40 CFR § 51.1117
Fee programs for Severe and Extreme nonattainment areas that fail to attain
June 9, 2020
For each area classified as Severe or Extreme for the 2008 ozone NAAQS, the state shall submit a SIP revision within 10 years of the effective date of designation that meets the requirements of CAA section 185.
[80 FR 12314, Mar. 6, 2015]