Title 40

SECTION 81.306

81.306 Colorado.

§ 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 State X

Colorado - 2010 Sulfur Dioxide NAAQS

[Primary]

Designated area 1 Designation
Date 3 Type
Colorado Springs, CO 9/12/16 Unclassifiable.
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, CO 9/12/16 Unclassifiable.
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 02 Attainment/Unclassifiable.
Larimer County
Weld County
State AQCR 03 Attainment/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 05 Attainment/Unclassifiable.
Cheyenne County
Elbert County
Kit Carson County
Lincoln County
State AQCR 06 Attainment/Unclassifiable.
Baca County
Bent County
Crowley County
Kiowa County
Otero County
Prowers County
State AQCR 07 Attainment/Unclassifiable.
Huerfano
Las Animas
Pueblo
State AQCR 08 Attainment/Unclassifiable.
Alamosa County
Conejos County
Costilla County
Mineral County
Rio Grande County
Saguache County
State AQCR 09 Attainment/Unclassifiable.
Archuleta County 2
Dolores
La Plata 2
Montezuma 2
San Juan
State AQCR 10 Attainment/Unclassifiable.
Delta County
Gunnison County
Hinsdale County
Montrose County
Ouray County
San Miguel County
State AQCR 11 Attainment/Unclassifiable.
Garfield County
Mesa County
Moffat County
Rio Blanco County
State AQCR 12 Attainment/Unclassifiable.
Eagle County
Grand County
Jackson County
Pitkin County
Routt County
Summit County
State AQCR 13 Attainment/Unclassifiable.
Chaffee County
Custer County
Fremont County
Lake County
Southern Ute Indian Reservation 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 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
Date 1 Type Date 1 Type
Colorado Springs Area: October 25, 1999 Attainment
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 52 January 14, 2002 Attainment
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, 2003 Attainment
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 Area Nov. 23, 1999 Attainment
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 1 Unclassifiable/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 county Unclassifiable/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 5-13 Unclassifiable/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
Date 1 Type Date 1 Type
Denver-Boulder Area:
Adams County (part)
West of Kiowa Creek 10/11/01 Attainment
Arapahoe County (part)
West of Kiowa Creek Attainment
Boulder County (part) excluding Rocky Mountain National Park Attainment
Denver County Attainment
Douglas County Attainment
Jefferson County Attainment
State AQCR 01 Unclassifiable/Attainment
Logan County
Morgan County
Phillips County
Sedgwick County
Washington County
Yuma County
State AQCR 02 Unclassifiable/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 11 Unclassifiable/Attainment
Garfield County
Mesa County
Moffat County
Rio Blanco County
Rest of State Unclassifiable/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 Area 8/14/01 Attainment
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 area 10/16/02 Attainment
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
Telluride 8/14/01 Attainment
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
Lamar 12/27/05 Attainment
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, 2643-26 7/14/03 Attainment.
Fremont County
Canon City Area 7/31/00 Attainment
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 Springs 11/24/04 Attainment.
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 1 11/15/90 Unclassifiable
AQCR 2 11/15/90 Unclassifiable
AQCR 3 (excluding the Denver Metropolitan PM-10 nonattainment area) 11/15/90 Unclassifiable
AQCR 4 11/15/90 Unclassifiable
AQCR 5 11/15/90 Unclassifiable
AQCR 6 (excluding the Lamar PM-10 nonattainment area) 11/15/90 Unclassifiable
AQCR 7 11/15/90 Unclassifiable
AQCR 8 11/15/90 Unclassifiable
AQCR 9 (excluding the Pagosa Springs PM-10 nonattainment area) 11/15/90 Unclassifiable
AQCR 10 (excluding the Telluride PM-10 nonattainment area) 11/15/90 Unclassifiable
AQCR 11 11/15/90 Unclassifiable
AQCR 12 (excluding the Aspen/Pitkin County and Steamboat Springs Area Airshed PM-10 nonattainment areas) 11/15/90 Unclassifiable
AQCR 13 (excluding the Canon City PM-10 nonattainment area) 1/15/90 Unclassifiable

Colorado - 1997 Annual PM2.5 NAAQS

[Primary and Secondary]

Designated area Designation a Classification
Date 1 Type Date Type
Denver-Boulder Area:
Adams County (part) West of Kiowa Creek Unclassifiable/Attainment
Arapahoe County (part) West of Kiowa Creek Unclassifiable/Attainment
Boulder County (part) Excluding Rocky Mountain National Park Unclassifiable/Attainment
Broomfield County Unclassifiable/Attainment
Denver County Unclassifiable/Attainment
Douglas County Unclassifiable/Attainment
Jefferson County Unclassifiable/Attainment
State AQCR 01:
Logan County Unclassifiable/Attainment
Morgan County Unclassifiable/Attainment
Phillips County Unclassifiable/Attainment
Sedgwick County Unclassifiable/Attainment
Washington County Unclassifiable/Attainment
Yuma County Unclassifiable/Attainment
State AQCR 02:
Larimer County Unclassifiable/Attainment
Weld County Unclassifiable/Attainment
State AQCR 03 (remainder of):
Adams County (remainder) Unclassifiable/Attainment
Arapahoe County (remainder) Unclassifiable/Attainment
Boulder County (remainder) Unclassifiable/Attainment
Clear Creek County Unclassifiable/Attainment
Gilpin County Unclassifiable/Attainment
State AQCR 04:
El Paso County Unclassifiable/Attainment
Park County Unclassifiable/Attainment
Teller County Unclassifiable/Attainment
State AQCR 05:
Cheyenne County Unclassifiable/Attainment
Elbert County Unclassifiable/Attainment
Kit Carson County Unclassifiable/Attainment
Lincoln County Unclassifiable/Attainment
State AQCR 06:
Baca County Unclassifiable/Attainment
Bent County Unclassifiable/Attainment
Crowley County Unclassifiable/Attainment
Kiowa County Unclassifiable/Attainment
Otero County Unclassifiable/Attainment
Prowers County Unclassifiable/Attainment
State AQCR 07:
Huerfano County Unclassifiable/Attainment
Las Animas County Unclassifiable/Attainment
Pueblo County Unclassifiable/Attainment
State AQCR 08:
Alamosa County Unclassifiable/Attainment
Conejos County Unclassifiable/Attainment
Costilla County Unclassifiable/Attainment
Mineral County Unclassifiable/Attainment
Rio Grande County Unclassifiable/Attainment
Saguache County Unclassifiable/Attainment
State AQCR 09:
Archuleta County Unclassifiable/Attainment
Dolores County Unclassifiable/Attainment
La Plata County Unclassifiable/Attainment
Montezuma County Unclassifiable/Attainment
San Juan County Unclassifiable/Attainment
State AQCR 10:
Delta County Unclassifiable/Attainment
Gunnison County Unclassifiable/Attainment
Hinsdale County Unclassifiable/Attainment
Montrose County Unclassifiable/Attainment
Ouray County Unclassifiable/Attainment
San Miguel County Unclassifiable/Attainment
State AQCR 11:
Garfield County Unclassifiable/Attainment
Mesa County Unclassifiable/Attainment
Moffat County Unclassifiable/Attainment
Rio Blanco County Unclassifiable/Attainment
State AQCR 12:
Eagle County Unclassifiable/Attainment
Grand County Unclassifiable/Attainment
Jackson County Unclassifiable/Attainment
Pitkin County Unclassifiable/Attainment
Routt County Unclassifiable/Attainment
Summit County Unclassifiable/Attainment
State AQCR 13:
Chaffee County Unclassifiable/Attainment
Custer County Unclassifiable/Attainment
Fremont County Unclassifiable/Attainment
Lake County Unclassifiable/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 area 1 Designation Classification
Date 2 Type Date 2 Type
State AQCR 01:
Logan County Unclassifiable/Attainment
Morgan County Unclassifiable/Attainment
Phillips County Unclassifiable/Attainment
Sedgwick County Unclassifiable/Attainment
Washington County Unclassifiable/Attainment
Yuma County Unclassifiable/Attainment
State AQCR 02:
Larimer County Unclassifiable/Attainment
Weld County Unclassifiable/Attainment
State AQCR 03:
Adams County Unclassifiable/Attainment
Arapahoe County Unclassifiable/Attainment
Boulder County Unclassifiable/Attainment
Broomfield County Unclassifiable/Attainment
Clear Creek County Unclassifiable/Attainment
Denver County Unclassifiable/Attainment
Douglas County Unclassifiable/Attainment
Gilpin County Unclassifiable/Attainment
Jefferson County Unclassifiable/Attainment
State AQCR 04:
El Paso County Unclassifiable/Attainment
Park County Unclassifiable/Attainment
Teller County Unclassifiable/Attainment
State AQCR 05:
Cheyenne County Unclassifiable/Attainment
Elbert County Unclassifiable/Attainment
Kit Carson County Unclassifiable/Attainment
Lincoln County Unclassifiable/Attainment
State AQCR 06:
Baca County Unclassifiable/Attainment
Bent County Unclassifiable/Attainment
Crowley County Unclassifiable/Attainment
Kiowa County Unclassifiable/Attainment
Otero County Unclassifiable/Attainment
Prowers County Unclassifiable/Attainment
State AQCR 07:
Huerfano County Unclassifiable/Attainment
Las Animas County Unclassifiable/Attainment
Pueblo County Unclassifiable/Attainment
State AQCR 08:
Alamosa County Unclassifiable/Attainment
Conejos County Unclassifiable/Attainment
Costilla County Unclassifiable/Attainment
Mineral County Unclassifiable/Attainment
Rio Grande County Unclassifiable/Attainment
Saguache County Unclassifiable/Attainment
State AQCR 09:
Archuleta County Unclassifiable/Attainment
Dolores County Unclassifiable/Attainment
La Plata County Unclassifiable/Attainment
Montezuma County Unclassifiable/Attainment
San Juan County Unclassifiable/Attainment
State AQCR 10:
Delta County Unclassifiable/Attainment
Gunnison County Unclassifiable/Attainment
Hinsdale County Unclassifiable/Attainment
Montrose County Unclassifiable/Attainment
Ouray County Unclassifiable/Attainment
San Miguel County Unclassifiable/Attainment
State AQCR 11:
Garfield County Unclassifiable/Attainment
Mesa County Unclassifiable/Attainment
Moffat County Unclassifiable/Attainment
Rio Blanco County Unclassifiable/Attainment
State AQCR 12:
Eagle County Unclassifiable/Attainment
Grand County Unclassifiable/Attainment
Jackson County Unclassifiable/Attainment
Pitkin County Unclassifiable/Attainment
Routt County Unclassifiable/Attainment
Summit County Unclassifiable/Attainment
State AQCR 13:
Chaffee County Unclassifiable/Attainment
Custer County Unclassifiable/Attainment
Fremont County Unclassifiable/Attainment
Lake County Unclassifiable/Attainment

1 Includes areas of Indian country located in each county or area, except as otherwise specified.

2 This date is April 15, 2015, unless otherwise noted.

Colorado - 1997 24-Hour PM2.5 NAAQS

[Primary and Secondary]

Designated area Designation a Classification
Date 1 Type Date Type
Denver-Boulder Area:
Adams County (part) West of Kiowa Creek Unclassifiable/Attainment
Arapahoe County (part) West of Kiowa Creek Unclassifiable/Attainment
Boulder County (part) Excluding Rocky Mountain National Park Unclassifiable/Attainment
Broomfield County Unclassifiable/Attainment
Denver County Unclassifiable/Attainment
Douglas County Unclassifiable/Attainment
Jefferson County Unclassifiable/Attainment
State AQCR 01:
Logan County Unclassifiable/Attainment
Morgan County Unclassifiable/Attainment
Phillips County Unclassifiable/Attainment
Sedgwick County Unclassifiable/Attainment
Washington County Unclassifiable/Attainment
Yuma County Unclassifiable/Attainment
State AQCR 02:
Larimer County Unclassifiable/Attainment
Weld County Unclassifiable/Attainment
State AQCR 03 (remainder of):
Adams County (remainder) Unclassifiable/Attainment
Arapahoe County (remainder) Unclassifiable/Attainment
Boulder County (remainder) Unclassifiable/Attainment
Clear Creek County Unclassifiable/Attainment
Gilpin County Unclassifiable/Attainment
State AQCR 04:
El Paso County Unclassifiable/Attainment
Park County Unclassifiable/Attainment
Teller County Unclassifiable/Attainment
State AQCR 05:
Cheyenne County Unclassifiable/Attainment
Elbert County Unclassifiable/Attainment
Kit Carson County Unclassifiable/Attainment
Lincoln County Unclassifiable/Attainment
State AQCR 06:
Baca County Unclassifiable/Attainment
Bent County Unclassifiable/Attainment
Crowley County Unclassifiable/Attainment
Kiowa County Unclassifiable/Attainment
Otero County Unclassifiable/Attainment
Prowers County Unclassifiable/Attainment
State AQCR 07:
Huerfano County Unclassifiable/Attainment
Las Animas County Unclassifiable/Attainment
Pueblo County Unclassifiable/Attainment
State AQCR 08:
Alamosa County Unclassifiable/Attainment
Conejos County Unclassifiable/Attainment
Costilla County Unclassifiable/Attainment
Mineral County Unclassifiable/Attainment
Rio Grande County Unclassifiable/Attainment
Saguache County Unclassifiable/Attainment
State AQCR 09:
Archuleta County Unclassifiable/Attainment
Dolores County Unclassifiable/Attainment
La Plata County Unclassifiable/Attainment
Montezuma County Unclassifiable/Attainment
San Juan County Unclassifiable/Attainment
State AQCR 10:
Delta County Unclassifiable/Attainment
Gunnison County Unclassifiable/Attainment
Hinsdale County Unclassifiable/Attainment
Montrose County Unclassifiable/Attainment
Ouray County Unclassifiable/Attainment
San Miguel County Unclassifiable/Attainment
State AQCR 11:
Garfield County Unclassifiable/Attainment
Mesa County Unclassifiable/Attainment
Moffat County Unclassifiable/Attainment
Rio Blanco County Unclassifiable/Attainment
State AQCR 12:
Eagle County Unclassifiable/Attainment
Grand County Unclassifiable/Attainment
Jackson County Unclassifiable/Attainment
Pitkin County Unclassifiable/Attainment
Routt County Unclassifiable/Attainment
Summit County Unclassifiable/Attainment
State AQCR 13:
Chaffee County Unclassifiable/Attainment
Custer County Unclassifiable/Attainment
Fremont County Unclassifiable/Attainment
Lake County Unclassifiable/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 Designation a Classification
Date 1 Type Date Type
Denver-Boulder Area:
Adams County (part) West of Kiowa Creek Unclassifiable/Attainment.
Arapahoe County (part) West of Kiowa Creek Unclassifiable/Attainment.
Boulder County (part) Excluding Rocky Mountain National Park Unclassifiable/Attainment.
Broomfield County Unclassifiable/Attainment.
Denver County Unclassifiable/Attainment.
Douglas County Unclassifiable/Attainment.
Jefferson County Unclassifiable/Attainment.
State AQCR 01:
Logan County Unclassifiable/Attainment.
Morgan County Unclassifiable/Attainment.
Phillips County Unclassifiable/Attainment.
Sedgwick County Unclassifiable/Attainment.
Washington County Unclassifiable/Attainment.
Yuma County Unclassifiable/Attainment.
State AQCR 02:
Larimer County Unclassifiable/Attainment.
Weld County Unclassifiable/Attainment.
State AQCR 03 (remainder of):
Adams County (remainder) Unclassifiable/Attainment.
Arapahoe County (remainder) Unclassifiable/Attainment.
Boulder County (remainder) Unclassifiable/Attainment.
Clear Creek County Unclassifiable/Attainment.
Gilpin County Unclassifiable/Attainment.
State AQCR 04:
El Paso County Unclassifiable/Attainment.
Park County Unclassifiable/Attainment.
Teller County Unclassifiable/Attainment.
State AQCR 05:
Cheyenne County Unclassifiable/Attainment.
Elbert County Unclassifiable/Attainment.
Kit Carson County Unclassifiable/Attainment.
Lincoln County Unclassifiable/Attainment.
State AQCR 06:
Baca County Unclassifiable/Attainment.
Bent County Unclassifiable/Attainment.
Crowley County Unclassifiable/Attainment.
Kiowa County Unclassifiable/Attainment.
Otero County Unclassifiable/Attainment.
Prowers County Unclassifiable/Attainment.
State AQCR 07:
Huerfano County Unclassifiable/Attainment.
Las Animas County Unclassifiable/Attainment.
Pueblo County Unclassifiable/Attainment.
State AQCR 08:
Alamosa County Unclassifiable/Attainment.
Conejos County Unclassifiable/Attainment.
Costilla County Unclassifiable/Attainment.
Mineral County Unclassifiable/Attainment.
Rio Grande County Unclassifiable/Attainment.
Saguache County Unclassifiable/Attainment.
State AQCR 09:
Archuleta County Unclassifiable/Attainment.
Dolores County Unclassifiable/Attainment.
La Plata County Unclassifiable/Attainment.
Montezuma County Unclassifiable/Attainment.
San Juan County Unclassifiable/Attainment.
State AQCR 10:
Delta County Unclassifiable/Attainment.
Gunnison County Unclassifiable/Attainment.
Hinsdale County Unclassifiable/Attainment.
Montrose County Unclassifiable/Attainment.
Ouray County Unclassifiable/Attainment.
San Miguel County Unclassifiable/Attainment.
State AQCR 11:
Garfield County Unclassifiable/Attainment.
Mesa County Unclassifiable/Attainment.
Moffat County Unclassifiable/Attainment.
Rio Blanco County Unclassifiable/Attainment.
State AQCR 12:
Eagle County Unclassifiable/Attainment.
Grand County Unclassifiable/Attainment.
Jackson County Unclassifiable/Attainment.
Pitkin County Unclassifiable/Attainment.
Routt County Unclassifiable/Attainment.
Summit County Unclassifiable/Attainment.
State AQCR 13:
Chaffee County Unclassifiable/Attainment.
Custer County Unclassifiable/Attainment.
Fremont County Unclassifiable/Attainment.
Lake County Unclassifiable/Attainment.

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

1 This date is 30 days after November 13, 2009, unless otherwise noted.

Colorado - NO2 (1971 Annual Standard)

Designated area Better than national standards
Entire State X

Colorado - NO2 (2010 1-Hour Standard)

Designated area Designation a
Date 1 Type
State AQCR 01:
Logan County Unclassifiable/Attainment.
Morgan County Unclassifiable/Attainment.
Phillips County Unclassifiable/Attainment.
Sedgwick County Unclassifiable/Attainment.
Washington County Unclassifiable/Attainment.
Yuma County Unclassifiable/Attainment.
State AQCR 02:
Larimer County Unclassifiable/Attainment.
Weld County Unclassifiable/Attainment.
State AQCR 03:
Adams County Unclassifiable/Attainment.
Arapahoe County Unclassifiable/Attainment.
Boulder County Unclassifiable/Attainment.
Broomfield County Unclassifiable/Attainment.
Clear Creek County Unclassifiable/Attainment.
Denver County Unclassifiable/Attainment.
Douglas County Unclassifiable/Attainment.
Jefferson County Unclassifiable/Attainment.
Gilpin County Unclassifiable/Attainment.
State AQCR 04:
El Paso County Unclassifiable/Attainment.
Park County Unclassifiable/Attainment.
Teller County Unclassifiable/Attainment.
State AQCR 05:
Cheyenne County Unclassifiable/Attainment.
Elbert County Unclassifiable/Attainment.
Kit Carson County Unclassifiable/Attainment.
Lincoln County Unclassifiable/Attainment.
State AQCR 06:
Baca County Unclassifiable/Attainment.
Bent County Unclassifiable/Attainment.
Crowley County Unclassifiable/Attainment.
Kiowa County Unclassifiable/Attainment.
Otero County Unclassifiable/Attainment.
Prowers County Unclassifiable/Attainment.
State AQCR 07:
Huerfano County Unclassifiable/Attainment.
Las Animas County Unclassifiable/Attainment.
Pueblo County Unclassifiable/Attainment.
State AQCR 08:
Alamosa County Unclassifiable/Attainment.
Conejos County Unclassifiable/Attainment.
Costilla County Unclassifiable/Attainment.
Mineral County Unclassifiable/Attainment.
Rio Grande County Unclassifiable/Attainment.
Saguache County Unclassifiable/Attainment.
State AQCR 09:
Archuleta County Unclassifiable/Attainment.
Dolores County Unclassifiable/Attainment.
La Plata County Unclassifiable/Attainment.
Montezuma County Unclassifiable/Attainment.
San Juan County Unclassifiable/Attainment.
State AQCR 10:
Delta County Unclassifiable/Attainment.
Gunnison County Unclassifiable/Attainment.
Hinsdale County Unclassifiable/Attainment.
Montrose County Unclassifiable/Attainment.
Ouray County Unclassifiable/Attainment.
San Miguel County Unclassifiable/Attainment.
State AQCR 11:
Garfield County Unclassifiable/Attainment.
Mesa County Unclassifiable/Attainment.
Moffat County Unclassifiable/Attainment.
Rio Blanco County Unclassifiable/Attainment.
State AQCR 12:
Eagle County Unclassifiable/Attainment.
Grand County Unclassifiable/Attainment.
Jackson County Unclassifiable/Attainment.
Pitkin County Unclassifiable/Attainment.
Routt County Unclassifiable/Attainment.
Summit County Unclassifiable/Attainment.
State AQCR 13:
Chaffee County Unclassifiable/Attainment.
Custer County Unclassifiable/Attainment.
Fremont County Unclassifiable/Attainment.
Lake County Unclassifiable/Attainment.

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

1 This date is 90 days after October 31, 2011, unless otherwise noted.

Colorado - 1997 8-Hour Ozone NAAQS

[Primary and Secondary]

Designated area Designation a Category/classification
Date 1 Type Date 1 Type
Denver-Boulder-Greeley-Ft. Collins-Loveland, CO:
Adams County 2 Nonattainment 6/13/12 Subpart 2/Marginal.
Arapahoe County 2 Nonattainment 6/13/12 Subpart 2/Marginal.
Boulder County (includes part of Rocky Mtn. Nat. Park) 2 Nonattainment 6/13/12 Subpart 2/Marginal.
Broomfield County 2 Nonattainment 6/13/12 Subpart 2/Marginal.
Denver County 2 Nonattainment 6/13/12 Subpart 2/Marginal.
Douglas County 2 Nonattainment 6/13/12 Subpart 2/Marginal.
Jefferson County 2 Nonattainment 6/13/12 Subpart 2/Marginal.
Larimer County (part) 2 Nonattainment 6/13/12 Subpart 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) 2 Nonattainment 6/13/12 Subpart 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 01 Unclassifiable/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 11 Unclassifiable/Attainment
Garfield County
Mesa County
Moffat County
Rio Blanco County
Rest of State Unclassifiable/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
Date 1 Type Date 1 Type
Denver-Boulder-Greeley-Ft. Collins-Loveland, CO: 2 Nonattainment 1/27/2020. Serious.
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 Reservation 3 Unclassifiable/Attainment
Rest of State and Rest of Indian Country Unclassifiable/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 area 1 Designation Classification
Date 2 Type Date 2 Type
Denver Metro/North Front Range, CO Nonattainment Marginal.
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 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.
Alamosa County 1/16/18 Attainment/Unclassifiable
Archuleta County 1/16/18 Attainment/Unclassifiable
Baca County 1/16/18 Attainment/Unclassifiable
Bent County 1/16/18 Attainment/Unclassifiable
Chaffee County 1/16/18 Attainment/Unclassifiable
Cheyenne County 1/16/18 Attainment/Unclassifiable
Clear Creek County Attainment/Unclassifiable
Conejos County 1/16/18 Attainment/Unclassifiable
Costilla County 1/16/18 Attainment/Unclassifiable
Crowley County 1/16/18 Attainment/Unclassifiable
Custer County 1/16/18 Attainment/Unclassifiable
Delta County 1/16/18 Attainment/Unclassifiable
Dolores County 1/16/18 Attainment/Unclassifiable
Eagle County 1/16/18 Attainment/Unclassifiable
Elbert County Attainment/Unclassifiable
El Paso County Attainment/Unclassifiable
Fremont County 1/16/18 Attainment/Unclassifiable
Garfield County Attainment/Unclassifiable
Gilpin County Attainment/Unclassifiable
Grand County Attainment/Unclassifiable
Gunnison County 1/16/18 Attainment/Unclassifiable
Hinsdale County 1/16/18 Attainment/Unclassifiable
Huerfano County 1/16/18 Attainment/Unclassifiable
Jackson County Attainment/Unclassifiable
Kiowa County 1/16/18 Attainment/Unclassifiable
Kit Carson County 1/16/18 Attainment/Unclassifiable
Lake County 1/16/18 Attainment/Unclassifiable
La Plata County 1/16/18 Attainment/Unclassifiable
Larimer County (part remainder) Attainment/Unclassifiable
Las Animas County 1/16/18 Attainment/Unclassifiable
Lincoln County 1/16/18 Attainment/Unclassifiable
Logan County 1/16/18 Attainment/Unclassifiable
Mesa County 1/16/18 Attainment/Unclassifiable
Mineral County 1/16/18 Attainment/Unclassifiable
Moffat County Attainment/Unclassifiable
Montezuma County 1/16/18 Attainment/Unclassifiable
Montrose County 1/16/18 Attainment/Unclassifiable
Morgan County 1/16/18 Attainment/Unclassifiable
Otero County 1/16/18 Attainment/Unclassifiable
Ouray County 1/16/18 Attainment/Unclassifiable
Park County Attainment/Unclassifiable
Phillips County 1/16/18 Attainment/Unclassifiable
Pitkin County 1/16/18 Attainment/Unclassifiable
Prowers County 1/16/18 Attainment/Unclassifiable
Pueblo County 1/16/18 Attainment/Unclassifiable
Rio Blanco County Attainment/Unclassifiable
Rio Grande County 1/16/18 Attainment/Unclassifiable
Routt County 1/16/18 Attainment/Unclassifiable
Saguache County 1/16/18 Attainment/Unclassifiable
San Juan County 1/16/18 Attainment/Unclassifiable
San Miguel County 1/16/18 Attainment/Unclassifiable
Sedgwick County 1/16/18 Attainment/Unclassifiable
Summit County 1/16/18 Attainment/Unclassifiable
Teller County Attainment/Unclassifiable
Washington County 1/16/18 Attainment/Unclassifiable
Weld County (part) remainder Attainment/Unclassifiable
Yuma County 1/16/18 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 August 3, 2018, unless otherwise noted.

Colorado - 2008 Lead NAAQS

Designated area Designation for the 2008 NAAQS a
Date 1 Type
Whole State Unclassifiable/Attainment.

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

1 December 31, 2011 unless otherwise noted.

[43 FR 8964, Mar. 3, 1978] Editorial Note: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.