MS4 - Municipal Separate Storm Sewer System

Research output: NRELFact Sheet


Stormwater refers to the rainwater or melted snow that flows over land surfaces - including streets, rooftops, and parking lots - that does not infiltrate into the ground. It is collected by storm drains and conveyed through a network of pipes and channels, eventually discharging into streams, rivers, lakes, or oceans. The storm sewer systems on NREL's South Table Mountain (STM) campus, distinct from the sanitary sewer systems, is known as a Municipal Separate Storm Sewer System (MS4).The Environmental Protection Agency (EPA) issued NREL an MS4 Permit for the STM campus to regulate stormwater operations within the boundaries of the STM campus. The STM campus is the only NREL campus to have an MS4 Permit.
Original languageAmerican English
PublisherNational Renewable Energy Laboratory (NREL)
Number of pages2
StatePublished - 2024

NREL Publication Number

  • NREL/FS-1900-88652


  • Environmental Protection Agency
  • EPA
  • MS4
  • sewer
  • stormwater


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