MS4 Stormwater Program

Stormwater Management Resources

What is an MS4?

MS4 stands for Municipal Separate Storm Sewer System. MS4s are conveyances or systems of conveyances including roads with drainage systems, municipal street, catch basins, curbs, gutters, ditches, man-made channels, or storm drains that are owned or operated by a public entity, are designed or used for collecting or conveying stormwater, and are not a combined sewer or part of a publicly-owned treatment wastewater treatment plant.

A Municipality is bound by the US Environmental Protection Agency (EPA) regulations associated with the Federal Clean Water Act for MS4s when all or a portion of a municipality lies within an urbanized area (UA), as determined by the US Census Bureau. Approximately 25% of West Earl Township is considered urbanized area.

MS4 Program

In Pennsylvania, the MS4 program is managed by the Pennsylvania Department of Environmental Protection (PADEP). The PADEP has provided a streamlined process for Municipalities to meet State and Federal stormwater requirements. Operators of an MS4, such as West Earl Township, must obtain a National Pollutant Discharge Elimination System (NPDES) permit and develop and implement a stormwater management plan (aka MS4 Program). Mandatory elements of the stormwater management plan include 6 minimum control measures (MCM); each MCM has a number of associated Best Management Practices (BMPs). These 6 MCMs include public education and outreach, public involvement and participation, illicit discharge detection and elimination, construction site runoff control, post-construction stormwater management and pollution prevention and good housekeeping.

Why Is Stormwater Regulated?

The MS4 program requires municipalities to implement a series of programs to reduce the discharge of pollutants from the storm sewer system in a manner that protects water quality. Water quality standards are set by the State of Pennsylvania. These standards seek to protect the waters for aquatic life, water supply, recreation and fish consumption, and areas that need special protection. The MS4 program focuses on managing discharges into the waters of the Commonwealth by educating and implementing proper control measures and best management practices some of which are outlined below.

Minimum Control Measures & Best Management Practices

MCM #1 – Public Education and Outreach. The goal of this MCM is to educate the public about stormwater activities. It aims to build greater support for the MS4 program, increase compliance, and promote environmental awareness in the local community. West Earl Township regularly makes efforts to keep Township residents informed about stormwater management and stormwater runoff pollution by publishing articles in newsletters, and on the Township’s website and Facebook page.

MCM #2 – Public Participation and Involvement. The goal of public participation and involvement is to involve the public in stormwater activities such as workshops, adopt-a-drain program and any opportunities to volunteer. West Earl also encourages residents to attend any public meetings where the MS4 program will be discussed.

MCM #3 – Illicit Discharge Detection and Elimination. An illicit discharge is any discharge to an MS4 that is not composed entirely of stormwater (with some exceptions). These discharges can include wastewater, effluent from septic tanks, oil, dog waste, pesticides, and household toxics. These pollutants can make their way directly to our waterways untreated and are dangerous to the public and environmental health. The Township currently has a written Illicit Discharge Detection & Elimination as part of its MS4 program requirements. This plan includes procedures for detecting illicit discharges and the methods to mitigate any potential pollution. Township residents are encouraged to report illicit discharges by either calling the Township office or filling out the form that’s provided under the Illicit Discharges link.

MCM #4 – Construction Site Runoff. The goal of this MCM is to protect our waterways from stormwater-related pollution that can result from construction activities. West Earl Township relies on the PADEP to help meet some of the requirements for this MCM.

MCM #5 – Post-Construction Stormwater Management. The of goal of the Post-Construction Stormwater Management MCM is to avoid increased stormwater runoff problems and pollution that often accompanies the development of land and the associated increase in impervious surfaces. As with MCM #4 West Earl Township relies on the PADEP to help meet some of the requirements for this MCM.

MCM #6 – Pollution Prevention/Good Housekeeping. The goal of this MCM is to help ensure a reduction in the amount and type of pollution that is generated from municipally-owned and maintained facilities and eventually discharged into local waterways. West Earl Township has developed and implemented an Operation and Maintenance Plan (aka Good Housekeeping Plan) for all its municipal operations and facilities. The Operation and Maintenance Plan includes practices, policies and procedures to reduce or prevent pollutant discharges in the MS4 such as removing maintenance-area floor drains and proper disposal of street sweeping debris. Also included in this MCM is employee training that addresses appropriate topics to further the goal of preventing or reducing the discharge of pollutants from municipal operations.

What are Best Management Practices (BMPs)?

Best Management Practices (BMPs) are important, because they can provide some actions that can be taken by the Municipality or individuals can take to help reduce or prevent stormwater pollution. There are two types of BMPs – structural and non-structural. Structural BMPs are engineered systems that are designed to mitigate the impacts of stormwater. Some examples of structural BMPs include, infiltration trenches, rain gardens and bio-swales. Structural BMPs are effective tools for stormwater management in development. Non-structural BMPs focus on prevention of stormwater generation, therefore effectively reducing runoff volume, and decreasing development costs while increasing property value and marketability. Some examples include protecting riparian areas and wetlands and reducing impervious coverage.

Below are several links to educational brochures and websites where you can find useful information about stormwater management and the Township's MS4 program.

Annual Reports



For Kids

Fact Sheets

Brochures and Articles

Lancaster County Conservancy - rain barrel assessment & order forms