Stormwater Management

What is MS4 Stormwater?

Municipal Separate Storm Sewer System (MS4) refers to our community’s system of roads and streets, catch basins, curbs, gutters, ditches, man-made channels, storm drains, and underground infrastructure that convey stormwater. As stormwater runs over driveways, lawns, and sidewalks it picks up debris, chemicals, dirt, and other pollutants.


Polluted stormwater runoff is often conveyed to and within the MS4 and ultimately discharged into adjacent and downstream rivers and streams without treatment. Anything that enters a storm sewer system is discharged into the waterbodies we use for recreation and providing drinking water. Polluted runoff is the nation’s greatest threat to clean water.


The MS4 Program details how our community is working to improve water quality through annual activities to educate and involve the public and prevent pollution from entering our stormwater conveyance system.

Join the Watershed Alliance of York (WAY)

September 16-25th for the 19th Annual Watershed Week

Clean Water: A Long Journey from the Source to Our Tap (2:19)

How Can Your Household Help?

Stormwater Information

By practicing healthy household habits, homeowners can keep common pollutants like pesticides, pet waste, grass clippings, and automotive fluids off the ground and out of stormwater.

For more information, please see the “Stormwater Documents” located at the bottom of this page.

Illicit Discharges

illicit discharge

An illicit discharge is defined as any unauthorized discharge other than clean stormwater released into the Municipal Separate Storm Sewer System (MS4). Illicit connections may be intentional or may be the result of connections made years ago when water quality issues were not a concern.

The types of illicit discharges vary widely with some examples being:

  • Waste oil, antifreeze, paint, trash, or other household chemicals
  • Car wash, laundry, and industrial wastewaters
  • Pool water discharge (chlorinated and dechlorinated)
  • Spills on roadways and other accidents
  • Failing septic systems and illegal dumping practices
  • Improper disposal of sewage from recreational practices such as boating or camping

Common indicators of illicit discharges include abnormal odors, strange colors, or oil sheen present around or inside storm inlets or pipes. Keeping harmful substances out of our water benefits everyone; both environmentally and economically.

Kids Corner

Play The Storm Drain Game!

What Is An MS4 Program?

Listed below are the six minimum control measures that the Township must incorporate into the stormwater management program.  These measures are expected to result in significant reductions of pollutants discharged into receiving water bodies.


  1. Public Education and Outreach– An informed and knowledgeable community is crucial to the success of a stormwater management program since it helps to ensure greater support and program compliance as the public becomes aware of individual actions they can take to protect or improve the quality of area waters.


  1. Public Participation/Involvement – An active and involved community allows for broader public support, a broader base of expertise, and a connection to other local environmental programs.


  1. Illicit Discharge Detection and Elimination– Illicit discharges are untreated discharges that could contribute to high levels of pollutants, including heavy metals, toxins, oil and grease, solvents, nutrients, viruses, and bacteria to receiving water bodies. The Township is required to develop, implement and enforce an illicit discharge detection and elimination program.


  1. Construction Site Runoff Control – Stormwater runoff from construction activities can have a significant impact on water quality. As stormwater flows over a construction site, it can pick up pollutants like sediment, debris, and chemicals and transport these to a nearby storm sewer system or directly to a river, lake, or stream.


  1. Post-Construction Runoff Control– Increased impervious surfaces, like parking lots, driveways, and rooftops, interrupt the natural cycle of gradual percolation of water through vegetation and soil. Instead, water is collected from surfaces such as asphalt and concrete and routed to drainage systems where large volumes of runoff quickly flow to the nearest receiving water. The effects of this process can include stream bank scouring and downstream flooding, which often lead to a loss of aquatic life and damage to property. Ordinances and other regulations are required to determine the appropriate best management practices and to ensure adequate long-term operation and maintenance of stormwater controls.


  1. Pollution Prevention/Good Housekeeping– This measure involves recognizing the benefits of pollution prevention practices and includes the development and implementation of an operation and maintenance program. Reducing pollutant runoff from municipal operations into the storm sewer system can include employee training on how to incorporate pollution prevention/good housekeeping techniques into municipal.

What Is An MS4 Program?

Are you a member of the (MS4 Name) Community? Click on the links below to see how you can help as a homeowner, resident, business owner, employer, or employee in the Township.

Other Helpful Links and Information

The Environmental Protection Agency, also referred to as EPA

PA Department of Environmental Protection, also referred to as DEP

PA DEP MS4 Resources can be found here

The Chesapeake Bay Foundation

Information about the Susquehanna River’s importance on the Chesapeake Bay and how Pennsylvania is helping, here

Chesapeake Conservancy – Envision the Susquehanna

The Envision the Susquehanna initiative was launched by a core team comprised of the Chesapeake Conservancy, the National Park Service, the Pennsylvania Department of Conservation and Natural Resources, Susquehanna River Heartland Coalition for Environmental Studies, Susquehanna Greenway Partnership, and the Wildlife Management Institute in 2013. The core team as well as an advisory council of almost 40 organizations have encouraged individuals, community leaders, and organizations to describe their vision for the Susquehanna River watershed. This report details the results of the initial planning process and lays out a vision for the future of the Susquehanna River.

The Homeowners Guide to Stormwater Management

This guide is intended to help property owners evaluate and assess the current runoff pathways on their properties and identify practices to better manage stormwater. The guide outlines several practices to choose from that are fairly simple to plan and construct. All efforts have been made to ensure the material in this guide is accurate and up to date.

Additional Educational Materials and Volunteer Opportunities can be found at:

Homeowners Guide
1 3 downloads
Stormwater Documents August 10, 2021
reCAP Newsletter
1 1 download
Stormwater Documents February 17, 2021
York County SWA Guide to Managing Residential Waste
1 0 download
Stormwater Documents November 12, 2020
York County Coalition for Clean Water RE CAP October 2020 Issue
1 0 download
Stormwater Documents November 12, 2020