NAAQS

    [Primary and Secondary]

    Designated area Designation Classification
    Date1 Type Date1 Type
    Denver-Boulder-Greeley-Ft. Collins-Loveland, CO:2 NonattainmentNovember 7, 202211/7/22Severe.
    Adams County
    Arapahoe County
    Boulder County
    Broomfield County
    Denver County
    Douglas County
    Jefferson County
    Larimer County (part)
    That portion of the county that lies south of a line described as follows: Beginning at a point on Larimer County's eastern boundary and Weld County's western boundary intersected by 40 degrees, 42 minutes, and 47.1 seconds north latitude, proceed west to a point defined by the intersection of 40 degrees, 42 minutes, 47.1 seconds north latitude and 105 degrees, 29 minutes, and 40.0 seconds west longitude, thence proceed south on 105 degrees, 29 minutes, 40.0 seconds west longitude to the intersection with 40 degrees, 33 minutes and 17.4 seconds north latitude, thence proceed west on 40 degrees, 33 minutes, 17.4 seconds north latitude until this line intersects Larimer County's western boundary and Grand County's eastern boundary.
    Weld County (part)
    That portion of the county that lies south of a line described as follows: Beginning at a point on Weld County's eastern boundary and Logan County's western boundary intersected by 40 degrees, 42 minutes, 47.1 seconds north latitude, proceed west on 40 degrees, 42 minutes, 47.1 seconds north latitude until this line intersects Weld County's western boundary and Larimer County's eastern boundary.
    Southern Ute Indian Tribe of the Southern Ute Reservation3 Unclassifiable/Attainment
    Rest of State and Rest of Indian CountryUnclassifiable/Attainment

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

    2 Excludes Indian country located in each area, unless otherwise noted.

    3 Includes Indian country of the tribe listed in this table located in the identified area. Information pertaining to areas of Indian country in this table is intended for CAA planning purposes only and is not an EPA determination of Indian country status or any Indian country boundary. EPA lacks the authority to establish Indian country land status, and is making no determination of Indian country boundaries, in this table.

    Colorado—2015 8-Hour Ozone NAAQS

    [Primary and Secondary]

    Designated area1 Designation Classification
    Date2 Type Date2 Type
    Denver Metro/North Front Range, CONonattainmentNovember 7, 202211/7/22Moderate.
    Adams County.
    Arapahoe County.
    Boulder County.
    Broomfield County.
    Denver County.
    Douglas County.
    Jefferson County.
    Larimer County (part).
    Including the portion of Rocky Mountain National Park therein and that portion of the county that lies south of a line described as follows: Beginning at a point on Larimer County's eastern boundary and Weld County's western boundary intersected by 40 degrees, 42 minutes, and 47.1 seconds north latitude, proceed west to a point defined by the intersection of 40 degrees, 42 minutes, 47.1 seconds north latitude and 105 degrees, 29 minutes, and 40.0 seconds west longitude, thence proceed south on 105 degrees, 29 minutes, 40.0 seconds west longitude to the inter-section with 40 degrees, 33 minutes and 17.4 seconds north latitude, thence proceed west on 40 degrees, 33 minutes, 17.4 seconds north latitude until this line intersects Larimer County's western boundary and Grand County's eastern boundary.
    Weld County12/30/20213
    Alamosa County1/16/18Attainment/Unclassifiable
    Archuleta County1/16/18Attainment/Unclassifiable
    Baca County1/16/18Attainment/Unclassifiable
    Bent County1/16/18Attainment/Unclassifiable
    Chaffee County1/16/18Attainment/Unclassifiable
    Cheyenne County1/16/18Attainment/Unclassifiable
    Clear Creek CountyAttainment/Unclassifiable
    Conejos County1/16/18Attainment/Unclassifiable
    Costilla County1/16/18Attainment/Unclassifiable
    Crowley County1/16/18Attainment/Unclassifiable
    Custer County1/16/18Attainment/Unclassifiable
    Delta County1/16/18Attainment/Unclassifiable
    Dolores County1/16/18Attainment/Unclassifiable
    Eagle County1/16/18Attainment/Unclassifiable
    Elbert CountyAttainment/Unclassifiable
    El Paso CountyAttainment/Unclassifiable
    Fremont County1/16/18Attainment/Unclassifiable
    Garfield CountyAttainment/Unclassifiable
    Gilpin CountyAttainment/Unclassifiable
    Grand CountyAttainment/Unclassifiable
    Gunnison County1/16/18Attainment/Unclassifiable
    Hinsdale County1/16/18Attainment/Unclassifiable
    Huerfano County1/16/18Attainment/Unclassifiable
    Jackson CountyAttainment/Unclassifiable
    Kiowa County1/16/18Attainment/Unclassifiable
    Kit Carson County1/16/18Attainment/Unclassifiable
    Lake County1/16/18Attainment/Unclassifiable
    La Plata County1/16/18Attainment/Unclassifiable
    Larimer County (part remainder)Attainment/Unclassifiable
    Las Animas County1/16/18Attainment/Unclassifiable
    Lincoln County1/16/18Attainment/Unclassifiable
    Logan County1/16/18Attainment/Unclassifiable
    Mesa County1/16/18Attainment/Unclassifiable
    Mineral County1/16/18Attainment/Unclassifiable
    Moffat CountyAttainment/Unclassifiable
    Montezuma County1/16/18Attainment/Unclassifiable
    Montrose County1/16/18Attainment/Unclassifiable
    Morgan County1/16/18Attainment/Unclassifiable
    Otero County1/16/18Attainment/Unclassifiable
    Ouray County1/16/18Attainment/Unclassifiable
    Park CountyAttainment/Unclassifiable
    Phillips County1/16/18Attainment/Unclassifiable
    Pitkin County1/16/18Attainment/Unclassifiable
    Prowers County1/16/18Attainment/Unclassifiable
    Pueblo County1/16/18Attainment/Unclassifiable
    Rio Blanco CountyAttainment/Unclassifiable
    Rio Grande County1/16/18Attainment/Unclassifiable
    Routt County1/16/18Attainment/Unclassifiable
    Saguache County1/16/18Attainment/Unclassifiable
    San Juan County1/16/18Attainment/Unclassifiable
    San Miguel County1/16/18Attainment/Unclassifiable
    Sedgwick County1/16/18Attainment/Unclassifiable
    Summit County1/16/18Attainment/Unclassifiable
    Teller CountyAttainment/Unclassifiable
    Washington County1/16/18Attainment/Unclassifiable
    Yuma County1/16/18Attainment/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 August 3, 2018, unless otherwise noted.

    Colorado—2008 Lead NAAQS

    Designated area Designation for the 2008 NAAQSa
    Date1 Type
    Whole StateUnclassifiable/Attainment.

    a Includes Indian Country located in each county or area, except as otherwise specified.

    1 December 31, 2011 unless otherwise noted.

    [43 FR 8964, Mar. 3, 1978]

    Editorial Note

    Editorial Note:

    For Federal Register citations affecting § 81.306, see the List of CFR Sections Affected, which appears in the Finding Aids section of the printed volume and at www.govinfo.gov.