(1) This subchapter is intended to be applied together with ARM Title 17, chapter 30, subchapters 12 and 13 to establish a system for regulating discharges of potential pollutants from point source discharges of storm waters into surface waters.  This subchapter and subchapter 13 of ARM Title 17, chapter 30, which regulate storm water discharges through Montana pollutant discharge elimination system (MPDES) general permits, permit authorizations, and notices of intent, are intended to be compatible with the national pollutant discharge elimination system (NPDES) as established by the United States environmental protection agency pursuant to section 402 of the federal Clean Water Act (CWA) , 33 USC 1251, et seq.  Except as expressly modified in this subchapter, all requirements in ARM Title 17, chapter 30, subchapters 12 and 13 remain effective pertaining to point source discharges of storm water.

(2) The rules in this subchapter pertain to point source discharges of storm water that do not contain routine process wastewater and that do not contain non-storm water discharges except for the potential non-storm water discharges from MS4s that are listed in ARM 17.30.1111(6) (c) (iii) .  ARM Title 17, chapter 30, subchapter 13 contains additional requirements pertaining to point source discharges of storm water that routinely contain process wastewater or non-storm water discharges (other than the potential non-storm water discharges for MS4s listed in ARM 17.30.1111(6) (c) (iii) ) that are regulated using an individual MPDES permit.