What is an MS4?

MS4 is an acronym for a Municipal Separate Storm Sewer System. An MS4 is defined as a collection and conveyance system or a group of collection and conveyance systems owned, operated and maintained by a state, city, township, borough or other public entity that is dedicated solely for the handling of stormwater runoff and discharging it into tributaries, streams, rivers, or other natural or man-made receiving waters within the Commonwealth of Pennsylvania.

The MS4 system may include such structures designated for the collection, storage and conveyance of stormwater runoff as:

  • Catch basins
  • Conveyance channels
  • Detention ponds
  • Infiltration basins
  • Rain gardens
  • Roadside swales and cross drains
  • Storm pipes
  • Trench drains

Show All Answers

1. What is an MS4?
2. What is stormwater runoff?
3. What is non-stormwater discharge?
4. Why can stormwater runoff be a problem in the Township?
5. What is Hempfield Township doing about stormwater runoff?
6. What can residents of Hempfield Township do to improve stormwater quality in the Township?