Stormwater Management

What is Stormwater Runoff?

Stormwater is water that originates during precipitation events or snow/ice melt that runs off surfaces such as rooftops, paved streets, highways, and parking lots. It can also come from hard grassy surfaces like lawns, play fields, and from graveled roads and parking lots.

What is Stormwater Pollution?

When stormwater runoff flows over surfaces it picks up and carries with it many different pollutants such as:

  • Garbage
  • Oil and grease
  • Gasoline
  • Sediment from construction sites and urban runoff
  • Metal flakes from rusting vehicles and brakes
  • Road salt
  • Lawn pesticides
  • Agricultural herbicides
  • Heavy metals from roof shingles
  • Pet waste
  • Leaves
  • Grass clippings
  • Bacteria
  • Nutrients such as phosphorus and nitrogen
  • Other chemicals
  • Illicit discharges such as paints, cleaning solution products and used motor oil

These pollutants cause stormwater runoff to be the number one cause of stream impairment in urban areas.  Specific to Norwalk, these pollutants can close our beaches, shellfish industry, and other recreational water activities.

What is Stormwater Management?

The intentional capture, placement, or movement, and treatment of stormwater runoff in order to minimize pollution and/or flooding.  The City of Norwalk manages and maintains the stormwater system as required under the Connecticut Department of Energy and Environmental Protection’s (CT DEEP) General Permit for the Discharges of Stormwater from Small Municipal Separate Storm Sewer Systems (MS4).  The purpose of the MS4 general permit is to protect waters of the state from urban stormwater runoff through municipal stormwater sewer systems. The permit outlines a program of the following six Minimum Control Measures:

  • Public education and outreach
  • Public involvement / participation
  • Illicit discharge detection and elimination
  • Construction site stormwater runoff control
  • Post-construction stormwater management
  • Pollution prevention/good housekeeping

City Stormwater Management Plan and Annual Reports:

The City of Norwalk will publish a draft of their Municipal Small Separated Stormwater (MS4) Permit 2023 Annual Report on the City’s Stormwater Management webpage ( for public comment by February 15, 2024. The draft annual report will also be available as a hard copy for review at 15 South Smith Street Norwalk, CT 06855. Comments can be submitted to Nelya Bauer, Wastewater Systems Manager at or 203-854-7235. The public comment period will be open for 30 days, and close on March 16, 2024.  

Customer Service Center:

If you have questions, comments, or would like to report water pollution, please contact our Customer Service Center at 203-854-3200. 

Stormwater Educational Materials:

Related Information: