Car oils and fluids can cause pollution

Planning and Stormwater: A Perfect Match

MS4: The Planner's Strategy


Stormwater runoff, or water from rain or melting snow, does not soak into the ground as it flows over sidewalks, driveways, parking lots, roads, and rooftops. On its way downslope, it picks up pollutants and debris such as spilled fuel, oils, greases, antifreeze, grass clippings, litter, animal waste, fertilizer, and pesticides.

Unfortunately, stormwater carries these pollutants into our local creeks, streams, and other waterways. This causes harm to plants, fish, animals, and even people as we often use these waterways for swimming, recreation, or as a source of drinking water. Stormwater can also create flooding problems when local stream levels rise dangerously.

In urban areas, runoff and sewer overflows from stormwater result in lower water quality for the community and degraded watersheds.

Using green infrastructure in planning reduces discharge volumes, filters water for better quality, and helps mitigate flood risk. Adding signage to explain the benefits of green infrastructure educates the community. Responsible stormwater management is an important planning action for both commercial and residential developers, as well as urban and growing local municipalities. We need to work together to reuse and restore the quality of stormwater runoff, such as constructing a marsh or wetland.

In Pennsylvania, the MS4 permit, which stands for Municipal Separate Storm Sewer Systems, is an important component of a green infrastructure approach to improving water quality. The U.S. Environmental Protection Agency and the Pennsylvania Department of Environmental Protection require local governments to develop and implement best management practices to protect water quality, enhance availability of water, and reduce flooding potential. This can be achieved through MS4 systems such as:

  • Curbs
  • Gutters
  • Ditches
  • Natural or man-made channels
  • Pipes
  • Tunnels
  • Catch basins
  • Storm drains
  • Permeable pavement
  • Rainwater collection
  • Rain gardens
  • Tree planting and riparian buffers
  • Disconnecting downspouts from storm drains
  • Debris-free storm drains
  • Proper yard waste disposal
  • Proper hazardous materials disposal
  • Proper pet waste disposal


In planning and guiding development, we need to promote these green infrastructure projects to reduce stormwater pollution.