Municipal Separate Storm Sewer System (MS4) is a conveyance or system of conveyances (including roads, catch basins, curbs, gutters, ditches, man-made channels, or storm drains) owned or operated by a public body, designed and used for collecting storm water, is not a combined sewer, an is not a Publicly Owned Treatment Works (POTW). The U.S. EPA's storm water program addressed storm water runoff in two phases. Phase I addressed storm water runoff from large and medium MS4s. Large municipalities with a separate storm sewer system serving a population greater than 250,000 and medium municipalities with a service population between 100,000 and 250,000 had to obtain NPDES permits. Initial application deadlines for large and medium municipalities were November 16, 1992 and May 17, 1993, respectively. As part of their individual NPDES permit applications, the large and medium MS4s had to develop a storm water management program (SWMP). The Phase II regulations address storm water runoff of MS4s serving populations less than 100,000, called small MS4s. More particularly, small MS4s located partially or fully within urbanized areas (UAs), as determined by the U.S. Bureau of the Census, and also on a case-by-case basis for those small MS4s located outside of UAs that Ohio EPA designates into the program. Automatically designated Small MS4s, those in UAs, were required to apply for permit coverage and develop and submit a SWMP by March 10, 2003.Ohio considers the Urban Areas defined under the 2000 and 2010 Census, as well as more than 30 cities located outside of the the urban areas that are also covered by a storm water permit, as a Regulated MS4 Area.