What Is MS4?

Water Logo

MS4 is an acronym that stands for Municipal Separate Storm Sewer System. A MS4 is a publicly-owned system of conveyances that include catch basins, curbs, gutters, ditches, man-made channels, pipes, tunnels, or storm drains that discharges into waters of the United States. Antrim Township was designated as a Small MS4 in 2004. A National Pollutant Discharge Elimination System (NPDES) permit is issued by the Pennsylvania Department of Environmental Protection (PA DEP) to the public operator. In Antrim Township, the municipality is the owner of many of the roads that convey stormwater runoff into privately owned roadside swales, ditches, catch basins or other features. The NPDES permit is a tool used by the PA DEP to ensure that our waterways are clean and that water pollution is prevented. The Township is the regulatory body that makes sure that the privately-owned systems (road side swales, stormwater ponds, inlets, culverts, raingardens, filter strips, infiltration terraces etc.) are maintained by the property owner or HOA and functioning properly.

The creeks and streams in our area eventually flow into the Potomac River which empties into the Chesapeake Bay. The MS4 program focuses on cleaning up the Chesapeake Bay. Unless, we keep pollutants out of our waterways, they will end up in the Chesapeake Bay.

Chesapeake Bay
Chesapeake Bay

In summation, a MS4 makes sure that our stormwater is clean and properly managed through the implementation of 6 Minimum Control Measures (MCM). They are:

The Minimum Control Measures Are:

  • MCM # 1 – Public Education and Outreach on Stormwater Impacts.
  • MCM # 2 – Public Involvement / Participation.
  • MCM # 3 – Illicit Discharge Detection and Elimination (IDD&E).
  • MCM # 4 – Construction Site Run Off.
  • MCM # 5 – Post Construction Stormwater Management (PCSM) in New and Re-Development Activities.
  • MCM # 6 – Pollution Prevention / Good Housekeeping for Municipal Operations.

You can read more about our minimum control measures by clicking on the "Stormwater Management Plan". Learn more about stormwater and get involved.

Martins Mill
Martins Mill

Malissa Drive from Preston
Malissa Drive from Preston