Wednesday, May 31, 2023

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Municipal Separate Storm Sewer Systems (MS4)

South Williamsport's Infiltration Trench   

South Williamsport’s Infiltration Trench Williamsport Resident’s Rain Barrel



















What is MS4?

There are stormwater requirements under the federal Clean Water Act, and these requirements are administered under the Pennsylvania Department of Environmental Protection’s (PA DEP) Municipal Separate Storm Sewer System (MS4) program. The MS4 program requires the Municipalities to incorporate 6 elements into their stormwater management programs, called minimum control measures:

·         Public Outreach and Education

·         Public involvement and participation

·         Illicit discharge detection and elimination

·         Construction site runoff control

·         Post-construction stormwater management in new development and redevelopment

·         Pollution prevention and good housekeeping for municipal operations and maintenance

What is Stormwater?

 Storm water is water from precipitation that flows across the ground and pavement when it rains or when snow and ice melt. The water seeps into the ground or drains into storm sewer systems – a system with inlets and pipes that directly connect to local waterways. Storm water becomes a problem when it picks up pollutants such as oil, grease, metals and coolants from vehicles.


Storm Drain Marker in Williamsport

   River Walk and West Branch Susquehanna River



Who is an MS4?

 Under the 1987 Clean Water Act Amendments, the U.S. EPA developed storm water regulations to address stormwater that might impact water quality.  These regulations were set up depending upon the US Census population data. The stormwater regulation phase affects about 1,000 municipalities in Pennsylvania.  Those municipalities that are located within and "urbanized area" as defined by the 2010 Census were required to apply for a National Pollutant Discharge Eliminations System (NPDES) permit to discharge stormwater from their municipal separate storm sewer system (MS4). 


The map below is the urbanized area and the municipalities and non-municipalities that are required to have an MS4 permit.


Lycoming County MS4 Coalition

 The nine MS4 municipalities and one higher education institute joined together to create the Lycoming County MS4 Coalition.  A Memorandum of Agreement (MOA) executed in August 2014 describes cooperative partnership efforts to be undertaken with the assistance of Lycoming County.  The MS4 Coalition consists of representatives from all ten MS4s who meet monthly to oversee the program.  A new position, MS4 Planner, was created in the County Planning Department and is fully funded by the ten MS4s.  The MS4 Planner’s role is to assist the individual MS4s to achieve full regulatory compliance in the most cost-effective manner possible, and alleviate the workload required of municipal staff and officials.


The following are the 10 MS4s in the Lycoming County MS4 Coalition:


  • ·         City of Williamsport
  • ·         Borough of Duboistown
  • ·         Borough of Montoursville
  • ·         Borough of South Williamsport
  • ·         Fairfield Township
  • ·         Hepburn Township
  • ·         Loyalsock Township
  • ·         Lycoming Township
  • ·         Old Lycoming Township
  • ·         Pennsylvania College of Technology

How does this affect the individual?

Responsible storm water management helps protect our local waterways from unnecessary pollutants from entering to the West Branch Susquehanna River, which flows to our neighboring communities. It is important that everyone is aware of the pollutants that are harmful to our water quality.

 Ever Wonder Where the Rain Drains?     Sustainable Drainage Animation” 


What is an illicit discharge?

Please see brochures below:
Only Rain Down the Storm Drain Brochure

When it Rains, It Drains Brochure

DEP Fact Sheet on Swimming Pool Water Discharge Guidlines

DEP Fact Sheet Tips for Residential Heating Oil Tank Owners

An illicit discharge is an unauthorized to a municipal separate storm system that is not storm water. Examples of illicit discharges include:


  • ·         Motor Vehicle Fluids
  • ·         Household hazardous wastes
  • ·         Grass Clippings
  • ·         Leaf Litter
  • ·         Animal Wastes
  • ·         Unauthorized discharge of sewage
  • ·         Unauthorized discharge of industrial waste
  • ·         Unauthorized discharge of restaurant waste

An illicit discharge can be accidental or intentional. If you see an illicit discharge, please report the incident to your local municipal (borough, city, or township). For emergencies only: call North Central PA DEP 24 Hour Office at 570-327-3636 or Lycoming County 911 Center at 911.


Chesapeake Bay Pollutant Reduction Plans

The Chesapeake Bay Pollutant Reduction Plan is a separate plan under the MS4 Permit that is required when any MS4 discharges to the Chesapeake Bay. It includes a narrative of the MS4 that drains to the Chesapeake Bay (including pervious and impervious cover, and land use), the incorporation of environmental improvements to municipal infrastructure upgrades, and the identification of control measures that reduce pollutant discharges including nitrogen, phosphorus, and sediment to the Chesapeake Bay.


Williamsport Area Joint MS4s CBPRP

Appendix A CBPRP

Appendix B Stormwater Best Management Practices

Appendix C BMP Implementation Schedule

Appendix D Structural BMP Priortization Methodology

Appendix E Maps

Appendix F Evidence of Public Involvement and Municipal Adoption

Chesapeake Bay Pollutant Reduction Plan


 Rain barrels, rain gardens, and other best management practices can help infiltrate the storm water and reduce the runoff from your property.

5 Easy Steps to Make a Rain Barrel

Eco-Friendly Rain Barrels

Homeowners Guide to Stormwater Management

Eco-Friendly Homeowners Guide to Stormwater

Reducing Water Pollution



 EPA stormwater Page for Kids

Stormwater Placemat

Stormwater Stickers:

Splish and Splash (A Tale of Two Raindrops)

 K-3 Activity Book

 K-3 Water Cycle

 4-8 Word Scramble

 4-8 Water Purification

 4-8 Non-Point Pollution

 4-8 Plants and Water Purification

4-8 Fun Facts Matching Game

Keeping Your Streams and Lakes Healthy


 PA BMP Manual

EPA Design and Guidance Manuals for LIDs

Developer Fact Sheet


Municipal Employees 

Field Screening Program Data Collection Form

Illicit Discharge Inspection Summary Report Form

Basin Retrofit

PA BMP Manual





Additional Resources

DEP MS4 Website

EPA MS4 Website

EPA Stormwater Website

Penn State Extension Program on Stormwater

PA’s Water Plan

Susquehanna River Basin Commission

DEP CBPRP Training Materials Fall 2016

1-TOC & Agenda.pdf
2-Public Participation.pdf
3-Mapping part 1.pdf
4-Mapping part 2.pdf
5-Mapping part 3.pdf
6-Mapping part 4.pdf
8-Pollutants of Concern.pdf
7-Mapping part 5 small.pdf
9-Existing Load part 1.pdf
10-Existing Load part 2.pdf
11-Existing Load part 3.pdf
12-BMP Effectiveness.pdf
13-BMP Selection.pdf
14-TDML Plans.pdf
15-BMP Funding part 1.pdf
16-BMP Funding part 2.pdf
19-Permit part 1 small.pdf
20-Permit part 2.pdf
21-Retrofit small.pdf
22-Resources part 1.pdf
23-Resources part 2.pdf
24-PRP Methodology.pdf
25-Runoff curve.pdf


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