https://19january2021snapshot.epa.gov/sips-ar/arkansas-sip-reg-19-chapter-9-effective-2015-04-03-ard18-2015-08-05_.html
Arkansas SIP: Reg 19, Chapter 9: effective 2015-04-03 (ARd18) to 2015-08-05 | Approved Air Quality...
Jul 13, 2020 - AR SIP: Reg 19, Chap 9: effective 2015-04-03 (ARd18) to 2015-08-05