This image shows a person document findings while inspecting an outfall
Image of a person document findings while inspecting an outfall

It is easier to prevent pollution at the source than restore a surface water. MS4s are the first line of defense for many pollutants entering storm sewer systems within their jurisdiction, such as

  • sand and salt for de-icing
  • fertilizers and pesticides on municipal properties
  • vehicle fueling and maintenance chemicals

MS4s must have a program to prevent or reduce pollutant discharges from municipally owned or operated properties.