Understanding MS4 and Reporting Illicit Discharges




Question: What does the acronym “MS4” stand for?

Answer: Municipal Separate Storm Sewer System.

Questions: What is MS4?

Answer: MS4 is a system owned or operated by a public agency, such as a city, town, county flood control district, state or federal agency that does not connect to the sanitary system and does not lead to a wastewater treatment plant.

The federal Clean Water Act (CWA) prohibits the discharge of pollutants into waterways without the appropriate permits. Pennsylvania’s Stormwater Management Act (Act 167) MS4 Program, Chapter 102 (Erosion and Sediment Control Requirements), and National Pollutant Discharge Elimination System (NPDES) Permit Program for Stormwater Discharges Associated with Construction Activities are among the Commonwealth’s methods for meeting the runoff-related requirements of the Clean Water Act.

For all practical purposes, though, implementation of stormwater management efforts in Pennsylvania occurs at the community level because individual municipalities are ultimately responsible for adopting zoning ordinances, subdivision and land development regulations, and other programs that keep their locality’s runoff water under control.

Since the passage of the Clean Water Act (CWA), the quality of our Nation’s waters has improved dramatically. Despite this progress, however, degraded waterbodies still exist. Storm water discharges are generated by runoff from land and impervious areas such as paved streets, parking lots, and building rooftops during rainfall and snow events that often contain pollutants in quantities that could adversely affect water quality. Polluted stormwater runoff is often transported to municipal separate storm sewer systems (MS4s) and ultimately discharged into local rivers and streams without treatment. The EPA’s Stormwater Phase II Rule establishes an MS4 stormwater management program that is intended to improve the Nation’s waterways by reducing the quantity of pollutants that stormwater picks up and carries into storm sewer systems during storm events.

The Township is required to include in its MS4 program a vehicle by which Londonderry Township residents may report illicit discharges. An “illicit discharge” is defined as any discharge to the MS4 system that is not composed entirely of stormwater (except for discharges allowed under NPDES permits or waters used for firefighting operations). The United States Environmental Protection Agency defines an Illicit Discharge as “ANY DISCHARGE into a storm drain system that is not composed entirely of stormwater”. This means that anything other than simply the water that falls from the sky is an illicit discharge. Therefore, the Township asks each citizen to be aware of and report any illicit discharges of water into the MS4 system by filling out and submitting the FORM PROVIDED BY CLICKING HERE.

The Township appreciates each citizen’s efforts to help protect our streams and waterways.

Londonderry Township

103 Daleville Road
Cochranville, PA  19330
(610) 869-2138
(610) 869-5525 (Fax)
Contact Us

Township Hours
Mon - Thurs 10am - 1pm
Holiday Schedule
Meeting Schedules

Permits and Zoning Officer
Bill Beers (610) 857-1285

Open Records Officer 
Janice H. Hearne (610) 869-2138

Emergency Management Coordinator
Chuck Freese (610) 869-3307

Right to Know
in Londonderry Township