SIP Status Reports
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Status of Montana Designated Areas
Status of Montana Designated Areas
Montana Areas by NAAQSNOTE: As of 03/12/2021, these reports are no longer being updated. For the latest information, see the SIP Status Tools.
Jump to Montana section for: CO (1971) Lead (1978) Lead (2008) NO2 (1971) Ozone-1Hr (1979) Ozone-8Hr (1997) Ozone-8Hr (2008) Ozone-8Hr (2015) PM-10 (1987) PM-2.5 (1997) PM-2.5 (2006) PM-2.5 (2012) SO2 (1971) SO2 (2010)
Montana CO (1971) Areas Return to map |
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Click on the Area name to view SIP Required Elements Area |
Status | Designation Date |
Classification | 2010 Population (state portion) |
Meets NAAQS Basis |
Design Value Annual (ppm) (entire area) |
Meets NAAQS |
SIP Requirements Original/ Approved |
Clean Air Determination Citation Effective Date Click to view FR notice |
Redesignation Request Date |
Redesignation Citation Effective Date Click to view FR notice |
Billings Area | Maintenance | 11/15/1990 | Not Classified | 104,360 | 2019 | No Data | 1 / 1 | |
02/09/2001 | 04/22/2002 67 FR 7966 |
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Great Falls Area | Maintenance | 11/15/1990 | Not Classified | 57,573 | 2019 | No Data | 1 / 1 | |
02/09/2001 | 07/08/2002 67 FR 31143 |
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Missoula Area | Maintenance | 11/15/1990 | Moderate <= 12.7ppm | 59,733 | 2019 | No Data | 4 / 4 | |
05/27/2005 | 09/17/2007 72 FR 46158 |
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Montana Lead (1978) Areas Return to map Top of page |
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Click on the Area name to view SIP Required Elements Area |
Status | Designation Date |
Classification | 2010 Population (state portion) |
Meets NAAQS Basis |
Design Value Annual (µg/m3) (entire area) |
Meets NAAQS |
SIP Requirements Original/ Approved |
Clean Air Determination Citation Effective Date Click to view FR notice |
Redesignation Request Date |
Redesignation Citation Effective Date Click to view FR notice |
Lewis & Clark County (part); City of East Helena and vicinity | Maintenance | 01/06/1992 | 2,669 | 2009-2010 | No Data | 2 / 2 | |
10/28/2018 | 10/11/2019 84 FR 47895 |
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Montana Lead (2008) Areas Return to map Top of page |
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No designated areas for this pollutant. | |||||||||||
Montana NO2 (1971) Areas Return to map Top of page |
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No designated areas for this pollutant. | |||||||||||
Montana Ozone-1Hr (1979) Areas Return to map Top of page |
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No designated areas for this pollutant. | |||||||||||
Montana Ozone-8Hr (1997) Areas Return to map Top of page |
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No designated areas for this pollutant. | |||||||||||
Montana Ozone-8Hr (2008) Areas Return to map Top of page |
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No designated areas for this pollutant. | |||||||||||
Montana Ozone-8Hr (2015) Areas Return to map Top of page |
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No designated areas for this pollutant. | |||||||||||
Montana PM-10 (1987) Areas Return to map Top of page |
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Click on the Area name to view SIP Required Elements Area |
Status | Designation Date |
Classification | 2010 Population (state portion) |
Meets NAAQS Basis |
Average Estimated Exceedances (est. exc.) (entire area) |
Meets NAAQS |
SIP Requirements Original/ Approved |
Clean Air Determination Citation Effective Date Click to view FR notice |
Redesignation Request Date |
Redesignation Citation Effective Date Click to view FR notice |
Flathead County; Columbia Falls and vicinity | Maintenance | 11/15/1990 | Moderate | 4,610 | 2017-2019 | 0.0 | Yes | 3 / 3 | 04/01/2011 76 FR 5280 |
07/27/2020 85 FR 38327 |
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Flathead County; Kalispell and vicinity | Maintenance | 11/15/1990 | Moderate | 18,422 | 2017-2019 | 0.0 | Yes | 3 / 3 | |
07/27/2020 85 FR 38327 |
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Flathead County; Whitefish and vicinity | Nonattainment | 11/18/1993 | Moderate | 6,138 | 2017-2019 | 0.3 | Yes | 3 / 3 | |
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Lake County; Polson | Nonattainment | 11/15/1990 | Moderate | 4,099 | 2017-2019 | No Data | 3 / 0 | |
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Lake County; Ronan | Nonattainment | 11/15/1990 | Moderate | 2,734 | 2017-2019 | No Data | 3 / 0 | |
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Lincoln County; Libby and vicinity | Maintenance | 11/15/1990 | Moderate | 3,378 | 2017-2019 | 0.0 | Yes | 3 / 3 | 04/01/2011 76 FR 5280 |
07/27/2020 85 FR 38327 |
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Missoula county; Missoula and vicinity | Maintenance | 11/15/1990 | Moderate | 59,733 | 2017-2019 | 0.0 | Yes | 3 / 3 | |
08/03/2016 | 06/24/2019 84 FR 24037 |
Rosebud County; Lame Deer | Nonattainment | 11/15/1990 | Moderate | 527 | 2017-2019 | No Data | 3 / 0 | |
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Sanders County (part); Thompson Falls and vicinity | Nonattainment | 01/20/1994 | Moderate | 1,317 | 2017-2019 | 0.4 | Yes | 3 / 3 | |
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Silver Bow County; Butte | Nonattainment | 11/15/1990 | Moderate | 34,201 | 2017-2019 | 0.0 | Yes | 3 / 3 | |
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Montana PM-2.5 (1997) Areas Return to map Top of page |
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Click on the Area name to view SIP Required Elements Area |
Status | Designation Date |
Classification | 2010 Population (state portion) |
Meets NAAQS Basis |
Design Value Annual (µg/m3) (entire area) |
Meets NAAQS |
SIP Requirements Original/ Approved |
Clean Air Determination Citation Effective Date Click to view FR notice |
Redesignation Request Date |
Redesignation Citation Effective Date Click to view FR notice |
Libby | Nonattainment | 04/05/2005 | Moderate | 9,429 | 2017-2019 | 13.4 | Yes | 8 / 4 | 08/13/2015 80 FR 40911 |
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Montana PM-2.5 (2006) Areas Return to map Top of page |
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No designated areas for this pollutant. | |||||||||||
Montana PM-2.5 (2012) Areas Return to map Top of page |
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No designated areas for this pollutant. | |||||||||||
Montana SO2 (1971) Areas Return to map Top of page |
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Click on the Area name to view SIP Required Elements Area |
Status | Designation Date |
Classification | 2010 Population (state portion) |
Meets NAAQS Basis |
Design Value Annual/24-Hr (ppb) (entire area) |
Meets NAAQS |
SIP Requirements Original/ Approved |
Clean Air Determination Citation Effective Date Click to view FR notice |
Redesignation Request Date |
Redesignation Citation Effective Date Click to view FR notice |
East Helena Area | Maintenance | 11/15/1990 | 2,669 | / | 2 / 2 | |
10/26/2019 | 10/11/2019 84 FR 47897 |
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Laurel Area | Nonattainment | 11/15/1990 | 6,525 | / | 1 / 1 | |
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Montana SO2 (2010) Areas Return to map Top of page |
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Click on the Area name to view SIP Required Elements Area |
Status | Designation Date |
Classification | 2010 Population (state portion) |
Meets NAAQS Basis |
3 Year 1-Hour Design Value (ppb) (entire area) |
Meets NAAQS |
SIP Requirements Original/ Approved |
Clean Air Determination Citation Effective Date Click to view FR notice |
Redesignation Request Date |
Redesignation Citation Effective Date Click to view FR notice |
Billings | Maintenance | 10/04/2013 | 2,621 | 2017-2019 | 24 | Yes | 6 / 1 | 06/09/2016 81 FR 28718 |
12/14/2015 | 06/09/2016 81 FR 28718 |
We have made our best effort to ensure that the data contained in these reports is accurate. We note that there may be brief delays in
updating the reports as we receive new state submissions and we take rulemaking action on plans. In order to assist us in providing
accurate information, we request that you contact us by clicking on the "Contact Us" link near the top of this page with any comments
regarding or corrections to the posted information, including concerns about whether the entries reflect the most recent status. Current and historical design value data can be found on the EPA Air Quality Design Values website and the EPA Green Book contains comprehensive nonattainment area, designation status, and historical information. The level of the 1-hour NAAQS for sulfur dioxide is 75 parts per billion (ppb) calculated as the 3-year average of the 99th percentile of the annual distribution of daily maximum 1-hour average concentrations. |