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  1. Home
  2. State and Local Transportation

Conformity Adequacy Review: Region 8

State Implementation Plans (SIP) Submissions that EPA has Found Adequate or Inadequate
Region 8:  Colorado, Montana, North Dakota, South Dakota, Utah, and Wyoming 

For more information about adequacy review, return to the main adequacy page.

Contact: Gregory Lohrke at 303-312-6396 Lohrke.gregory@epa.gov
U.S. EPA Region 8, 1595 Wynkoop St., Denver, Colorado  80202.

Colorado
Area
Pollutant
SIP Submission
Finding (date budgets apply)
Additional Information/ Comments
Aspen PM10 maintenance plan Adequate (6/11/2012)
Letter
FR Notice
Budgets found adequate through the adequacy review process.
Adequate (9/4/2002)
Letter
FR Notice
Budgets found adequate through the adequacy review process.
Canon City PM10 maintenance plan Adequate (8/17/2011)
Letter
FR Notice
Budgets found adequate through the adequacy review process.
Adequate (7/31/2000)
FR Notice
Budgets found adequate through SIP approval process.
Colorado Springs carbon monoxide limited maintenance plan Adequate (8/17/2011)
Letter
FR Notice
Budgets found adequate through the adequacy review process.
maintenance plan 1998-2009 budgets Inadequate (4/29/1999) Determination made under old process
maintenance plan 2010 budget and beyond Adequate (4/29/1999) Determination made under old process
Denver 2008 8-hour ozone reasonable further progress Adequate (6/8/2023)
Letter (pdf) (219.08 KB, May 3, 2023)
FR Notice
Budgets found adequate through the adequacy review process.
attainment plan Adequate (4/2/2018)
Letter
FR Notice
Budgets found adequate through the adequacy review process
1997 8-hour ozone attainment plan Adequate (3/19/2010)
Letter
FR Notice
Budgets found adequate through the adequacy review process.
pm10 maintenance plan Adequate (6/28/2007)
Letter
FR Notice
Budgets found adequate through the adequacy review process.
Adequate (10/29/2001)
Letter
FR Notice
Budgets found adequate through the adequacy review process.
carbon monoxide maintenance plan Adequate (6/28/2007)
Letter
FR Notice
Budgets found adequate through the adequacy review process.
Adequate (8/18/2000)
Letter
FR Notice
Budgets found adequate through the adequacy review process.
Fort Collins carbon monoxide limited maintenance plan Adequate (6/11/2012)
Letter
FR Notice
Budgets found adequate through the adequacy review process.
maintenance plan Adequate (1/15/2003)
Letter
FR Notice
Budgets found adequate through the adequacy review process.
Greeley carbon monoxide limited maintenance plan Adequate (8/17/2011)
Letter
FR Notice
Budgets found adequate through the adequacy review process.
maintenance plan Adequate (1/20/2004)
Letter
FR Notice
Budgets found adequate through the adequacy review process.
Lamar PM10 second maintenance plan adequate 10/20/2014
79 FR 59767 printed 10/03/2014
Budgets found adequate through the adequacy review process
maintenance plan Adequate (11/12/2002)
Letter
FR Notice
Budgets found adequate through the adequacy review process.
Longmont carbon monoxide maintenance plan Adequate (6/28/2007)
Letter
FR Notice
Budgets found adequate through the adequacy review process.
Inadequate (5/14/1999) Determination made under old process
Pagosa Springs PM10 maintenance plan Adequate (8/17/2011)
Letter
FR Notice
Budgets found adequate through the adequacy review process.
Adequate (8/18/2000)
Letter
FR Notice
Budgets found adequate through the adequacy review process.
Steamboat Springs PM10 second maintenance plan adequate 10/20/2014
79 FR 59767 printed 10/03/2014
Budgets found adequate through the adequacy review process.
maintenance plan Adequate (11/12/2002)
Letter
FR Notice
Budgets found adequate through the adequacy review process.
Telluride PM10 maintenance plan Adequate (8/17/2011)
Letter
FR Notice
Budgets found adequate through the adequacy review process.
Adequate (8/18/2000)
Letter
FR Notice
Budgets found adequate through the adequacy review process.
Montana
Area
Pollutant
SIP Submission
Finding (date budgets apply)
Additional Information/ Comments
Missoula PM 10 maintenance plan Adequate (10/12/2018) Letter (Missoula PM10 Limited Maintenance Plan) (pdf) (903.64 KB, July 23, 2018)
FR Notice (printed 9/27/2018) 83 FR 48715
Budgets found adequate through the adequacy review process.
carbon monoxide maintenance plan Adequate (11/13/2017 )82 FR 43180 printed 9/14/2017) Budgets found adequate through the SIP approval process.
Adequate (6/16/2006)
Letter
FR Notice (PDF)(2 pp, 141 K, published June 1, 2006,  About PDF)
Budgets found adequate through the adequacy review process.
Utah
Area
Pollutant
SIP Submission
Finding (date budgets apply)
Additional Information/ Comments
Ogden carbon monoxide maintenance plan Adequate (6/10/2005)
Letter
FR Notice (PDF)(2 pp, 144 K, published May 26, 2005, About PDF)
Budgets found adequate through the adequacy review process.
carbon monoxide maintenance plan Adequate (4/29/1999) Determination made under old process
Provo (Utah County) carbon monoxide attainment demonstration Adequate (8/4/2004)
Letter
FR Notice (PDF)(1 pp, 138 K, published July 20, 2004, About PDF)
Budgets found adequate through the adequacy review process.
PM10 attainment demonstration (2010 & 2020 budgets) Adequate (10/16/2002)
Letter
FR Notice
Budgets found adequate through the adequacy review process.
carbon monoxide attainment demonstration Inadequate (5/14/1999) Determination made under old process
Salt Lake City Area carbon monoxide maintenance plan Adequate (6/15/2005)
Letter
FR Notice (PDF)(1 pp, 139 K, published May 31, 2005, About PDF)
Budgets found adequate through the adequacy review process.

Utah portion of Logan UT-ID Area

PM2.5

attainment demonstration

Adequate (9/28/2015)
FR Notice(published September 11, 2015)

Budgets found adequate through the adequacy review process

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Last updated on April 1, 2025
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