The Municipal Separate Storm Sewer System

The Municipal Separate Storm Sewer System (MS4) Program is a Pennsylvania Department of Environmental Protection (PA DEP) program that establishes minimum goals through a permit process to reduce the discharge of pollutants from municipal storm sewers to protect the environment and improve water quality in the Commonwealth. Federal Regulations issued through the Environmental protection Agency (EPA) in 1999 established the new permit requirements that apply to discharges to surface waters through municipal separate storm sewer systems. The MS4 permittee through this permit program is tasked with the goal of protecting water quality to reduce the discharge of pollutants to the maximum extent possible thereby satisfying the requirements of the Clean Water Act and the
Pennsylvania Clean Streams Law.

The MS4 permit is issued though a PA DEP General Permit or individual Permit guidelines and follows federal regulations that have established six categories of Best Management Practices (BMPs). These BMP categories are also referred to as the “six minimum controls” in the federal regulations.

They are:
• Public Education and Outreach
• Public Participation and Involvement
• 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

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