Stormwater Management

Stormwater runoff is generated from rain and snowmelt events that flow over land or impervious surfaces, such as paved streets, parking lots, and building rooftops, and does not soak into the ground. Stormwater drains along curbs and gutters into a network of inlets, pipes, and manmade and natural channels that eventually drain into streams, lakes, and rivers. The runoff picks up pollutants like trash, chemicals, oils, and dirt/sediment that contaminates water sources. To protect these resources, communities, construction companies, industries, and others, use stormwater controls, known as best management practices (BMPs). These BMPs filter out pollutants and/or prevent pollution by controlling it at its source. 

Water Quality

Mandated by Congress under the Clean Water Act in 1990, the National Pollutant Discharge Elimination System (NPDES) Stormwater Management Program is a comprehensive national program for addressing non-agricultural sources of stormwater pollution that adversely affect the quality of our nation's waters. The Program uses the National Pollutant Discharge Elimination System (NPDES) to require cities to implement controls designed to prevent harmful pollutants from being washed by runoff into local water bodies.

Issued by the State of Kansas, the NPDES Permit requires cities and counties, including the City of Merriam, to prepare a Stormwater Management Plan which addresses required program elements, including Best Management Practices (BMPs) and a schedule of activities. The six program elements included in the NPDES Municipal Separate Storm Sewer System (MS4) include:

  • Public Education and Outreach
  • Public Participation/Involvement
  • Illicit Discharge Detection and Elimination
  • Construction Site Runoff Control
  • Post-Construction Runoff Control
  • Pollution Prevention/Good Housekeeping


Program Documents

Merriam MS4 NPDES Discharge Permit(PDF, 537KB)

Merriam Stormwater Management Plan 2021-2024(PDF, 994KB)

2021 Stormwater Annual Report for MS4(PDF, 3MB)


Reporting Illicit Discharges

If you see illicit discharges occurring, please submit the matter through our Report a Problem feature on our website or call the Johnson County Stormwater Hotline at 913-715-6900. 



Learn what you can do to help reduce water pollution. 

Only Rain Down the Drain

Contain the Rain Program

If It's On the Ground, It's in Our Water - Stormwater and Regional Water Quality(PDF, 857KB)   

Pick Up After your Pet(PDF, 581KB)