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Pacific Southwest, Region 9

Serving: Arizona, California, Hawaii, Nevada, Pacific Islands, Tribal Nations

Air Actions, California

Particulate Matter (PM10) Pollution in California's Great Basin

Actions Taken

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September 2015: Mammoth Lakes Coarse Particulate Matter (PM10) Maintenance Plan and Redesignation Request

September 18, 2015 - EPA is finalizing approval of the Mammoth Lakes PM10 maintenance plan and redesignation request. The Great Basin Unified Air Pollution Control District's maintenance plan and redesignation request address the Clean Air Act requirements for EPA to redesignate the area to attainment of the PM10 National Ambient Air Quality Standard (NAAQS). The maintenance plan shows that the area will continue to meet the PM10 NAAQS through 2030.

July 10, 2015 - EPA proposed to approve the coarse particulate matter (PM10) National Ambient Air Quality Standard redesignation request and maintenance plan for the Mammoth Lakes nonattainment area.


July 2010: Final Action on Coso Junction Planning Area 2010 PM-10 Maintenance Plan & the State of California's Redesignation Request

On July 29, 2010, in a final rulemaking action, we redesignated the Coso Junction Planning Area (CJPA) to attainment for the PM-10 National Ambient Air Quality Standard (NAAQS) and approved the PM-10 maintenance plan for the area, as requested by the State of California. The primary cause of the PM-10 problem in the CJPA has been windblown dust emissions from Owens Lake. With jurisdiction over the Owens Lake area and the CJPA, the Great Basin Unified Air Pollution Control District (GBUAPCD) has adopted significant controls for Owens Lake dust and we are approving them as part of the CJPA's maintenance plan. We provided a 30-day comment period for our June 24, 2010 proposal and received no comments.

June 2010: Proposed Action on Coso Junction Planning Area 2010 PM-10 Maintenance Plan & the State of California's Redesignation Request

On June 24, 2010, we proposed that the Great Basin Unified Air Pollution Control District (GBUAPCD) fulfilled The Clean Air Act (CAA) requirements for redesignations and maintenance plans for the Coso Junction Planning Area (CJPA). Consequently, as requested by the State of California, we are proposing to redesignate the CJPA to attainment of the PM-10 National Ambient Air Quality Standard (NAAQS). Our proposal discusses how the CJPA has met the requirements for redesignation including attainment of the PM-10 NAAQS, permanent and enforceable emission reductions resulting in attainment of the standard, an accurate and up to date emissions inventory, commitments for ensuring continued attainment of the PM-10 NAAQS, and contingency measures.

For our determination of attainment of the PM-10 NAAQS for the CJPA, please see our actions described below.


May 2010: Final Determination of Attainment for the PM-10 Standard in the Coso Junction Planning Area

On May 13, 2010, we finalized our determination that the Coso Junction Nonattainment Area (CJNA) has attained the 24-hour National Ambient Air Quality Standard (NAAQS) for particulate matter with an aerodynamic diameter less than or equal to a nominal ten micrometers (PM-10) based on quality-assured and certified air quality data from 2006 through 2008.  In addition, air quality data for 2009 and preliminary data for 2010 show that the CJNA continues to attain the PM-10 NAAQS.  Also, we finalized our determination that certain Clean Air Act requirements are not applicable for as long as the CJNA continues to attain the PM-10 NAAQS.  Currently, we are obligated under a consent decree either to reclassify (or “bump-up”) the CJNA from “moderate” to “serious”, or to redesignate the area to attainment for PM-10 by July 31, 2010.

March 2010: Proposed Determination of Attainment for the PM-10 Standard in the Coso Junction Planning Area

On March 23, 2010, we proposed to determine that the Coso Junction Nonattainment Area (CJNA) has attained the 24-hour PM-10 National Ambient Air Quality Standard (NAAQS) based on quality-assured and certified air quality data from 2006 through 2008.  In addition, air quality data for 2009 and preliminary data for 2010 show that the CJNA continues to attain the NAAQS.  Also, we proposed to determination that certain Clean Air Act requirements are not applicable for as long as the CJNA continues to attain the PM-10 NAAQS.


Final Rule PM-10 Nonattainment Finding

May 25, 2007: EPA has finalized its March 15, 2007 proposal to find that the Owens Valley area has failed to attain the PM-10 standard.

Proposed PM-10 Nonattainment Finding

March 15, 2007: Owens Valley is classified as a serious PM-10 nonattainment area and had an attainment deadline of December 31, 2006. EPA is proposing to find that the Owens Valley has failed to attain the 24-hour PM-10 standard by the attainment deadline. For more information on EPA's proposed action, please see the documents below or contact Larry Biland (biland.larry@epa.gov) at (415) 947-4132.


Final EPA Approval of the PM-10 Plan for the Owens Valley Nonattainment Area

August 18, 1999: EPA gave final approval to California’s particulate matter (PM-10) State Implementation Plan (SIP) for the Owens Valley to ensure clean and healthful air. EPA also approved the State’s request for a five-year extension, to December 31, 2006, to meet the PM-10 National Ambient Air Quality Standards (NAAQS).

Contact Information

Larry Biland (biland.larry@epa.gov)
Technical Support Office, EPA Region 9
(415) 947-4132

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