Municipal Separate Storm Sewer System (MS4)

A Municipal Separate Storm Sewer System (MS4) (Penn State Extension) is a system of conveyances owned by a public entity and discharges stormwater runoff to waters of the Commonwealth. The system is designed to collect or convey stormwater. Please note that the storm sewer system is not a combined sewer system. The township's stormwater conveyance system, unlike the sewer system, conveys surface water runoff from rain, irrigation, and outdoor water use directly to our waterways without treatment. The stormwater conveyance system includes:

  • Catch basins
  • Curbs
  • Ditches
  • Gutters
  • Man-made channels
  • Sidewalks
  • Storm drain inlets
  • Streets

In Lower Macungie Township, the stormwater conveyance system ultimately discharges to the Lehigh River, which then flows westward to its end point at the Delaware River. In our township, the MS4 is monitored for erosion, flooding, and spills to ensure the best quality runoff into our waterways.

To learn more, view the Pennsylvania State University Extension's "What is an MS4?" video.

Diagram showing how the municipal storm sewer system and its components work to convey stormwater