The following is a selection of resources for those seeking more information on MS4-related mapping requirements.
Links to resources outside of DEP's website do not necessarily constitute an endorsement.
This DEP application can be used to view urbanized areas (UAs) based on the 2000 and 2010 censuses along with other facilities and features. Note that use of the web-based GIS application may be more appropriate for Pollutant Reduction Plans because it does not include 2016 tentative stream impairments, which are not required to be addressed in the 2018-2023 permit term.
PA Urbanized Areas (PDF)
This map of PA UAs is based on 2010 census data.
EPA Urbanized Area Website
2010 UA maps
Model Map (PDF)
An example map developed by DEP that illustrates the detail necessary to meet the basic requirements of MCM #3 as well as the advanced requirements for Pollutant Reduction Plans, TMDL Plans and Pollutant Control Measures for the current NPDES permit term. DEP has posted instructions (PDF) on how to use the Model Map.
MS4 Storm Sewershed/Planning Area Scenarios
Scenario #1: Urban area and drainage above and below the urban area
Scenario #2: Urban area and drainage below the urban area
Scenario #3: Urban area
Scenario #4: Urban area and drainage above the urban area
Scenario #5: Urban area, drainage below the urban area, with outfall in a downstream municipality
Scenario #6: Outside the urban area
Scenario #7: Outside the urban area, with upstream drainage from an upstream municipality
Scenario #8: Urban area, with drainage above the urban area and from an upstream municipality
Scenario #9: Urban area, with drainage from an upstream urban municipality
EPA National Stormwater Calculator
This calculator may be used to compute small site hydrology for any location within the US by estimating the amount of stormwater runoff generated from a site under different development and control scenarios over a long term period of historical rainfall.
EPA Stormwater Management Model
A dynamic rainfall-runoff simulation model used for single event or long-term (continuous) simulation of runoff quantity and quality from primarily urban areas.