The MS4 Phase II general permit authorizes stormwater discharges from small MS4s located with an Urbanized Area in accordance with the Phase II of the federal stormwater rules (40 Code of Federal Regulations 122.32). In 2012, the Census Bureau published the final listing of urbanized areas for the 2010 Census. An urbanized area is a densely settled territory with a population of at least 50,000 people.
MS4s that are located within the new urbanized area boundaries are subject to stormwater regulation, unless waivers are submitted and approved by DEQ. The 2010 Census delineated 12 new jurisdictions that they may now subject to the stormwater program. DEQ approved five waivers. The seven remaining communities will be required to apply for permit coverage under the stormwater program.