Conformity Adequacy Review: Region 10

State Implementation Plans (SIP) Submissions that EPA has Found Adequate or Inadequate
Region 10: Alaska, Idaho, Oregon, and Washington

On this page:

Alaska
Idaho
Oregon
Washington

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

This page provides a list of state implementation plans that include motor vehicle emission budgets that EPA Region 10 has found either adequate or inadequate for the purposes of transportation conformity.

Contact: For the Region 10 contact person (name, phone number, email address), see EPA’s Regional Contacts for State and Local Transportation.

Alaska
Area	Pollutant	SIP Submission	Finding (date budgets apply)	Additional Information/ Comments
Anchorage	carbon monoxide	maintenance plan	Adequate Letter (12/2011) (pdf) (88.91 KB) December 11, 2011 FR Notice (2/2012) (pdf) (147 KB, published February 14, 2012)	Budgets found adequate through the adequacy review process.
		maintenance plan	Adequate FR Notice (6/2004) (pdf) (147 KB, published June 23, 2004)	SIP found adequate through SIP approval process.
		attainment demonstration	Adequate FR Notice (9/2002) (pdf) (132 KB, published September 18, 2002)	Budgets adequate by virtue of SIP approval.
		attainment demonstration	Inadequate (05/14/1999)	Determination made under old process.
Eagle River	PM10	limited maintenance plan	Adequate Letter (4/2012) (pdf) (46.44 KB) April 2, 2012 FR Notice (4/2012) (pdf) (194 KB, published April 27, 2012)	Budgets found adequate through the adequacy review process.
Fairbanks	2006 PM2.5	attainment demonstration and reasonable further progress	Adequate (05/23/2025) Letter (04/04/2025) (pdf) (254.37 KB) FR Notice (5/2025) (pdf) (262 KB, published May 8, 2025)	Budgets found adequate through the adequacy review process
	carbon monoxide	maintenance plan	Adequate (09/27/2004)	Budgets adequate by virtue of SIP approval.
		attainment demonstration	Adequate (04/05/2002)	Budgets found adequate through SIP approval process.
		attainment demonstration	Inadequate (05/14/1999)	Determination made under old process

Idaho
Area	Pollutant	SIP Submission	Finding (date budgets apply)	Additional Information/ Comments
Northern Ada County	PM10	second limited maintenance plan	Adequate FR Notice (6/2013) (pdf) (187 KB, published June 6, 2013) Letter (Idaho Northern Ada County) (5/2013) (pdf) (795.07 KB) May 17, 2013	Budgets found adequate through adequacy review process.
Northern Ada County	carbon monoxide	limited maintenance plan	Adequate (12/27/2002) FR Notice (10/2002) (pdf) (148 KB, published October 28, 2002)	Budgets found adequate through SIP approval process.
Pocatello	PM10	maintenance plan	Adequate Letter (8/2004) (pdf) (394.08 KB) August 31, 2004 FR Notice (9/2004) (pdf) (142 KB, published September 17, 2004)	Budgets found adequate through adequacy review process.
Pocatello	PM10	attainment demonstration	Inadequate (8/14/2000) Letter (6/2000) (pdf) (18.83 KB) June 8, 2000 FR Notice (7/2000) (pdf) (215 KB, published July 28, 2000)

Oregon
Area	Pollutant	SIP Submission	Finding (date budgets apply)	Additional Information/ Comments
Grants Pass	CO	limited maintenance plan	Adequate (09/28/2015) FR Notice (7/28/2015) (pdf) (235 KB, published July 28, 2015)	Budgets found adequate through the SIP approval process.
Grants Pass	PM10	limited maintenance plan	Adequate (09/28/2015) FR Notice (7/30/2015) (pdf) (275 KB, published July 30, 2015)	Budgets found adequate through the SIP approval process.
Klamath Falls	2006 24-hour PM2.5	Redesignation request and maintenance plan	Adequate (09/05/2025) Letter (4/2025) (pdf) (199.41 KB, April 23, 2025) FR Notice (8/21/2025) (pdf) (234 KB, published August 21, 2025)	Budgets found adequate through the adequacy review process.
Klamath Falls	2006 PM2.5	attainment plan	Adequate (08/17/2015) FR Notice (7/31/2015) (pdf) (194 KB, published July 31, 2015)	Budgets found adequate through the adequacy review process.
Medford	PM10	maintenance plan	Adequate (08/18/2006) FR Notice (6/19/2006) (pdf) (191 KB, published June 19, 2006)	Budgets found adequate through SIP approval process.
	carbon monoxide	second maintenance plan	Adequate Letter (3/2016) (pdf) (28.89 KB) March 1, 2016 FR Notice (4/28/2016) (pdf) (199 KB, published April 28, 2016)	Budgets found adequate through the adequacy review process.
	carbon monoxide	maintenance plan	Adequate Letter (3/2002) (pdf) (14.32 KB) March 21, 2002 FR Notice (4/11/2002) (pdf) (132 KB, published April 11, 2002)	Budgets found adequate through adequacy review process.
Oakridge	2006 pm2.5	attainment plan	Adequate FR Notice (6/16/2017) (pdf) (206 KB, published June 6, 2017) Letter (Oakridge) (4/2017) (pdf) (105.86 KB) April 24, 2017	Budgets found adequate through the adequacy review process
Portland	carbon monoxide	maintenance plan	Adequate FR Notice (1/24/2006) (pdf) (150 KB, published January 24, 2006)	Budgets found adequate through SIP approval process.
Salem	carbon monoxide	limited maintenance plan	Adequate (3/02/2009) FR Notice (12/30/2008) (pdf) (165 KB, published December 30, 2008)	Budgets found adequate through SIP approval process.

Washington
Area	Pollutant	SIP Submission	Finding (date budgets apply)	Additional Information/ Comments
Kent, Seattle, and Tacoma	PM10	Limited maintenance plan	Adequate (08/20/2014) FR Notice (8/20/2008) (pdf) (286 KB, published August 20, 2014)	Budgets found adequate through the SIP approval process.
Spokane	PM10	limited maintenance plan	Adequate (04/12/2016) FR Notice (4/12/2016) (pdf) (237 KB, published April 12, 2016)	Budgets found adequate through the SIP approval process.
	PM10	limited maintenance plan	Adequate (08/30/2005) FR Notice (7/01/2005) (pdf) (182 KB, published July 1, 2005)	Budgets found adequate through SIP approval process.
	carbon monoxide	maintenance plan	Adequate (08/29/2005) FR Notice (6/29/2005) (pdf) (160 KB, published June 29, 2005)	Budgets found adequate through SIP approval process.
		attainment demonstration	Adequate Letter (11/2002) (pdf) (16.03 KB) November 1, 2002 FR Notice (11/19/2002) (pdf) (133 KB, published November 19, 2002)	Budgets found adequate through adequacy review process.
		attainment demonstration	Inadequate (5/14/1999)	Determination made under old process
Tacoma-Pierce County	2006 PM2.5	maintenance plan	Adequate (2/10/2015) FR Notice (2/10/2015) (pdf) (261 KB, published February 10, 2015)	Budgets found adequate through the SIP approval process.
Vancouver	carbon monoxide	limited maintenance plan	Adequate Letter (11/2007) (pdf) (28.25 KB) November 7, 2007 FR Notice (11/19/2007) (pdf) (139 KB, published November 19, 2007)	Budgets found adequate through adequacy review process.
Yakima	PM10	limited maintenance plan	Adequate Letter (12/2004) (pdf) (1.27 MB) October 12, 2004 FR Notice (11/12/2004) (pdf) (144 KB, published November 12, 2004)	Budgets found adequate through adequacy review process.
Yakima	carbon monoxide	limited maintenance plan	Adequate (12/31/2002) FR Notice (11/1/2002) (pdf) (155 KB, published November 1, 2002)	Budgets found adequate through the SIP approval process.