Description: MS4 Phase II permitted areas were derived for Region 3 by integrating data from multiple sources. This resulted in an areal data layer that represents the land area that is covered under an MS4 permit, Please note that this should be used as a reference only and should not be relied upon for precise calculations when it comes to permitted area, as combining data sources of different resolutions results in a loss of accuracy.These polygons represent urbanized area that are within the municipality boundaries and incorporated places of Region 3 states. U.S. Census 2000 data was utilized to represent areas within municipalities that should be encompassed in the existing Phase II permit for those municipalities. U.S. Census 2010 data was then utilized to represent expanded areas of Phase II coverage. Features representing MS4 coverage of government agency entitities, such as state Departments of Transportation and federal lands and sites are not currently represented here.Note that these methodolgies apply to the majority of the data but exclude Phase II permits in Maryland and also an exception in West Virginia (mentioned in the Summary above).Steps to deriving these data:1) Municipal boundaries for PA, DE, VA, and WV were integrated. Municipal boundaris for Maryland were embedded into the county boundaries for Maryland (due to MS4 permitting nuances followed by the state of Maryland). This resulted in an administrative layer representing administrative localities that have MS4 obligations to the federal governemt.2) U.S. Census 2000 urban area coverage was modified to represent only land area by removing areas of water, as determined by waterbody data (100K resolution). This resulting urbanized land area was clipped to the administrative layer created in step (1).3) The resulting polygon layer depicts urbanized land area (as of 2000) that is within municipal boundaries of Region 3.4) In progress: MS4 permit administration point data (aka the physial location of the permit, usually a city hall) are now being linked to the polygon area representing MS4 Phase II permitted areas based on spatial location and the permit holder.5) Steps 2 and 3 were repeated using U.S. Census 2010 urban area coverage and appended to the existing MS4 Phase II areas to show additional land area that will soon be (or is currently being) incorporated into existing permits.6) Exceptions:MD Phase II boundaries were not determined by urban area coverage, but rather defined by the municipality boundaries.For Cecil and Washington Counties in MD and Berkeley County in WV, the county boundary (minus muncipal boundaries within the county), was used to represent Phase II coverage for these particular permits.