What is a MS4 (Municipal Separate Storm Sewer System)?

Full definition

An MS4 (Municipal Separate Storm Sewer System) is a publicly-owned drainage system that conveys stormwater (and only stormwater) to surface waters, regulated under EPA Clean Water Act rules. KC-metro MS4 jurisdictions (Wyandotte County, Kansas City MO, etc.) have rules about what may discharge into the storm sewer.

For gutter contractors, MS4 rules mean we cannot discharge wash water containing sealant, paint chips, or construction debris into storm inlets. Most municipalities also require sediment-control measures (silt sock, gravel pad) when soil is disturbed.

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