The Borough of West Mifflin is covered under a National Pollutant Discharge Elimination System (NPDES) Permit for discharging stormwater from the municipal separate storm sewer system (MS4). The MS4 Permit is issued by the Pennsylvania Department of Environmental Protection (PA DEP) and requires municipalities to manage the stormwater runoff (rain, snow, sleet, and ice) from their separate storm sewer system to help reduce pollutants entering the waterways of the Commonwealth. The Borough of West Mifflin and the West Mifflin Sanitary Sewer and Stormwater Authority (WMSSSA) has recently joined as co-permittees approved through DEP on this permit.

Please visit for the following:

        • more information relating to stormwater and how you can help us reach our MS4 requirements
        • illicit discharge information and complaint form”

Stormwater Educational Materials

Best Management Practices (BMPs) for Stormwater-Public Education