Plumas County Air: EPA Says 'Clean Enough' by Deadline
Published Date: 8/13/2026
Rule
Summary
The Environmental Protection Agency (EPA) is finalizing our determination that the Portola nonattainment area in Plumas County, California, attained the 2012 annual fine particulate matter ("PM<INF>2.5</INF>") national ambient air quality standard (NAAQS or "standard") by the December 31, 2025 "Serious" area attainment date. This determination is based on ambient air quality monitoring data from 2023 through 2025. We are also finalizing a clean data determination (CDD) based on the 2023 through 2025 data and our evaluation of preliminary air quality monitoring data from 2026.
Analyzed Economic Effects
3 provisions identified: 2 benefits, 1 costs, 0 mixed.
Portola Attained PM2.5; SIP Submissions Suspended
The EPA determined the Portola nonattainment area in Plumas County attained the 2012 annual PM2.5 standard by the December 31, 2025 attainment date based on 2023–2025 monitoring data and finalized a Clean Data Determination. Because of the Clean Data Determination, the state’s requirement to submit an attainment demonstration, a reasonable further progress plan, quantitative milestones, quantitative milestone reports, and contingency measures is suspended for as long as the area continues to attain the 2012 annual PM2.5 NAAQS.
No New Costs for Small Entities
The EPA certified under the Regulatory Flexibility Act that this action will not have a significant economic impact on a substantial number of small entities and that it will not impose any requirements on small entities beyond those imposed by state law.
Emissions Inventories, BACT, NSR Still Required
The EPA stated that even with the Clean Data Determination, the requirements to submit emissions inventories, implement best available control measures (including control technologies), and maintain a nonattainment new source review (NSR) permitting program for the Serious nonattainment area remain in effect.
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