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

On this page:

Colorado
Montana
Utah

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

Contact: For the Region 8 contact person (name, phone number, email address), see EPA’s Regional Contacts for State and Local Transportation.

Colorado
Area	Pollutant	SIP Submission	Finding (date budgets apply)	Additional Information/ Comments
Aspen	PM10	maintenance plan	Adequate (11/18/2013) Letter (8/2011) (pdf) (1.3 MB, August 11, 2011) Adequacy letter FR Notice (5/2012) (pdf) (243 KB, May 25, 2012)	Budgets found adequate through the adequacy review process.
Aspen	PM10	maintenance plan	Adequate (9/4/2002) Letter (8/2002) (pdf) (89.06 KB) Adequacy letter FR Notice (8/2002) (pdf) (128 KB, published August 20, 2002)	Budgets found adequate through the adequacy review process.
Canon City	PM10	maintenance plan	Adequate (8/17/2011) Letter (5/2011) (pdf) (1.16 MB, May 4, 2011) Adequacy letter FR Notice (7/2013) (pdf) (284 KB, published July 10, 2013)	Budgets found adequate through the adequacy review process.
Canon City	PM10	maintenance plan	Adequate (7/31/2000) FR Notice (5/2000) (pdf) (233 KB, published May 30, 2000)	Budgets found adequate through SIP approval process.
Colorado Springs	carbon monoxide	limited maintenance plan	Adequate (8/17/2011) Letter (3/2011) (pdf) (1.27 MB, March 3, 2011) Adequacy letter FR Notice (8/2011) (pdf) (161 KB, published August 2, 2011)	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 5/2023 (pdf) (219.08 KB, May 3, 2023) FR Notice (5/2023) (pdf) (276 KB, published May 9, 2023)	Budgets found adequate through the adequacy review process.
	2008 8-hour ozone	attainment plan	Adequate (4/2/2018) Letter (1/2018) (pdf) (116.99 KB, January 30, 2018) Adequacy letter FR Notice (3/2018) (pdf) (184 KB, published March 16, 2018)	Budgets found adequate through the adequacy review process
	1997 8-hour ozone	attainment plan	Adequate (3/19/2010) Letter (1/2010) (pdf) (1.28 MB, January 21, 2010) Adequacy letter FR Notice (4/2010) (pdf) (144 KB, published April 1, 2010)	Budgets found adequate through the adequacy review process.
	pm10	maintenance plan	Adequate (6/28/2007) Letter (5/2007) (pdf) (161.75 KB, May 3, 2007) Adequacy letter FR Notice (6/2007) (pdf) (146 KB, published June 13, 2007)	Budgets found adequate through the adequacy review process.
	pm10	maintenance plan	Adequate (10/29/2001) Letter (9/2001) (pdf) (35 KB) Adequacy letter FR Notice (10/2001) (pdf) (128 KB, published October 12, 2001)	Budgets found adequate through the adequacy review process.
	carbon monoxide	maintenance plan	Adequate (6/28/2007) Letter (5/2007) (pdf) (154.83 KB, May 3, 2007) Adequacy letter FR Notice (6/2007) (pdf) (146 KB, published June 13, 2007)	Budgets found adequate through the adequacy review process.
	carbon monoxide	maintenance plan	Adequate (8/18/2000) Letter (7/2000) (pdf) (42.98 KB, July 12, 2000) Adequacy letter FR Notice (8/2000) (pdf) (152 KB, published August 3, 2000)	Budgets found adequate through the adequacy review process.
Fort Collins	carbon monoxide	limited maintenance plan	Adequate (6/11/2012) Letter (8/2011) (pdf) (970.14 KB, August 9, 2011) Adequacy letter FR Notice (5/2012) (pdf) (243 KB, published May 25, 2012)	Budgets found adequate through the adequacy review process.
Fort Collins	carbon monoxide	maintenance plan	Adequate (1/15/2003) Letter (1/2003) (pdf) (25.49 KB, January 15, 2003) Adequacy letter FR Notice (2/2003) (pdf) (131 KB, published February 4, 2003)	Budgets found adequate through the adequacy review process.
Greeley	carbon monoxide	limited maintenance plan	Adequate (8/17/2011) Letter (3/2011) (pdf) (1.3 MB, March 4, 2011) Adequacy letter FR Notice (8/2011) (pdf) (161 KB, published August 2, 2011)	Budgets found adequate through the adequacy review process.
Greeley	carbon monoxide	maintenance plan	Adequate (1/20/2004) Letter (10/2003) (pdf) (31.46 KB, October 29, 2003) Adequacy letter FR Notice (1/2004) (pdf) (131 KB, published January 5, 2004)	Budgets found adequate through the adequacy review process.
Lamar	PM10	second maintenance plan	adequate 10/20/2014 Notice of adequacy (10/2014) (pdf) (204 KB, published October 3, 2014)	Budgets found adequate through the adequacy review process
Lamar	PM10	maintenance plan	Adequate (11/12/2002) Letter (9/2002) (pdf) (115.65 KB, September 25, 2002) Adequacy letter FR Notice (10/2002) (pdf) (132 KB, published October 28, 2002)	Budgets found adequate through the adequacy review process.
Longmont	carbon monoxide	maintenance plan	Adequate (6/28/2007) Letter (5/2007) (pdf) (151.68 KB, May 3, 2007) Adequacy letter FR Notice (6/2007) (pdf) (146 KB, published June 13, 2007)	Budgets found adequate through the adequacy review process.
Longmont	carbon monoxide	maintenance plan	Inadequate (5/14/1999)	Determination made under old process
Pagosa Springs	PM10	maintenance plan	Adequate (8/17/2011) Letter (3/2011) (pdf) (1.47 MB, March 17, 2011) Adequacy letter FR Notice (8/2011) (pdf) (161 KB, published August 2, 2011)	Budgets found adequate through the adequacy review process.
Pagosa Springs	PM10	maintenance plan	Adequate (8/18/2000) Letter (7/2000) (pdf) (42.98 KB, July 12, 2000) Adequacy letter FR Notice (8/2000) (pdf) (152 KB, published August 3, 2000)	Budgets found adequate through the adequacy review process.
Steamboat Springs	PM10	second maintenance plan	Adequate 10/20/2014 FR Notice (10/2014) (pdf) (204 KB, published October 3, 2014)	Budgets found adequate through the adequacy review process.
Steamboat Springs	PM10	maintenance plan	Adequate (11/12/2002) Letter (9/2002) (pdf) (115.65 KB, September 25, 2002) Adequacy letter FR Notice (10/2002) (pdf) (132 KB, published October 28, 2002)	Budgets found adequate through the adequacy review process.
Telluride	PM10	maintenance plan	Adequate (8/17/2011) Letter (3/2011) (pdf) (1.49 MB, March 21, 2011) Adequacy letter FR Notice (2/2011) (pdf) (161 KB, published August 2, 2011)	Budgets found adequate through the adequacy review process.
Telluride	PM10	maintenance plan	Adequate (8/18/2000) Letter (7/2000) (pdf) (42.98 KB, July 12, 2000) Adequacy letter FR Notice (8/2000) (pdf) (152 KB, published August 3, 2000)	Budgets found adequate through the adequacy review process.

Montana
Area	Pollutant	SIP Submission	Finding (date budgets apply)	Additional Information/ Comments
Montana	PM 10	maintenance plan	Adequate (10/12/2018) Letter (7/2018) (pdf) (903.64 KB, July 23, 2018) FR (9/2018) (pdf) (207 KB, published September 27, 2018)	Budgets found adequate through the adequacy review process.
	carbon monoxide	maintenance plan	Adequate (11/13/2017 FR Notice (9/2017) (pdf) (248 KB, published September 14, 2017)	Budgets found adequate through the SIP approval process.
	carbon monoxide	maintenance plan	Adequate (6/16/2006) Letter (5/2006) (pdf) (324.72 KB, May 4, 2006) Adequacy letter FR Notice (6/2006) (pdf) (144 KB, published June 1, 2006)	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 (5/2005) (pdf) (302.09 KB) May 2, 2005 FR Notice (5/2005) (pdf) (144 KB, published May 26, 2005)	Budgets found adequate through the adequacy review process.
Ogden	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 (6/2004) (pdf) (86.7 KB) June 30, 2004 FR Notice (7/2004) (pdf) (139 KB, published July 20, 2004)	Budgets found adequate through the adequacy review process.
	PM10	attainment demonstration (2010 & 2020 budgets)	Adequate (10/16/2002) Letter (9/2002) (pdf) (100.19 KB, September 5, 2002) Adequacy letter FR Notice (10/2002) (pdf) (128 KB, published October 1, 2002)	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 (5/2005) (pdf) (283.41 KB, May 2, 2005) Adequacy letter FR Notice (5/2005) (pdf) (139 KB, published May 31, 2005)	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 (9/2015) (pdf) (186 KB, published September 11, 2015)	Budgets found adequate through the adequacy review process